The Myth: Climate scientists were not on the global cooling bandwagon in the 1970s

Advisory:  heavy reading ahead…have to fill time during current cloud drought

In an article published in the Bulletin of the American Meteorological Society (BAMS) in 2008, it was asserted that there was no “concensus” on global cooling in the 1970s.  Why address this now?  I was busy before now….

Overall response to this BAMS assertion:

Hogwash!  Rubbish!  Bilge!  (I’m pretty “excited” here).

In fact, perhaps the most outrageous statement I have ever seen in a peer-reviewed journal was that of the BAMS Editor, quoted below in red.  In defense of the Editor, he was only parroting the conclusions of a major article in that BAMS issue purporting this distortion.  The appearance of such an article can be seen as a failure of peer review.   Here is what the BAMS Editor wrote in summarizing that bogus claim:

“In this issue, (the authors-names omitted) show that we were indeed misled about global cooling–but not by scientists. (emphasis added by the present writer).   Rather, we are confused about the recent history of our own science.”

I wanted to gag when I read this.  I was doing decadal climate studies in the early 1970s and so I was “pretty familiar” with the literature.

First of all, what were scientists really saying about climate change back then?  I will cite two major sources from the 1970s:

Below, a quote by Wilmot N. Hess, then the Director of 11 NOAA programs,  from the preface of  Chapter F on Climatic Change in the book, Weather and Climate Modification, published by Wiley Interscience in 1974.  (The volume, a collection of essays by experts,  targeted senior-level college students in the sciences and engineering, or working scientists or engineers who don’t know much meteorology.)

“It has been suggested recently that we are near the end of an integlacial period.  Studies of climate changes are in their infancy.  We know that there have been four episodes of glaciation in the recent past covering a period of about 1,000, 000 years.  A conference at Brown University in January 1972 discussed this problem and the MAJORITY (the font can’t be big enough here!) of the participants concluded that:

Warm intervals like the present one have been short-lived and the natural end of our warm eposch is undoubtedly near when considered on a geological time scale.   Global cooling and related rapid changes of environment, substantially exceeding the fluctuations experienced by man in historical times must be expected within the next few millenia or even centuries.‘”

Here’s what those climate scientists were looking at over just the past 100, 000 years of the earth’s climate.   Their concern will be obvious.  Note the “present” is on the left, not right as per normal.  The numbers “4” and “5” represent “interglacial” warm periods, the first the present one, called the Holocene, and “5”, the Eemian interglacial period.  Look, too,  how the temperature was trending DOWNWARD over all that glacial time until our present interglacial.  Source:  National Academy of Sciences, 1975.

Now imagine you are a journalist at that Brown University Conference…and you also learn that the earth’s temperature has been falling for more than 25 years (not shown in the above graph).  Futhermore, the CO2 people also inform you that the recent decline in temperatures over that 25 years would even be GREATER if it wasn’t for the mitigating effect of CO2!

What are you going to tell your public?   It’s obvious.

So how did such a scientific distortion get published in BAMS in 2008 by supposedly knowledgeable authors? Were they themselves confused about the history of climate change?  Was it due to their methodology?  Or was it a propaganda piece all along, a revisionist history resembling something analogous to the type of pieces that came out of Pravda of the former Soviet Union, a piece written to correct an earlier error,  so that that we scientists look like we had it right all along?  Probably all of these, in this writer’s opinion.

Lets look at what the authors did.   The full article is here.  In support of their phony claim, the authors of the BAMS article used a “bean counting” approach, the results of which they display in a contingency table.   They tabulated articles on climate change and its likely causes in peer-reviewed journals, looked at the conclusions, and if the article concluded that CO2 was going to warm the world, it would be placed in the warming world column, if the conclusion was ambiguous they gave it a nul ranking, and if the article concluded we were headed for a cooling, it went into that column.  The authors then told us that because they were more articles about CO2 and warming than nul or cooling articles, that must be what everyone believed, a major fallacy in reasoning.

However, either out of ignorance of our science hierarchy,  or having an axe to grind, they counted prestigious reviews with the same as that assigned to a single publication by “Joe Blow”, somebody who might never have been heard from again.   So when they counted an 1975 assessment by the National Academy of Sciences, an organization that periodically reviews subjects of critical interest, employing dozens of experts and reviewing dozens of peer-0revied articles, the authors assigned that review the same weight as the other publications.   It was like assigning an elephant the weight of a flea.

Nor did the authors mention the 1968 American Meteorological Monograph, The Causes of Climatic Change; not ONE paper in that tome discusses CO2 and its possible effect on climate!

And, of course, they did not cite the Wiley-Interscience volume with its contents concerning climate,  quoted above.

But why were scientists in the 1970s concerned with global cooling and not paying so much attention to CO2?

By 1975, the earth’s temperature had been in DECLINE for about 30 years!   This was in spite of massive increases in CO2 during that 30 years.   The cause of that decline has not been ascertained even as of today.  That decline in temperatures was reversed in the late 1970s,  as has the cause of the leveling of the earth’s temperature during the past 10-12 years, also in spite of increasing CO2.  Furthermore, some authors attributed that reversal to changes in the Pacific Decadal Oscillation which occurred in the late 1970s, not to CO2.

Against that background of a long term decline in temperature by the mid-1970s, it was known that the current “interglacial” period we are in (also known in science-speak as the “Holocene”)  would not last forever.   In fact, it had gone on about as long as the earlier one about 100, 000 years ago, called the Eemian (number “5” in the figure above), or about 10-12,000 years.  This was of concern to paleoclimatologists in the mid-1970s against the backdrop of declining temperatures.   Recall we departed from ice age conditions in fits and starts only about 18,000 years ago, and after a few thousand years reached the current Holocene “warmth.”

Here’s what the National Academy of Sciences (Understanding Climatic Change) had to say in 1975, p188:

“One may still ask the question:  When will the present interglacial end?  Few paleoclimatologists would dispute that the prominent warm periods (or interglacials) that have followed each of the terminations of the major glaciations  have had durations of 10,000 +-2,000 years.  In each case, a period of considerably colder climate has followed immediately after the interglacial interval.  Since about 10,000 years has elapsed since the onset of the present period of prominent warmth, the question naturally arises as to whether we are indeed on the brink of a period of colder climate.   Kukla and Mathews (1972) have already called attention to such a possiblity.  There seems little doubt that the present period of unusual warmth will (emphasis in the original) eventually give way to a time of colder climate, but there is no consensus with regard to either the magnitude or the rapidity of the transition.  The onset of this climatic decline could be several thousand years in the future, although there is a finite probability that a serious worldwide cooling could befall the earth within the next hundred years.”

So, global cooling is in our future, no doubt about it.  However, the NAS pointed out that the bad for us cooling might be offset by CO2, or, if there was a further warming, that before the eventual cooling, that CO2 would exacerbate that.  To me, what was being written by the NAS was vastly different than the mere “0” assigned to that piece by the BAMS authors.

Now, when a journalist reads a statement by the prestigious National Academy of Sciences that there is a possibility of a “climatic decline” (that’s how cooling was looked at, namely, it would be worse weather for us than we have now in the Interglacial) in just a hundred years, what is he going to write?  If he wrote about that for, say,  Time magazine, that global cooling was “in the bag” and might even happen within a 100 years,  he would have gotten it  from our highest scientific organization.

In sum, there WAS widespread concern among climatologists and scientists about global cooling, particular in the early 1970s.   It was no myth.



By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.