I wonder if anyone else watching the U.S. president's state of the union address on Wednesday evening noticed the hilarity during his brief reference to global warming.

"I know that there are those who disagree with the overwhelming scientific evidence on climate change," Barack Obama intoned, and had to pause until the guffaws died down. We could all see Vice-President Joe Biden and House Speaker Nancy Pelosi laughing at the president's back.

Obama himself acknowledged with a "humph" his unfortunate understatement. Messiahs don't do frivolity well.

Some groups that are convinced that human beings are helping to destroy the planet were able to take some comfort, apparently, that he mentioned the subject at all.

It was tacked on at the part of the speech dedicated to "American innovation" in clean energy, mainly as a contributor to job creation, to reduce dependency on foreign supplies and to boost the sagging economy.

The most ardent tree-huggers, though, won't have liked some of the examples he used -- particularly nuclear power, even though it would be "safe" and "clean," new offshore oil and gas development, even though it would involve "tough" decisions, and coal technologies, even though they, too, would be "clean."

And his appeal to the Senate to get on with passing a comprehensive energy and climate bill, of course, was based on the bottom line.

Even if those in Congress doubt the evidence for global warming, Obama argued, "providing incentives for energy efficiency and clean energy are (sic) the right thing to do for our future -- because the nation that leads the clean energy economy will be the nation that leads the global economy. And America must be that nation."

And, as Prime Minister Stephen Harper has made clear, Canada must be one of the followers. If he was looking in that speech for clues as to where Canada's climate change non-policy is headed, he wouldn't have found many.

You'd think that with such a large percentage of the American population convinced that global warning is a real and almost-present danger, the people they elect would be more attuned to the public mood.

But all the polling by think-tanks and news media has marked a sharp decline in global warming concern over the past two years.

Researchers at Yale and George Mason universities reported this week that their polling suggests 57 per cent of Americans believe global warming is happening, down from 71 per cent who did so in 2008.

The percentage of believers who think human activities are mostly responsible has dropped to 47 from 57 per cent.

Scientists are partly to blame: The percentage of Americans who think most scientists are convinced of global warming has dropped to 34 from 47; the percentage who thinks there's a lot of disagreement among scientists on the issue has risen to 40 from 33 in 2008.

We all remember that infamous hockey stick that the deniers point to as the start of all this nonsense -- the one on the chart produced in 1998 deliberately designed to show that rising temperatures began with the Industrial Revolution.

More recently, we've heard accusations that British climate researchers have intimidated climate skeptics and suppressed inconvenient truths. We've heard that the shocking prediction by the International Panel on Climate Change that the Himalayan glaciers could disappear by 2035 was based on an unchecked claim by an Indian scientist who may or may not have been a fakir.

It may be that predicting the future of the planet based on tree rings is no more reliable than teacup-reading. It may be that with so many experts in so many fields involved, things get overlooked by absent-minded professors.

It sometimes does seem that they've done all the homework that's needed. They insist the science is "robust" despite the glitches.

They've been accused of becoming advocates rather than dispassionate researchers. Sometimes they seem like Henny Pennys, flapping their wings and proclaiming that the sky is falling, but if they can't explain where their evidence is leading, who can?

With all the flat-Earth flatheads watching, scientists can't afford to make mistakes -- and we can't afford them to.

Pace those smug American legislators, global warming's nothing to laugh at.