The unusual public tiff between two powerful GOP lawmakers highlights the sharp divide that drives the nation's climate change debate. [Joe Barton], along with President Bush and many other House Republicans, opposes mandatory curbs on greenhouse gas emissions and questions the science underlying such efforts. [Sherwood L. Boehlert], who backs limits on carbon dioxide pollution, said he fears such attacks could chill future scientific inquiry.

In a sharply worded letter sent last week, Boehlert called Barton's probe into the findings of Michael E. Mann, Raymond S. Bradley and Malcolm K. Hughes a "misguided and illegitimate investigation." Mann will direct the Earth System Science Center at Pennsylvania State University as of next month, Bradley is a geosciences professor at the University of Massachusetts at Amherst and Hughes is a professor at the University of Arizona's Laboratory of Tree-Ring Research.

Barton, however, said he plans to proceed with the probe. He also dismissed a July 1 protest by Rep. Henry A. Waxman (Calif.), a senior Democrat on the Energy and Commerce Committee, who wrote Barton that some might interpret the probe "as a transparent effort to bully and harass climate change experts who have reached conclusions with which you disagree."