Conservatives at odds with Obama, and science, on climate

US conservatives backed by the powerful gas and coal lobbies are at loggerheads with both the scientific world and President Barack Obama on the environment -- but have failed to block his path on climate change. Among them are several Republican White House contenders, who deny or downplay the impact of humans on global warming and reject efforts to reduce greenhouse gases, saying it could hurt the economy and favor China, the world's top carbon dioxide emitter ahead of the United States.