Global Warming Debate
Humans have known about global warming for many years.
MANY people think that our concern about carbon dioxide and global warming is a modern preoccupation driven by the attention of high-profile personalities, politicians and green activists. But Al Gore did not discover global warming. Nor did Tim Flannery, Peter Garrett, Greenpeace or Malcolm Turnbull. Scientific concern about global warming is not new.
A single scientific paper, published more than three decades ago, can place the discussions about climate change into historical perspective. Tomorrow it will be 35 years since the leading science journal Nature published a review paper entitled "Man-made ...view middle of the document...
Considering that global temperatures had, if anything, been falling in the decades leading up to the early 1970s, Sawyer's accurate prediction of the reversal of this trend, and of the magnitude of the subsequent warming, is perhaps the most remarkable long-range forecast ever made.
Sawyer's succinct summary of the climate change science understood at that time can be compared with the four volumes of the IPCC Fourth Assessment on Climate Change being released through 2007. The IPCC assessment involves more than 400 authors, about 2500 reviewers, and runs to several thousand pages with many thousands of references. Such a comparison shows that much has been done to address the concerns and uncertainties expressed by Sawyer at the time. He was concerned that the rudimentary understanding of cloud processes and other climate system feedback resulted in uncertainties regarding predictions of warming. At the time, climate models were in their infancy, but Sawyer saw them as the best way to examine this feedback and reduce the uncertainties in climate change predictions. Since then, models have improved substantially and now include many more processes in more detail than was possible in the early 1970s, and the various climate processes that may enhance or offset the effects of carbon dioxide have been studied in detail.
Despite these advances, our best estimate of the warming to be expected from a doubling of atmospheric carbon dioxide concentration has changed little from Sawyer's time. Our best estimate of the temperature increase that would result from a 25 per cent increase in atmospheric carbon dioxide concentrations is still around 0.6 degrees. The scientific consensus of Sawyer's time was very similar to the...