eric c
Lv 5
eric c asked in EnvironmentGlobal Warming · 1 decade ago

Is it possible to have gotten the temperature increases in the late 20th century from negative feedbacks?

The reason why I ask this question some web sites are saying climate scientist Christy is not skeptic, saying that he believes in the IPCC's claim that humans are primarily responsible for most of the 20th century warming.

I found this statement a bit puzzling since Christy is a co-author of a paper that states that instead of clouds acting as a positive feedback, they act as a negative one.

http://blog.acton.org/uploads/Spencer_07GRL.pdf

Can a person believe in negative feedbacks and still come to the conclusion that humans are primarily responsible for most of the late 20th century warming?

Why do believers feel the need to portray Chrisy as being on their side? Is it because believers are losing faith in the AGW theory, and this is a way of maintaining their belief? Is it a way of saying that if skeptics are becoming believers, that is proof that we are right and you shouldn't lose your faith?

Update:

GCNP: It seems odd that your claim that being two faced is good for ones reputation.

A paper by Spencer has been submitted that will answer criticisms on negative feedbacks.

Update 2:

Dana: I was kind of hoping your would have answered the second part.

I asked that question because if the judge understood the global warming theory, he would not have made that statement. Those are the judges words you quoted, not Christy's.

Update 3:

Dana: You have not provided any proof that the judge is quoting Chrisy and not misquoting him (Unintentionally). Given Christy's well known stance on negative feedbacks it would would appear he is misquoting him.

GCNP: The AGU quote was in 2003. Given his public statements today it appears he is becoming more and more of a skeptic, not less or a delayer (as the alarmist blog says he is).

Christy is 58 years old, he is not young anymore.

If the AGW theory is correct, and Christy knows it is correct as you say, then misleading the public the way he does would not only tarnish his reputation as a scientist, but as a human being. So your arguments make no sense.

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  • Anonymous
    1 decade ago
    Favorite Answer

    I assume you are referring to John R. Christy, Director of the Earth System Science Center, University of Alabama in Huntsville.

    If so, I'm not really sure what you are asking. It seems fairly clear that he accepts AGW as an overall accurate theory, though he finds faults with some of the future predictions and current findings.

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  • 1 decade ago

    "Plaintiffs’ own expert, Dr. Christy, agrees with the IPCC’s assessment that in the light of new evidence and taking into account remaining uncertainties, *most of the observed warming over the last fifty years is likely to have been due to the increase in GHG concentrations*. Tr. vol. 14-A, 145:18-148:7 (Christy, May 4, 2007). Christy agrees that the increase in carbon dioxide is real and primarily due to the burning of fossil fuels..."

    * - emphasis mine. Source below. In response to Jim, he agreed with the IPCC conclusion that the majority (a.k.a. "most") of the warning has been anthropogenic. That is a quantification. If you read this, now you're aware of it.

    It's true that Christy believes water vapor will be a net negative feedback, and it's true he believes human CO2 emissions are responsible for most of the recent warming. Therefore, the answer to your question according to John Christy is yes.

    *edit* I'm sorry, I don't understand what you're getting at. The judge is summarizing Christy's sworn testimony in the quote provided above. Are you accusing the judge of lying about the testimony presented in his court? That's not really something a judge can get away with.

    I don't "need" Christy to agree with AGW. The fact is that he agrees with the causes and disagrees on future warming and effects. I said as much because it's a fact, and I have this personality defect that I like to get the facts right. I know, some people find this hard to comprehend.

    Source(s): Page 44 of the document, Page 48 of the PDF: http://www.columbia.edu/%7Ejeh1/2007/VermontDecisi...
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  • gcnp58
    Lv 7
    1 decade ago

    Stop being so Manichean. In order for Christy to maintain some semblance of scientific credibility, he has to agree with the conclusions of the IPCC, mainly because they are correct. However, in order to maintain credibility in his political circles, to get more publicity, and in order to save face in a big way for messing up the MSU data for so long, Christy also has to stick to the line that global warming won't be so severe. The only way he can do this is to adopt the stance he has, namely that CO2 is warming the planet, but that the effects won't be all that bad. Most of the "scientific" skeptics adopt this position, namely the Pelke's, Gray, and Lindzen (to some degree).

    If Christy et al. are correct, they need to explain why there is no evidence that these negative feedbacks are not operating, and temperature is tracking the forcing from increasing CO2. They need to propose a plausible mechanism by which there is a lag between the radiative forcing and the negative feedbacks. I can't figure out what that would be, maybe they (or you) can.

    edit: Being two-faced is extremely detrimental over the long run. Christy has run his string on climate, and continued adherence to his line "the changes won't be severe" is going to cost him in the near future. But he can't back down now and admit he is wrong. However, unlike Lindzen and Gray, who will be dead before they are roundly ridiculed, he is young enough that he will end his career in ignominy, like the grand old geologists who argued strenuously that continents do not move.

    The planet is warming, short term variability aside, that warming is accelerating (see reference below), negative feedbacks aren't going to stop that, but even if they were, the "negative feedbacks" themselves represent changes in climate, with resultant deleterious consequences for civilization.

    http://news.yahoo.com/s/ap/20090225/ap_on_sc/un_un...

    Edit: Eric, see Christy's quote here:

    http://www.sfgate.com/cgi-bin/article.cgi?file=/c/...

    Sounds pretty definitive to me. Humans are affecting climate. Christy's position had to evolve, just as Lindzen's has. Unlike Spencer, Christy and Lindzen have to maintain a small shred of scientific credibility.

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  • Anonymous
    1 decade ago

    Atmospheric forecasting is done primarily through complex computer modeling using dynamical equations of fluid motion. These models correllate the warming of the atmosphere to be dependent on increased CO2 emmissions.

    Anything is possible, but so far nobody has been able to create a model demonstrating the present conditions through any other means other than increased CO2 emmissions. So negative feedback may have something to do with it, but nobody has been able to give it soild support because nothing else works as well in the models.

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  • JimZ
    Lv 7
    1 decade ago

    GCNP, like most alarmists can't see through their political biased glasses. Christy believes that humans are a cause of the warming. I have never heard him quoted that he thought we were the primary cause. He doesn't believe in the predicitons of catastrophe. I frankly don't have a problem that he thinks humans may be adding to warming particularly since it isn't quantified. I agree with him that the problem comes from some who predict gloom and doom and particularly those that use it to push a political agenda.

    I don't think negative feedbacks could be responsible for warming but other factors could be such as positive feedbacks and solar, of course.

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