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PBS: But my question is: What could convince you that you were wrong? What could convince them they were wrong? What could actually resolve this debate to the satisfaction of honest scientists? If people can always interpret what happened within their model, how do you resolve it?
Singer: I think that we would have to try to get the models to become better, and try to find more specific fingerprints-as I call them-- in the observations that can either be verified or falsified by models. And the global average temperature simply isn't good enough. It has to be based on geographic variation, or variation with altitude, or temporal variation, or much more detailed measurements. Certainly we know that the models do not agree amongst themselves. So I think the first step is to find out why this is so, and work very hard to at least resolve the differences between [models], and then try to resolve differences between models and observations.
I want to finally get at this mix-up some people have between weather and climate. When we see Al Gore standing in front of forest fires in Florida, or talking about the droughts in Texas, or people saying, "Last July was extremely hot," does this constitute evidence of global warming? Or, the hot summer of 1998--is that evidence of global warming? Yes or no? What's going on there?
A hot summer, a warm winter, is no evidence for global warming. Don't forget, we've had a warm winter in the United States, but temperatures in Europe and Russia were extremely cold. Of course, we don't hear about this because we read American papers describing weather in the United States.
So all of these observations that we are bombarded with tend to be anecdotal. And if we have cold weather, that doesn't mean that an ice age is coming. But if we have many, many cold periods in succession, as we did, for example, between 1940 and 1975, where even global temperatures were decreasing, then people become quite concerned--and I do remember this period--about a coming ice age. And it's interesting that many of the kind of people who are now concerned about a coming global warming catastrophe were then concerned about a coming global cooling catastrophe.
And what was their recommendation? Government has to do something about this. The National Academy of Sciences published a report in 1971, saying, as best as I recall, that a coming ice age was a definite probability within the next hundred years. The National Academy of Sciences...supposedly a collection of the best scientific minds to deal with this issue. Naturally, they're not--they're only as good as the particular panel that was chosen to do this work.
PBS: Anything else? . . .
Singer: Let me say something about this idea of scientific consensus. Well, you really shouldn't go by numbers. I think it's significant to straighten out misconceptions. One misconception is that 2,500 IPCC scientists agree that global warming is coming, and it's going to be two degrees Centigrade by the year 2100. That's just not so. In the first place, if you count the names in the IPCC report, it's less than 2,000. If you count the number of climate scientists, it's about 100. If you then ask how many of them agree, the answer is: You can't tell because there was never a poll taken. These scientists actually worked on the report. They agree with the report, obviously, in particular with the chapter that they wrote. They do not necessarily agree with the summary, because the summary was written by a different group, a handful of government scientists who had a particular point of view, and they extracted from the report those facts that tended to support their point of view.
For example, they came up with a conclusion--the only conclusion of this 1996 report--that there's a discernible human influence on climate. I don't know what that means. Nobody really knows what that means. On the one hand, it's easy to agree with a statement "a discernible human influence on global climate." Sure, why not? Nights are getting warmer. Maybe that's it. On the other hand, it certainly does not mean--as politicians think it does--it does not mean that the climate models have been validated, that there's going to be a major warming in the next century. It does not mean that. And they don't say that. They just imply it.
PBS: If people can't rely on statements like "most scientists agree" and so forth, like that, with an issue of this complexity, how are they supposed to come to an opinion on it?
Singer: How should people come to some conclusion when scientists disagree? I think this is a problem that people will have to ask themselves. They'll have to say: What happens in the worst case? Supposing the scientists who say it will warm are correct, is that good or bad? And the answer is: If it warms, it will be good. So what is the concern, really? Even if the warming should take place, and the warming will be noticeable...if that should be the case, if it is measurable, that does not mean that it is economically damaging. In fact, the opposite is true.
PBS: But you might get, for instance, flooding in Bangladesh or in the [Maldive] Islands, or in southern United States. Those have to be scenarios. If you have a warming up,four or five degrees, those are possibilities, aren't they?
Singer: We have to ask, what is the impact of a warmer climate? It's not the warming itself that we should be concerned about. It is the impact. So we have to then ask: What is the impact on agriculture? The answer is: It's positive. It's good. What's the impact on forests of greater levels of CO2 and greater temperatures? It's good. What is the impact on water supplies? It's neutral. What is the impact on sea level? It will produce a reduction in sea-level rise. It will not raise sea levels. What is the impact on recreation? It's mixed. You get, on the one hand, perhaps less skiing; on the other hand, you get more sunshine and maybe better beach weather.
Let's face it. People like warmer climates. There's a good reason why much of the U.S. population is moving into the Sun Belt, and not just people who are retiring.
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It is true the polar caps are essentially deserts, so the increased evaporation can actually help build snowpack. And as more ground remains covered by snow, more light is reflected back into space.
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