Evidence to support the idea that human emissions are causing global warming has been piling up for more than three decades. Denial of this demonstrable scientific truth has become a litmus test for Republicans. The reasons for this denial seem to be a massive PR campaign funded by the coal and oil industries combined with a deep-seated and angry cultural strain of American know-nothingism.

"Tucked between treatises on algae and prehistoric turquoise beads, the study on page 460 of a long-ago issue of the U.S. journal Science drew little attention.

'I don’t think there were any newspaper articles about it or anything like that,' the author recalls.

But the headline on the 1975 report was bold: 'Are We on the Brink of a Pronounced Global Warming?' And this article that coined the term may have marked the last time a mention of 'global warming' didn’t set off an instant outcry of angry denial.

In the paper, Columbia University geoscientist Wally Broecker calculated how much carbon dioxide would accumulate in the atmosphere in the coming 35 years, and how temperatures consequently would rise. His numbers have proven almost dead-on correct. Meanwhile, other powerful evidence poured in over those decades, showing the 'greenhouse effect' is real and is happening. And yet resistance to the idea among many in the U.S. appears to have hardened.

What’s going on?"

Charles J. Hanley reports for the Associated Press September 23, 2011. [2]