The Chairman of the House Committee on Energy and Commerce, Rep. Henry Waxman (D-Ca), and the Chairman of the House Subcommittee on Energy and Environment, Rep. Edward Markey (D-Ma), have sent a letter to the American Public Power Association (APPA), demanding to know whether the APPA disputes the scientific validity of U.S. EPA's greenhouse gas endangerment finding, and if so, the basis for that dispute. See here. The Congressmen expressed a deep concern that "APPA appears to be actively misinforming its members about this issue."
