McCarty Glacier, Alaska. Left: 30 July 1909. Right: 11 August 2004. Rights information: Glacier Photograph Collection, National Snow and Ice Data Center/World Data Center for Glaciology. 1909 picture taken by Ulysses Sherman Grant. 2004 picture taken by Bruce F. Molnia.

By Peter Gwynne, Guest Columnist,
21 May 2014

(Inside Science) – "The central fact is that, after three quarters of a century of extraordinarily mild conditions, the Earth seems to be cooling down. Meteorologists disagree about the cause and extent of the cooling trend, as well as over its specific impact on local weather conditions. But they are almost unanimous in the view that the trend will reduce agricultural productivity for the rest of the century." – Newsweek: 28 April 1975

That's an excerpt from a story I wrote about climate science that appeared almost 40 years ago. Titled "The Cooling World," it was remarkably popular; in fact it might be the only decades-old magazine story about science ever carried onto the set of a late-night TV talk show. Now, as the author of that story, after decades of scientific advances, let me say this: while the hypotheses described in that original story seemed right at the time, climate scientists now know that they were seriously incomplete. Our climate is warming -- not cooling, as the original story suggested.

Nevertheless, certain websites and individuals that dispute, disparage and deny the science that shows that humans are causing the Earth to warm continue to quote my article. Their message: how can we believe climatologists who tell us that the Earth's atmosphere is warming when their colleagues asserted that it's actually cooling?

Well, yes, we should trust them, despite the views of detractors such as comedian Dennis Miller, who brought my story to The Tonight Show in 2006. Several atmospheric scientists did indeed believe in global cooling, as I reported in the April 28, 1975 issue of Newsweek. But that was then.

In the 39 years since, biotechnology has flowered from a promising academic topic to a major global industry, the first test-tube baby has been born and become a mother herself, cosmologists have learned that the universe is expanding at an accelerating rate rather than slowing down, and particle physicists have detected the Higgs boson, an entity once regarded as only a theoretical concept. Seven presidents have served most of 11 terms. And Newsweek has become a shadow of its former self.

And on the climate front? The vast majority of climatologists now assure us that Earth's atmosphere is not cooling. Rather it's warming up. And the main responsibility for the phenomenon lies with human activity.

"There's no serious dispute any more about whether the globe is warming, whether humans are responsible, and whether we will see large and dangerous changes in the future – in the words of the National Academy of Sciences – which we didn't know in the 1970s," said Michael Mann, a climatologist at Pennsylvania State University in University Park. He added that nearly every U.S. scientific society has assessed the evidence and come to the same conclusion.

The recent National Climate Assessment takes an equally emphatic view.

"What is new over the last decade is that we know with increasing certainty that climate change is happening now," it states. "While scientists continue to refine projections of the future, observations unequivocally show that climate is changing and that the warming of the past 50 years is primarily due to human-induced emissions of heat-trapping gases."

I'm sure it's clear by now that I accept the views of the National Academy, National Climate Assessment, Mann, and the huge majority of his fellow climatologists. Nevertheless, websites devoted to denying the existence of human-caused climate change – or at least promoting the idea that nothing should be done about it – continue to use my article to validate their thinking. In fact the article has reportedly become the most-cited article in Newsweek's history.

Those that reject climate science ignore the fact that, like other fields, climatology has evolved since 1975. The certainty that our atmosphere is indeed warming stems from a series of rigorous observations and theoretical concepts that fit into computer models and an overall framework outlining the nature of Earth's climate.

These capabilities were primitive or non-existent in 1975. In fact my report reflected a real strand of climatological thinking back then. I was far from the only science writer to cover the possibility of global cooling. Time, Science News, and the New York Times, among other media outlets, wrote about it, because some climate scientists had genuine reasons to believe that the global climate might be cooling and had published scholarly papers on the matter. [more]

My 1975 'Cooling World' story doesn't make today's climate scientists wrong



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