Some of the US' leading scientists have accused Republican politicians of intimidating climate-change experts by placing them under unprecedented scrutiny.
A far-reaching inquiry into the careers of three of the US' most senior climate specialists has been launched by Representative Joe Barton, the chairman of the House of Representatives committee on energy and commerce. He has demanded details of all their sources of funding, methods and everything they have ever published.
Barton, a Texan closely associated with the fossil-fuel lobby, has spent his 11 years as chairman opposing every piece of legislation designed to combat climate change.
He is using the wide powers of his committee to force the scientists to produce great quantities of material after alleging flaws and lack of transparency in their research. He is working with Ed Whitfield, the chairman of the sub-committee on oversight and investigations.
The scientific work they are investigating was important in establishing that man-made carbon emissions were at least partly responsible for global warming, and formed part of the 2001 report of the Intergovernmental Panel on Climate Change, which convinced most world leaders -- US President George W. Bush was a notable exception -- that urgent action was needed to curb greenhouse gases.
The demands in letters sent to the scientists have been compared by some US media commentators to the anti-communist "witch-hunts" pursued by Joe McCarthy in the 1950s.
The three US climate scientists -- Michael Mann, the director of the Earth System Science Center at Pennsty; Raymond Bradley, the director of the Climate System Research Center at the University of Massachusetts; and Malcolm Hughes, the former director of the Laboratory of Tree-Ring Research at the University of Arizona -- have been told to send large volumes of material.
Barton's inquiry was launched after an article in the Wall Street Journal quoted an economist and a statistician, neither of them from a climate science background, saying there were methodological flaws and data errors in the three scientists' calculations. It accused the trio of refusing to make their original material available to be cross-checked.
Barton then asked for everything the scientists had ever published and all baseline data. He said the information was necessary because Congress was going to make policy decisions drawing on their work, and his committee needed to check its validity.
There followed a demand for details of everything they had done since their careers began and funding received.
The inquiry has sent shock-waves through the US scientific establishment, already under pressure from the Bush administration, which links funding to policy objectives.
Representative Henry Waxman, a Californian Democrat, wrote complaining that this was a "dubious" inquiry which many viewed as a "transparent effort to bully and harass climate-change experts who have reached conclusions with which you disagree."