On November 5, the House Science and Technology Committee held the first congressional hearing on geoengineering, the deliberate large-scale modification of Earth’s climate systems to counteract climate change. Committee Chair Bart Gordon (D-TN) explained that his decision to hold this hearing “should not in any way be misconstrued as an endorsement of any geoengineering activity.” Instead, he said, “Geoengineering carries with it a tremendous range of uncertainties, ethical and political concerns, and the potential for catastrophic environmental side effects. But we are faced with the stark reality that the climate is changing, and the onset of impacts may outpace the world’s political and economic ability to avoid them.” Gordon said that the hearing will be the first part of a joint effort to examine issues surrounding geoengineering by the House and the House of Commons of the United Kingdom. The two bodies will hold parallel hearings, and the chairman of the Commons committee will testify before the Science and Technology Committee in a spring 2010 hearing on domestic and international governance issues surrounding geoengineering. Ken Caldeira, senior scientist with the Carnegie Institution of Washington, outlined two main categories of geoengineering activities. The first, solar radiation management, would add tiny particles to the stratosphere to reflect the Sun’s rays back to space. This technique is intended to mimic the cooling that occurs after volcanic …