Well, sometimes even the most authoritative analyses get things wrong. And if dissenting opinion-makers and politicians based their dissent on hard work and hard thinking  if they had carefully studied the issue, consulted with experts and concluded that the overwhelming scientific consensus was misguided  they could at least claim to be acting responsibly.

But if you watched the debate on Friday, you didn’t see people who’ve thought hard about a crucial issue, and are trying to do the right thing. What you saw, instead, were people who show no sign of being interested in the truth. They don’t like the political and policy implications of climate change, so they’ve decided not to believe in it  and they’ll grab any argument, no matter how disreputable, that feeds their denial.

Indeed, if there was a defining moment in Friday’s debate, it was the declaration by Representative Paul Broun of Georgia that climate change is nothing but a “hoax” that has been “perpetrated out of the scientific community.” I’d call this a crazy conspiracy theory, but doing so would actually be unfair to crazy conspiracy theorists. After all, to believe that global warming is a hoax you have to believe in a vast cabal consisting of thousands of scientists  a cabal so powerful that it has managed to create false records on everything from global temperatures to Arctic sea ice.

Yet Mr. Broun’s declaration was met with applause.

Given this contempt for hard science, I’m almost reluctant to mention the deniers’ dishonesty on matters economic. But in addition to rejecting climate science, the opponents of the climate bill made a point of misrepresenting the results of studies of the bill’s economic impact, which all suggest that the cost will be relatively low.

Still, is it fair to call climate denial a form of treason? Isn’t it politics as usual?

Yes, it is  and that’s why it’s unforgivable.

Do you remember the days when Bush administration officials claimed that terrorism posed an “existential threat” to America, a threat in whose face normal rules no longer applied? That was hyperbole  but the existential threat from climate change is all too real.

Yet the deniers are choosing, willfully, to ignore that threat, placing future generations of Americans in grave danger, simply because it’s in their political interest to pretend that there’s nothing to worry about. If that’s not betrayal, I don’t know what is.