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June 11, 2008


My goodness, you think that anthropogenic global warming has been proved not merely by a preponderance of the evidence but beyond a reasonable doubt? Remind me not to have you on the jury that tries me for a criminal offense.

If the "poll after poll" quote refers to a poll of qualified scientists, then it's reasonable. A majority of scientists in the climate field agree that anthropogenic CO2 is the dominant cause of global warming, but a substantial number disagree with the theory.

The pop-culture campaign is important because it may partially explain why so many scientists agree with anthropogenic CO2 models. It's in their interest to do so, for the pupose of getting grants, publications, promotions, etc.

Even non-scientists may be under pressure to conform. E.g., if Brendan publicly denied the importance of anthropogenic CO2, would that affect his career at Duke?

Brendan brought up the topic of how the scientific process works. That's actually a deep subject. E.g., I recommend Judging Science: Scientific Knowledge and the Federal Courts by Kenneth R. Foster and Peter W. Huber, which discusses when a theory is acceptible enough to be permitted in the court.

The widespread belief in global cooling 30 or 40 years ago is an example of how scientists can be swayed by prevailing opinion. There are lots of other examples where a majority of scientists were wrong, going back to whether the sun revolves around the earth. A more recent one was the supposed canals on Mars. They were considered to be established fact for many years.

The anthropogenic CO2 GW models may turn out to be correct, but they're surely not beyonod a reasonable doubt as of today. It's easy to make a model that agrees with past data and which gives anthropogenic CO2 a major role. It's equally easy to create a model that gives anthropogenic CO2 a minor role or no role at all. How should we judge which model is correct? A model can be validated by running it for a period of time to see how well it predicts the future. Unfortunately, global warming models deal with such a long time period that there hasn't been enough time for an adequate test.

The global temperature dropped dramatically from January 2007 to January 2008. AFAIK none of the models predicted this drop in advance. The anthropogenic CO2 folks correctly point out that a one year drop doesn't invalidate the long-term warming trend. Factors other than CO2 at play.

However, the fact that GW models don't fully reflect these other factors shows that the models are still pretty crude.

See this paper for a brief discussion of some of those other factors that affect global temperatures.

It is true that current models deal crudely with some factors other than greenhouse gas concentrations. Note, however, that "although even the sign of the current total [impact of greenhouse gases and other factors] is in question, the sign of the [total effect] by the middle of the 21st century will certainly be positive."

The denialist case seems to require misunderstanding the concept of uncertainty.

David/Rob -

1) there is not any meaningful disagreement in the scientific community that AGW is occurring. You can say there is disagreement and doubt but it doesn't exist.

And no, it is not evidenced by a poll of scientists showing a 'substantial number disagree with the theory'. That poll doesn't exist.

2) it's science - yes there are theories, models and estimates involved but that doesn't mean there is doubt or disagreement over the basic conclusions.

3) you ascribe motives (types of self-interest) to those who are concerned about the issue to aid in challenging the science. That's all very interesting but it doesn't "prove" anything about the science itself.

4) pointing to earlier "scientific" misconceptions only illustrates that "science" advances over time. Does that mean we shouldn't use the best available scientific evidence we have?

The conservative "pop-culture campaign" to denounce the existence of a significant human/climate impact will slowly die away (that's already happening).

Too bad it has been used for over ten years to delay implementing meaningful steps to address the issue.

Contrary to Howard's contention, many qualified scientists disagree with the mainstream view that global warming occurring and is primarily caused by human activity. See wikipedia for a partial list and discussion .

N.B. The only peer-reviewed citation (of 58) in that wikipedia article drew a stinging rebuttal.

Quote from Freeman Dyson, professor of physics at the Institute for Advanced Study in Princeton:

My first heresy says that all the fuss about global warming is grossly exaggerated. Here I am opposing the holy brotherhood of climate model experts and the crowd of deluded citizens who believe the numbers predicted by the computer models. Of course, they say, I have no degree in meteorology and I am therefore not qualified to speak. But I have studied the climate models and I know what they can do. The models solve the equations of fluid dynamics, and they do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields and farms and forests. They do not begin to describe the real world that we live in. The real world is muddy and messy and full of things that we do not yet understand. It is much easier for a scientist to sit in an air-conditioned building and run computer models, than to put on winter clothes and measure what is really happening outside in the swamps and the clouds. That is why the climate model experts end up believing their own models.

Please see the paper I cited above. The uncertainties you mention exist, but they do not invalidate the conclusions of mainstream climate research.

almostaquantum, I am not a member of the AAAS and am unwilling to pay to read the paper. Can you summarize it or quote some key passages?

It is hilarious that Freeman Dyson talks about the scientist sitting in an "air conditioned building".

Yes, the world is a complex dynamic system. Yes, it is difficult to predict exactly how the world will respond to extreme increases in human activity. Does that mean we should abandon models ?

Dyson say a problem exits and its more complex than we know. Fine. Where are his solutions (to the problem that he acknowledges)?

There are other scientists who make the argument that the current level of "hysteria" is far too understated (that climate change will accelerate beyond the levels of our current models and that the consequences will be even more severe).

What is wrong with promoting conservation, renewable energy and reduced emissions on a national level?

Aren't there multiple benefits to these activities?

Why does that have to be anti-American (as one Congress-person expressed it)?

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