Workshop on Global Climate Change - John Deutch, John Sununu, guests - Sloan School

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[MUSIC PLAYING]

DEUTCH: The purpose of this workshop is really quite simple. It Was to gather together for a one day session a group of people who have been thinking about the issues of global climate change from a variety of points of view, tackle scientific issues, economic environmental effects, and what some of the policy issues are facing the United States both domestically and in the international arena.

The idea of the workshop came, I guess, in last November when John Sununu and I were at a gathering in Washington. And we were talking about whether there was, in fact, a common view-- not an exact and precise view, but a consensus-- on what some of these issues were among those people in government and outside of government who had been diverting attention to this question. And we allowed-- I guess both of us felt that there was an opportunity for everybody to become better informed by spending a day looking at these issues.

It's especially timely with the international activities going on in this and the meeting coming up in Brazil in June. And so we put together this one day session. And I'm really very pleased and delighted that all of you have managed to attend.

Let me make a remark about how the day will go. We have divided it into three sections. The first will be the technical session, where we will have brief presentations-- 15 or 20 minutes-- from Gordon MacDonald and Ron Prinn on what some of the technical issues are. We'll then proceed to spend about an hour of time discussing this from whatever perspective points of view is of interest to the group.

Second session will deal with economics and environmental effects. We will hear from Bill Nordhaus and Bob Frye. We'll then go right across the way to have lunch at the faculty club. And the last session in the afternoon will be on policy matters with Jake Jacoby of MIT, focusing on domestic issues and Richard Cooper focusing on international matters.

It is my firm intention to conclude the day at 4:00 PM because I have arranged for John Sununu and possibly a couple of others of us to go over and talk with some students. And I hope that that will be more or less convenient for those of you who have travel plans.

Let me also say that I decided some months back to have this session recorded in its entirety. I did that for principally one reason-- in the hopes that there might be some educational value to the session that we're having here and that the tapes would be available to any and all members of the public who care to find out what enormous pearls of wisdom were scattered among us. So the tapes will be available to anybody who wants them through MIT-- the Center for Advanced Engineering Studies, which is for the people who put this together.

I should also say that I was very pleased that the modest amount of cost to put this conference together was provided by the Sloan Foundation. And I do want to thank them for, once again, providing me and this institution with some support.

I don't know whether you want to make any remarks, John, at this stage of the game. Do you have anything you'd like to say?

SUNUNU: Just a couple. Even in phasing out from the White House, I have to keep the lawyers happy. Therefore I have to tell you that everything I express today is my own personal view--

[LAUGHTER]

--and not the view of the administration. I certainly can speak historically from the point of view of one who make policy historically. But I must say I am very fortunate that, in the last couple of weeks I'm there, I'm not involved in making policy on this issue. And I think that will keep the lawyers happy.

But beyond that I want to thank all of you for accepting the invitation to be a part of this. It is an important issue. It is an issue that is not easy to deal with, even when we are having discussions amongst those who understand it well.

Therefore, there is an added obligation since there are those who don't understand it at all who will be making policy on it based on issues that are developed in the realities of the analysis. I hope it's the realities of analysis that flows from both the technical side, the scientific side, and as well as the economic side.

And what, under other conditions, might have made for interesting academic lunchtime discussions are now leading to interesting significant-- I think that it is not an exaggeration to say trillion dollar decisions. Over the long haul, it will be based on a perception of what the issues associated with global climate change are. And therefore, it adds a little bit to the obligation to try and hone this down as well as possible and as rapidly as possible.

I just-- I will confess to a bias. And I'm sure that it has been apparent in some of the comments printed in the press. But I can assure you the press never reflects reality. And therefore, let me give it to you first hand.

I am very concerned that there is a rush to judgment. I have no idea which direction the rush to judgment really is in. But it always bothers me when there is a haste to make policy. It means that people have an uncertainty in their position that they are afraid will be clarified over time in a direction that is not favorable to their perspective.

I can tell you this administration has committed well over a billion dollars a year in trying to fund the clarification of the nuances of this issue. It is in recognition that it is a trillion dollar decision that a billion dollars a year for analysis model improvement data collection is not an unreasonable sum to request and, in fact, was received.

And I can tell you that having talked to the president about this issue specifically, he is committed to a long term funding and is willing to take action. I think the action the administration took in '89 on ozone was real and a reflection that when the data and the conclusions are relatively clear, it will move. But I think it is incumbent on the technical community to try and help sort out the differences.

I have two examples in my mind that are always the nightmare examples of public policy. And fortunately, they did not get acted on, even though there was a momentum established. One is the global cooling phenomena that a comet was supposed to produce. And the other was the Club of Rome-- the world is going to end tomorrow scenario, no matter what you do.

And both of those, I think, are excellent examples of at least some constituencies out there who constantly seem to be looking for calamitous surrogates to creating anti-growth, anti-dynamic investment policies. And the impact on billions of people in terms of their standard of living and quality of life that decisions of that kind can make has got to be put on the ledger someplace.

And it is incumbent then that analysis of the structure of response to complicated systems such as climate be looked at as more than just involvement by people who are good and interested in that area and be recognized to have to be presented at all times within the limitations of the assumptions and the certainty or the lack of certainty that the conclusions have.

And there is no question that we are dealing with a multiplicity of constituencies. We are dealing with a press that has a bias and a perspective in one direction. They always will. It is part of the process of selling papers.

No change does not sell papers. Tranquility does not sell papers. And that is real. And there is no way to cope with it.

There is a political constituency around the world that in parliamentary structures carries a non-linear capacity to influence policy. You look at the way parliamentary majorities are made around the world. The 3, 4, 5% of the political constituency that is defined by the Green Movement, which has a perspective and a viewpoint that is significant on this issue, has a non-linear impact on-- it is weighted well beyond their elected role in that structure.

And that is real. And I bring all this up because I think it defines the scope of responsibility that is involved in the discussions that will follow from what is evolving on this issue around the world.

I do feel that there is an opportunity to do well what scientists and engineers, technologists ought to do well. And that is define what they know and define what they don't know with a little bit more precision than perhaps they are usually accustomed to. And try and be active participants in the framing of this policy.

This policy will be framed in very specific terms in the next five years. There are those who would like it to be done in the next five days and those who would like it to be done in the next five decades. But I think it will be framed in the next five years in ways that will impact the next generation rather drastically.

And there will be derivatives to that policy that will be significant. And that's why I'm so pleased that you've all been willing to come down and help us, perhaps, create a framework under which that policy development can be done in a slightly more rational way than has been taking place over the last decade.

DEUTCH: Well, there's one thing I want to stress here. There is obviously, in this group, a wide variety of views on these issues. People will have an opportunity to express and discuss them as the day goes by.

I thought that maybe one thing which might be helpful is to just briefly go around the table, have everybody identify where they are from. Although many of us know each other, it is not universally true. And it might be helpful to just start with you, Lester, and go around the table and identification [INAUDIBLE].

LAVE: Lester Lave, an economist from Carnegie Mellon University.

MAYNARD: Nancy Maynard, Office of Science and Technology Policy.

WHITE: Bob White, President National Academy of Engineering.

AUSUBEL: Jesse Ausubel, the Rockefeller University.

JACOBY: Jake Jacoby from MIT.

HOGAN: Bill Hogan from the Kennedy School at Harvard.

SCHMALENSEE: Dick Schmalensee, an economist at MIT.

NIERENBERG: Bill Nierenberg, Scripps Institution, oceanography.

FRYE: Bob Frye, Resources for the Future.

YEAGER: Kurt Yeager, Electric Power Research Institute.

COOPER: Dick Cooper, Harvard University, economics.

LEVINE: Duane LeVine, Exxon Incorporation.

LEE: Tom Lee from MIT.

MACDONALD: Gordon MacDonald, University of California.

BRAS: Rafael Bras, MIT.

SUNUNU: John Sununu, still at the White House.

WASHINGTON: Warren Washington, the National Center for Atmospheric Research.

PRINN: Ron Prinn, MIT.

BROWN: Harold Brown, Johns Hopkins, Foreign Policy Institute.

BRADFORD: David Bradford, Council of Economic Advisers.

OPPENHEIMER: Michael Oppenheimer from the Environmental Defense Fund.

NORDHAUS: Bill Nordhaus, economics, Yale University.

DEUTCH: And you can now say, Dale.

JORGENSON: I'm Dale Jorgenson--

DEUTCH: Perfect.

JORGENSON: --University.

DEUTCH: Thank you very much. Well, with that, I think we should begin with the technical section. And I guess that my friend Gordon MacDonald is going to give us a bit of a orientation.

MACDONALD: Thank you, John.

SPEAKER: Televised for education.

MACDONALD: Let's do the smart [INAUDIBLE].

20 minutes or so to touch on four topics. One, the changing composition of the atmosphere-- what we know about it and what we don't. What we can learn from the observed temperature records that extend back a little over a century. Some comments on predictability of climate-- what is meant by that. How well can you tell what the future holds.

And then end up on what I consider to be the most important and also a very neglected subject-- extreme events. And how does one try to get a handle on what might happen by and by extreme events. I mean, changes in the nature and intensity of storms, changes in the nature and frequency of droughts or floods and so forth.

Let's start off by reviewing briefly the story on carbon dioxide. This is, of course, familiar to all of you. The variation of carbon dioxide in terms of parts per million, as a function of time.

It's the closely spaced points that are of course Dave Keeling's observations. The points before that are taken from observations and composition of gases trapped in ice. A much greater scatter in those observations.

I go back to 1740. There are data that can extend the carbon dioxide concentration back to about 10,000 years with increasing scatter. But the points at 10,000 years would be around 280 parts per million.

Concentration of carbon dioxide was more or less constant for a very long period of time. And since the beginning of the Industrial Revolution, has increased. The current rate of increase is about a half a percent per year.

The same kind of story holds for methane. Here is a representation. It's a little different. This is going back in time.

A much greater scatter because of the difficulties in the instruments. But again, a very rapid rise over the last two centuries. For a number of years, the rise was about a percent a year. In the last five or six years, it seems to have increased to about 7/10 of a percent per year.

And quite importantly, you have similar variations and concentration of both these gases over much longer periods of time. The curve or the solid line links the observations made on carbon dioxide from bubbles that they are trapped in our core of ice taken in Vostock, Antarctica. This is the concentration of CO2 on the right-hand side, the concentration of methane on the left-hand side. The methane concentrations are even triangles or solid dots, depending where they're taken.

Now the point here is that in the previous glacial period, concentrations were low. Interglacial concentrations higher. Past glaciation was characterized by lower concentrations, both of methane and carbon dioxide. And then the present interglacial period-- high concentrations once again.

The association is close. The issue of cause and effect is open. I have argued that there is a [INAUDIBLE] mechanism that involved methane clathrates-- that is methane stored in compounds buried at shallow depths near the surface of the Earth and release due to warming. There are alternative hypothesis related to changes in ocean circulation.

But I think one can say, the correlation is close. The arguments as to whether it is a positive feedback or just a result of changing climate where the climate is changing for other reasons.

There is a further mystery with the changing composition of the atmosphere. And we can sum it up in a very few figures. Currently, as of 1990, we're putting about 6 billion tons of carbon into the atmosphere-- six gigatons of carbon. And you can multiply by whatever it is-- 44 with 12 to get CO2.

That comes from a mission of power plants, other industrial and transportation activities. That's probably an uncertainty of 5% to 10%.

SPEAKER: It's all man-made.

MACDONALD: That's all man-made. There's an additional 400 million tons of carbon that come from the oxidation of methane. So the total carbon input is 6.4. Now, some of that 4/10 of a gigaton due to methane is natural. Some of it is associated with man-made activities.

The observed increase of carbon dioxide in the atmosphere observed by measurements at Mauna Loa and around the globe corresponds to 3.8. The difference between 3.8 and 6.4 then go someplace. The best estimate for the ocean uptake, in my view, is 2 gigatons. This is a number also adopted by the Intergovernmental Panel on Climate Change, the international effort that is preceding the negotiations currently underway at Greenhouse Convention.

So 3.8 and 2 gives you 5.8. The difference between 5.8 and 6.4 probably is well within the uncertainty. But left out of these considerations is what happens in the biosphere. The best guess, according to IPCC, of the carbon introduced into the atmosphere as a result of deforestation is 1.6 but with a large uncertainty band.

And I've worked on some of those problems of going from satellite photograph and a few field observations. And I must say that those numbers-- that number is quite uncertain.

But that means if 1.6 is added, and there's already 6/10, another 2.2 gigatons of carbon must be taken up somewhere. And that is a current mystery. There are some people who would point to the northern temperate forest, say, regrowth is taking place there. And some of the carbon is being absorbed. Observations are just beginning to be made at various places to see if that uptake can be measured and at least some estimate be made. Currently, it's very much a problem.

Now let me turn to what we can say about temperatures.

[INAUDIBLE]

Sure.

SUNUNU: Isn't there a-- these are looked at as the components to the carbon flux into the atmosphere. It's from man-made. Isn't there a huge component of natural fluxes that are also there?

MACDONALD: There is a seasonal fluctuation. But you can see in-- I didn't bring the--

SUNUNU: I don't mean in the concentrations. I mean transfers into the atmosphere.

MACDONALD: During the growing season, carbon goes into plants.

SUNUNU: That's right.

MACDONALD: During the--

SUNUNU: And those numbers are huge.

MACDONALD: Those numbers-- let's see. The total seasonal flux-- it's about 5%.

SUNUNU: But you can average it out.

MACDONALD: You can average it out.

OPPENHEIMER: Isn't that 200 gigatons a year each way. But the point is that it's been-- we know it's been in balance because of the ice core measurements for 10,000 years. It's really finely balanced so that the 7 or 8 gigatons from human activity make a big difference because the system is so close [INAUDIBLE].

MACDONALD: These figures-- okay. You've got the appropriate view graph. There it is.

PRINN: Even those numbers on this is a bit foxy.

Photosynthesis exceeding respiration decay that occurs in the spring and summer pulls down the amount by 2%. And then that's given back at 2% in the fall and winter. But an additional important thing is since this record began in '57 to the present time, [INAUDIBLE]. Oscillation is growing. And that's odd.

One possible hypothesis put forward is that CO2 fertilizers-- photosynthesis in vegetation. And CO2 is rising and leading to this [INAUDIBLE]. But that's pure hypothesis.

MACDONALD: Yes, that's one of theirs when we were talking about the sink for carbon. The fertilization is one possible sink.

Now, let me turn to the observations on temperature. This is temperature versus time derived from reductions of observation, reduction carried forward at East Anglia in Britain. The technique is to take observations from the logical stations, from ships at sea, average them, in this case, over the globe and over the years. So these are global annual average temperatures as a function of time.

There's two other sets that have been reduced by a group in the Soviet Union. One by Jim Hansen, [INAUDIBLE] that have similar characteristics. There is one individual record, which I think has some validity. It goes back to 1680 central England put together by a man by the name of Manley, again, having many of the same features.

Now what can we learn about this graph that may guide us in looking ahead? I decompose it into three components. One, a linear trend. Two, a low frequency component. And three, a high frequency component.

The purpose of that is to start to feel our way towards what aspects of the atmosphere do we have a chance of predicting in the future-- Large changes. What might we do?

With the removal of a linear trend, you find that the residual values are indistinguishable from that of a normal distribution. That is that the values themselves are distributed as if they were normal, not only about the mean, but very importantly, in my view, in the extremes.

This curve is in time. The dotted curve is the expected range-- maximum minus minimum for a normal distribution. And the stepped curve is what you get out of the observations.

Now what do the-- let's say this is important curve. This is the power spectrum for that temperature curve once the linear trend has been removed. And the important thing is the very large amount of power contained within the low frequencies.

And you can see that the first dip in the power spectrum is at about 0.45 or 0.4 cycles per year-- 0.04 cycles per year for about 20 years-- 25 years. We see that in frequencies less than corresponding to [INAUDIBLE] is less than 10 years, 60% of the energies there, 60% of the variance.

Now let's filter that and see what the residual temperature looks like. This is the low frequency part of that curve. That is the dashed one. The solid curve is the same operation conducted on Hansen's record of global temperature.

These are the swings in temperature, having periods on the order of 20 years or longer. Now if you remove this part and the linear track, the residual record is white noise, indistinguishable from white noise. No correlation structure whatsoever. And therefore, any attempt to predict, you have the classical problem of predicting white noise.

Here, however, you have structure. My argument is, of course, that this represents slow motions in the ocean, that on a short term, when you're looking at weather forecasting, the coherent structures in the atmosphere lead to persistence. That is high pressure areas, low pressure areas give rise to persistence over periods of days or weeks.

There is no long term persistence in the atmosphere per se. That you have large coherent structures in the ocean that could give rise to persistence. And this persistence may provide, if one can obtain adequate models of the ocean, a guide to predictability.

The next one just shows the white noise after you've removed the low frequencies and the linear trend that really is, by any test, independent increments that give rise to a random walk-- classical random walks.

This strives makes another point. This now is the integrated spectrum for-- the global T is the East Anglia record. That's the observed temperature record. And you can see that for 10 years, 60% of the total variance is at frequencies longer than 10 years.

This is a model provided of the atmosphere run for 100 years on the community climate model one, where the ocean only interacts with the atmosphere through putting the seasonal fluctuation-- observed seasonal fluctuations in the ocean into the model. Therefore, it cannot represent changes in ocean circulation. And as you can see, it has very little energy at the lower frequencies.

The top is a much simplified ocean atmospheric model that captures much more of the energy in the lower frequencies than does the observed.

Out of these kinds of analysis, I think it becomes very clear that an emphasis in both observation and modeling should be placed on the ocean. It is the great region of uncertainty. It obviously controls the low frequencies. And we have to develop better schemes.

Warren Washington, of course, is one of the most active workers in that field. And Warren may wish to comment.

Now, let me turn to extreme events and argue by analogy. This is a busy chart. But I think you'll find it entertaining.

This is Venice.

SPEAKER: California?

[LAUGHTER]

MACDONALD: Starting at 580 AD more or less to the present, this is relative sea level where the gondolas come in and out over time. Part of it is due to actual changes in sea level. Part of it is due to the drop of land. As you can see, sea level has gone up almost 2 and 1/2 meters over this period of time.

The frequency of extreme events is shown by those solid lines at top. Those are the periods when there's heavy flooding. And when the sea level was low, of course, there were infrequent advance. A thin line is a single event.

As you come into the 19th century, you get the lines now are much heavier-- four amounts, three amounts. As you go into the 20th century, the lines now represent eight 25 events.

I mean, there's something magical about this. The sea level goes up. Relative sea level goes up. The frequency of flooding goes up.

You also see here what happens to the population. In those times in which there were heavy flooding, there were drops in population. Of two causes, it related that during the flooding sanitary conditions were very bad. You had plague. Even when plague wiped out, you see in this last period a very large drop in the population.

Then there are some wonderful things as far as the distribution of population. What I found incredible was around 1600, there were the female population, which numbered approximately 40,000, had 2,500 registered whores. And you can see that as a great trading center, Venice had a variety of forms of entertainment.

I think this is trying to make the point that as climate changed, the incidence of extreme events will also change-- either go up or down. Very, very little work has gone into this area. Yet it is those extreme events that have the biggest impact on economic and social conditions as seen clearly in these correlations. That's it.

DEUTCH: Thank you. Do we have any brief questions for Gordon? Or we ready to hear from Ron?

NIERENBERG: I do. Just one thing.

I, like a lot of oceanographers-- my colleague Walter Munk learned a good deal about the preservation of Venice, which is-- most of you are familiar with the severe problems involved. That last drop is, I thought, very well understood. Bill Nordhaus, somebody can correct me, was strictly due to economic changes-- that the young people just leaving in droves, and have been for the last 40 or 50 years, because of lack of employment. And they're going to the nearby coastal towns. Nothing to do with extreme events.

LINDZEN: Yeah. I mean, I don't doubt for a minute that as you stress something, extreme events become more likely. But that diagram is specious in the sense, first of all, as you correctly mentioned, sea level rise in Venice is not a marker of climate but a marker of construction on Venice. It's just like LaGuardia Airport. Its construction changed the sea level a foot and a half.

And then you pick extreme events associated with the population in the bay without referring to the fact that most of those occurred throughout Europe, where there was no such climatic or other environmental stress.

MACDONALD: Certainly the [? efflux ?] where plague was dominant is quite correct. There were-- in more recent times, those changes are not reflected in the rest of Europe. And as I pointed out, that is relative sea level-- a major component being the movement of sediment and of the land with an added component of the smaller added component of increase in sea level.

SUNUNU: Gordon, I would like ask a clarifying question about this amount of material-- carbon-- which is placed flux into the atmosphere due to the biosphere. That can be the biosphere. What is that amount of material placed in and the amount of material taken out?

MACDONALD: We couldn't--

SUNUNU: I'm not talking about-- that's a composition.

MACDONALD: No. This will give it to you quite clearly. What is this amplitude? That's-- it's about 8.

SPEAKER: It's 4, 4.

MACDONALD: 4?

SPEAKER: It goes down 2. Maximum is 4.

MACDONALD: Down 2 parts per million and up-- no, it's 1.

SPEAKER: The percent.

MACDONALD: No, I'm thinking of it as actual figures because I'm going to convert it to bigger times. So this is, let's say, 5.

SPEAKER: It's 10.

MACDONALD: The total lanes-- it's let's see, 11--

SPEAKER: It started out around 5.

MACDONALD: 5. Let's say 5. That's 5 times 2.12, which is what concentration converts to at the gigatons. So that's 11 gigatons of carbon.

SPEAKER: No. No. It's 200 gigatons of carbon.

MACDONALD: No.

SPEAKER: You direct the total annual flux.

MACDONALD: No. Sorry.

OPPENHEIMER: It's natural source-- the total annual flux is about 200 up and about 200 down. It's a seasonal variation in the balance, but it's about 200 up and 200 down.

SUNUNU: But then the annual flux is, as you say, 200 out, 200 in. And what we are talking about is a collection of phenomena that impose on what you want to call as the base case or mother nature's reference case or whatever you want to call it is 200 going up, 200 going down. And you're adding 3.8? Is that what you said?

MACDONALD: 3.8.

SUNUNU: OK. Net.

MACDONALD: That's net.

BROWN: That's a well taken point. But what you have to ask then is what's the difference between the about 200 up and 200.

SUNUNU: That's what he's saying. I'm not asking the question. I'm merely asking that we keep on the table the reality of 200 up and 200 down. And imposed on that is 3.8 as an argument.

MACDONALD: And imposed on that is a [INAUDIBLE]. What do you conclude on that?

SUNUNU: I haven't concluded anything. I just ask that you don't hide it in the back of the appendix and that you at least leave it on the front of the table for the policy makers to look at.

MACDONALD: And you observe about 11 gigaton shift in carbon from winter to summer.

SUNUNU: Does this change depending upon which hemisphere you're taking-- I mean, is it an out phase?

MACDONALD: Yes. This is in Hawaii. The amplitude-- in the northern hemisphere the amplitude increases as you go to the pole-- the amplitude of the seasonal fluctuation. At the south pole, the amplitude essentially vanishes.

BROWN: How much of a change is there between the beginning and the end of that chart in the size of that 200, which may be another thing. That'd be another thing to compare.

SUNUNU: Yeah, and we need that too. Right.

[INTERPOSING VOICES]

MACDONALD: 2 gigatons more in the seasonal amplitude.

SUNUNU: And 40 where?

SPEAKER: No use.

MACDONALD: 40 and 58 versus 90?

BROWN: The difference between the swing in 58 and 90 is how much?

SPEAKER: 20%.

BROWN: 20% of?

MACDONALD: 2 gigatons of carbon.

BROWN: Okay, so it's 2 compared with 4, essentially.

SUNUNU: Okay.

DEUTCH: Thank you.

SUNUNU: Can I ask one more question? Because this is-- and maybe you can solve what has been a fundamental intuitive problem I've had with the modeling structures. And it has to do with some data you put up there. The thermal capacity of the top 1 meter of the ocean is as large as the thermal capacity of all the atmosphere.

MACDONALD: Yes.

SUNUNU: It's a well-mixed one meter. The thermal capacity of the top 10 meters is obviously 10 times as large as the thermal capacity of all the atmosphere. That's not as well-mixed but not too badly mixed. The coupling between the ocean and the atmosphere-- both thermally and as a result of water mass transfer-- is quite good.

There is an-- there are two arguments. Number one, that there is a long time lag in thermal response as a result of increase in CO2 concentration. If it were an instantaneous response that the models were giving, I could understand that what was being changed was the thermodynamic characteristics of the atmosphere in a way that created a very different system.

If it's argued that it's a long term response and that there is strong coupling between the atmosphere and the ocean, I have a very difficult problem in following why the damping effect of the ocean is not much more significant than has been observed in terms of any temperature change. What you have argued reinforces the fact that the ocean phenomenon is a very strongly coupled relationship.

And therefore, I feel less comfortable, not more comfortable, about the fact that the big problem in the models that I've seen is an inability to bring the dynamics of the ocean and rationalize that with what is the dire consequences being predicted for the atmospheric response. And I've got a real problem with that.

And I know it's probably because I don't know enough about it. So why don't you tell me a little bit about what I'm missing.

MACDONALD: No, I don't think you're missing anything. I think that the long time scales are associated with changes in large coherent structures in the ocean. And in order to predict and predict now rather than setting scenarios-- in order to predict, we're going to have to do a far better job of modeling the changes of those structures.

SUNUNU: And if I have any decent coupling then between the top 100 meters of the ocean and the atmosphere, I've got a heck of a dampening to any possible change in that temperature over the long term. And if I have, on an annual basis, a decent coupling, I should have an awfully good relationship between the ocean being a mitigating factor to the dire predictions that are there.

And my question then is why is there so little effort-- at least it appears to me-- being made to effectively-- even on a parametric basis-- provide that coupling in the long term scenarios that we've seen.

MACDONALD: No. I certainly don't have any disagreement with what you've said. I do think we have a couple of experiments that relate to the shortened time response. That is, what happens to the global temperature when you have a volcanic explosion? Does the temperature really go down?

SUNUNU: Jesse, you have the last word. Oh, I'm sorry. You can have the last word.

AUSUBEL: You make a good point. But I would take it in a slightly different direction, which is that the obsession with temperature is misguided. The issue is really climate change. And we can have a very significant global climate change, even with no change in global average temperature. And we're chasing something that really may not be a very important indicator.

And so you could change the circulation of the oceans a great deal. You could put a lot of heat into the oceans. And there could be a very different climate.

SUNUNU: I'd be more worried about that than what people are trying to draw a trillion dollar legislation.

DEUTCH: We are going to give Warren Washington the last word. We're supposed to be discussing this subject after these talks.

SUNUNU: I'm sorry.

DEUTCH: No, it's not-- no, it's my fault. Warren.

SUNUNU: I shouldn't have invited myself.

[LAUGHTER]

WASHINGTON: I just want to just add that there is a lot of misunderstanding about this issue of how the heat capacity of the ocean comes into the climate modeling. And obviously, the models of the 1980s, most of them dealt with just the very top part of the ocean-- something down to 50 or 70 meters thick. And that essentially lead to interactions between atmosphere and the ocean in terms of climate change of only one type of interaction.

In the late 1990s, and certain-- I mean '80s into the 1990s, we're going to have ocean models that are going to do a much more realistic job of having these interactions. And this is especially important for the very low frequency. You know, where you're talking about time changes of the order of hundreds of years-- frequencies of all of those spectra from 10 years to annual means, to el niños, to century time scales will be included. And even from our rather imperfect models, we're seeing that.

So I think we shouldn't judge what the models are telling us right now as being the definitive answer for how the--

SUNUNU: But you've got to formulate policy right now. They are shaping the debate. That's why the question is relevant.

SPEAKER: That's why I keep raising it.

SUNUNU: You're absolute right.

SPEAKER: Warren, the focus is on temperature.

SPEAKER: [INAUDIBLE]

MACDONALD: That's right.

DEUTCH: Sir.

SUNUNU: When did you say you thought we'd see these improved models?

WASHINGTON: I would say in the mid-1990s and of course into year 2000. But that doesn't mean that we have to wait entirely until the models give us definitive answers before we can start thinking about policy. I think that even right now they can tell us some things.

LINDZEN: I've given up. And this is the small thing in support of what Jesse is saying. In the rhetoric of the subject, temperature's given extreme prominence. But, for instance, typically, the climate of the earth has not dealt with mean temperature but difference in temperature between the equator and pole. And temperature of the earth has been a residual.

And yet one will hear comments like the Ice Age was only 5 degrees colder. In presence, you see what 5 degrees can do. 5 degrees was nothing to do with it. It's a residual calculation.

DEUTCH: Ron.

PRINN: May I begin?

DEUTCH: You may begin.

PRINN: I actually had a hand out. But there's copies of-- if you grab some, I'm going to show it. I made them especially for John Deutch, whose eyesight is getting very weak. And he may not be able to see the machine.

SPEAKER: The eyes are the second thing to go, John.

[LAUGHTER]

DEUTCH: I'm glad to hear that.

PRINN: Well, Gordon made an interesting introduction to some of the science issues. What I want to do in my 15 or 20 minute is first go through what I've called here emerging science issues. And I've chosen these because I think, at the end, they're going to have important policy implications, particularly if one wants to make policies in the next two or three or four years.

So if you'd like, these are sort of key uncertainties or big questions that are emerging out of the science community. And they sort of hit on the whole issue of what is the uncertainty with which we can predict climate change.

And I think that uncertainty is pretty easy to define if we think we know all of the physical and biological processes that are going on that control climate. And the difficulty is that we don't. And it's the things that we don't know and that we sort of discover from time to time or almost stumble upon that those are the things you really worry about-- the things that will just change the viewpoint all of a sudden that we have.

So I'm going to go through some of these emerging science issues. And there may be others. There may be others that people around the table can add to this list.

First, they concern the greenhouse gases and the budget uncertainty. Three years ago, the talk that Gordon MacDonald gave and said that the ocean was the big sink for CO2 would have been just fine. But one thing that's been done since then-- and I'll show the view graph-- is to just try to fit the latitudinal gradient of carbon dioxide with a model that just has the ocean as a sink and says the land does nothing. Okay. And I'll put those up. And I'll just--

This is a study by Tans, Fung, and Takahashi. It was published in Science in 1990. The observations of the red dots with standard deviations on them-- this is latitude here-- north, south. I don't know why south is always minus on these things. It should be plus.

Average CO2 concentration-- and the observations are there. And that red line is an important line. You can't obtain that red line with a model that just has the ocean as sinks. Now here are three ocean models, okay.

Now, these ocean models are done in an interesting way. There's not an attempt to model the dynamics of the process of the water from the surface of the ocean dropping to the bottom of the ocean and so on. One just simply takes all of the available measurements of CO2 partial pressure in the ocean water and the CO2 above it. And you use what's called a bulk flux formula to estimate the flux in and out of the ocean.

And if those ocean observations are sufficiently good and they cover all of the right geography of the ocean, then this is a pretty good approach. The point is that if you look at it, it says the oceanic sink only models just don't work. And they miss the latitudinal gradient bifactors of something like two.

So that's a serious issue. And you can fit that red curve there. You can produce that red curve by having a large sink in the northern hemisphere. And it's got to be not the ocean. Therefore, it's the land.

And that sink is about the size of the ocean sink that Gordon talked about before-- a couple of gigatons a year of carbon. In other words, if that's the case, we don't know. We've now got a big argument between oceanographers who think CO2 is going into the ocean and now biologists, if you'd like, who say, wow. Maybe it's going into the northern hemisphere land.

And there you've just got to look at things like the growth of carbon in the soil. The soil is a pretty big reservoir of carbon. And you've got to think of ways in which that reservoir could be growing.

A pure hypothesis is that that increasing amplitude in the up and down of CO2 is signaling a fertilization effect. Whether it be CO2 or anything else, it doesn't matter. It's growing in amplitude, which means more leaves are growing in the spring and summer and more falling down to the ground in the winter. And, of course, soil carbon is built up by the residual that doesn't decay. It's the more lignin based, often in the leaf and so on.

So maybe that's it. But it's pure hypothesis. I mean, that's where we are right now with state of knowledge.

So I would argue that we don't know enough about the carbon dioxide budget right now to take the anthropogenic input and project what that's going to be based on human activity for the next 50 years and then say, we've got a model for the biogeochemistry of that gas which is reliable for predicting ahead 50 years. I don't think we're there.

BROWN: Does the north south-- is there a disparity in north south observations that reflects the disparity in land mass amounts?

PRINN: I'm not sure what--

BROWN: Well, there's much more land in the north than in the south.

PRINN: Oh, of course.

BROWN: And I don't see a corresponding asymmetry in the observations. But maybe it's there.

PRINN: Well, the question of the normalization and moving up of this-- up and down on this curve-- is not the issue here. That just gives you the total amount removed. So as long as you-- and you've got to fit that. It's where it is removed as a function of latitude that this graph is really talking about.

BROWN: But this says it should be flatter in one place than the other. [INAUDIBLE] it is.

PRINN: I don't want to give the sense that I'm all equally certain that it is the land that's a big sink. The point is we don't know at the present time. So that's pretty-- that's not a very good circumstance if you're making policy, I think.

Methane-- another one of the big greenhouse gases-- its trend is decreasing. 10 years ago, it was rising at 1.2% per year. Now it's going up at only 0.8% a year. What's going on?

Methane has got a whole lot of natural sources. It's got some human induced sources. And they're about 50 50-- human activity versus natural processes.

And the sink is reaction with this hydroxyl free radical. John, you remember what that is. You used to be a chemist, right?

So the hydroxyl radical could be increasing. In fact, we've got some evidence from a network that we run measuring a compound that's very similar to methane, but it's totally man-made. So we can actually do a titration and determine what OH is. And we've actually looked and said, is there a trend in it? And it appears to be statistically significant.

So it may be that the sink is increasing. Or it may be that the source is decreasing. The point is methane, which was rising at 1.2% per year 10 years ago, is now rising at 0.8% per year.

Back 10 years ago, nobody would have predicted that would be the direction. People were predicting it would be the other direction-- that we're throwing all of these hydrocarbons into air through human activity, taxing this hydroxyl radical, which is the big cleanser oxidizing agent in the atmosphere. And it ought to be going down.

So here's another sort of big question mark that just simply appears as well. If that's the case, how do we have a predictive model for methane levels? Going into the future, if we restrict big methane sources like rice agriculture, how sure are we that the restrictions, which may be very costly to the people who depend on rice-- how sure are we that it's based on a good understanding of how methane behaves?

Nitrous oxide-- another of the naturally occurring greenhouse gases is increasing its trend. It was about 0.2% per year about 10, 12 years ago. And now it's around 0.3% per year. And we have that from our own network-- the so-called ALE GAGE Network. And Ray Weiss has a separate network that shows a similar acceleration.

Why is that? We don't know. I mean, I've got hypotheses, but I don't want to burden you with them here. But the point is it's increasing its trend. It's another of the greenhouse gases.

So greenhouse gases-- there are budget uncertainties that everyone should be aware of that make it difficult to reliably predict 50 years ahead what the levels of these gases will be if we try to restrict emissions in various ways.

The next issue is what's called indirect forcing these days. And this gets really complicated and affects policy in probably at least equally serious ways.

If you increase the chlorofluorocarbons-- well, the chlorofluorocarbons are a greenhouse gas, okay, and a very, very powerful greenhouse gases. But if you increase them in the atmosphere, well, you should increase the greenhouse radiative forcing, okay? But at the same time, you're going to decrease ozone.

Well, stratospheric ozone is a greenhouse gas. Okay, so if you add CFCs, increasing the greenhouse effect, they destroy stratospheric ozone, therefore decreasing the greenhouse effect. So there is some change there that is, in fact, not as large as you might have-- if you include that indirect so-called indirect forcing.

If you decrease stratospheric ozone, incidentally, you increase the hydroxyl radical concentration in the troposphere. And the reason is that that chemistry is driven by the little sliver of UV light around 300 nanometers that gets through the ozone layer down into the lower atmosphere. And so if you decrease ozone, you actually have a driving force increasing this OH radical.

Point is that these are really complicated couplings now. And some of them will cancel each other, like the CFCs, or tend to cancel. It's not fully proven. It'll tend to cancel.

But others-- here's another example-- increase methane. Okay, it turns out methane is good for the stratosphere because methane reacts with chlorine atoms and pulls them out of the ozone layer and sequesters them in a stable compound. And so there's less ozone destruction.

So you might expect increasing methane to cause an increase in stratospheric ozone. So now a greenhouse gas has actually aided the growth of another greenhouse gas. So this goes in the other direction-- this indirect effect.

OPPENHEIMER: But be careful there because methane also oxidizes--

PRINN: Yeah, it produces odd hydrogen.

OPPENHEIMER: It may cut the other way.

PRINN: Yeah. But I think the net effect at the chlorine levels we have now is sort of in the direction I've got here. But that's just-- you're pointing out yet a further complication in the whole thing.

And finally, here's another one. Increase NOx, hydrocarbons and CO. This is air pollution. If you increase that, what do you do? You increase tropospheric ozone, which is a greenhouse gas. And you also, incidentally, increase the OH radical concentration because it actually is quite high and very polluted there.

So these indirect forcings have only just, in the last year or so, been really thought about seriously and used to help make conclusions in groups like the IPCC. And my caution here is that I think there's going to be a lot of work done here. And there may be some significant surprises coming out of it.

Next, sort of emerging science issue is-- I need something to weigh this down.

Is it possible that we're getting enhanced cloud cover due to sulfur emissions? And clouds are the big reflector of sunlight back to space. Increase sulfur dioxide, burn lots of coal, you increase sulfuric acid. Tiny photochemically formed sulfuric acid particles are called cloud condensation nuclei.

And over the ocean, there's often a deficit of cloud condensation nuclei. And this, at least hypothetically, could lead to an increase in northern hemisphere cloud cover. Now this is hypothetical. And there's been a couple of papers published on it.

But the point is that if you believe those papers, this can, in fact, offset the radiative forcing that see the rise in CO2 would be expected to cause at least regionally. But you've got to be careful about thinking about the greenhouse effect as a regional thing. Point is it's important to think about it.

And another issue has always been-- for people running climate models-- if you look at the temperature increase global average, you lose something. If you then look at it in the southern hemisphere and the northern hemisphere, you find out something additional. And that is that the-- at least in recent times-- the temperature in the southern hemisphere is rising more rapidly than the temperature in the northern hemisphere.

Now that's counter to a simple idea that the ocean, for example, is a good thermal buffer. Because that would say the southern oceans ought to be keeping the southern hemisphere buffered in temperature and get the northern hemisphere on.

Well, another hypothesis-- realize I'm not stating these as facts. I'm just saying these are emerging science issues. Is this effect here of sulfur emissions sufficient to explain the greater southern hemisphere versus northern hemisphere temperature trends? Is it?

And I think that the answer to that may emerge. Or at least more definitive answer, that may emerge in the next couple of years.

Yeah.

MACDONALD: In fact, it's more likely that the sulfate particles are what affect the optical properties of the cloud, rather than their overall amounts.

PRINN: Yeah. Yeah, thank you, Gordon. That's true.

An ocean issue that I find intriguing is not the wind driven circulation, but the thermohaline circulation. This is the one where cold and salty water-- cold because it's in the polar regions and salty partly because if you form ice, the salt remains in the liquid phase, so that increases the density as well. But that drives the thermohaline circulation where water sinks in the polar regions. And, of course, there must be some compensatory upwelling at lower latitudes. That's called the thermohaline circulation.

It's interesting as a circulation because in the Atlantic, it's one of the sort of driving forces for needing water. Of course, if you sink water in the Norwegian Sea region, water has got to come in to replace it. And it'll come from lower latitudes. And it'll tend to be warmer.

So this is a warming mechanism for the North Atlantic, if you like. I'm not sure what it is-- how important it is relative to the wind driven circulation, but nevertheless it's there. If you increase the thermohaline circulation, you should, therefore, increase European temperatures.

And there are some ideas about the curious event that occurred as we were coming out of the last ice age or the Younger Dryas Event. And the earth-- well, apparently in the northern hemisphere, temperatures rose and then all of a sudden cool again and then rose again. And this is just the northern hemisphere and just the Greenland ice sheet temperature record that you see this. But it all happened maybe in the period of a few decades to maybe a century-- sort of up and down, very fast oscillation.

Now one idea is that it is due to some on off nature to this thermohaline circulation. Again, there's a question here. I'm not stating these as facts but stating them as hypotheses that people are going to work on and try to understand.

And finally, as emerging science issues, they emerge without even humans involved. And that's volcanic eruptions. These are really interesting. And it's the subject of does the temperature change when volcanoes erupt and so on has already been brought up.

And it's somewhere in my folder of view graphs there. I do have the temperature record with little arrows on it where volcanic eruptions did occur. And for the most part, there is a temperature decrease after a volcanic eruption.

SPEAKER: How soon after?

LINDZEN: Seven years.

PRINN: Thank you, Dick.

El Chichon and Pinatubo--

SPEAKER: We have network.

PRINN: Yes, sorry.

[INTERPOSING VOICES]

PRINN: No. No, I don't think it was serious response.

LINDZEN: No, no. There was a study by a man called Oliver at the [INAUDIBLE] asking if volcanism was associated with temperature changes. What ocean delay would give the best fit? And he came up with seven years.

SPEAKER: So that doesn't mean-- it's not-- the temperature change--

LINDZEN: No.

SPEAKER: It happens pretty quickly. It's stretched.

LINDZEN: Right. I'm saying the response time of the ocean--

SPEAKER: The response is dragged out over about seven years.

NIERENBERG: The point I'm trying to make, of course, is that time change should apply to any forcing, not just volcanic.

WASHINGTON: Well, that depends on-- no. No, that depends on whether it's ocean absorption or the settling out of--

SPEAKER: No, no, no. This is a thermal-- it's thermal.

NIERENBERG: They always use it so many watts per square meter or whatever.

OPPENHEIMER: But the trouble with that is the forcing is so quick-- the particles are up in the air for two years-- that you only tweak certain frequencies. You only get--

LINDZEN: If you took this seriously, it's the impulse forcings.

OPPENHEIMER: Right.

LINDZEN: You're looking for what delay the ocean optimizes the response. You get a number. And it's true. That number should be germane. And it's not worried about enough because it's much shorter than any one claims for the time scale.

OPPENHEIMER: But it isn't clear that if you have essentially a delta function forcing whether you're going to pick up the very long frequencies. You won't see them in the response.

[INTERPOSING VOICES]

But the one that will control the response is essentially the top layer.

LINDZEN: What I am saying--

OPPENHEIMER: But that is going to be-- look, they're going to do with Pinatubo. And it's a big forcing. And we'll see what happens.

PRINN: Some calculations have already be done and published, predicting what the effect of Pinatubo is going to be on global temperatures. They're done by Hansen and Company. And I think the temperature is predicted to drop by about 0.4 degrees centigrade over a period of a few years.

NIERENBERG: I thought he said, we're going to see it this year.

OPPENHEIMER: We are. In fact, the temperature is going down already. It It's still sort of in the noise. But if you look at the latest graphs, it's cooler in the last six months than it was before the volcano. It's still sort of in the noise level.

SUNUNU: It was cooler in '91 than '92.

[LAUGHTER]

PRINN: Okay, I want the floor back again. Can I have it?

SPEAKER: You have it.

PRINN: Just to give you a sense of how big Pinatubo was, it was three times the size of El Chichon, which was a pretty good volcano back in 1982. And this is-- a-- gosh darn it. It doesn't project very well, does it?

This is a picture of optical depth. That's just the dimensionless measure of opacity. And the white here-- the white up here shows you areas where the optical depth in the stratosphere is increased to be about 0.1. In other words, that would be 10% effect on the solar extinction at those latitudes.

So there's no doubt, even without worrying about Jim Hansen's calculations. There's no doubt that this is going to have an effect on the total amount of energy that the earth gets over the next few years while that cloud remains suspended in the stratosphere. Of course, it is going to be slowly diluted down until the troposphere all of the time. But it's there, and it's a big effect.

And it's an interesting geophysical experiment. But it couldn't have, in my mind, come along at a more difficult time because this adds noise to the temperature signal. If you're trying to look for trends, the last thing you'd ever want is unusual events like this. Yeah?

NIERENBERG: Do you have similar data for Mount Hudson?

PRINN: Not here. No. I don't even think I have it in my thick folder there.

NIERENBERG: It may be as big.

PRINN: Yeah.

So volcanoes-- in fact, if you have enough volcanoes-- if we knew how to turn the darn things on, we could tune the climate probably. Because I really think it is a few degrees-- a few tenths of a degree effect. So you could sit there and think you could tune the climate.

But that's a topic for another conference, I'm sure. And I don't want to be quoted to say I think that we ought to tune the climate. I'm just saying one can dream about these things. But you shouldn't probably try to implement them.

Next thing I want to do is just quickly go through the IPCC update because policy people are going to use this. The things I just had-- these emerging science issues-- some of them are brought out in the update of the IPCC. But others are not. So my caution is always be aware if you're taking documents produced by large groups of people that it's sort of a consensus thing. And sometimes it pays to just go to a few individuals and get individual opinions as well.

So those emerging science issues, you've got to take them into account. And don't get fooled that the pontifical statements at the front of IPCC documents are absolute and true. They change.

The IPCC update, in fact, doesn't do much more than the old one as far as I can see in the sense that they're pretty much sticking with the story. The good thing is that coupled ocean atmosphere climate models now exist. And they're getting, I think, better and better.

There is the issue of needing very high resolution to model the ocean. And I think it's beyond present computers to do it right. Or at least some people think so.

But anyway, people are working on that. And compared to the time three years ago when the first IPCC was putting together, now people are really pushing on this modeling issue. That's just sort of a editorial comment on it.

For the IPCC, business as usual-- greenhouse gas rise scenario. Remember, that was just simply said, I'll draw a curve into the future for the rise of CO2. And I'll call that business as usual. God knows what it means.

LINDZEN: It was specific. It was give me a curve with current chemistry that will double CO2 by 2010.

PRINN: Yeah, right, well.

SPEAKER: It has now been discarded and will never be referred to again.

[LAUGHTER]

PRINN: By the way, it is referred to. It is referred to in the draft of the update.

SPEAKER: No, it is not.

[INTERPOSING VOICES]

SPEAKER: You have the earlier draft.

PRINN: I have the December draft.

[INTERPOSING VOICES]

PRINN: I said, December 1991 draft. I realize that there's now a later one. That doesn't-- call it whatever you like, okay? We'll call it the base case. It's not going to change the fact that it is arbitrary. Okay?

The predictor-- so with that, they're sticking with about 0.3 degrees centigrade per decade. My big question there and a lot of people's big question is how uncertain is this number. Now, they say it's maybe only plus or minus 20% or 30% uncertainty or something on that. There's going to be a lot of debate as to whether it should be plus or minus 70% or 80% or something like that. The answer--

DEUTCH: Could you [INAUDIBLE], Jesse what the objection is? As I understand it, they said, let us assume that CO2 continues its trend of growth in emission.

AUSUBEL: The business-as-usual scenario was based on a set of assumptions which I think you might call sort of a Brezhnev vision of the economy in which there would be no technological change.

SPEAKER: That's not accurate.

AUSUBEL: That is accurate.

SPEAKER: Look, I was involved in developing it and--

AUSUBEL: Well, I'm not surprised you're defending it.

DAN: It was not-- the business-as-usual scenario incorporates significant improvements in energy efficiency per unit of GNP over time. It does. I mean, and some people challenge it as having too much of that. Other people said it's not enough. The new reference scenario, the middle reference scenario that was developed is very similar in terms of total emissions as the original business-as-usual scenario. There's a range of additional scenarios around that. Of course, future missions are uncertain. But, I mean, I don't think it's accurate to portray the IPCC as rejecting the business-as-usual scenario as not a reasonable, middle-case scenario of where emissions would go.

SCHMALENSEE: But you're not going to argue that that scenario came from a careful, detailed economic forecasting exercise, are you?

DAN: It came from about as careful a forecasting exercise as you can do for 100 years, yeah.

DEUTCH: It sounds to me entirely reasonable. I want to understand why there's all this emotion around this. I mean, you would say there, I expect that the amount of CO2 to be produced over time is going to grow. I might add on that data whatever else I know about other greenhouse gas trends. And I would say if that emission trend continues that I have assumed, then I want to ask how well can I guess what the future temperature is.

SCHMALENSEE: John, one of the problems is--

DEUTCH: What's the matter with that?

SCHMALENSEE: --labelling that scenario business-as-usual labels it as a forecast, an economic forecast, which is what that is, over 60 years is very, very uncertain. And part of the problem a lot of us had with that first report was it was treated as a known emissions trajectory. And, of course, it's not.

LINDZEN: A major difference in the new report is they list the assumptions.

DEUTCH: Well, that's okay.

SCHMALENSEE: They list the assumptions and they have scenarios--

SPEAKER: It's still there in the report--

SCHMALENSEE: None of which is preferred.

SPEAKER: It's still cracking [INAUDIBLE]

SPEAKER: They have a multiplicity of scenarios. And there's an explicit statement to the effect that none of them is preferred.

DEUTCH: Yeah, but let's, among us, I mean--

NIERENBERG: Mr. Chairman, why don't we wait for Bill Nordhaus? I suspect he's going to say something about that.

DEUTCH: Bill Nordhaus, you going to say something about this?

PRINN: No, he's got time to talk later.

DEUTCH: Bill Nordhaus, you going to say something about this?

PRINN: Hey, this is my time, isn't it? They also come out with key uncertainties in the science. And I certainly agree with these. I've already mentioned the greenhouse gas budgets being up in the air, no pun intended. There's a lot of work to do, clouds and albedo. And I would add into that the whole picture of convection and how convection is responsible for heat transport, water vapor, water substance transport into the upper troposphere, and so on.

There are big uncertainties revolving around the subject of convection in clouds, the ocean circulation, just no doubt about it. The more we know there, the more people will begin to believe some of these climate model predictions. And the polar ice sheets and sea level, I would add to their list issues to do with the coupling of the ozone layer and the lower atmosphere and also issues to do with changes in the land surface and effects on albedo and the hydrologic cycle and so on.

Now, to sort of finish up, I actually have additional view graphs that I'll use only if people think that there's enough reason to go through them. They're attached at the back. One is called societal needs for climate prediction. And they just sort of show from my viewpoint what's important for society to know and also one just telling you what the science needs are in the next few years.

And I can go through those if people think that it's useful. But what I want to finish up with here, in fact, is this whole science policy interface issue. Because I, as a scientist, have become dragged into this, initially kicking and screaming. But occasionally now I enjoy it, just occasionally. I don't think that-- this is a personal opinion-- the IPCC update still does not make the necessary linkages and interactions.

It is still one committee producing a document, throwing it to the next committee who tries to catch as much as possible and so on. But it is not an integrated study at all. And I'll just say a little bit more with the diagram in a second. An integrated study, I regard as one where you start out with some ideas about what emissions will be based on good, sensible economic models and population models, and so on.

These, then, you use to predict concentrations. These are then put into climate models to produce predictions of regional climate. It's very important to talk about regional climate, I think, for impacts on the human system, be it humans or just the natural ecosystems. So you want to do the predictions and work out what the impacts are.

When you do that, you'll find that some of the things that the scientists are predicting are not what you need to assess the effects. So there's going to be backwards and forwards here in a true integration. And say, look, you guys, turns out this variable x is not so important and you've gone to a lot of trouble to predict it to great accuracy. It's this variable y that is very important. So backwards and forwards for awhile where the scientists learn what's important and impacts and vise versa.

SPEAKER: You're covering up what's important.

PRINN: Oh, am I? Yeah, I'll raise it. So impacts, and then that leads to the basis for sensible discussion of the policy alternatives. And there's going to be backwards and forwards there, as well, between this and this. And then that's the basis of some negotiation. And then you've got some new emissions scenario. And you've got to go around that circle again and again.

That's what I call the needed integration. I think this is in your little folder. And I believe that Jake Jacoby is going to come back, at least him will come back to this issue this afternoon. This is the needed integration. And it is not happening at the present time. And I think it's a serious research gap.

The requisite people that you need to do this, of course, are so interdisciplinary, so broad in the needed disciplines, okay, that you need somebody here who might be a biologist who understands natural emissions of trace gases. And sitting over here, you have economists and so on. So it's an incredibly diverse discipline. But each are going to have to communicate with one another in a fairly intimate way. So this is what I call the needed integration. I'll finish up there. And we can go to discussion.

DEUTCH: Thank you, Ron. Bill?

NIERENBERG: I have a real quick one. I enjoyed your presentation very much, despite all the help you got from the audience, I might add. But enlisting the important new questions, you left out one, I thought, that I think is important. And that is the order of magnitude change in our estimate of the lifetime of the added CO2 in the atmosphere. You remember 10 years ago, five years ago, one talked about 1,000 years. Dick knows slightly better than I, much better than I, it's dropped as low as 60, some of the estimates.

SPEAKER: 45.

NIERENBERG: 45. Even. That has a dramatic impact not only on the science, but on the policy.

SPEAKER: That always gets shoved under the table.

LINDZEN: I'll give you an example.

OPPENHEIMER: Wait, well let's be fair. What the IPCC report says--

NIERENBERG: I'm not talking about the IPCC.

OPPENHEIMER: All right, what the science says is there's multiple timescales and the best model we have made before which range from 50 to well over 1,000 years for the rate at which the CO2 equillibrates between the atmosphere and the ocean. You can't pick a single timescale. It's a complicated situation. If you did pick a single timescale today, it would probably be more like 100 years than 1,000.

NIERENBERG: Please, what I said was correct. 5 years ago the estimate was flat. It was 1,000 years. And it made a dramatic difference in policy.

OPPENHEIMER: Well, it's much more complicated than that.

DEUTCH: Richard?

LINDZEN: Just a simple statement on it. It's a technical issue and we'll go through it. But there's no question, the model with 100 year timescale, if applied to the past 150 years, would today say we have 525 parts per million volume. Only 45 years gives you that history. Martin Heimann's model at the Max Planck [INAUDIBLE] shop now says business-as-usual, which was designed to double by 2030, won't double by 2105. You know, that's the impact of the timescale.

SPEAKER: What, in brief, is the chemistry of the disappearance of CO2?

LINDZEN: The biosphere is increasingly coming in. The point is, none of these seasonal effects, interhemispheric effects and so on, are compatible with even 100 years. And so the chemists, almost ad hoc, are just bringing the timescale down so it fits.

DEUTCH: Tom Lee, Tom Lee.

LEE: I just want to ask you this question. You have one arrow going from THG concentrations to regional climate related variables. How hopeful is it to make that step really credible or meaningful?

PRINN: You mean, how good a climate model?

LEE: Yeah.

SPEAKER: On a regional basis.

LEE: On a regional basis.

PRINN: On a regional basis.

LEE: That arrow, that step seems to be a very difficult step. Is that true?

PRINN: Well, certainly with current climate models it is a very difficult step. And if you worry about things like soil moisture, you know, this is a very popular graph for people who are asked that question. It just sort of gives a comparison of some soil moisture predictions in five general circulation models. The [INAUDIBLE] one that Warren can give us more details about, the geophysical fluid dynamics lab, the NASA GISS, the UK Met Office, and Oregon State University.

And this is increases and decreases in soil moisture in the winter. And this is when CO2 has doubled in these models and the area shaded with those where there's a decrease or a change to drier conditions. And you see it goes all over the place, depending on the model. And you look at these various models and you realize that what's very important in them is the way they parameterize the things that are going on at scales less than the grid scale.

And those are a very important. And different models make different assumptions and they lead to these issues. It's not that they have different fluid dynamics equations, they have different parameterizations for the sub-grid scale processes and that's the difficulty.

DEUTCH: Jesse.

AUSUBEL: I just wanted to follow up on Ron's very good presentation and Howard Gruenspecht may want to comment on this as well. The supplement to the IPCC is soon to appear. And let me just mention some of the other main conclusions from it. First of all, the supplement appears more cautious than the 1990 IPCC assessment, a greater sense of uncertainty of the science as communicated.

Then it discusses some of the reasons. The net effect of CFCs is more controversial. The sulfate question, as Ron discussed, is more controversial. The indirect effects are more controversial. The unexpected rate of slowing of the methane is mentioned. The IPCC supplement no longer claims a global rate of temperature increase of 0.3 degrees C per decade, which was a key conclusion of the 1990 report. Due to aerosols, ozone depletion, and slower rates of greenhouse gas increases, the calculated rate of temperature increase is expected to be less than the previously calculated 0.3 degrees C, but the supplement was unable to provide a revised rate value.

Adoption of a range of scenarios for future trace gas emissions improves the realism of the assessment while the single scenario of the 1990 assessment has been slightly modified. This was Stan's scenario. And it continues to be one of the cases. The range is important because it more accurately reflects uncertainties of projecting future emissions. And more important, it gets rid of the unrealistic and widely criticized business-as-usual case that was promulgated in 1990. It says there will no longer be any reference to BAU, business-as-usual, exclamation point.

And finally, the issue that was just raised by Bill about lifetimes is very important for the calculation of the so-called global warming potentials. And there are growing concerns about the use of the global warming potentials as an index for comparing the relative forcing of different greenhouse gases. There are considerable uncertainties about sources and sink strengths and the affected lifetimes, and shortcomings in the calculated values for the direct GWPs and the indirect ones. And so I would say the net effect is that the 1992 supplement will be a much more cautious document.

DEUTCH: What were you reading from?

SPEAKER: That's a summary.

AUSUBEL: This is a summary.

DEUTCH: Oh, [INAUDIBLE], your own summary.

AUSUBEL: Yes.

DEUTCH: Bill Nordhaus.

SPEAKER: Whose summary is it? Your summary, right?

AUSUBEL: This is-- Howard may want to comment.

GRUENSPECHT: Yeah, can I comment?

DEUTCH: We'll get back to you. We gotta do it in order. We gotta do it in order.

NORDHAUS: This comes from the earlier IPCC report and in a way it seems to me the central dilemma that the model is facing. I'm not sure I can explain this correctly, but as I understand it, it took the estimated historical greenhouse forcings, put those through a mini-model with different values for the doubling coefficient. The family of lines here shows for a delta T for doubling CO2, five, four, three, two, one, what the increases would be.

Actually, these are not equilibrium calculations, but one that respect the transients that are in some model. I'm not quite sure. Because it didn't really say. That's why I'm asking you this. And you then put on this the observed and it comes out halfway between 1 and 2 degrees per W. Now, the embarrassment, of course, is that that's below any single number of the models that the IPCC review. I mean, it had a range, as I recall, from 1.8 to up above 4.

SPEAKER: So it assumes all the change was due to-- [INAUDIBLE]

NORDHAUS: I understand that. But I've just really got a question. As I looked at the report, this seems to me the central uncertainty that the scientists are trying to deal with it, which is, how can you have models which are predicting in this range, whereas if you actually look at the historical data it's giving you a lower number? I'm just curious for your response.

PRINN: I would say, anyone that wants to use this family of models up here to predict into future has difficulty. And I think Dick maybe wants to add something.

SPEAKER: I won't challenge that remark.

OPPENHEIMER: Let me comment on that. The problem with using the historical temperature--

NORDHAUS: May I just-- Are you saying that any-- Let me just comment--

PRINN: If I were looking at this, okay, I'd say, well, I'd want to know a lot more about the models. And I'm trying to remember the details. I think these are very simple, a very simple model here and It doesn't have an ocean.

LINDZEN: It does.

PRINN: Does it?

LINDZEN: It does.

PRINN: But in a very crude way.

LINDZEN: No, but you have to be fair here. It uses the mixed layer diffusive upwelling model. And there is no significant improvement in time lags, grossly, from more sophisticated models. As long as you tune this to give the same gross time lags as those models, it's not going to be way off.

OPPENHEIMER: That's one factor. Second factor, the aerosols aren't included in here. And a more recent analysis which is going to be published shortly in Nature, shows that if you include the historical effect of anthropogenic aerosols, that you would move the match. That is, if you backed them out of the observed temperature curve, you would move the match-up more to the 2 to 2 and 1/2 degree range.

You don't conclude at all the effect of changes over the last 15 years in forcing due to decreases in the ozone, which has had some marginal effect in the end of the temperature record. Then there are a few other factors. So at this point, using the historical temperature record as a way to validate models is totally unreliable.

SPEAKER: What do you use?

[INTERPOSING VOICES]

DEUTCH: I would like to bring us back to Earth in this moment that [INAUDIBLE] might be able to same something.

BRAS: I just want, again, for the sake of fairness and I want to essentially address something that Ron presented. You presented the soil moisture distribution of the different models in winter. I keep arguing that that is absolutely true. If you want to bring in the issues of uncertainties, what we don't know, that is true. But compare in the summer. In summer you would find that the agreement is a lot higher. Most of that difference that you see there is largely due to mainly the difficulty of the models in predicting the precipitation in the winter and whether it's snow or rain.

PRINN: Okay, but that's a scale, sub-grid scale processes.

BRAS: In essence, put both sides of the coin and, you know, Peter Stone has used that many times. I've always made the same argument. Unquestionably, that is true. But put the summer figure, it's not that different.

DEUTCH: Dan?

DAN: [? Yeah, ?] I guess I'll make a couple of points on the IPCC update. What you heard is one summary of the summary of the IPCC update. And I urge people to read the real summary that the IPCC produced based on their consensus process. And I think you can interpret it in many different ways. One of the things that they say is the observed global warming from the '80s has continued into 1990 and 1991. Those were also very warm years.

The increase in greenhouse gas concentrations has continued into the future. It has continued. Although, there is some slowing in the rate of the methane. And the improvement in the coupled atmosphere-ocean models show results which are very consistent with what the previous models had said, which improve our confidence in those. So you can say, some things in the science make you feel more confident. And I don't think it's correct to characterize that report as unambiguously being more cautious about what's going to happen in the future.

And in particular, on the issue of aerosols and ozone depletion creating an offset, offsetting negative forcing. And the issues that Bill Nordhaus just rose, they specifically say that when you include those effects, the agreement between the historical record and the models is actually improved. And when you consider the ranges of uncertainties, which are not linear, the historical record is consistent with a climate sensitivity anywhere between 2 and 12 degrees centigrade from a doubling of carbon dioxide. That's in the report. So, you know--

SPEAKER: Which proves that consistency is a pretty weak test to the [INAUDIBLE]

DAN: Exactly, exactly. It's a very weak test.

SPEAKER: Dan, can you show me in the report where it said 12 and the data is consistent and what the circumstances were?

DEUTCH: Bob Frye.

FRYE: My idle curiosity is stimulated. I don't think there are very many climate meetings.

PRINN: Excuse me.

FRYE: And I don't sit through very many climate meetings. So I see the long-wave phenomenon here at I'm not sure whether the rate of change of uncertainties in the science was positive or negative in the last couple I sat through. And my question is for the guys who do know, how long is it going to take to sort this out and what's it going to cost?

DEUTCH: There's an impatient government official.

FRYE: No, I'm not impatient, I just want to know whether I ought to be working on something else.

DEUTCH: That's a good question, actually. How long will it take to straighten some of these things out? 20 years is a currently--

SPEAKER: You got an answer. You have an answer.

OPPENHEIMER: Yes, I want to show you this picture because, not that I think it's hopeless, I think we will sort it out. But just to remind everybody, the notion of sorted out in this context-- it's not a view-graph, unfortunately-- it's dicey. I'm sorry I don't have an overhead. This is the history of prediction of ozone depletion from the models as they existed up between the time in 1974 when Rowland and Molina projected that chlorofluorocarbons would destroy the ozone eventually.

Through the early part of the '80s before the Antarctic ozone hole was discovered. I don't have the central value, but the range of prediction is indicated by the orange. And you notice, well, the range started out relatively high. And this has all been normalized per unit chlorine in the atmosphere. So it is not subject to uncertainties about emissions inventories. It has only to do with chemical response. The predictions started out rather high and then drifted down so that they reached a value of what I'll call a half in this unit system as of about 1983 to 1985.

With the discovery of the Antarctic ozone hole, actual depletion measured, and this is a broken scale, was up around 20. About 40 times at that location and during that time of year. And lately the ozone depletion values even mid-latitude seasonally averaged range of the order of four or five times what the last prediction in the model was. So I just want to make the point that no one should sit around hoping that we get 10 years from now and we have a prediction that will necessarily be borne out in any sense by reality. I think we're going to find out, most of what we find out about this problem, unfortunately, by applying the forcing to the atmosphere, unless we're wise enough to reduce the forcing. That is not a knock on the research, just a reality check.

PRINN: Yes, sir.

LEVINE: I just wanted to observe that much of the debate sounds like dipping into a soup of scientific unknowns to support one or the other side of the position, which makes the point that do we really know enough to be making these projections?

DAN: Or do we know enough to not be making policy responsibly.

DEUTCH: I think we may be getting a little bit, losing sight of the bubble here. I don't there's anybody who says that we're not going to be adding incrementally more CO2 to the atmosphere over time. Is that right? Worldwide, am I right about that? Nobody says in--

BRAS: No, nobody's argued that one yet, anyhow.

PRINN: Mr. Schmalansee apparently is.

SCHMALENSEE: John, I really think they're at the core of the debate. Because the core of the debate is, how do you react to large uncertainties in a large stake situation? Do you say, we can't afford to run this experiment on the planet? Or do you say, we can't afford to impose drastic constraints on the economy in the absence of more knowledge? And those are the two points of view, I think. And it really comes down to reaction to uncertainties.

DEUTCH: Well, I mean, I think that that's right. But I do believe that we shouldn't lose sight of the fact that it is likely, as I understand it, that everybody in the globe is going to be adding more C02.

LINDZEN: John, in that statement that is rather important, however, the slower you add it, the less the fraction that appears in the atmosphere.

DEUTCH: I understand that, too. I understand there are huge uncertainties. But you are going to be adding more CO2. And I think eventually it's going to go in one direction, eventually.

LINDZEN: Well, if you add it slowly enough, you do nothing.

DEUTCH: The magnitude in time-- Is that true?

LINDZEN: Yeah, because the response time effects that.

DEUTCH: But you really have to add it slowly. Yes, Jake.

JACOBY: I'm unhappy with the answer to Bob Frye's question. Can we ask it again? I mean, there are key experiments that are going on in the ocean and the atmosphere. There is data gathering. There is the possibility of building larger models. Can we go around one more time about when the people working in the science think that some of these key processes will be better understood?

PRINN: Well, okay, okay, let me give my own feeling. I think that in the next few years that scientists are going to be thinking about all of these special issues, these new emerging issues, and add more to it. So in fact, over the next few years, I think, to an outsider looking at it, it's going to look like the uncertainty is just growing. Because people are saying, huh, I know another way, you know.

The issue of anthropogenic aerosols is an interesting one. Yes, you can add those to models and make them agree with observation. But let me tell you, we don't know from observations what the aerosol loading of the atmosphere is. There are no observations worth talking about of the aerosol loading in the atmosphere, not even of one place in a trend measured over many years. The only place that it even has some validity is in the South Pole where they measured some aerosols for about 20 years.

And it's flat as a pancake. Nothing's happened at the South Pole. Maybe you don't expect it to. But there are no observational records of the loading of aerosols in the atmosphere. So when you see people putting them in the models, they're putting in the amount they need to bring the models into agreement with observation. So be careful. It's a good tuning parameter, aerosols.

DEUTCH: How does that answer Mr. Jacoby's--

PRINN: Well, Mr. Jacoby, well, OK, I think that these issues are going to be debated hotly and more ones are going to be added in the next few years. So it will look confusing. But I want to make the point that real science goes forward with a combination of observations and theory. And I think we need observations right now. We don't need more ideas. We need more observational tests of ideas.

DEUTCH: Warren and then Tom Lee.

PRINN: That will take 20 years.

DEUTCH: Warren?

WASHINGTON: Well, all of us probably have different estimates on when things are going to get better in terms of the science, but the improvement of the climate models is happening on a timescale of say 5 to 10 years. Because we're getting the kinds of observational programs that are going to tell us how to improve our models. But that's going to happen, certainly not over two years or three years. It's going to take longer than that.

And having EOS the satellite program is very important. The need for higher resolution models, both of the atmosphere and the ocean, we can't get those probably significantly until the mid-1990s just because we need these new multi-processor type computers that can give us speeds of tens to hundreds of times faster than what we're able to do with the present generation computers. So I don't think having an IPCC every year is going to settle this.

SPEAKER: [INAUDIBLE]

DEUTCH: Tom?

LEE: I guess my question really relates to Bob Frye's question. When I asked you that one step, one arrow from THG concentrations to the region of predictions. I think Warren has sort of commented somewhat on that. How long do we have to wait before we can really have outputs from the models that relates to the issues that are important, instead of the average temperature?

PRINN: Well, I'd say, you know, the models themselves, just the theory and the development of the models, as Warren's already pointed out, there's going to be some steady improvements as time goes on. And certainly if we can get these massively powerful machines built quicker than it looks like they're going to be built at the present time and then apply them to it, we will address the resolution issue. But we won't address the issue of how good is the physics of the various processes and the chemistry of the processes in those models.

And that is a separate, not a separate, but it's an area of development that has to go on along with the development of the models. And in the end, the models are going to have to be, then, tested with really good observation. And their feet held to that fire, the observational fire, as it were, a very, very long time until they get it so that there's no more heat.

SPEAKER: They should be able to predict history before we make policy on the future based on that.

PRINN: The trouble with predicting history is we don't have enough ob-- we have a temperature record, for example. But you'd like to know what the aerosol loading really was.

SPEAKER: So you have no data for the future, though.

DEUTCH: Excuse me, Mr. Lindzen is next.

PRINN: We better start taking it, that's the point.

DEUTCH: Mr. Lindzen?

LINDZEN: First of all, I think Tom's question actually introduces a very important thing, which is a sociological problem. The more important the policy community says the problem is, the less likely the science community is to give an answer. Because it is telling you it's very important, hang on to it, it will sponsor research forever. There is a prejudice against giving answers. And that is well known.

SPEAKER: You may have recommended a solution to the dilemma.

LINDZEN: Unfortunately. But there's another issue and that is, if you look at it, there's a prediction, 0.3 degrees per decade. That isn't to begin tomorrow. That was to have begun in the '40s and '50s. And that is not being-- No, I mean, you do the same calculation. It's more effective then. We're not seeing it, there is a constant problem here. The predictions are being made. They are being broken on a regular basis. And we're trying to figure out, well, maybe they're still true. Maybe it'll be worse. Maybe it will be that.

DEUTCH: Gordon, when you took out your linear term, what was it?

MACDONALD: It's 6/10 of a degree over the last 130 years.

DEUTCH: Uh-huh. Sir?

YEAGER: This discussion seems to me to underscore, and this is in the spirit of transitioning forward in our discussion, that really somewhat irrelevant. Whatever happens in the climate arena from a policy standpoint is really secondary to what do you do about it. We're dealing with a risk issue which is going to be uncertain for a good deal of time. And the fundamental question is, what are the degrees of freedom you have to do something about it, whatever level of risk you want to attach to the issue?

DEUTCH: I think that's unfair. I thought that this was logically arranged to say first of all, what do you know? And later on today to talk about what do you do about it. Now, there seem to be a lot of objections to that.

BROWN: No, but John--

DEUTCH: Harold, yeah?

BROWN: One thing that emerges from this to me is that if you make a policy decision, don't say that it's because of a technical judgment which clearly can't be sustained.

DEUTCH: That's certainly true. It

SPEAKER: But don't use the technical judgment to create a political climate in which you force yourself to make a policy judgment.

DEUTCH: Michael?

BROWN: You ask too much.

OPPENHEIMER: I want to make two narrow technical points [INAUDIBLE] before they slip off into oblivion, by John Sununu and then go back to the policy thing. First of all, to go back to your point about the 200 up 200 down. Since you wouldn't ask the question, I'll pose it this way. Isn't the important point the following, that we ought to watch, knowing that there's a very finely tuned balance of 200 up and 200 down, knowing that a 3% or 4% change in the source over the sink is projected to have substantial influence on climate in the future, that we ought to be very careful that we don't do anything that effects the balance of natural sources and sinks.

SUNUNU: Let me respond to that because--

OPPENHEIMER: Let me finish. Because small increments in natural sources and sinks can have a vast effect on what is a substantial force.

SUNUNU: I'd feel better if you could tell me where the 200 up and 200 down go to more than plus or minus 10%, 15%. I'd feel better if you were asking for policies that have trillion dollar impacts that represent changes in more than 0.1% of 200. And I'd feel a lot better if you could talk about what the reality is of reversibility or irreversibility over time or absorption by the ocean of what you are talking about as increments that you want to set trillion-dollar policies on. And I would feel a lot better if the uncertainty that was outlined by the presentation we just saw in which there's a difficulty in dealing with the ocean and the land mass, if I understood it correctly, you're talking about only the 3.8.

SPEAKER: That's right.

SUNUNU: And having heard the uncertainty on the 3.8, tell me a little bit more about the uncertainty on the 200. Because if you can't deal with the uncertainty on the 3.8, I can't believe that there are not parameters that-- I can't believe that 200 is 200.04 up and down exactly every year. I have difficulty in believing mother nature functions that way.

OPPENHEIMER: I don't have it in my head, but the ice core record certainly shows that the difference between the 200 plus and the 200 minus is extremely small, of the order--

[? SPEAKER: ?] [? Not ?] per year?

SUNUNU: No, not per year.

SPEAKER: That's saying rapid--

OPPENHEIMER: Averaged over 10 year periods, maybe. There's pretty good [INAUDIBLE]

SUNUNU: The average over eternity is always a good, solid number.

SPEAKER: Oh, it isn't numbers over eternity.

[INTERPOSING VOICES]

DAN: The resolution in the ice cores is in rapid accumulation cores, which are used over the millennial timescale.

SUNUNU: The data that was shown on the CO2 is not that rock solid.

PRINN: The ice cores doesn't have resolution to resolve what we're talking about here. We're talking here about the big fluxes in and out seasonally.

DAN: But if the big flux is out of balance by a significant fraction seasonally, then in the period from 10,000 years ago to today, you would see big fluctuations in the CO2 concentrations.

OPPENHEIMER: Wait a minute, this is all away from my point. Let me make the one point I'm trying to. It's just this, that human activity does affect the natural balance and that you don't have to affect the natural balance much to force the climate substantially. I'm not saying what the outcome is. And therefore we ought to be very careful about anything that feeds back on natural ecosystems which control the carbon ups and downs. And that means we ought to be careful about small global temperature changes.

DEUTCH: Harold?

SPEAKER: Is there any argument that the difference between 315 and 350 is a human product?

DEUTCH: No.

SPEAKER: All right. So that clearly is something to be aware of.

DEUTCH: I don't believe that there's any argument that if that trend were to keep going on a long, long time, you would have a temperature and climate effect.

LINDZEN: By the way, there's a very important break in that curve that is fairly visible in '73. And you find one consequence of that is that a--

PRINN: This here, Dick?

LINDZEN: Yeah, a smaller proportion of what's admitted is appearing in the atmosphere since then, which is exactly how--

OPPENHEIMER: No, that's wrong. That's wrong.

LINDZEN: Tell me.

OPPENHEIMER: Since 1975, the airborne fraction has increased from an average of about 0.5, leaving aside deforestation, 0.5 before '75 to about 0.6 now. The amount remaining in the atmosphere has increased. There's no question about it. You can check Dave Keeling's data.

DEUTCH: Richard, Richard Schmalansee.

SCHMALENSEE: I want to return briefly to the question that was put on the table and never answered and elaborate on it a little bit, based on a remark of Ron's We've been talking largely about uncertainties associated with global mean temperature changes. And I would simply point out that from the point of view of trying to think about how important it is or isn't to do something or not do something about this problem, global mean temperature is not terribly important.

And the remark that Ron made about regional scale effects is really what matters. A degree or two difference in temperature period strikes me is utterly unimportant. Others may disagree. The question is what does that carry with it in terms of extreme events perhaps, in terms of risks of things we don't understand happening to the large system, in terms of soil moisture and agricultural effects and so on. Those are the things that actually matter.

And so there are really two stages at least of resolution of uncertainty. One, that sort of planet-wide processes that come down to global mean temperature. And then all of these other things. What are the regional effects? And also what about the distribution of risks? I guess the center of the distribution of what might happen strikes me as less interesting in some respects than the tails, given the lags in this process. And what I hear from people like Ron is that if one really wants those kinds of uncertainties resolved, one is talking not about two or three or five years, but about a couple of decades.

SPEAKER: [INAUDIBLE] are more important and less predictable.

SCHMALENSEE: Yes.

SPEAKER: Is what you're saying.

DEUTCH: Warren?

WASHINGTON: Yeah, I just have one sort of thing to add to that point out of some new research, which isn't even yet in the IPCC '91. Some of our model simulations and some of them showing up at other places are indicating that, for example, El Niños are stronger in our coupled atmosphere-ocean models. And if the El Niños are stronger and the southern oscillation which is associated with the El Niños are also stronger, that indicates, for example, and this could affect economies, that monsoons would be stronger, sort of one way or the other, either drier in the El Niño situation or the converse.

And that could have a big effect on economy. So I think even with these imperfect coupled models that have the entire ocean in it, that we can start to look at these regional patterns and try to figure out how that might affect economies even at this point.

DEUTCH: I was going to call on you actually, so go ahead.

WHITE: I was going to say, it's an enormous leap of a scientific extrapolation to go from a global average temperature to a global climate. It's a surrogate at best. And it's a very, very poor surrogate. And there's another basic assumption we're making in here. And it is that all climate changes are going to be adverse. They're going to be unacceptable. All of the implications here is that some of the climate changes, if they occur, would be, not only quite acceptable, but quite desirable.

What the models show is a lessening of the intensity of the gradient of temperature between equatorial regions and polar regions. We experience that kind of thing every year from winter to summer so we have some idea what happens when you weaken the temperature gradient between equatorial and polar regions, OK? And we know that stone tracks move farther north. All I'm saying is that there may be some areas, and especially perhaps in more polar regions, which would find a climate warming of the kind we're talking about perhaps acceptable because of lengthening of growing seasons and things of this nature. So I think we've got to be very careful about making the assumption that all climate changes are going to be unacceptable and adverse. Some may be be very favorable.

DEUTCH: Rafael.

BRAS: I'd like to make three different points, first on the issue of regional impacts. I agree that that is the key. What progress are we making? I may be optimistic, but I do believe that the progress is fast and quick and, in fact, we will have much better handle of the regional problems in, let's say, a 5-year period than we're giving credit to. Another point, the issue is the issue of risk, as Dick mentioned and many others, about making and establishing policy under large uncertainties.

But again, let's face it, don't we do that all that time? As an amateur follower of the economy and hearing many people who have been involved in that, looking across the table, well, for God's sake, you know, I follow it. You make policy decisions on uncertainties that, to me, as a non-economists, look higher and bigger than many of the scientific uncertainties that I deal with as a scientist. So I don't see the difference. Maybe we have to put it in perspective for what it means.

Finally, let me address that last point. Yes, the mean average temperature, maybe it's not that important. I agree completely with that. Yes, we face changes in gradients every year and maybe there are benefits locally that will occur. But that is not the only question. The question is, in the global system, are there going to be distortions, for example, relative to viability of whole regions, population movements, demands from non-industrialized to industrialized countries caused by distortions from the have-nots to the haves or the haves that will be have-nots then. That is the problem. That, I think, is some of the concerns that we have to face. It's not whether in my local region I will be better off or worse, it's how is the surrounding going to impact me.

DEUTCH: Thank you. We are coming to the end of this session. And what I would like to do is to give Gordon and Ron a couple of minutes to just say whatever they want to say. But before that happens, I want to hear from Richard Cooper who has asked, Lester Lave, and Bill Hogan, briefly. Because then we will turn to the two speakers just to sum up for us. Richard?

COOPER: Well, I was, like others, going to come back to Bob Frye's question. It seems to me that the answers we got are of no value for policy purposes. And I'd like to narrow the scope of that question very sharply and focus on the question which Prinn emphasizes, ocean circulation, about which we know far too little, and its interactions with the atmosphere. And again to rephrase Frye's question, but just focusing on that issue.

When can we reasonably expect and at what cost to have a reasonable grip on the relationship between the oceans and the atmosphere? This strikes me as tremendously important because the oceans, as Sununu pointed out, have a tremendous capacity to absorb heat. And therefore, if there is to be a global climate warming, the transient is very strongly influenced by the ocean atmosphere interaction.

And the cost to society of adapting to change depends, in my view, intimately on the pace of change. And so if the pace of a change from a given forcing is 400 years, it just is very different from if it's 40 years. And so this is at least potentially a very important issue. Can we expect to answer it in a reasonable period of time much better than we now do and at what cost?

DEUTCH: Gordon, you will be asked to answer that question when I call on you after I call on Lester Lave and Bill Hogan.

LAVE: Taking it back, we've actually-- just two things. One for Rafael, about managing the economy. There's certainly a lot of uncertainty, indeed. Some of us economists would say that what goes on is more tea leaf reading than science in managing the economy. But the point is, it's done in real time. The feedbacks appear right now. And so you're not talking about trillion dollar mistakes that get made one way or another. But the other one is, you people really haven't yet come to grips with what it is we need to know if we're going to make policy.

It is not what the global mean temperature is. It's not even what the regional indications are. It is what is the effect on people and the effect on ecology. I don't care what the effect is on global temperature or even regional temperature. What I want to know is what's going to happen to ecology and what's going to happen to people? That's what I care about. I don't really care whether the ocean warms or cools, I want to know what happens to the creatures I care about in there.

What we're talking about is really immensely more difficult than anything that people have talked about so far because we have to take a look at, first of all, some ecological equilibria that take place. What do the transients look like, what does the new equilibrium look like, in some sense, is that better or less good? I don't particularly want to put value judgments on it right now. But we have to look at what that is. And when we look at people, don't tell me that the climate has warmed, the soil is a little bit drier, we have to find out how people react to that, right?

If we can have people react to it in such a way that it has no effect on agriculture or no effect on the rest of us, then at least in terms of the human component, it's not very relevant. And we have to take a look at what the timescale is for that. What I'd submit to that is that we cannot make scientific predictions all the way to the end of what the ecology and what the effect on people look like. What we have to do is, we're actually going to run that experiment. I didn't say I wanted to run it. But in the end, we're going to have immense uncertainty that the science is not going to reduce down.

DEUTCH: Bill Hogan.

HOGAN: All right, on the same theme, I don't want to anticipate too much what Bill Nordhaus is going to talk about. But this is not a trillion dollar decision, once and for all today. The sequential resolution of uncertainty is the problem we ought to be thinking about trying to structure. Just an example of where I think the discussion is going wrong. Because I think the way that it works.

And I'm remembering a paper done by a student at the Kennedy School on this, which is the longer the period of time under which the scientific uncertainty is going to be resolved, the more we should be doing in the near term. If we knew what was going to happen, it's going to be resolved next year, we should just wait. If we don't know what's going to happen for 20 years until we figure it out, we should do something now in anticipation of it.

DEUTCH: That certainly makes sense to me. Now, because we're going to run out of time here, I want to just conclude this session with hearing briefly from Gordon and then from Ron so we stay on schedule.

MACDONALD: Yeah, I'll start off with a remark on Dick Cooper's question. Progress is going to be very slow in terms of getting a better idea of what the ocean is all about. There is the tropical ocean global atmosphere experiment which will be going on in the Western Pacific that will provide some very important data and hopefully that particular set of observations will be supplemented by rather detailed atmospheric observations.

But to get a picture of the large scale ocean structures and how they change in time, which leads to persistence in climate as we discussed, is going to take several decades at a minimum. Progress in modeling will proceed, at least initially, much faster because we're just starting to put together coupled, ocean-atmosphere models. So a lot of progress can be expected initially. And then it's going to slow and await obtaining of much better ocean data.

There is then a further problem, one that bothers me a lot is, is climate predictable in any real sense? We're dealing with a highly nonlinear system. Certainly aspects of the-- at the shorter-- at the higher frequencies, shorter periods, the chaotic behavior, those limit predictability. My own view is that, as far as the ocean atmosphere models are concerned, we'll be able to construct a series of scenarios based on differing initial data and differing models of what the economy is going to do in the future.

And, thus, build up a range of possible future climates. I don't think that within the foreseeable future, that is, the next few decades, we'll have either the observational, computational, or theoretical understanding to permit prediction, in quotes, that it has anywhere near 70% confidence, or much less anything greater than that.

DEUTCH: Thank you, Gordon. Ron.

PRINN: Okay. I think the question that Lester and others brought up, you know, saying what does society need from scientists at the present time is, you know, the big issue that should be carried on into the rest of the day. These are my own feelings. And they're out there in the view graph handout that I-- that you have.

Just from my own viewpoint, the two big issues that scientists have got to face are accurate prediction of meaningful variables for human, health, agriculture, construction, and so on. Let's get back to this issue. You know, fine, don't talk about all of the machinations of Earth climate machine. Tell me how well you'll do these-- rainfall, severe storms, sea level, temperature extremes. You know, we do know something about these at the present time even. I think we've got an idea of the range of possibilities. Okay.

We've got an idea of the range of possibilities. You know, this terrible map of soil moisture differing in all these models looks bad. But, at least, it gives us a sense of, while there is a possible amplitude that you might see in a particular region, but we can't tell you what region right now. Okay. So those sorts of things we can say something about even now.

We can say something about the percentage, possible percentage changes in rainfall, the possibilities for the increase in severe storms, the possibilities for sea level and temperature extremes. We can't get down to geographical and temporal detail. We can't tell you in the year 2010, it's this, or in this region of the world, it's going to be that. But we-- but we can define the range of possibilities.

But we've got to work on these, and work very hard. And it's going to take, I think, one or two decades before we're at a stage where we can say we can do this rather well. And that assumes that the system's not chaotic or-- you know, that there are unpredictable components, and that we-- that then it's beyond us to do serious prediction. And we'll still be talking about ranges of possibility.

The other thing is we do need these climate models, because another important thing that needs to be done is predictions have got to be done in these climate models addressing alternative scenarios for future development. And that activity, you know, here are some very important activities that we can talk about, human activities, energy, and energy, fossil versus nuclear, transportation, fossil versus hydrogen, agriculture, rice versus wheat, forestry, growth versus clearing, wetlands, creation or destruction. These, all of them, have serious effects on, you know, the climate forcing parameters

So, we've got to have models that are also efficient. You can run them in many different scenarios, as well. We have models that can do that. The point is, at the moment, of course, these models are not fully believable. But they're there, so. As I say, I think there are things we can say now that I think can be used for policy discussion.

DEUTCH: Thank you. The liberal structure of this workshop is to take us from the place which we are most uncertain and unsure about, which is the scientific and technical, and then bring us back to the area where there's greater certainty, greater [INAUDIBLE] with this policy. So we will now take a 15-minute break. And I ask you all to return by 10:45 for our next section on economics and mitigation.

DEUTCH: We are very fortunate to have my friend, Bob Fry, if I might say a great American, who's going to tell us about the influence of these matters on the environment, and the like. Bob.

FRYE: Thank you, John.

DEUTCH: This, Jess Ausubel gave me.

FRYE: I'm trying to figure out whether the physical scientists can predict what's going to happen with client change-- climate change. And I think, the purpose of this session is to ask a rather different question, which is who cares if they can? Because, as someone noted earlier on, Dick, I think, that if all that really happened was that the place got a little bit warmer and zero happened, this might be a relatively uninteresting phenomenon, because relatively few costs would be imposed on society by that simple phenomenon.

But as, again, someone else, Lester, someone noted, that's not what happens. What happens is that there's a series of effects that takes place in consequence of climate change, should it occur, on the natural and environmental resource systems on which society depends. And a certain amount of work has gone into trying to suggest what some of those changes in those systems might be.

And I listed on this slide a kind of synthesis from the IPCC and Academy reports of the categories that people worry about, when they're worried about the underlying systems that might be affected by climate change, and could impose a cost on society. And that's the last you're going to see of this list, because I'm not going to try and go through and paint for you a scenario of what I think sea level change is going to be, or agricultural production is going to be, but rather try to take a somewhat more general approach.

The interest, as I say, is really getting some sense of what the costs that climate change might impose on society could be. And as Lester has already pointed out for me, the sequence of events that one has to go through to get a sense of those costs are shown on this chart. First, you have to understand what the effects of climate change might be on these natural resource and environmental systems on which society depends.

You have to understand what the impacts of those systemic changes would be on the marketed and unmarketed services provided to society by those resources. And, then, you have to understand the adaptive response to those impacts. If the impacts are adverse, one can expect that society will try to do something about it. What one of my colleagues calls the dumb farmer syndrome. Farmers will not keep planting the same crop after 27 crop failures. They'll do something about it.

[INTERPOSING VOICES]

FRYE: And-- unless-- unless, of course, unless-- unless--

[LAUGHTER]

SPEAKER: Wrong.

FRYE: There is-- there is--

SPEAKER: Wrong.

FRYE: Admittedly, if it's corn, I may be wrong in this case, but it's-- and clear-- and, clearly, we know if it's sugar, it's wrong, right?

SPEAKER: Yes.

FRYE: But other than that-- in a-- in the conceptual and reasonable world in which economists believe, this is what happens. I hasten to add that I'm not suggesting that the answer to climate change is adaptation. That is a theological, not a policy question. I am only indicating that people will respond to impacts. To change them, if they are adverse. To enjoy them, if they are not.

Now, in the spirit of this meeting, I will quickly point out that, of course, we don't know enough to estimate these costs. We don't know enough, in part, because we don't know enough about the climate, how it's going to, the magnitude of the change, if any, and the regional distribution of it, which is the direct cause of effects on the underlying system. But we, also, add that we don't know very much about the mechanisms by which these impacts develop and produce costs or benefits, much less the mechanisms of the adaptive response.

And, unfortunately, these mechanisms tend to be local and regional, not global. And, so, it takes a lot of work to figure out what they are. Well, having started out by making the requisite bow to our lack of certainty, what can we say about some near certainties in the business of impacts and adaptive response?

I think one can say a few things, at least, I'm going to venture a few things, not about specific levels of sea level rise, a little bit about where some of the larger risks seem to me to lie in the system, and where some of the less large risks lie. Just reading the literature, I come up with kind of these conclusions.

The impact on unmanaged systems and unmarketed goods, you know, environmental amenities and like, are more likely than not to be among the largest risks that-- of a potential climate change. In large part because these systems tend not to have-- many of them, not to have the ability to respond adaptively in the presence of a rapid change.

And the ones that are at most risk are the ones least able to adapt, ones whose time constant of change is less than the rate of climate change, whatever that turns out to be. Systems that are isolated, arctic systems, wetlands, that have no place to go, in effect. And, therefore, can't do much about an adaptive response.

And, a complicated thing, I must admit I don't understand too well in ecosystems, where a few species that may be subject to particularly sensitive climate change, and which perform important ecological functions in the active system, if they go, the whole ecosystem goes, even though the rest of the system may not be particularly susceptible to change. Now, this is not to say all this is going to happen. This is just to say that if you think places like this exist, then probably the greatest risks exist there. The same thing--

PRINN: Can you give us an example of a place where you think there's a limited range of species?

FRYE: Well, just recalling something from one of the-- it's not my field, none of this is, that's why I'm here, of course.

[LAUGHTER]

If a few plants are responsible for nitrogen fixation in an ecosystem, those plants happen to be particularly sensitive to climate change. They go, the nitrogen fixation goes. And the rest of the ecosystem could be adversely impacted, even though, for all other purposes, the rest of the species in the ecosystem might be largely unaffected.

The same kind of principle actually applies in terms of assessing risk to societies. The ones that are least able to do something about climate change, if it's adverse, and if it occurs, are the ones that are at greatest risk. Pretty obvious point, but not unimportant for policy.

Ones that depend on resources that are operating at their biological margin. The Sahel being an example of that. Ones that just, basically, have a low social resiliency, because they have weak economies and lousy technological infrastructures are not in a position to do much about climate change, if they should be.

Economies that depend on one or two resources, which might be affected by a change, or which exist only in one fairly homogeneous climate regime, could be more effected, and are at the highest risk. Again, I say, these are where I think one can conclude from the literature the risks lie. Whether the risks are large, depends on your assessment of how large the climate change might be, and what the nature of the driving effects might be.

In the case of managed systems, by which, I mean, things like agriculture, and silver culture, done to grow products for fiber purposes, water systems that are under human control, and so forth, one can make this statement, I think, and that, which is much more heads than it may look, it is that the economic services from these managed systems are relatively robust, it seems to me, in the presence of moderate climate change scenarios.

And this is because, almost by definition, these managed systems are capable of some adaptive response. And that adaptive response can be very powerful. We've done some work at RFF on a pretty detailed examination of all of this in the Midwestern United States. And in the case of agriculture, which is the most important single industry in the Midwestern United States, it's pretty clear that relatively inexpensive adaptive responses can maintain the aggregate level of agricultural production at pretty much what it would be in the absence of the presence of climate change.

But this isn't a magic bullet, for several reasons. One is that the nature of the adaptive response is regionally variable. Just because it works for agriculture in the Midwestern United States, doesn't mean it's going to work in India or anyplace else. You got to work that out separately for each region. It's also true that these responses bring with them their own cost. And it may be more costly to do something about an impact than just to suffer the impact.

In the case of the Midwest-- again, there's a small band of forest in southeastern Missouri, which is operating in its biological margin. And if you assume a fairly modest climate change, it undergoes fairly traumatic change. It's uninteresting economically. And there just simply is not any economic motivation to do anything about that change. In some forests, there would be. But, in that case, the costs clearly exceed any possible benefit.

Another important point to realize that, even if the aggregate change in economic services provided by these managed systems, as I call them, is trivially small, there can be large intra-regional impacts which carry a cost. For example, again, to use my Midwestern example, the water resource in the Midwest can be rearranged to meet-- provide most of the required services in the presence of moderate climate change, except for navigation on the Missouri River, which is no big deal.

But to do so requires reallocating rights to use the water to the highest economic value, which requires substantial institutional and economic change creating winners and losers within the region, even though the aggregate service is not particularly effective. So you can't operate at kind of an aggregate level, and see all of the costs.

Well, what does all of this tell you? If anything, all of these sort of anecdotal semi-certainties, a term of art I've discovered in the economics profession, what is all of this tell you about policy? Well, it suggests a couple of things that I'll throw out for further discussion. First of all, it seems to me to suggest a series of possible no-regret strategies that haven't been much discussed. I mean, maybe ice, as I said earlier, I don't spend a lot of time at climate meetings, but it seems to me a lot of times no regrets means energy efficiency.

However, if you look at the problem some societies have today with climate variability, the extreme events in climate today, and try to increase their resiliency to existing variability, you've got a strategy that meets the duck test. It walks and quacks rather like a duck.

Because these existing vulnerabilities have costs quite unrelated to climate change, which may be worth reducing. And it may be worth making the northeast of Brazil, a semi-arid region subject to drought, more economically viable for a lot of reasons that have absolutely nothing to do with climate change. I can assure you the Brazilians think so at any rate.

It's also true that existing vulnerability to climate variability is highly correlated with risks of climate change. So that by reducing-- increasing resiliency to existing variability, you, in effect, buy an insurance policy against future climate change, much like the mitigating no-regret strategies are intended to do. So it has many of the same characteristics.

The kinds of strategies that one might include are research to produce the technology that's necessary to make the adaptive response more vigorous, institutional reform that lets-- that responds, move forward smoothly. My water resource example in the Midwest, one might try that in California, as well. It's also, it seems to me, true that economic development, making poor people richer, is an important no-regrets strategy.

SPEAKER: That's a major contributor in the IPCC to emissions.

FRYE: Making poor people richer, yes, there is a trade-off. Nevertheless, you know, it's something some people would like to do. And I think, if you took a vote on it, we'd lose, Okay? Most people want it. And technology cooperation between North and South being developed and developing becomes a major, I think, a major kind of no-regret strategy in this context, because technology is going to be important to improve the adaptive response at a relatively-- at a lower cost than it might otherwise be.

One last point that we've already talked a little bit about, but I think is worth emphasizing is based on the theorem that scientific research is a black hole for money. And-- and, it seems to me that analyzing the consequences of climate change, as somebody has already said, can help identify the things that are most important for the scientists to tell policymakers.

A list of candidates, if CO2 fertilization works out in the open the way it does in the lab, that is an important phenomenon we ought to know something about it. We don't know much about how these unmanaged systems behave. And, although you can speculate, the risks are high. We've talked about extreme events already.

That's particularly important in understanding the potential impacts of climate change, because you can think of climate change as just more and better extreme events. And regional distribution, though, not necessarily of temperature, to some degree of precipitation, but what really drives the water equation is the factors that effect evapotranspiration. And that's an important thing, I think, some folks would like to hear about, although that requires predicting cloud cover humidity, and so forth.

So, it seems to me that further work on some of these impacts and adaptive responses has some utility in identifying useful short-term policy options of the no-regrets character in driving the other research to give it some coherence. And, happily, and even more happily after listening to this morning's discussion, a certain amount of this work can go on without the physical scientists and climatologists telling us, you know, what's going to happen.

Much of this impact work can go on an scenario, in sensitivity analysis basis for these kinds of purposes. Not to predict the future, but to help policy along. I'll answer some clarifying questions before turning it over to Brother Nordhaus.

YEAGER: Yes, sir. I can't help, Bob, but-- I know it's not your term, but, as I travel around the world on this topic, I run into it a great deal, and that is a negative connotation that is either written into or accepted about the term no regrets. The policies, themselves, what they mean, I think, arguably, are very positive. But the tone of the term is one that does not play well. It plays very much into a certain amount of arrogance perception that the world might look on the United States as having. And I wonder if there's any effort to perhaps re-coin that phrase in a manner that would be more supportive of the strengths of the policies?

FRYE: Ask somebody who is more into the-- I mean, I may be a year out of date. We're gonna hold a contest for a new term.

[INTERPOSING VOICES]

YEAGER: It's just an observation.

[INTERPOSING VOICES]

YEAGER: It seems that we tend to shoot ourselves in the foot a little bit by using that kind of analogy.

[INTERPOSING VOICES]

FRYE: Whether it's the term--

SUNUNU: [INAUDIBLE] the effort was to get rid of no regrets. I think there's a return to it coming back, now that I've gone. I didn't like it either.

SPEAKER: It's hard to find a good alternative though.

SPEAKER: The alternative I want here at most is some kind of have insurance notion, except it doesn't really fit classical notions of insurance.

[INTERPOSING VOICES]

SPEAKER: It's awful. I don't like it. Yeah.

SPEAKER: Like that--

SPEAKER: I like Duane's expression-- low hanging fruit.

SPEAKER: Well--

SPEAKER: Low hanging fruit--

FRYE: Kurt makes an important point here. I mean, it's not just a semantic problem. It is an attitude that sometimes comes through--

SPEAKER: How about just low cost?

FRYE: Yeah, low cost might do it, but an attitude that sometimes comes through, it seems to me that, let's do something for our sake, that is the developed countries' sake, without suggesting that there's anything in this for 90% of the people.

YEAGER: Well, the term that I-- that I used in this, which seems to work out a little better, is sustainable policies, because, really, when you're getting down to it, you're looking at things which play to the issues of sustainability.

FRYE: There's a term we understand.

YEAGER: We agree that sustainability is entered into the connotation, why not play to the strengths of that, because it seems to me, that's what no regrets means. Let's do those things that are-- make sense in their own right in the name of moving the globe forward.

DEUTCH: Duane?

LEVINE: Well, if you had a matrix which was lower cost, higher cost, lower risk, higher risk, wouldn't this be in the 1-1 box? It's not just lower cost, it's also lower risk, isn't it?

FRYE: It's lower cost in an incremental, marginal sense. I mean, you're not paying extra for the coproduct of protection against climate change. It may be-- economic development is a very high cost policy up front, but from a climate change standpoint, it's low cost, and it's intended to both mitigate even and adaptive kind of policy, [INAUDIBLE] but are intended to reduce the highest potential risk, potentially.

LEVINE: Whatever you call it, I submit that it's lower cost, lower risk.

DEUTCH: Lester?

LAVE: I think that the discussion of the term sort of forgets the fact that [INAUDIBLE] like this, just like Chiefs of Staff, have a very finite half-life. That is that the term begins to get some [INAUDIBLE] factors built into it. There's nothing wrong with the term to begin with, but over time, it accumulates some bad baggage that goes on. And it's like [INAUDIBLE].

SUNUNU: I didn't know it was the term Chief of Staff that had a finite half-life.

LAVE: Just the incumbents.

DEUTCH: Bill?

NIERENBERG: Well, I want to go off the semantics. May I?

DEUTCH: Yeah.

NIERENBERG: The question of agriculture, your points are all very well made, but in the adaptation question, you didn't talk about the possibilities of the advances in technology. And let me explain-- the one area that I find very interesting are the agricultural sciences. And the reason I find them interesting is invariably in a group like this, that science is very poorly represented.

And just to give you a number of what can be done is doing in the case of corn. The yield of corn, for about the last 70 years, has been going up pretty steadily at 2% per year per acre. That's the actual yield. And there's no sign of its really decreasing. The-- I've forgotten the exact number, but corn changes so rapidly, let us say the improvement of varieties, changes about every three years in this country. And that's a kind of an adaptation automatically out of the choices the farmers have.

Now, I say that, of course, because another example-- this goes back to us oceanographers about 25 years ago, when we first got seriously interested in global change. We had coffee talk. Fortunately, noe of it was published. That came later and caused a lot of trouble. And one of them was amateur economics that, with global warming, the corn line would grow northward. It would have corn in Canada and in Russia, and they'd beat the hell out of us economically.

Of course, what's happened is quite independently-- it's amateur, as I said-- quite independently of global change, the agricultural people have been and are still developing corns that are moving northward at a very rapid rate. And in fact, to date, Canada is growing corn and selling it. Russia is not, presumably for other reasons. And that's a technological change that so overwhelms any climate change that could have taken place in the last 70 years. It's extraordinary.

FRYE: I didn't use it because I didn't take time to use this picture. Here is the yields per hectare in tons per hectare for dryland corn in the Midwest. The case A is the 1951 to 80 baseline average. The next bar is what happens in the presence of technological change without climate change. The yields will probably get considerably better.

The next is the analog climate in this case is rerunning the Dust Bowl, which is not all that different in 2030 from what the IPCC report has for 2025. And then these are the responses that could take place. I mean, this is no dead sent. This is why CO2 fertilization is important. If it happened, it does have-- on crops, it can have a significant restorative impact, and then these adaptations are in management practices and technology, some but not all of which are listed on the page.

DEUTCH: Rafael.

FRYE: And so forth.

BRAS: I just want to add that what you say is absolutely correct, but the rate of yield increases per year has gone down. It is my understanding that the average-- the last number I saw-- was on the order of 1% a year in the United States, for across all crops. Which is--

NIERENBERG: I'm talking about corn.

BRAS: No no, I know, but don't limit it only to corn. And the other thing that I have seen is that they yield production of some other crops-- for example, rice in other parts of the world-- has in fact, the yield increase have in fact gone negative. And a lot of it can be associated with regional environmental impact.

NIERENBERG: I'm talking about the United States and the science.

BRAS: So no no, but what I'm arguing is that--

NIERENBERG: Don't spoil my point. My point isn't the specific example of agriculture. It's the one I happen to know. What I'm trying to say that in making these future estimates, we have to take account of technology improvements in general. Not just agriculture.

BRAS: Absolutely. and I'm agreeing with the point except to say that technology is beginning to see that the incredible strength of technology on increasing yields is beginning to see some braking for a variety of reasons, which I don't necessarily understand, but it's certainly happening in parts of the world.

DEUTCH: I would like to ask you a question if I could. Is there anybody who has made the effort for making a quantitative estimates of what some of these connections are? That is, somebody who goes and he takes a regional global model output for a change, let's say, in the northern hemisphere or in the United States, and then really tries to quantitatively characterize what these impacts are going to be.

FRYE: Some have tried it, and probably some here know more about that than I. Martin Perry in the UK has done work in agriculture. I'm sure others others have done it. We have done this integrated assessment of agriculture, water, energy, and forests in the Midwest. You don't kind of get a simple one number answer.

DEUTCH: No, I understand that. I'd expect [INAUDIBLE] the points been made by several people-- that's really sort of what you care about if you want [INAUDIBLE] economic and--

FRYE: Early on, I think it's safe to say that a lot of the predictions of what would happen if the climate change of impact were-- what happens if you instantaneously imposed a future climate on today's world, without taking into account the fact that this phenomenon happens over time. During that time, the world changes anyway, technologically, as Bill said. There are interactions between water and agriculture [INAUDIBLE] sorted out.

We now-- we have a rudimentary idea of how to do that. It's not-- it's hardly an exact science, although compared to what I heard this morning, I'd feel better about it.

COOPER: The adaptation panel of the National Academy of Science panel on greenhouse warming had the initial assignment of trying to do that. They did not, in fact, do it. I don't know why, exactly. I assume because they decided it was too hard. Their fallback position was to give a series of illustrations-- historical illustrations-- of adaptation to major changes that have taken place. So it doesn't answer your question, but it sort of gives an idea of how societies have adapted to major changes in the past. Quantitatively.

FRYE: [INAUDIBLE] candidates-- even if you could calculate that aggregate agricultural, global agricultural production wouldn't change, let's say. The regional and inter regional effect--

DEUTCH: Robert, I understand. I understand conceptually, how to classify this. The question is [INAUDIBLE] work.

FRYE: There are some methods for doing this. They're messy and all that.

MACDONALD: Yes, and there are some really quite interesting studies combining lab work and looking at specific regions. I'm thinking of the work of Tony Hall at Riverside, looking at the Central Valley of California, and looking-- in the lab work looking both at increased CO2 and increased temperature at the same time, taking into account that most of the increase in temperature is nighttime temperature, rather than daytime. And looking--

FRYE: There's a complicated biological effect that takes place.

MACDONALD: It is. Much of the fertilization effect seems to go away if you combine it with a temperature effect.

DEUTCH: David.

BRADFORD: Just changing the subject slightly, I wanted to find out what-- you mentioned the response of unmanaged systems and I wanted to know whether there's any kind of central catalog or what state of research is on these risks to unmanaged systems.

FRYE: The catalogs I've read are basically the Academy and IPCC reports. There may be others. Mike, you probably know more about this than I.

OPPENHEIMER: Very rudimentary.

FRYE: Yeah, but there's a catalog of what could happen, rather than--

OPPENHEIMER: The closest I know is the book that Yale University Press is going to put out, which lists-- has article by article a bunch of ecosystems that have been looked at. [INAUDIBLE] going to come out this year. Rob Peters is the author.

But basically what's been done are two sorts of things. Either look at these shifts in climate zones that are projected to occur if you accept a certain GCM projection of global circulation of the future. And see where that puts future-- what that does to future places, natural ecosystems could exist based on their temperature and precipitation or soil moisture adaptability, versus where they are today.

And it gives a measure of how far they're going to have to move if they were going to move in the space of 50 or 100 years. The other thing that's been done is a somewhat more complicated look which realizes that ecosystems are not just determined by temperature and soil moisture, they're determined by a variety of ecological interactions, and attempt to model those interactions with, say, forests.

And the modeling is rudimentary, but what it comes out the bottom line is that if warming rates exceed about a tenth of a degree per decade, that large scale changes are going to happen in natural ecosystems, and catastrophic changes in some systems.

DEUTCH: Harold.

BROWN: Has anyone looked at history to see what the regional changes and the effects on the ecosystem have been over the past 1,000-- over the 1,000 years before 1750, and compare them with what people think the eco- changes as a result of global warming are likely to be? It's not a fair comparison, it may be more sensitive now--

FRYE: [INAUDIBLE] and I suspect you could only make that comparison fairly for unmanaged system. Because with the Industrial Revolution, and then--

BROWN: Well, you could argue--

FRYE: The cultural revolution [INAUDIBLE]--

BROWN: You can argue you can argue that management gives you a much more capability, you can also argue that you've made it more fragile. I don't know what [INAUDIBLE].

FRYE: You could make gee whiz statements like the following-- the red winter wheat in the last 50 years has spread in the United States in this growing area over a larger temperature variance than is predicted for climate change. Gee whiz.

BROWN: What about the unmanaged systems?

FRYE: That-- I don't know. Somebody else--

OPPENHEIMER: You're asking how they respond in the past to natural climate variation versus what's projected in the future.

BROWN: Well, what's imagined in the future.

OPPENHEIMER: OK, well, yeah. There has been some work. The problem is that since the retreat of the last glaciation, the sorts of variability that you get climatologically over extended areas is not-- is smaller than what's being projected for the future. So there's a limit to how it informs you if you accept the projections.

COOPER: No, but let's take Europe between 1700 or 1650, the Little Ice Age, and 1800.

FRYE: Right, which is pre- carbon.

COOPER: That was that was a indiscernible temperature change-- rise-- and Howard's question is, what do we know about what happened [INAUDIBLE].

OPPENHEIMER: Well, We know, for instance, things like, vineyards moved out of England. You couldn't grow them there anymore. And people moved out of Greenland. And--

COOPER: But that was going in.

OPPENHEIMER: Oh, [INAUDIBLE] in and out.

COOPER: I was talking about coming out.

OPPENHEIMER: Moved in and a lot of them too just died there. It got cold. They were trapped, in face. So yeah, there are records of those sorts of changes. In terms of unmanaged ecosystems, yes the data is there, I don't know what to say about it off the top of my head. The trouble with that event is, of course, it's relatively restricted in some sense in terms of what we know about it, to the North Atlantic base.

COOPER: But people were a lot less mobile, too, so it's relevant.

OPPENHEIMER: Yeah, there's a lot of data there. Yes.

FRYE: And I think it's important. These are interesting questions. I simply want to make a favorite point of mine, that-- well and good, but if you consider the fact-- I think this is the right number, but it's close-- five of the 10 largest natural disasters in recorded history wiped out Bangladesh. And killed a zillion people.

It strikes me that worrying about the impact of sea level change in Bangladesh is, if you're worried about Bangladesh at all, is a rather less urgent problem than the one you've already got. And there are some strategies that if you're worried about those effects, there are some strategies one could debate that might produce some benefits and also be useful for climate change.

DEUTCH: Tom.

LEE: Bob, I was very happy to see you-- on your slides, you said some of these research studies can be done without the scientific uncertainty being resolved. It's my general feeling that we do not support impact research anywhere near enough in the United States as we support scientific understanding. When you mentioned Martin Perry's work, Martin did that work in [INAUDIBLE] when I was there on the-- it's an impact study on climate change and agriculture.

And there were some American scientists also worked there, and those people who came back and recently told me that they're just having a hell of a time finding support for impact research.

FRYE: I run a social science research institute and you're asking me if we spend enough money on this stuff?

LEE: No, no, no, I'm making this general comment that for the impacts, that it is possible to do some of these studies without having all the scientific knowledge on rhia global change.

FRYE: What you can do is use known climate records where there was a stress as an analog climate. That's one possibility. Once you've done enough of that, you kind of learn what the sensitive points are, you can use a much simpler scenario. You're not predicting the future. You're only trying to identify what the risks are, and what policies might be robust [INAUDIBLE]

LEE: What I'm really urging is that we consider more efforts in the impact research.

DEUTCH: Except that John has just looked it up and he says that it looks like there's about $140 million of the billion he was talking about going into this. So it's not--

SPEAKER: Areas in which this could draw.

DEUTCH: Yeah, environmental and ecological impacts. It's not trivial.

[INTERPOSING VOICES]

DEUTCH: Sorry, sir?

FRYE: The impact research takes up the whole billion dollars, and I don't believe that.

SUNUNU: It's a billion four. It's a billion four, in the whole budget.

FRYE: The budget. Oh, I'm okay, I was talking about last year.

DEUTCH: Lester?

LAVE: 10 years ago I was asked to write a paper given a climate change, which was what was then believed to be a doubling of CO2, to write the most optimistic and pessimistic scenario that were reasonable. And what I came out of that was that basically what they had to do with was not technology at all. What they had to do with human actions that took place.

If you were looking at the human part of it-- I'm not dealing with the unmanaged ecosystem-- but the human part of it, the pessimistic one is that climate change leads to regional conflict, to civil war, and to strife. Not to people starving, but basically it gets to, a have not a small country which gets poorer and decides to use some suitcase nuclear weapons to even up the score a little bit, or to get what they want.

The optimistic scenario is a scenario with more solar energy, with some carbon.

SPEAKER: It's a bit optimistic.

LAVE: We know that there are certain types of plants that will be benefited by this. Other types of plants won't. In my optimistic scenario, people don't insist on eating rice. They're willing to eat any cereal. And in that kind of a world, you can clearly grow more. You can have more agricultural output that takes place. I'm not talking about any necessary technological change. What I'm saying is, everything really comes down to human adaptation.

Does this climate change stress society so much that we're at each others throats and wind up blowing each other up, or do we use it in such a way that we're able to really help each other and do much more? That's got much more to do with what we're talking about. For the 100 million, I have as a researcher a reaction-- I'm sorry about this-- to the bureaucrats thing of saying, oh, don't worry about adaptation, it's in our budget.

I really heard that in Washington for a long time. And it gets me to be very non-rational and uncool. Because the problem with this is that, yes, there's some money being spent. But it doesn't get at the essential issue I'm really hard-pressed when the bureaucrat says, it's in our budget here, don't worry about it.

SUNUNU: The uncool part was asking the question whether there's any money for it.

DEUTCH: I was the one who did that. I just said, I thought that [INAUDIBLE] that there was a remarkably small fraction of the $1 billion, most of it going to NASA to make measurements, but a small part of it would be even conceptually in this problem there, and it turns out not to be the case.

[INTERPOSING VOICES]

SUNUNU: If the budgeting isn't important, that can always be taken care of. Just just tell.

DEUTCH: Jesse.

AUSUBEL: Yeah, let me say a word about the impact's research, and then I'd like to turn to some of the other more substantive questions. But there are real problems in the impacts-- in conducting the impacts research, and having been one of the first people involved in trying to do it in the late 70s. NASA really wanted to use the impacts research as a marketing arm for its satellite programs.

They really wanted horrible answers to come out of the impacts research. And when the people--

SPEAKER: That was EPA.

AUSUBEL: Well, then EPA in the early '80s began to produce some of those numbers. But by that time, it was a somewhat different story. But you have a situation where on the one hand, parts of the government and not just in this country have a very strong interest in people-- in turning out very scary so-called impacts studies, which will justify the rest of the program. At the same time, in a certain sense, the impacts and adaptation research is taboo because people are afraid that if you do the adaptation research and find any reasonable adaptation, that it will discourage discussion of prevention of emissions.

So there's-- it's been a it's been a very difficult game right from the beginning, which I don't think has been successfully navigated in this country or in others.

DEUTCH: I think everybody's in agreement that it is an important area for research, and that it is an important subject, which is the point that you've made. I don't think anybody [INAUDIBLE] want to get into analyzing whetehr the federal budget is being properly allocated on, but it is an important subject, it seems to me, because it really is a damage function for this, has been pointed out.

AUSUBEL: It's inherently very political research, and has been right from the beginning. But let me turn to the substantive question, which I think-- and Bob described very effectively-- let me first ask Bill Nordhaus, are you going to say anything about adaptation, or just about-- okay, so then why don't I wait, and see what [INAUDIBLE].

DEUTCH: Bob White, do you want to say something for us?

WHITE: Yeah, it was mentioned here that unmanaged ecosystems, which everybody seems to agree may be the most vulnerable to climate change-- managed systems of all kinds being less vulnerable can adapt to a rate of change pf about 1/10 of a degree per decade, translated to one degree per century, which has now gotten built in to the IPCC views, and it's now become scripture that what we want to do is to constrain temperature increases to no more than one degree centigrade per century, which then impacts what you want to do about CO2 emissions and other greenhouse gas emissions and other ways of mitigating or adapting to climate change.

Where do these numbers come from?

OPPENHEIMER: I think I can answer that.

WHITE: And how valid are they that they've now become scripture and we're now basing our entire policy on these CO2 emissions based on this number of 1 degree centigrade per century? Can you answer that?

[INTERPOSING VOICES]

COOPER: If I can just add to the question, what requires that currently unmanaged systems remain unmanaged?

[INTERPOSING VOICES]

OPPENHEIMER: That's a very important point, the extent to which you can manage success [INAUDIBLE] create a halfway situation and manage natural ecosystems into survival. But let me put that aside. Just historical point, at the third or fourth [INAUDIBLE] conference in 1987, Bill Clark pulled together a working group of people that included a bunch of ecologists, like Margaret Davis from the University of Minnesota, to ask the question, if you look at mid-latitude forests, what sorts of rates of temperature change would be consistent with the ability of those forests to continually replace themselves at continually more northerly latitudes, based on what we know about what happened during the glacial retreat.

And there's a lot of data about what happened during the glacier retreat, and that working group put together that data, and came up with the notion that if rates of change-- global temperature in those latitude regimes were faster than about 1 degree per century, you could not argue that the forests were going to be able to replace themselves successfully in the north. At three degrees, it was clear that there were going to be catastrophic changes in forests, and then there was a gray area in between. So this one degree comes out as sort of a lower limit safety factor on how-- at what rate of climate change it is expected that the northern latitude-- the mid-latitude canopy forests can sustain successfully. That was the basis of it.

WHITE: So it's forests, it's canopy forests, it's mid-latitudes. And now we've adopted it for global aggregate temperatures.

OPPENHEIMER: No no no, then it was taken-- then the Dutch Environmental Ministry at another working group that was put together looked at and developed a few more ecosystems, and got respectability because it seemed to apply to more than forests. I can point you to the reports. It's a crude number, obviously. Yeah.

DEUTCH: Thank you, Bob Frye. Thank you very much. You want to oay a special attention to Bill Nordhaus, who's an ex-provost, who's about to speak. Deserves careful attention. He's actually from Yale. We have two ex provosts from Yale.

SPEAKER: We have even one from MIT.

DEUTCH: He always deserves--

SPEAKER: Like Chiefs of Staff, they also have a finite half-life.

SPEAKER: But they like going back [INAUDIBLE].

NORDHAUS: Do I need this? Do I need this? Is this [INAUDIBLE]?

OK, well I think Bob's-- what Bob did is a very good introduction for what I'm doing. He hit some of the major points of background and overview. And what I'd like to do is really a couple of things. First, say a word about the economic approach, approach that economists would take or are taking in thinking about the policy issues of global warming. And I'll talk about the two halves of the-- the two partners in the dance, the impact side and the cost side, and then I'll end up with what happens when you put the two of them together.

So first, let's just say a word-- just, I think most of you know this, but I think it will motivate we're I'm going to go. If you ask an economists to think about the economic and policy aspects of global warming, what he or she will probably do is say, well, okay, first, we have to understand the physical side of things. What are some likely scenarios? What is likely to happen over the relevant time horizon? We've already talked about that.

Then we'd want to talk about, secondly, the likely impacts of these changes on things we care about, and the adaptations that we can make, or that we will make, to the climate change-- again, some of the things that Bob talked about a few minutes ago. Then we'd want to understand the kinds of policies that we can take to, say, slow climate change, and there are wide variety of those. And we'd want to find out what the costs of these different measures would be. And then in the end you'd want to put these together, and if you were, say, doing a dynamic cost benefit analysis, you'd want to ask, what kinds of policies make sense, in the sense that the ones whose benefits of taking these outweigh their costs, and at the margin for the last little steps you take, the incremental benefits of those are not outweighed by the incremental costs.

So that, just in a word, is how an economist might think about this. So this will focus you on a certain class of issues. You don't-- you won't try to study everything in the area, but you want to understand a little bit about the scenarios, you want to look on the impacts, you want to look at costs, and you want to put them together.

Now, so what I'm going to do is go through and show you some graphs which will give an idea of what kinds of things people looked at. So first, let's start with costs. And again, what do we mean by-- the cost side of this would be to ask, what would it cost to, say, reduce greenhouse gas emissions, CO2 emissions, or take other kinds of steps to slow global warming?

And this is a graph that came out of the-- it's unfortunately not quite going to fit-- well, it's close-- that came out of the recent National Academy study on the policy implications of greenhouse warming. It came actually out of the mitigation panel that was chaired by Tom Lee and had Dick Cooper on it.

What it has on this graph is first on the horizontal axis here is emissions reductions, and this is for the United States. And these are in-- this is a kind of-- this takes what's happening roughly now. It isn't a projection in the future. And where emissions are roughly 8 billion tons of CO2 a year, this uses unfortunately, CO2 rather than carbon, but that's the way they chose to do it. And on this axis asks the costs of reducing these emissions. And again, the unit here is dollars per ton of CO2 equivalent, CO2 weight, how much it would cost reduce these emissions at different steps.

Now, there are two-- now the reason that put this on is there are basically two approaches that have been taken to measuring the costs. One is what's known-- I call the engineering approach, and the other is the economic approach. The engineering approach is one that's is shown by the solid lines, and this basically is an approach where you go out, you do a census of all the processes in the economy or in the field that are emitting these gases.

You'd ask, are there ways that we can reduce the emissions? What would it cost to reduce those, assuming we did it either in very effective ways or modestly effective ways? And then rank orders those in terms of the most cost effective.

So at the very low end here, the Academy panel found that there were some that you could get-- you could get substantial emissions up to 2-- roughly up to 2 billion tons a year at-- in a negative cost way, that's to say, there were actually net benefits of these reductions. And then after that it was pretty flat. And this is for what I call an optimistic assumption, that you have 100% implementation of the potential in the economy. And then there is a more pessimistic one which uses a relatively higher cost for doing these and assumes that you can only have 25% implementation or penetration of these new processes. So this is one approach.

Another approach which has come out of the economic community is what is labeled here, energy modeling. And it's a very, very different philosophy. It looks at market processes, at supply and demand, if you like. It asks what the emissions are. Then it would build either a very crude or a very complicated model of the economy that includes supply and demand for goods that are emitting CO2 and other greenhouse gases, and then it would ask, what kinds of steps could be taken to reduce them?

The way you usually would think of these is either as regulations or as taxes on energy, or on CO2 emitting goods. And what this shaded region here shows you a-- this is a kind of hand-drawn region as to what the energy models-- the energy models are telling you about the incremental costs of reducing CO2 emissions.

So that's basically what the story looks like. There are obviously big disagreements. And I think the big disagreement comes in this region. It's apparently a big disagreement, where the engineering approaches identify a substantial amount of negative cost or low cost activities, whereas the economic models, by their assumption-- in this class of models; there are some that go beyond this-- in this class of models, rule out the negative costs region.

SPEAKER: The negative cost ones are all energy conservation issues.

NORDHAUS: No. Negative costs would be something like-- an example that is used, actually, in these numbers, would be the high efficiency light bulb. They're not literally ones that are negative cost. They're ones-- I think a better way to think of them is very high yield. So our rates of return--

[INTERPOSING VOICES]

COOPER: They are not negative cost. They yield-- I think those charts are drawn on a 6% rate of return. We also did 10%, and there's no substantial difference, it turns out. So the way to think of the negative cost is that it meets the average rate of return on US capital in the economy today.

NORDHAUS: Well, it's a negative present value.

DEUTCH: But basically in the category of these engineering [INAUDIBLE] energy productivity, energy efficiency changes.

NORDHAUS: Now, there is, I think, a way to think of the difference here. And that is that the engineering studies actually take the current level of economic activity and current capital stock and look for what kinds of reductions that can be made and identified, as I say, maybe-- I mean, different studies come out with different numbers. Almost all of them identify 10% to 20% reductions at this negative cost. Some of them go up to 50%, some of them even higher.

Now, the way to reconcile these is to realize that the energy models, include in them an autonomous technological change, which is an autonomous increase in energy efficiency, at a rate somewhere between a 1/2 a percent a year and a 1 and 1/2 percent a year. So for example, just to make-- show you how those are consistent, take the 1% a year as a kind of baseline for these.

If you assume that you can get 20% negative cost in the engineering studies, that would be consistent with a 1%-- roughly speaking, 1%-- a year over a 20 year lifetime of the capital. So in fact, if you look at the projections that would come out of these, although they're methodologically very different, I've, in my own mind, come to be able to sleep with the differences between them.

SPEAKER: [INAUDIBLE] very different question [INAUDIBLE].

NORDHAUS: No, they're really-- well, they're asking different-- I don't think they're asking different questions. I think they're asking the same question, but the but the engineering studies are more static in nature, and more micro in nature, and the energy models-- well actually, they vary. Some are very aggregate, and some are quite micro. But these basically are more equilibrium models.

SPEAKER: I don't think that's correct.

SPEAKER: [INAUDIBLE] vague ending there, Bill, The top curve? Is that your way ov vaguely ending the curve?

NORDHAUS: No, this actually-- this came out of the Academy panel. I don't remember why--

SPEAKER: The top [INAUDIBLE] come down at the end. No, no, the other one.

[INTERPOSING VOICES]

NORDHAUS: This one? Oh no, that's basically a truncation. This was--

DEUTCH: Bill Hogan, did you want to ask a question about this [INAUDIBLE]?

HOGAN: Clarify, because I'm now confused on my understanding of Dick's-- Cooper's summary of meeting the test of average return on capital. And there's another phrase was, and are not being done, is the definition of these things here.

NORDHAUS: I think that-- did Dick say--

HOGAN: He didn't say that. I'm adding that.

NORDHAUS: No, I don't think that's right. There are things that are potential in the economy now that have not been done, but that doesn't mean they're not being done or will not otherwise be done in the next 20 years. And this-- the engineering report actually doesn't ask whether they will be done. And that's-- as I say, that's the way you can reconcile them with the-- now, I don't want-- I want to-- I have a few things I want to do.

HOGAN: Then the implication is there's no policy required to do it.

NORDHAUS: Well--

SPEAKER: We didn't say that.

NORDHAUS: No, they certainly did not say that.

SPEAKER: If you wait long enough, that's correct. And the question is whether you can speed it up. And timing is critical in this area. I mean, everything is about timing. All the morning was about timing.

DEUTCH: I want to make the observation Mr. Hogan has the floor, and I also should not ask you any further.

NORDHAUS: I want to just-- why don't we have some of the clarifying questions now, substantive questions maybe delay, because otherwise I won't get through two slides.

LEE: Can I clarify this negative cost question [INAUDIBLE], since I was the chairman of the panel.

NORDHAUS: Yes.

SPEAKER: That gives you no particular standing.

LEE: The negative costs that come up with by the conservation people, but basically they are looking at, for example, the fish and light bulbs. You compare the costs you have incurred to buy the fish and light bulbs against the alternative of building new power supplies. That's where the negative costs come from.

NORDHAUS: We could go on all morning on that. Now, one of the things next I'd like to show you is some idea of how much uncertainty there is in the cost area. And this is a survey of what that last graph would have looked like for different energy models, and this is-- there are nine families of models in here that are represented in this diagram. And they vary-- they're very, very different in their construction.

Dale Jorgensen is one of these. He was added late because his model his estimates were done after the original was done. Some of them were done by myself, some were done in Europe, some of them are linear programming type models, some of them are computable general equilibrium models, some of them are just simple supply and demand models.

And what-- I don't know how to take that, how to interpret that except there's clearly uncertainly in the sense that we-- the models do not agree on the exact cost of reduction of, in this case, CO2. I would hope they would not agree, because there are major uncertainties as to the elasticities. But I actually am encouraged by the fact that there's some coherence between the different models.

I should say that one of the nice things about this, most of these, the models were actually-- unlike some other areas, the models were actually done in ignorance of what their-- where they would show up in this graph. Because almost all of the models were done as energy models and not as CO2 models, and basically they added a CO2 module on.

So that one of the reasons I like to look at this is, these are comparisons where the people have not been looking over their shoulders at other models to find what the other models are showing. So I think in a way it does give you a genuine dispersion without the wine tasting problem of people looking over their shoulders asking what other people have found.

Now, a final graph will be one that will show you-- and this is schematic, I don't want you to take this as too much-- too seriously, but this shows you an estimate of the impact on economic growth in the OECD region of different control rates on greenhouse gases and different efficiencies of these controls. And there are basically three families of curves here.

The top one shows you an estimate of taking a middle of the road estimate from that last graph of the costs of reductions of greenhouse gases, percentage reduction here, and what that shows is that actually you can get, according to these numbers, quite a substantial reduction in greenhouse gases at relatively low cost in terms of economic growth, up to somewhere around the 40%, 50% range, after which it begins to begins to curve down.

MACDONALD: What are the assumptions of the use of the taxes? Is this [INAUDIBLE]?

NORDHAUS: These are officially use taxes, they are, say, recycled back in terms of revenues. In the top line. I'll get--

SPEAKER: What does gradual mean?

NORDHAUS: Gradual means phased in over a 25-year period.

GRUENSPECHT: Bill, these are from baseline? They're not concurrent [INAUDIBLE]?

NORDHAUS: Oh, these are from baseline. Yes. But baseline what?

GRUENSPECHT: Baseline CO2 levels.

NORDHAUS: Oh no, these are-- all the numbers that I have are-- you should think of these as, particularly these, as from some baseline path growing at whatever you think it's growing-- 1% a year, 2% a year.

GRUENSPECHT: If you thought that CO2 was going to be doubled at some point, a 50% reduction is just in case it gets you back to where you are.

NORDHAUS: Exactly, so if you thought it was doubling, then 50% reduction would be equivalent to stabilization. Now, the point about this, however, that this emphasizes, is that you can actually get quite different results if you either phase it in more rapidly or if you do it rapidly and you introduce it in inefficient ways. So the rapid tact would be one that tries to get you to some target level of reduction, but does it instead of a gradual way, slaps you with a very big tax in the early years to get to this target reduction, makes you-- so it's when conceptually when you're not rolling over the capital stock and that gets you quite a larger impact on your growth.

And then the regulatory one-- and this actually comes out of some estimates of the lifetime of capital stock-- the last one of this is just a pure arbitrary estimate that says, on the base-- well, it's not purely arbitrary-- but there are a number of economic studies that suggest that the efficiency of existing regulations in the environmental area are such that we're paying roughly twice in many areas what we would if they were efficient. And the top line assumes it's efficient.

So if you assume in addition to do it rapidly, you do it with our average degree of bureaucratic inefficiency, then that gives you actually quite a substantial drop in economic growth in the bottom line.

SUNUNU: Does this curve say that you can get 90% reduction in CO2 efficiency at a cost of 1/10 of 1% of the growth rate?

NORDHAUS: Yes.

SPEAKER: Do you believe that?

SUNUNU: That means you can get an 80% reduction in current levels.

NORDHAUS: That is correct.

[INTERPOSING VOICES]

NORDHAUS: Compounded forever.

SPEAKER: No, no, no, no no.

SUNUNU: Sure it does, if it's based on a scenario [INAUDIBLE]--

NORDHAUS: No no. No, John. Let me show you. Let me just stay with us to be clear. Let's take this number-- it's between 85 and 90. You can get, say, 85% reduction in greenhouse gases. Not CO2, greenhouse gases. At the cost of 1% per year compounded indefinitely.

PANELIST: 1/10 of 1%.

NORDHAUS: 1/10 of 1% compound indefinitely.

SPEAKER: A reduction from--

SPEAKER: It ends up a big number also.

NORDHAUS: So that's roughly 2% to your income after 20 years, 4 and 1/2 percent after 40 years, and so on.

JACOBY: But that's not up to date, that's not reduction so that at the end of the process, we're only emitting 10%--

[INTERPOSING VOICES]

NORDHAUS: It's from a baseline. It's from a baseline.

JACOBY: So if it takes 50 years to get there, you don't know how that relates to today. It's not a reduction for today's level, it's reduction from some undefined [INAUDIBLE].

NORDHAUS: So again, all of these numbers are relevant if there's some baseline.

SUNUNU: That period, 90% reduction takes 20% of today.

SPEAKER: What's the period over which you're getting those reductions from baseline?

NORDHAUS: Well again, those are different, because in the gradual one, conceptually, that's assuming with a flexible capital stock. That basically means you're doing in sufficiently gradual way that you're rolling over the capital stock as you go along.

SPEAKER: So you're not getting--

NORDHAUS: So I think you ought to think of that at at least 20 year, maybe 40 year--

SPEAKER: Replacement [INAUDIBLE] capital.

DEUTCH: I'm sorry, I would like to I would like to put some order on this so I can interrupt. Now, I want to go on to impacts. I have to ask a question-- may I ask you a question, sir? Let's take the case in the extreme.

NORDHAUS: Yeah.

DEUTCH: Where you say you can get 90% reduction from baseline.

NORDHAUS: Yeah.

DEUTCH: Which is something like 80%. Do you really believe that there is a US or world outcome which permits that amount of reduction?

NORDHAUS: I don't know.

DEUTCH: You don't know.

NORDHAUS: I-- well--

[INTERPOSING VOICES]

NORDHAUS: Let me say something. I think that part of the problem with this is, if you go back and ask the database, the database on which we're drawing it is one where you probably observe something in this range, and I actually-- I actually-- it's undoubtedly not appropriate for a careful scientific group like this to go beyond observed data. It's in a way the same kind of thing as projecting 3% growth in CO2 for 100 years. You are into a region where you don't have observations. And that's true here.

DEUTCH: Well, I have a really serious [INAUDIBLE] question about whether such states are realizable at the level of economic activity that are implied. [INAUDIBLE].

DAN: But if you take the engineering approach that Bill discussed at the beginning, and you look at capital stock turning over over time, do the modeling explicitly over a 40 year period, you can show the technologies that you need to put in place in terms of both of the efficiency side and the supply side over that period of time, taking into account the turnover [INAUDIBLE] to get to, say, in the US, a 70% reduction in CO2 emissions from current levels by the year 2030. And we at least calculate that, in terms of net present value, you're ahead. And it's taking the engineering approach.

[INTERPOSING VOICES]

NORDHAUS: So I don't know if I believe them because they're extrapolating way beyond the range of current experience. But some people actually think these are sensible.

DAN: You can imagine a heavily nuclear world in which-- which gets that kind of thing.

[INTERPOSING VOICES]

NORDHAUS: I want to do the impacts, because in a way, that's more interesting, and more difficult.

SPEAKER: Not with US regulations.

DEUTCH: Bill, it's your floor now.

NORDHAUS: So I'm going to-- I'm limited to 20 minutes. I'm not even doing very well with that. So I want to turn onto the second. Turn onto the second question. The cost side actually is much less controversial than the next area, even though you can see here that what I've done is-- has raised all kinds of problems. I have lots of problems with it. I've tried to give you what the sense of the modeling community is telling you-- impacts is actually much more controversial and much more difficult.

So let's first back up and ask what do we mean-- what are we going to mean by impacts? Okay, I think we have a general idea from what Bob said, but let me make a number of comments. First, the impacts damages adaptation area is actually much more complicated, because of the cascading uncertainties. So you have uncertainties-- emissions, concentrations, climate response, then you get down to kind of a fourth level, how would the impact on society, then you have another one which is, how are people going to adapt to that?

So whatever uncertainty, you think you have at the front end in terms of the emissions and the climate, then it's going to cascade and be greater uncertainties down at the other end. So that's the first point. Surprisingly, however, at least in some ways, the uncertainty is not as great as you might think, because we know actually a lot about the impact of climate on economic activity. Because we have enormous range in climate in existing societies. So to some extent at least, we can, for example, know where climate does not tend to be very important, and where it does tend to be very important. And we can focus our research on those areas where, from in existing societies, climates tend to be important.

Now, I tend to sort of segregate things into-- well, let's back up. If you look at the analysis, you can think of two general levels of impacts or concerns-- ones are the non-economic ones, having to do with our views about ecosystems, the natural world, the soul of the coral reef, and so on. I don't think we-- we don't have much, obviously, to say about that as economists. But then there's a second class, which are the economic kinds of activities. And these are-- these fall in two classes-- ones that go through the meter of the marketplace, and therefore you get some societal valuation on these activities, and ones which do not go through the meter of the marketplace, and where your life is a little more complicated.

I should say, the second one-- although it's complicated-- doesn't mean it's hopeless, because environmental economists have spent roughly 40 years trying to develop techniques for valuing things like leisure, things like recreational activities, that don't go through the marketplace, but where people in their own behavior have some ways to reveal the evaluation that they put on that. So that's the first point, is just to realize that there are these three general areas. The first one I don't know how to talk about, the second, which are the two non-economic-- or non-market and marketed areas-- are ones where we actually can make some progress.

All right. Now, then there-- in looking at those, there are basically four ways that economists have dealt with impacts adaptations and so on. The first is a survey. You've asked people what they think about it. I think that's, in this area, useless. And although there have been some surveys, I just-- I think people don't know enough. If you surveyed even experts in this room, you'd probably get some answers that people would go back and think about and change their mind on. I've done some surveys and I've found them completely uninformative.

A second area is, in a way, the analog in the impacts area of the engineering approach in the cost area. And what this does is take [INAUDIBLE]-- and this, you were asking about this, John. There are actually hundreds of studies of this kind. You take a climate scenario. You go and you try to measure some impacts on first physical activities, then on human activities. Then you value those using some device or other. Then you ask, what is the effect on agriculture, on value of coastal properties, on education, on microelectronics, whatever it is, of the climate change.

This is-- now EPA has sponsored a number of this, and this is a survey I did a number of years ago, just to give you some idea of the kinds of things that come out of this. Basically, I divided the economy into severely impacted sectors, moderately impacted sectors, and then the others. And on the basis of the EPA work-- really the farming and forestry were the severely impacted areas. According to the EPA study, the costs of a CO2 doubling was between plus and 12-- plus and minus $12 billion a year in terms of costs and farming, billions of dollars-- 1981 dollars-- national income, on the national income basis.

SPEAKER: This is all US? Just US.

NORDHAUS: This is US only. All of this is only for the United States. And there are-- the differences there have to do with the climate scenario, and with whether or not CO2 fertilization is taken into account. I think this is probably an overestimate of damages because it actually does not allow for a number of adaptations that could take place. For example, it does not-- most of these do not include changing cultivars. They do not include the possibility of introducing tropical crops in the south of the United States. They don't include the possibility of transfer of activities from the non-farm to the farm sector. But that gives you some idea of why we're having-- we're in some trouble in estimating the economic impact.

There are some other pluses and minuses here. I'll just go down to another-- the one where there's I think an unambiguous loss, and no one's come up with any clever reason why it will be a gain to the economy, and that's in the area of sea level rise and the loss of land, and the loss of structures there. But here again, I think you have to be very careful. Some of the early studies had the analog of Bob's dumb farmers scenario, and I'd call this the dumb yuppie scenario.

And that is some of the early studies of the costs assumed that the structures that were in place on the seacoast were basically inundated and lost by sea level rise. And there was no adaptation in the sense of moving them, letting them decay, or some of the coastal policies that we have or where something is flooded, and there's damage that they may not be rebuilt.

So anyway, this will give you some idea. I don't want to really focus on the bottom line of this number, we'll give you some idea that actually there's a tremendous amount of work going on in this engineering type studies for the United States, contrary to my earlier perception. I, like Jesse-- Jesse and I have been thinking about this for a number of years. I actually thought the impacts were going to be much larger than they've turned out to be, but the careful analysis that is taking place in this area has led me to think that people are actually much more adaptive than my intuitive mind set in thinking about this led me to believe.

So a clarifying question.

NORDHAUS: Yeah?

SPEAKER: How much of this sort of thing has been done outside the US [INAUDIBLE]? How much has been done for the developing world?

NORDHAUS: Okay, there's been a great deal of work for the high income countries. We have work on Australia and the Netherlands, Germany, Britain, and so those are the ones that I know. Come to roughly the same. The order of magnitude estimates are that the impact of a CO2 doubling will be between minus 2% and plus 1% on national income. That's the order of magnitude of the numbers that I've seen for the high income countries.

I have not seen careful-- I've seen some, but I have not seen careful studies outside of agriculture for developing countries. There are a number