As a practicing chemist I have followed the whole AGW “discussion” with much interest and a large dose of skepticism. One quite interesting book I am reading now is “Plows, Plagues and Petroleum” by William Ruddiman,(2005, Princeton Univ. Press) a retired Professor of Environmental Science at U-VA. The subtitle of the book is “How humans took control of climate”. Control isn’t quite the right term, but Ruddiman makes an interesting case that human activity, especially agriculture, has been significantly influencing climate for the last 5000-10000 years, long before the industrial revolution of the last 200 years. Lots of charts of orbital precession, wobble and ellipticity to explain the natural cycles upon cycles that will put a lot variability to climate over 1000s of years, the evidence for 40-50 glacial episodes over the last 2.5 million years, etc. And how the methane and CO2 data dont fit what up then had been well behaved, cycles. Haven’t finished it yet, but the style so far has been scientific- complete with doubts and uncertainities expressed honestly. Well worth a read.