Duncan - Re: July 10 letter from Don Graham.
As a fellow geologist I felt I could offer Mr. Graham some of the evidence he was seeking regarding human-caused climate change.The International Panel on Climate Change (IPCC.ch) has recently produced its fifth report on the state of the world's climate. It is conveniently broken down into three sections which address 1. Physical science basis 2. Impacts, Adaptation and Vulnerability and 3. Mitigation. This report also represents one of most thoroughly peer-reviewed documents ever produced. To summarize the report, "It is extremely likely (95-100 per cent probability) that human influence was the dominant cause of global warming between 1951-2010." (IPCC ar5, sections 10.3 -10.6, 10.9) And as for Mr. Graham's cited authority Mr. Bjorn Lomberg, who postulates sun spots and solar winds as the main driver for climate change, here is what I could find. Mr. Lomborg's only scientific education is in political science, an extremely far cry from anything to do with atmospheric physics or climate modeling. This same global warming "skeptic" has been quoted numerous times stating not only that global warming is real, but that "it [global warming] is man-made and it is an important problem". (New Statesman, Sept. 24, 2010).All things considered, I would say that reasonable doubt for human-caused climate change has been dealt with. Unreasonable doubt, however, is something else entirely I guess.Jonn Lisson Duncan