An all-too-common claim people use to justify ignoring the widespread scientific agreement on climate change is, “The scientists were all predicting an ice age in the 70s, and that didn’t happen.”
Last year, a publishing climatologist, the highest category for an individual on our credibility spectrum, decided to investigate just how valid this claim was.
Dr Andrew Weaver is a Canadian climatology professor at the University of Victoria, the chief editor of the peer-reviewed Journal of Climate, a lead author on the 2nd, 3rd, and 4th IPCC reports,and the Canada Research Chair in Climate Modelling and Analysis. I think we can establish strong credibility for Dr Weaver’s statements.
In a 2008 article in the Ottawa Citizen, Dr Weaver explains how he searched through the enormous ISI Web of Science database for peer-reviewed studies claiming the world was heading into an ice age. He discovered that “there is not a single peer-reviewed original scientific study that argued this to be the case.” Only one paper mentioned the idea at all.
“The only paper that came close was one written by NASA scientists Ichtiaque Rasool and Stephen Schneider in 1971. A throwaway sentence at the end of their abstract noted: “An increase by only a factor of 4 in global aerosol background concentration may be sufficient to reduce the surface temperature by as much as 3.5° K. If sustained over a period of several years, such a temperature decrease over the whole globe is believed to be sufficient to trigger an ice age.” Of course this statement is riddled with weasel words, assumptions and the hypothetical. Nevertheless, its scientific shelf life was only a few months before the assumptions underpinning the study were shown to be questionable.”
The peer-review process worked. The insufficient study was retracted. The idea of an ice age held hardly any agreement whatsoever in the scientific community, compared to the widespread agreement regarding the current climate change. Read the rest of Dr Weaver’s article if you’re interested in how scientists determined the cause of the slight drop in global temperatures post-WWII, despite the increasing levels of greenhouse gases.
Sadly, sources such as Time magazine, Newsweek, and the Globe and Mail (a major Canadian newspaper) got a hold of the recently discredited study. They liked the idea of controversial, attention-grabbing headlines that would engage their readers and, ultimately, bring money and attention to their writers. They published stories with titles such as, “Does man trigger trouble in the world’s climate cycle?” and “Another Ice Age?”
The public ate it right up. And now, 30 years later, this media-induced theory still persists.
At the same time that climatologists were studying the drop in temperatures, many of them were worried that the positive forcing of greenhouse gases would eventually outweigh the negative forcing of aerosols, volcanoes, and the solar minimum. Sources such as the National Academy of Sciences and science advisory committees to the President of the United States held this opinion. Check out this video by Peter Sinclair to see their exact statements (as well as a great clip from a 1958 Bill Nye-esque science show!). Dr Weaver’s article also mentions a 1975 article in the journal Science by Wally Broecker of the Lamont Doherty Earth Observatory.
With the ISI search tool, Dr Weaver was able to find one discredited study that mentioned an aerosol-induced ice age. When he searched the phrases “climate change” and “global warming”, he found 30 913 studies from the period 1965-2008. He speculates,
“That’s a lot of science and you can bet that if there were an Achilles heel to the theory of global warming it would have been discovered long ago.”
The 70s theory of an ice age simply cannot be compared to the current theory of anthropogenic warming. Their levels of support are completely opposite. The ice age theory was held by the extreme minority of publishing climatologists; the current climate change theory is held by the extreme majority.
In the 70s, the media misrepresented the science by overstating an almost non-existent theory. Currently, they are misrepresenting the science by suppressing an overwhelming theory and overplaying the opposition to it.
Personally, I’m going to refrain from basing my knowledge of climate change on the popular press. I suggest you do the same.