Reuters: Signs the United States will soon respond to global warming and a new climate pact now under discussion are set to drive the carbon market further in the next two years, Lehman Brothers said on Monday. Several states in the United States, the world’s biggest emitter of carbon dioxide, have recently moved to choose carbon trading, instead of carbon taxation, paving the way for Washington to take similar moves. "I’m fairly confident that no later than 2010 you’ll see a …