14 April 2008Read it all here. This was the first I had heard of this letter.
Dear Dr. Pachauri and others associated with IPCC
We are writing to you and others associated with the IPCC position – that man’s CO2 is a driver of global warming and climate change – to ask that you now in view of the evidence retract support from the current IPCC position [as in footnote 1] and admit that there is no observational evidence in measured data going back 22,000 years or even millions of years that CO2 levels (whether from man or nature) have driven or are driving world temperatures or climate change.
If you believe there is evidence of the CO2 driver theory in the available data please present a graph of it.
H/T - Power and Control