Garnaut Climate Change Review - Update 2011. Update Paper five: The science of climate change

Abstract

I have been deeply immersed in many dimensions of the climate change question for almost four years, since I was commissioned in April 2007 by all of the State and Territory Governments and then by the Commonwealth Government as well to the undertake 2008 Garnaut Climate Change Review. At the commencement of the Review, I faced the question that confronts all who are not climate scientists and who are required for one reason or another to take a position on the climate science: how do we know if propositions put forward by some climate scientists are right? I began with some general awareness of the issues (derived in part from my association with the International Food Policy Research Institute in Washington, which was undertaking research on the effects of climate change and its mitigation on global food security), but with no strong view and no more than a common knowledge of climate change science. I did not know how strongly the main propositions of climate change science were held in the mainstream science community. I was aware of sceptical views and set out to understand them.