Is anything in life 100 percent certain?
Most reasonable people would agree that's not the case. But climate-change skeptics and deniers demand absolute proof, certitude beyond the slightest shadow of a doubt, that warming of the atmosphere and oceans over the past 50 years is caused by human activity, specifically industrial pollution.
The release Friday of a summary on climate research by a United Nations panel of scientists is unlikely to quiet the chorus of naysayers. They won't accept the report's finding that "it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century."
The U.N. document was carefully worded following an all-night editing session in Stockholm.
The panel acknowledges that global warming is at least 95 percent certain, caused primarily though not exclusively by industrial emissions. The summary of the 2,000-page report states that "human influence has been detected in warming of the atmosphere and the ocean, in reductions in snow and ice, in global sea level rise, and in changes in some climate extremes."
It calls for upper limits to be set on carbon dioxide emissions, the principal source of greenhouse gas pollution caused by industry and the destruction of forests.
This is the fifth report the international panel has released since 1990, and each one boosts the level of certainty.
The skeptics have seized on that 95 percent figure, arguing that it's not good enough -- after all, some pointed out, no one would board an airliner if it had only a 95 percent chance of landing safely. The logic of that argument is easily debunked.
More importantly, as scientists point out, 95 percent certainty is the gold standard in any serious research study. "Uncertainty is inherent in every scientific judgment," Johns Hopkins University epidemiologist Thomas Burke told the Associated Press.
The degree of certainty about climate change is the same as the age of the universe -- 18.8 billion years -- and is comparable to evidence that cigarettes are deadly. Scientists are more certain about warming than that vitamins are healthy and that dioxin in Superfund sites is dangerous.
Is anything more certain than climate change? Scientists point to gravity, a 100 percent sure shot.
At George Washington University, George Gray, director of the Center for Risk Science and Public Health, declared that "there's a group of people who seem to think that when scientists say they are uncertain, we shouldn't do anything. That's crazy. We're uncertain and we buy insurance." Gray, no flaming liberal, was chief scientist for the U.S. Environmental Protection Agency during the presidency of George W. Bush.
But wait, the skeptics insist. What about findings showing that the increase in warming has leveled off since 1998, hitting a supposed plateau?
The international panel of scientists addressed the issue briefly by noting that short-term records are sensitive to natural variation, and that meaningful trends require examination of 30-year records. Besides, 1998 was an unusually hot year and represents a high point. The decade from 2000 to 2010 was the warmest of any in 150 years, they noted.
Some skeptics such as David Kreutzer of the conservative Heritage Foundation admit the existence of climate change but don't see danger or catastrophe looming. He cautions against spending trillions of dollars to attack a problem that's not so severe and is likely to elude a solution by humans.
Nicholas Stern, a leading British climate and economics specialist, brands the climate change non-believers as "unscientific" and "irrational." He told reporters in London that "it is astonishing, irrational and unscientific to suggest the risks are small. The clear conclusion from 200 years of climate science and observations shows a strong association between carbon dioxide rises and global surface temperature."
As reported by Britain's Guardian newspaper, Stern declared: "The science is unequivocal and shows there is serious danger. What is coming from skeptics is just noise, and should be treated as noise. It looks very well-organized. They are deliberately distorting the way we understand risk."
Sadly, efforts by the United States to limit industrial emissions have bogged down in the same partisan wrangling that has not only overthrown modest immigration reform, gun-safety legislation, budget and tax-code solutions but also threatens a partial government shutdown and, even more ominously, financial upheaval if the nation's ability to borrow is derailed in three weeks.
Given the extremely hyperventilated political climate surrounding the current bogeyman -- the Affordable Care Act -- the latest findings on global warming are likely to be greeted by a national shoulder-shrug.
Without the weight of scientific evidence, I'd venture to say with 95 percent confidence that most people are tuning out the political cacophony from Washington in favor of diversions ranging from pro and college sports to the new TV season, social networking, the Twitterverse and the latest iGadgets.
People are burrowing into their cocoons, and it's hard to blame them. Much too "hot" out there.
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