Canadian oil sands producers should brace for further bad news - this time from south of the border, as the U.S. government moves toward a national climate change policy that could target dirtier fossil fuels such as the oil sands bitumen, a former U.S. energy official said yesterday. His warning was issued yesterday at a conference on Canada as an energy superpower, and came as a new poll suggests Canadians want to protect the country's natural resources from voracious U.S. demand for energy. David Pumphrey, a former official in the Department of Energy and now a senior fellow at the...