Economist: CLIMATE-change legislation, dormant for six months, is showing signs of life again in Washington, DC. This week senators and industrial groups have been discussing a compromise bill to introduce mandatory controls on carbon (see article). Yet although green activists around the world have been waiting for 20 years for American action, nobody is cheering. Even if discussion ever turns into legislation, it will be a pale shadow of what was once hoped for. The mess at Copenhagen is one …