The Source of the Ice Age Claim

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 The insufficient study was retracted.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.


8 thoughts on “The Source of the Ice Age Claim

  1. Interesting post. So this ‘in the 70’s the scientists thought we were in danger from an ice age’ is a myth!

    Personally, I’m going to refrain from basing my knowledge of climate change on the popular press. I suggest you do the same.
    Problem is, most of us rely on the media to interpret complex science issues for us – because we don’t have the knowledge/access to information/time to look into it ourselves, as I’ve just posted in response to one of your other entries. Maybe more scientists ought to become journalists (but their editors would still want those attention-grabbing headlines).

    • Thanks for all your comments Tracy – sorry it took me a while to reply, I was out of town for a few days. There is nothing wrong with skeptical voices – the problem is when they are significantly overrepresented in the media, or when they are spouting claims such as “it’s the sun” which the majority of the scientific community has ample evidence to disprove. All good scientists start out as a skeptic on everything, whether it’s climate change or particle physics – if you’ve been properly trained in the scientific method, it should take a lot of evidence to get you to change your mind. The catch is that you do change your mind when the evidence warrants it, that you aren’t so hardheaded in your beliefs that you’ll never change them.

      Some good places for non-scientists to understand climate change include science magazines (such as Discover), summaries for policymakers of reports (the IPCC is free online), the EOS articles at NASA (check out the link in the right margin), or, if you’re lucky enough, becoming friends with a climatologist – helped me a lot!

      Thanks for reading. I hope you’ll keep reading lots on the subject from a variety of sources. Spread ClimateSight around to your friends.

      • Hope you don’t mind but I did post a link to your blog in the Guardian comments section,
        in response to the following comment:

        I am a true “sceptic” as defined by unconvinced yet by the arguments. My problem is that there are so many sources of information that it is impossible for the layman to assess them for accuracy

        nickmy – here’s a useful guide – yes, it’s from a woman’s blog, apologies to the purists – but I like this blog, and for us laypeople, blogs can be useful even when they’re at the bottom of the credibility spectrum.
        And personally, I distrust anything on WattsUpWithThat. If you want accuracy, go with published science.

      • Thanks very much for that Tracy – I greatly appreciate any advertising help!

        In response to your other comment: your assessment of journalists sounds about right. Many articles (especially editorials) are strikingly uninformed, but some of them are much better. It really depends on what background the journalist has, whether they specialize in science journalism, etc.

  2. I appreciate the link to Weaver’s article

    You might wish to take a look at further material. My discussion of the Global Cooling myth when taking on George Will’s Willful Deceit ( might be of interest with a variety of links.

    In particular, last fall, the Bulletin of the American Meteorological Society published the peer-reviewed review of this issue with the revealing title of The Myth of the 1970s Global Cooling Scientific Consensus

    • That report looks fascinating. I’ll take a closer look at it when I have time. Great job on your “will-ful deceit” article – sadly, situations like that aren’t too unusual. I have yet to find work by a skeptic which is not uninformed/misleading/full of errors.

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