More Evidence CO2 Not Culprit

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Tuesday, December 29, 2009
More evidence CO2 not culprit

By Michael Asten From: The Australian

THE Copenhagen climate change summit closed two weeks ago in confusion, disagreement and, for some, disillusionment. When the political process shows such a lack of unanimity, it is pertinent to ask whether the science behind the politics is as settled as some participants maintain.

Earlier this month (The Australian, December 9) I commented on recently published results showing huge swings in atmospheric carbon dioxide, both up and down, at a time of global cooling 33.6 million years ago.

Paul Pearson and co-authors in a letter (The Weekend Australian, December 11) took exception to my use of their data and claimed I misrepresented their research, a claim I reject since I quoted their data (the veracity of which they do not contest) but offered an alternative hypothesis, namely that the present global warming theory (which was not the subject of their study) is inconsistent with the CO2-temperature variations of a past age.

Some senior scientists, who are adherents of orthodox global warming theory, do not like authors publishing data that can be used to argue against orthodoxy, a point made by unrelated authors with startling clarity in the Climategate leaked emails from the University of East Anglia.

In the scientific method, however, re-examination of data and formulation of alternative hypotheses is the essence of scientific debate. In any case, the debate on the link between atmospheric CO2 and global temperature will continue since it is not dependent on a single result.

Another example is a study by Richard Zeebe and colleagues, published in Nature Geoscience, of a release of CO2 and an increase in temperature 55 million years ago. At this time there was an increase in global temperature of between 5C and 9C, from a temperature regime slightly warmer than today’s (that I will call moderate Earth) to greenhouse temperatures. It can be argued this example may have a message for humanity because the rate of release of CO2 into the atmosphere at the time of this warming was of a similar order to the rate of anthropogenic release today. However, the analogy turns out to be incomplete when the data is compared with present estimates of climate sensitivity to atmospheric CO2, and Zeebe and his colleagues conclude that the large temperature increase cannot be explained by our existing understanding of CO2 temperature linkage. Indeed, they write, “our results imply a fundamental gap in our understanding of the amplitude of global warming associated with large and abrupt climate perturbations. This gap needs to be filled to confidently predict future climate change."...