Almost alone in the world of science, there is a substantial U.S. effort to discredit some basic conclusions in the global warming debate. There are always legitimate reasons to query scientific conclusions, but the tenor of the debate has taken on a flavor of its own. Since the epicenter of the dispute is in Washington, D.C., the suspicion arises that not all of the discussion is business-as-usual scientific disagreement.The most recent example of the heightening level of the dispute involves a 23 June 2005 letter from U.S. Rep. Joe Barton (R-Tex.), chair of the House Committee on Energy and Commerce, to Michael Mann (University of Virginia) and his collaborators, Raymond Bradley (University of Massachusetts) and Malcolm Hughes (University of Arizona). The dispute centers on the much discussed ``hockey stick'' reconstruction of Mann et al. [1998,1999]. In those reconstructions, the twentieth century warming stands well above Northern Hemisphere temperature fluctuations of the last 1000 years. Other investigators, using some of the same data but with different approaches, have also reconstructed temperatures of the last millennium (see Mann et al. [2003] for a summary discussion). In general, there is more agreement than disagreement among the various reconstructions. The differences stem mainly from the scaling of the oscillations, but in all cases the late twentieth century is anomalous in a millennial context.