On June 7, 2005, a joint statement on climate change was issued by the national science academies of the G8 countries (the UK, France, Germany, Italy, Russia, Canada, Japan, and the United States) along with China, India and Brazil. The statement emphasized two primary points, 1) that climate change (as caused by human-induced alterations of the composition of the atmosphere) is real, and 2) something needs to be done about it.
As has been the case in the climate change debate for years, the second point simply does not follow from the first.
Simply stating, as the Academies do that climate change is a very real thing, and then saying that “The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action” is akin to saying that “After years of careful study we have compiled enough scientific evidence to conclude that the sky is blue. Now we must do something about it.”
What is missing is the scientific assessment of the putative “threats” from climate change balanced against likely benefits. Without this type of analysis, a simple scientific finding on its own doesn’t warrant any specific action, no matter how scientifically ground-breaking it might be. For instance, how are our daily lives changed because of Einstein’s Theory of General Relativity—arguably one of the greatest scientific breakthroughs in our history? Virtually not at all. So unless the finding has an implication that impacts us in some way, we are not likely to change our actions.
The reason that there is no threat assessment is that there is no scientific consensus on what the threat level is—or at least one that could be agreed upon by the 11 signatories. The best that they could come up with was a smattering of climate changes that even they admit could be either beneficial or detrimental depending on their degree, timing, or location. “The projected changes in climate will have both beneficial and adverse effects at the regional level, for example on water resources, agriculture, natural ecosystems and human health. The larger and faster the changes in climate, the more likely it is that adverse effects will dominate.”
And “larger and faster” is hardly likely. The joint Academies parrot the ridiculously large range given by the United Nations’ Intergovernmental Panel on Climate Change “the average global surface temperatures will continue to increase to between 1.4 centigrade degrees and 5.8 centigrade degrees above 1990 levels, by 2100.” The low end of this range represents a change that is likely to be more beneficial than adverse, while the upper end of this range represents a situation which may prove to be more adverse than beneficial. Without some sort of scientific guidance—guidance that is absent from the statement of the joint academies—the finding alone, that “climate change is real” does not justify “taking prompt action.”
The fact of the matter is, is that there does exist a growing body of scientific evidence that the climate changes in the coming decades will be modest and proceed at a rate that will lie somewhere near the low end of the IPCC projected temperature range. For instance, NASA’s James Hansen—a leading climate change scientist—has analyzed trends in the emissions of greenhouse gases and concluded, in an article published in the Proceedings of the National Academy of Sciences, that the IPCC warming scenarios “includes CO2 growth rates that we contend are unrealistically large.” Based upon current trends in greenhouse gas emissions and the rate of atmospheric composition changes, Hansen argues that the future rate of global warming “can be predicted much more accurately than generally realized.” Hansen predicts that for the next 50 years, the earth will experience a warming rate of 0.15 ± 0.05ºC per decade leading to a warming of 0.75 ± 0.25ºC. This is near the low end of the IPCC’s range of warming rates. A similar conclusion is reached by studying the behavior of climate models. In aggregate, climate models project that the earth warms at a linear (constant) rate when greenhouse gases are increasingly added to the atmosphere. However, the models differ on what the actual warming rate is, but here, observations adjudicate the differences. During the past 30 years or so, a constant warming rate indeed has been established , at 0.17ºC per decade. If the collection of the world’s climate models are correct in form, then this established warming rate should be our best guidance as to what to expect in the future. A warming rate of 0.17ºC per decade corroborates Hansen’s findings and further supports the low end of the IPCC projected warming range as the most likely course into the future.
Having established a future temperature rise near the low end of the IPCC projected range, then, according to the joint statement, there is less likelihood that the impacts will be adverse and in many regions they may prove beneficial. If this is the case, should the joint academies still push corrective actions? What if these actions reverse some the benefits? In the United States for example, the 20th century has seen an increase in precipitation of about 10 percent. In today’s world where water resources are becoming more and more precious, are we willing to give back this extra water if it turns out to be related to global warming?
Obviously, the justification for action is far from clear.
That the national academies are pressing for action when the consequences of such actions are far from being well understood is a clear indication (along with the timing of the release of the statement—a month before the next meeting of the G8) that the national academies have stepped beyond the boundaries of science and into the arena of politics. This is a slippery slope, because once the national science academies have taken a policy position, they can no longer be considered an honest broker of scientific fact, but instead, simply another advocacy group (for more on this idea, see an excellent series of articles on Roger Pielke Jr.’s blog http://sciencepolicy.colorado.edu/prometheus/). And that’s exactly what this joint statement represents—an advocacy piece which selectively ignores large portions of the overall scientific understanding of climate change and its impacts in an effort to push for legislative action to limit greenhouse gas emissions. In actuality, when all the evidence is accounted for, such actions are far from justified.