By TIM WHEELER
Have the news media become bored with global warming already? It was one of the top news stories of 2007, thanks in large part to the Nobel-winning labors of the Intergovernmental Panel on Climate Change and former Vice President Al Gore. But as presidential contenders slogged through the snowy caucuses and primaries in their quest for the White House, the topic barely registered in news coverage of the campaigns. It almost never came up in televised debates.