Global warming – doubt and uncertainty remain

19 02 2007

…..but not over the reality of global warming.  Rather, whether we are underestimating it’s scale.

This letter in the Age tells us why:

 SENATOR Minchin is right ( The Age, 18/2): there is intense scientific debate about climate change. However, the debate is not about the reality of human-induced climate change; the debate is about whether or not predictions from the Inter- governmental Panel on Climate Change (and similar predictions by Al Gore) underestimate the likely extent of climate change.

The debate is about such things as the strength of climate feedbacks. Feedbacks are when climate impacts add to the causes of climate change and consequently magnify the human influences on climate. Barrie Pittock, formerly of CSIRO, includes several emission feedback mechanisms in a recent summary of ways in which consensus science may be underestimating the degree of climate change. Over the 21st century, the amount of extra carbon dioxide added by such feedbacks may equal all human inputs over the 20th century as warming and drying trigger processes that emit more greenhouse gases.

Currently these concerns fall short of the IPCC’s criterion of “well-established science”. The IPCC consensus process is slow and cautious. Developing well-established science for climate feedbacks is where the real scientific debate over climate change is taking place.

Meanwhile, the US journal Science is about to publish a study showing that recent years have followed the high end of projections made by the IPCC in 2001.
Professor Ian Enting, former head of the greenhouse gas modelling team at CSIRO, University of Melbourne




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