Carl Wunsch: I should never have trusted Channel 4
Our credibility as scientists rests on being protective of our authority and expertise
Published: 15 March 2007
I believe that climate change is real, a major threat, and almost surely has a major human-induced component. But I have tried to stay out of the "climate wars" because all nuance tends to be lost, and the distinction between what we know firmly, as scientists, and what we suspect is happening, is so difficult to maintain in the presence of rhetorical excess. In the long run, our credibility as scientists rests on being very careful of, and protective of, our authority and expertise.
The science of climate change remains incomplete. Some elements are based so firmly on well understood principles, or on such clear observational records, that most scientists would agree that they are almost surely true (adding CO2 to the atmosphere is dangerous; sea level will continue to rise...). Other elements remain more uncertain, but we as scientists in our roles as informed citizens believe society should be deeply concerned about their possibility: a Mid-western US megadrought in 100 years; melting of a large part of the Greenland ice sheet, among many other examples.
I am on record in a number of places as complaining about the over-dramatisation and unwarranted extrapolation of scientific facts. Thus the notion that the Gulf Stream would or could "shut off" or that with global warming Britain would go into a "new ice age" are either scientifically impossible or so unlikely as to threaten our credibility as a scientific discipline if we proclaim their reality. They also are huge distractions from more immediate and realistic threats. I've focused more on the extreme claims in the literature warning of coming catastrophe, both because I regard the scientists there as more serious, and because I am very sympathetic to the goals of those who sometimes seem, however, to be confusing their specific scientific knowledge with their worries about the future.
When approached by WAGTV, on behalf of Channel 4, I was led to believe that I would be given an opportunity to explain why I, like some others, find the statements at both extremes of the global change debate distasteful. This seemed like a good opportunity to explain why, for example, I thought more attention should be paid to sea level rise, which is ongoing and unstoppable and carries a real threat of acceleration, than to the unsupportable claims that the ocean circulation was undergoing shutdown.
I wanted to explain why observing the ocean was so difficult, and why it is so tricky to predict with any degree of confidence such important climate elements as its heat and carbon storage and transports in 10 or 100 years. I am distrustful of prediction scenarios for details of the ocean circulation that rely on extremely complicated coupled models that must run unconstrained by observations for decades to thousands of years. Nonetheless, and contrary to the impression given in the film, I firmly believe there is a great deal about the mechanisms of climate to be learnt from models. With effort, all of this ambiguity is explicable to the public.
In the part of The Great Climate Change Swindle where I am describing the fact that the ocean tends to expel carbon dioxide where it is warm, and to absorb it where it is cold, my intent was to explain that warming the ocean could be dangerous - because it is such a gigantic reservoir of carbon. By its placement in the film, it appears that I am saying that since carbon dioxide exists in the ocean in such large quantities, human influence must not be very important - diametrically opposite to the point I was making - which is that global warming is both real and threatening.
Channel 4 now says they were making a film in a series of "polemics". There is nothing in the communication we had that suggested they were making a film that was one-sided, anti-educational, and misleading. I took them at face value - a great error.
As a society, we need to take out insurance against catastrophe in the same way we take out homeowner's protection against fire. I buy fire insurance, but I also take the precaution of having the wiring in the house checked, keeping the heating system up to date, etc.How large a fire insurance premium is it worth paying? How much is it worth paying for rewiring the house? $10,000 but perhaps not $100,000? Answers, even at this mundane level, are not obvious.
How much is it worth to society to restrain CO2 emissions - will that guarantee protection against global warming? Is it sensible to subsidise insurance for people who wish to build in regions strongly susceptible to coastal flooding? These and others are truly complicated questions where often the science is not mature enough give definitive answers, much as we would like to be able to provide them.
Scientifically, we can recognise the reality of the threat, and much of what society needs to insure against. Statements of concern do not need to imply that we have all the answers. Channel 4 had an opportunity to elucidate some of this ambiguity and complexity. The outcome is sad.
The writer is Professor of Physical Oceanography at MIT
Global Warning?Not true?
Originally Posted by Caius Flaminius
Re: Global Warning?Not true?
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