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watch what will happen in congressional testimony.

4.13 Someone here doesn't understand that trees naturally grow very well out of their competitive range. This is being written from Atlanta, where I'm surrounded by huge Red Spruce (Picea rubens) trees that are found "naturally" only above 5,500 feet here. Remarkably, they can also reproduce in Atlanta, because trees produce microclimates that are suitable for their propagation. Why does Abies balsamea (Balsam fir) grow naturally in Iowa? The distribution of microclimatic relicts is likely to greately attenuate the argument made in 4.13. The warming of 1-4° has to be reduced to be consistent with the SPM--see my arguments above. It should be change to "less than 0.8 to 2.4°C"

4.14 Suffers from the same problem as the previous section.

4.17. After setting up the straw arguments in the previous 4 sections, this one is used to claim that "dangerous" has been reached so that U.N. can mandate a carbon tax or something like that. Take this out, or else the whole straw man is going to be exposed.

4.21 One view is obviously correct--the first one; The second one has no basis in data except in the imagination of Paul Ehrlich, Donella Meadows, and Lester Brown, three folks who have yet to make an accurate prediction about the world food system. That's not a good record for 60 person-years of trying.

4.24 Wittwer (1995) argues in his new book for major beneficial effects to agriculture, even on C4 plants.

4.25 IPCC 1990 didn't talk much about CO2 fertilization, which resulted in a showtrial of Sherwood Idso for scientific heresy. Now its important. How about a letter of apology to Sherwood?

4.29 It is clear from the new Science paper by Ciaia, Tans et al that the vegetation responds rapidly and dramatically to even the small increases that we have made in CO2. Couple this to technological advancement (like genetic engineering) and many of the ecological problems minimize.

4.30 Change the temperature rate changes to reflect the SPM, also as I have modified it.

5.22 Much of this table is wrong because of the rapid uptake of CO2 now being observed.

6.25 Speaks of perfecting markets, and 6.28 speaks of distorting them. Which do you want? There a few unemployed central economic planners available should you need the expertise for the new five year plan.

6.29 Just my this one in the U.S. and watch the treaty evaporate.

7.3, pp35-36. Its also a question of forsaking capital for our children to use. I'm glad my parents didn't spend all their money fighting global cooling. Now I can buy an efficient car instead of that old polluting beater.

7.8 Lets hear it for free trade. Or for that matter, for the freedom of thought and faith in innovation that it generates. Maybe if we're all free enough we won't need the IPCC to help us live better lives through documents such as the 1995 Synthesis Report.

Mr. ROHRABACHER. I believe that is a fairly substantial charge, Dr. Michaels. And we will now move forward with some questioning.

First of all, before we go into questioning, let me give you the opportunity to ask a question or two of each other, and if I could just ask this: that we make this as direct as possible-answers and questions.

Do either of you have I mean, these are pretty substantial charges that Dr. Michaels is saying-do you have any questions, or vice versa?

Dr. MAHLMAN. If I may, Mr. Chairman

Mr. ROHRABACHER. Yes, sir.

Dr. MAHLMAN. Yes, thank you.

I agree with Dr. Michaels that the observed record does indicate a climate sensitivity lesser than that implied by the models in the past.

I do not agree that his analysis is logical or straightforward in that he is appealing to a comparison of a realistic case, namely the last 15 years, to an idealized increasing CO2 case, and that leaves out the effect of sulfate aerosols, as he properly points out. It also leaves out the fact that the satellites are now known to be seeing the strong ozone losses that have happened in the upper troposphere and the lower stratosphere.

Mr. ROHRABACHER. Do you have a specific question for him that might

Dr. MAHLMAN. My specific question is to speak to an assertion that he made. Okay?

And therefore I would submit that indeed it is true that it is most likely that aerosols are producing a temporary offset to the global warming problem, but I do not accept that this argument is as clear as he is arguing it is, merely because the comparison is not fully straightforward.

Dr. MICHAELS. Excuse me.

The ozone or the aerosols tend to lie in the bottom 5,000 to 7,000 feet of the atmosphere. That is the satellite's best temperature sense is from 5,000 feet to 30,000 feet in channel 2R. It is above the aerosol layer.

So you cannot say that the aerosols are what is preventing the warming in the satellite.

And you also cannot say that it is the ozone depletion that is preventing the warming in that record because most of the ozone depletion takes place above the 300 millibar layer, in fact, above the troposphere.

We had this discussion, I should say, Mr. Chairman, at our meeting on October 13th, 1994, and that discussion, which I have recorded, states the following:

The argument was made that, "Oh, you just have to dismiss the satellite data because ozone is what is compromising it." And a response was made.

Ozone is a direct radiative effect and it changes much from year to year. In the years in which the ozone shows a low spike, is that reflected in the satellite temperature?

Answer. "Oh, no, no, no. It is just a trend, you know."

Mr. ROHRABACHER. Dr. Michaels, maybe-well, let me just ask Dr. Guerrero if he something to throw in now as rebuttal or observation.

Mr. GUERRERO. Why not.

Mr. ROHRABACHER. You know, by the way, I am sure that there are people in the scientific community that will understand every single thing that you two fellas just said.

Dr. MAHLMAN. We hope so.

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Mr. GUERRERO. I would just point out that an important consideration to keep in mind when thinking about the models and their admitted limitations, which I think both of the panelists will agree, that there are limitations.

That the modelers themselves recognize those limitations and in fact conduct sensitivity analyses and assessments and make what they call flux adjustments to reflect the fact that models are indeed somewhat out of sync with when you go back and you look at the climatic record, they will be off to some extent.

And that that is a normal process. But the fact that modelers do that makes the models better in terms of the predicted capacity by removing error than compounding that error.

Dr. MICHAELS. I have a question. I did not get to ask one.

Mr. ROHRABACHER. Let's do this. Let's go through our regular questions and answers. Then we will have one final round of rebuttalism at the end.

I would like to ask about the-and why I stopped you, doctor, is that in the middle of your statement, to have you repeat that, is that you believe that the global warming and greenhouse effects basically are tied, and that there is no question in your mind, to human activity?

Dr. MAHLMAN. What I said, Mr. Chairman, is that the increasing greenhouse gases, particularly carbon dioxide and chlorofluorocarbons are specifically attributed to human activities, was my specific statement.

Mr. ROHRABACHER. But we are talking about global warming itself being a product specifically of human activity. That is what I am getting at.

Dr. MAHLMAN. Okay.

Mr. ROHRABACHER. Is that your position that if there is global warming, if after, if in the end people can agree on that, which is not something necessarily we agree on, an assumption we agreed on at the beginning of the hearing, but we will see about at the end of the hearing, but you, it is your position that that global warming is tied directly to human activity?

Dr. MAHLMAN. My position is, and my testimony reflects this, sir, that the observed warming over the last century is not unambiguously attributable to the greenhouse effect. Okay? There are alternative explanations.

My opinion is that there are virtually no credible counterhypotheses. Natural variability is often assumed or asserted to explain that. But there are some significant inconsistencies in that assertion.

So I cannot say with absolute certainty that the observed record is a reflection of greenhouse warming at this time.

Mr. ROHRABACHER. Repeat that last statement?

Dr. MAHLMAN. I cannot say, with absolute certainty, that the observed temperature change over the last century is ascribable to human-caused greenhouse warming. I cannot say that.

I just say that there is no plausible hypothesis that is nearly as credible.

Mr. ROHRABACHER. So you are saying that it is most likely that

Dr. MAHLMAN. Yes, indeed.

Mr. ROHRABACHER. When you have novices like myself looking at different arguments, and you hear someone say, well, you know, one volcano, and I will give some volcano, Mt. whatever it is, wherever it is, can spit this much into the air, and compared to what all of the industries of the earth produced in the last ten yearspeople are telling this all the time-that there are these natural causes that actually far outweigh anything that we have done in the industrial world for the last few years.

Should I just discount that as a charge?

Dr. MAHLMAN. Yes, I believe you should. Science is not a game of handwaving or a game of debating points; science is a game of numbers. And the problem with the volcanic type explanation is that they are transient things. They come, they blast stuff into the atmosphere and it causes a very big effect for a few years, and then it gets washed out and goes away. Okay.

So I can think of none of those natural causes that are nearly as credible as the argument that greenhouse warming is producing the observed warming.

We do indeed argue about whether or not this is completely consistent with what the models are predicting, as Dr. Michaels properly points out.

Mr. ROHRABACHER. Dr. Michaels, could you comment on that?

Dr. MICHAELS. Yes. The one point of disagreement, and I do not think it is particularly large, is that in the land-based temperature record, which begins in the late 19th century, that record begins in a very cold period that some people refer to as the end of the little ice age.

And so when we look at the temperature history, say of the northern hemisphere which is supposed to be most responsive to greenhouse gases, you see a warming that occurs mainly prior to 1940.

And then actually between the mid thirties and now, there is not that much net warming. That early warming can only have very little to do with the greenhouse enhancement, while the last warming could conceivably be that.

Be that as it may, Dr. Mahlman is right. It is not a game of debating points and it is a game of numbers.

And let us discuss those numbers for 15 seconds, if we could.

I want to elaborate upon the model that I was speaking about and about the old models.

The model that best tracked the past, according to the intergovernmental panel on climate change, is the model that only has 1.3

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