Whatever happened to Global Cooling in the 70s? & What do scientists think today?

A while back, a fan asked me:

“Sgt Scholar, love your page, but I have a question. I heard scientists were worried about “global cooling” in the ’70s. I saw your other posts about the warming trends since the [70’s]. How did it go from global cooling to global warming? What do scientists really think? Thanks!”

Thanks for the question! I love it when someone expresses a genuine interest in learning about science. It’s hard to know what’s even up these days. False and misleading information have saturated the internet more than a child pouring sugar into Koolaid.

Of course, I am no superhuman. I cannot write as fast as questions come in, so at the end is a link to a list of non-hippie, non-polishitan, non-naive resources so you can self-explore other questions. And also, as you know, I am not a climatologist, I am a science communicator who is under the delusion that his horrible jokes make science fun…

The short answer is the 70’s cooling was a sensationalized misunderstanding by the media. The global cooling idea was 1) a minority prediction, 2) a prediction based on very flawed models, and 3) most notably, this prediction required quadrupling sulfur dioxide outputs from coal (and other sources).

The short answer for what scientists think, is that it is near-unanimous agreement.

Let’s break it down.

Was global cooling predicted in the 1970s media?

For those who saw the headlines in the 70s espousing global cooling, I empathize with you. I can see why people would be raising an eyebrow, thinking, “can scientists make up their minds?”

Some of the more popular articles included Newsweek’s “The cooling world” (Gwynne, 1975) (shown below left) and National Geographic, “What’s happening to our climate?” (1976) (shown below right), and Time “Another ice age?” (1974). And of course, a bunch of local newspapers fed from this frenzy and printed similar stories.

But what did the scientists of the time think?

Headlines are always trustworthy and not misleading, amirite?

So what’s the dealioski? What was science saying at the time?

Along with badass sideburns and giant polyester collars, Peterson, Connolley, & Fleck (2008) found that, yes, some climatologists suspected if specific trends continued, the Earth might cool.

At that time, some researchers predicted that quadrupling the concentration of sulfur dioxide particulates (yes, quadrupling them) in the atmosphere could reflect enough sunlight away from the Earth’s surface to reduce the average global temperature by 3.5°C (Rasool & Schneider, 1971). But of course, that was a concern based on emission trends at that time, and regulations (such as the Clean Air Act) later limited lung-killing particulates like this.

Copy. B ut how prevalent was this potential global cooling idea among the scientific community in the 70s?

Not too common.

From 1965 to 1979, there were 71 known climatology papers that looked at large-scale/ global climate trends. Only 7 scientific papers predicted, implied, or provided supporting evidence for future global cooling. In comparison, there were 44 papers for global warming and 20 papers that were neutral.

Suffice it to say, the scientific community was not convinced there was an impending ice age knocking on our doorstep. In fact, it closer to the opposite. Such a contradiction with the headlines isn’t *cool*!!

Cool. And what do current scientists think?

So what does the current scientific community say? Depending on questions and methodology, the percentage of agreement typically varies in the high nineties among active climatologists, meteorologists, and study reviews (Cook et al., 2013; Cook et al., 2016; Oreskes, 2004, 2018; Powell, 2015, 2016, 2017). The scientific community is in agreement. Don’t take my word for it either. NASA even talks about this.

Cool. But what about the remaining experts

Scientists are what I lovingly call ‘pedandicks’ when it comes to details. And they need to be. Frankly, their career is built on scrutinizing details. So, as a good science communicator, let’s dive into some details as well.

Consider the Verheggen et al. (2014) study. They report only 91% agreement. Why? The agreement reflects responses to an essential set of questions (Q3a through c in the paper). These questions asked researchers if greenhouse gases were the strongest or tied-strongest contribution (out of other factors) to current global warming. If a scientist thought greenhouse gases (from human and natural sources) contributed to 45% of global warming, they would have answered “no.”

Of course, there is always disagreement over details of measurement. Some of these details are as minor as measuring climate (as shown below through NASA’s rarely seen snarky side).

Other details are more difficult to assess, especially for future estimates where human activity is difficult to account for. Will the Earth increase by 0.5 or 1 degree in 50 years? How exactly will this affect each region? Which crops will be most affected, and where? These are harder to predict because of human behavior and technology can influence them.

The point is differences in method and analysis can give some slightly different answers. Plus, there is always the human factor. One person, or even a small team, can be wrong in science. It happens. This is why science is a method that relies on scrutinizing peer-review. And believe me, they enjoy endlessly nitpicking each other’s work. Remember those nerds in high school always correcting each other? This is them now. So when a consensus happens, it means they have scienced the shit out of this question.

That makes sense. But are there some that disagree?

I would be surprised if there were not some. Indeed, some do, but hold your horses. You’re always gonna have a minority of scientists who believe in weird things. For example, a Nobel Laureate refused to believe HIV caused Aids. You can even find an example of a geology professor (Dr. John Morris) that believes the Earth is literally less than 10,000 years old.

But aside from pseudoscience advocates, you’ll always find some scientists that just either messed up a study, or random chance misled them. This happens too. Either way, this is why science is a collaborative method that relies on other experts checking and rechecking each others world.

The few dozen contrarian papers (which rejected climate change was happening or that humans were the cause) were very poor. Their evidence was scrutinized and debunked by the scientific community (Abraham et al., 2014). These few studies were plagued by a suite of problems such as lacking contextual analysis, lack of transparency, pigeonholed data, failed to have the same results replicated, and lacked peer review from climate scientists (Benestad et al., 2016). For example, in one study Benestad et al. tested, they found the researchers omitted 6,000 years of data from the recent holocene and forced a wonky curved-fit that involved the moon. Lo and behold, when you put that data back in, it shows climate change congruent with human causes. Another example tried claiming that climate change was due to Jupiter and Saturn. (You can see the supplemental material of Benestad et. al, (2016) for more, or check out this layman article written by a coauthor of the paper. Moreover, blind statistical analyses showed the conclusions of prominent contrarian papers were highly misleading (Lewandowsky et al., 2016). In short, the few studies that disagree don’t hold water.

So how is consensus measured?

There is no single answer. This is like asking how healthy are you? There are lots of factors we can weigh: body fat, immune system strength, genetic predispositions to diseases, mental health, diet, and so forth. There is no single formula, so we shouldn’t rely on any single study that answers this question. This is why Cook’s 2016 assessment of multiple studies is so useful. Let’s look at one.

The famous 97% statistic comes from the 2013 Cook paper. This study analyzed the abstracts (which is just a fancy summary) for almost 12,000 climate studies. They set aside the 63% that did not explicitly say (or obviously implied) that climate change is (or is not) real and is (or is not) human-caused. Of the papers that gave an explicit (or obviously implied answer), only 3% gave a “no” answer (which is statistically expected due to chance). This video can explain more in detail.

All methods have some sort of inherent flaw (even if only minor), and scientific papers do discuss those limitations. Though this method is helpful, there is a problem. It’s biased in a way that can easily conflate disagreement. Mind blown? Me too.

How? consider this: modern biology papers rarely ever say “natural selection is real,” and geology papers rarely say “plate tectonics is real,” and physics papers rarely say “gravity is real.” These are just understood facts (unless extraordinary evidence is discovered that overturns them). The scientific journals (i.e., the publishers) limit the length of the paper, and this is especially true for the abstract (the thing they technically measured). So why waste precious word-space on already understood facts?

I think I’m starting to get it. But is this an appeal to authority fallacy?

Great question. Not really. We should avoid the argument from authority fallacy should be avoided, and we should definitely value independent thought. But as I explained in those links, deferment to expertise is not the same as appealing to authority, especially when it comes to peer-reviewed science.

Does the public know there is a consensus?

This one makes me a little sad.

As I’ve noted before, this near-unanimous view among scientists is in contrast with the US public perception. Only 65% of Americans believe that most scientists believe global warming is occurring (Jones and Saad, 2019)… I’m no mathemasurgeon, but I now 65% is very different from 90-something.

How did this skewed perception of consensus happen?

Well, right or wrong, there are organized efforts to sow doubt among the public (Gentzkow et al., 2019; Dunlap and McRight, 2014; Michales, 2006; Oreskes and Conwy, 2011; Brulle, 2014; Farrell, 2016).

But another significant factor is the false balance effect—where media pundits give equal coverage to two sides even though both parties are not equally plausible, thus skewing the public’s perception of controversy (Freudenburg and Muselli, 2010). There is also the inflation of conflict, where a small set of fringe experts and special interests artificially make it look like the expert commnity is shotly debating an issue.

Takeaways

So in short, no, the scientific community had no consensus in the 70s another ice age was coming—although I would adore another Ice Age movie about Scrat, the prehistoric squirrel. And no, there isn’t much disagreement about the big ideas.

I think I ever answered the questions, but that is how I roll sometimes. Even still, this is just ‘scrat’-ching the surface (*slaps knee*). For other questions, you can check out this list of non-hippie, non-naive, non-polishitan resources. Good hunting on your journey!

Carpe Datum and Semper Sci!

Sgt Scholar Actual, out.

Be sure to like comment and share!

Use the menu at the top to navigate to other articles.

Did you love it and want to help support Sgt Scholar? Patrons of Sgt Scholar enjoy benefits such as early access to articles, helping decide the topics of coming articles, and more. Click here to support Sgt Scholar: https://www.patreon.com/sgtscholar.

References:

Abraham, J. P., Cook, J., Fasullo, J. T., Jacobs, P. H., Mandia, S. A., & Nuccitelli, D. A. (2014). Review of the consensus and asymmetric quality of research on human-induced climate change. (1), 3-18.

Benestad, R. E., Nuccitelli, D., Lewandowsky, S., Hayhoe, K., Hygen, H. O., van Dorland, R., & Cook, J. (2016, 2016/11/01). Learning from mistakes in climate research. Theoretical and Applied Climatology, 126(3), 699-703. https://doi.org/10.1007/s00704-015-1597-5

Brulle, R.J., Institutionalizing delay: foundation funding and the creation of U.S. climate change counter-movement organizations. Climatic Change, 2014. 122(4): p. 681-694.

Cook, J., Oreskes, N., Doran, P. T., Anderegg, W. R. L., Verheggen, B., Maibach, E. W., . . . Rice, K. (2016). Consensus on consensus: A synthesis of consensus estimates on human-caused global warming. Environmental Research Letters, 11(4), 048002. doi:10.1088/1748-9326/11/4/048002

Cook J, Nuccitelli D, Green S A, Richardson M, Winkler B, Painting R, Way R, Jacobs P and Skuce A. (2013). Quantifying the consensus on anthropogenic global warming in the scientific literature Environ. Res. Lett. 8 024024. doi:10.1088/1748-9326/8/2/024024

Dunlap, R.E. and A.M. McCright., Climate Change Denial: Sources, Actors, and Strategies., in Routledge International Handbook of Social and Environmental Change, C. Lever-Tracy, Editor. 2014, Routledge Press: New York.

Farrell, J., Corporate funding and ideological polarization about climate change. Proceedings of the National Academy of Sciences, 2016. 113(1): p. 92-97.

Freudenburg, W.R. and V. Muselli, Global warming estimates, media expectations, and the asymmetry of scientific challenge. Global Environmental Change, 2010. 20(3): p. 483-491.

Gentzkow, M., J.M. Shapiro, and M. Taddy, Measuring Group Differences in High-Dimensional Choices: Method and Application to Congressional Speech. Econometrica, 2019. 87(4): p. 1307-1340.

Gwynne, P., 1975: The cooling world. Newsweek, 28 April, p. 64.

Jones, J. and L. Saad. 2019, Gallup Poll. Data and image retrieved from article: Americans as Concerned as Ever About Global Warming. Lydia Saad, 25 March 2019. Gallup. https://news.gallup.com/poll/248027/americans-concerned-ever-global-warming.aspx

Lewandowsky, S., Ballard, T., Oberauer, K., & Benestad, R. (2016, 2016/07/01/). A blind expert test of contrarian claims about climate data. Global Environmental Change, 39, 91-97. https://doi.org/https://doi.org/10.1016/j.gloenvcha.2016.04.013

Mathews, S.W., 1976: What’s happening to our climate? National Geographic Magazine, 150, 576-615.

Michaels, D., Manufactured Uncertainty. Annals of the New York Academy of Sciences, 2006. 1076(1): p. 149-162.

Oreskes, N. (2004). Beyond the ivory tower. The scientific consensus on climate change. Science, 306(5702), 1686. http://dx.doi.org/10.1126/science.1103618

Oreskes, N. (2018). The Scientific Consensus on Climate Change: How Do We Know We’re Not Wrong? In E. A. Lloyd & E. Winsberg (Eds.), Climate Modelling: Philosophical and Conceptual Issues (pp. 31-64). Springer International Publishing. https://doi.org/10.1007/978-3-319-65058-6_2

Oreskes, N. and E.M. (2011). Conway, Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming: Bloomsbury USA.

Peterson, T. C., Connolley, W. M., & Fleck, J. (2008). The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorological Society, 89(9), 1325-1338. doi:10.1175/2008bams2370.1

Powell, J. (2017, 2017/12/01). Scientists Reach 100% Consensus on Anthropogenic Global Warming. Bulletin of Science, Technology & Society, 37(4), 183-184. https://doi.org/10.1177/0270467619886266

Powell, J. L. (2015, 2015/10/01). Climate Scientists Virtually Unanimous: Anthropogenic Global Warming Is True. Bulletin of Science, Technology & Society, 35(5-6), 121-124. https://doi.org/10.1177/0270467616634958

Powell, J. L. (2016, 2016/10/01). The Consensus on Anthropogenic Global Warming Matters. Bulletin of Science, Technology & Society, 36(3), 157-163. https://doi.org/10.1177/0270467617707079

Rasool, S. I., & Schneider, S. H. (1971). Atmospheric carbon dioxide and aerosols: Effects of large increases on global climate. Science, 173(3992), 138. doi:10.1126/science.173.3992.138

Time Magazine, 1974: Another ice age? Time, 24 June. Available from http://www.time.com/time/magazine/article/0,9171,944914,00.html

Verheggen B, Strengers B, Cook J, van Dorland R, Vringer K, Peters J, Visser H and Meyer L 2014 Scientists’ views about attribution of global warming Environ. Sci. Technol. 48 8963–71. doi:10.1021/es501998e