As a research scientist, I read the recent exchange of letters debating the relative strengths and weaknesses of the data concerning "human-caused" climate change with equal parts amusement and chagrin.
Amusement because it was so easy to see how each side cherry-picked the statistics which supported their argument while casually disregarding those which argued against. Chagrin because I've seen first hand how this type of "quasi-professional" exchange only serves to weaken the role of science in the public arena as people, including our elected leaders, incorrectly discount Science on the premise that scientists rarely, if ever, reach consensus on complex and controversial issues.
In regards to the specific question of what role humans have played in modern climate change, I've pasted below a short series of excerpts from the just released Intergovernmental Panel on Climate Change "Headline Statements from the Summary for Policy makers of the IPCC report on the physical science basis of climate change." The IPCC report has over 600 contributing authors and 50 external reviewers and represents the most comprehensive synthesis of climate science available. The full report and summary statements can be found at http://www.ipcc. ch/.
Key statements include: Warming of the climate system is unequivocal, and since the 1950s many of the observed changes are unprecedented over decades to millennia.
There's a difference between "not getting it" and "not liking it." Scientists can help with the former. The latter is opinion and you're welcome to it whatever it may be. However, there's never any excuse for willful ignorance.
Dr. Cooperman is an ecologist actively researching how climate change will affect freshwater fisheries yields of the developing nations of the tropics.