The 1970s Global Warming Consensus

And how political actors help doubters ignore it

In the public debate about whether humans really cause global warming, it’s often forgotten that the scientific consensus is really quite old. Those in denial have been given the impression that the consensus on global warming is a new phenomenon, something that was somehow created by the UN IPCC in the 1990s, after it was formed in 1988 to study the extent of human-caused climate change and its impacts. They will tell you — never with specific details — that somehow the IPCC or liberal governments “corrupted” scientists, causing most climatologists to reach a false conclusion.

They have the causation backwards, though: the scientific consensus came first, and the IPCC was formed afterward. In fact, there are climatology papers on the greenhouse effect and carbon dioxide dating back to the 19th century, but the wider scientific community paid little attention to the issue until the 1960s, after the post-war boom when burning of fossil fuels increased substantially.

This fact was illustrated by a review of climatology literature that was created by scientists Peterson, Connolley and Fleck to counter the myth of a “global cooling consensus of the 1970s”:

Among the 7 cooling papers they found was Steven Schneider 1971’s article, which contributed to Time’s famous one-page 1975 story predicting global cooling. Yet Schneider changed his mind soon afterward, and endorsed the majority opinion from then until his death in 2010.

One of the early quantitative predictions of global warming came from J.S. Sawyer, who predicted in 1972 that by the year 2000, atmospheric CO2 levels would rise 25% and that global temperatures would rise 0.6°C. In fact, CO2 didn’t rise 25% until after 2010; temperatures rose about 0.5°C by 2000 and about 0.7°C by 2015. The prediction was remarkably accurate, considering that it came before the first computer models, it came before the climatologist community had fully analyzed the issue, and it came during a global cooling trend.

But if you tell this to certain people, chances are they will immediately dismiss it as a “failed” prediction, either because they have impossibly high expectations (0.6 “isn’t close enough” to 0.5), or because the measured temperature increase was “fraudulent”.

Similarly, they have ways of denying there was any 1970s warming consensus at all.

The Denial Trick: Part 1

“…a strong case can be made that the present cooling trend will, within a decade or so, give way to a pronounced warming induced by carbon dioxide” - Broeker (1975)

Climatologists generally agreed by the late 1970s that Earth had been cooling for 30 years before 1976 (at least in the northern hemisphere), and would warm in the future.

Some scientists published on both topics, like Mikhail Budyko, one of the scientists who helped document the cooling trend shown here:

One estimate of northern cooling from 1940 to 1975

Yet Budyko also published papers like this one discussing future human effects on climate, including the warming effect of CO2.

Now read this version of events in the ironically-named “NoTricksZone”:

As will be shown here, the claim that there were only 7 publications from that era disagreeing with the presupposed CO2-warming “consensus” is preposterous. Because when including the papers from the 1960s and 1970s that indicated the globe had cooled (by -0.3° C between the 1940s and ’70s), that this cooling was concerning (leading to extreme weather, drought, depressed crop yields, etc.), and/or that CO2’s climate influence was questionable to negligible, a conservative estimate for the number of scientific publications that did not agree with the alleged CO2-warming “consensus” was 220 papers for the 1965-’79 period, not 7. If including papers published between 1960 and 1989, the “non-consensus” or “cooling” papers reaches 285.
[…] Interestingly, if we were to employ the hopelessly flawed methodology of divining the relative degree of scientific “consensus” by counting the number of papers that agree with one position or another […], the 220 “cooling” papers published between 1965-’79 could represent an 83.3% global cooling consensus for the era (220/264 papers), versus only a 16.7% consensus for anthropogenic global warming(44/264 papers).

This post generates an “83% cooling consensus” by adding together completely different things:

  • All 7 papers that suggested there may be future cooling
  • All papers that agreed there had been past cooling
  • All papers that said “CO2’s climate influence was questionable to negligible”

The article won’t tell us how many papers said “this cooling was concerning” or that “CO2’s climate influence was questionable to negligible”. This invites the reader to imagine some large number, even though it’s probably zero. For example, the last 1970s “cooling” paper (Sean Twomey 1977) ignored CO2 completely; it simply proposed that “pollution” could cause cooling by increasing cloud reflectance (in those days, “pollution” meant smog and aerosols, not CO2).

As another example, in Schneider’s 1971 paper predicting global cooling, the paper’s own summary acknowledges that CO2 causes warming. His argument wasn’t that CO2 does not cause warming, but rather that aerosols cause a very large cooling:

Effects on the global temperature of large increases in carbon dioxide and aerosol densities in the atmosphere of Earth have been computed. It is found that, although the addition of carbon dioxide in the atmosphere does increase the surface temperature, the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere. For aerosols, however, the net effect of increase in density is to reduce the surface temperature of Earth. Because of the exponential dependence of the backscattering, the rate of temperature decrease is augmented with increasing aerosol content…

Plus, his statement that “the rate of temperature increase diminishes with increasing carbon dioxide in the atmosphere” doesn’t contradict the consensus — it is an accepted fact even today, as I have discussed before. The paper also assumes increased emissions of aerosols, but catalytic converters in vehicles — introduced in the mid-1970s — ultimately decreased aerosol concentrations around the world.

Finally, “NoTricksZone” takes a shot at John Cook’s peer-reviewed study showing a 97% consensus for man-made global warming, by calling him a “blogger” that produced a “predetermined result”:

[…] counting the number of papers that agree with one position or another (just as blogger John Cook and colleagues did with their 2013 paper “Quantifying the Consensus…” that yielded a predetermined result of 97% via categorical manipulation)

In fact, John Cook is a cognitive scientist who studies global warming denial, his study is published in a peer-reviewed journal, and the full database of 12,000 papers are published online for anyone to review or search. There’s even a system that invites citizens to check the results.

There are several other studies that also show a consensus about global warming, as I have discussed before. Recently, Cook and his colleagues interviewed dozens of mainstream climatologists in person, and put together a free 7-week video course about climate science and the denial thereof.

The Denial Trick: Part 2

Adding up past cooling observations plus future cooling predictions to produce an “83% cooling consensus” is so obviously dishonest that the writer needs to butter up his audience to accept it first.

A big part of the denial playbook is ad-hominem attacks. Spreading myths isn’t enough, since one also needs to explain how mainstream scientists “got it wrong”. Solution: claim they are evil and dishonest!

So the article starts by attacking Connolley, one of the three authors of the article about the 1970s consensus:

Beginning in 2003, software engineer William Connolley quietly removed the highly inconvenient references to the global cooling scare of the 1970s from Wikipedia, the world’s most influential and accessed informational source.
It had to be done. Too many skeptics were (correctly) pointing out that the scientific “consensus” during the 1960s and 1970s was that the Earth had been cooling for decades, and that nascent theorizing regarding the potential for a CO2-induced global warming were still questionable and uncertain.
Not only did Connolley — a co-founder (along with Michael Mann and Gavin Schmidt) of the realclimate.com blog — successfully remove (or rewrite) the history of the 1970s global cooling scare from the Wikipedia record, he also erased (or rewrote) references to the Medieval Warm Period and Little Ice Age so as to help create the impression that the paleoclimate is shaped like Mann’s hockey stick graph, with unprecedented and dangerous 20th/21st century warmth.
A 2009 investigative report from UK’s Telegraph detailed the extent of dictatorial-like powers Connolley possessed at Wikipedia, allowing him to remove inconvenient scientific information that didn’t conform to his point of view.

No evidence is offered that Connolley did anything wrong, but none is needed — those who want to deny greenhouse-gas warming will assume the worst automatically.

Note, too, how today’s consensus of thousands of scientists all over the world is reduced to “[Michael] Mann’s hockey stick graph”. It’s much easier to believe in a few corrupt scientists than thousands of them.

Another trick here is that most people don’t really read articles — they read the beginning and skim the rest. To take advantage of this, the dishonest analysis is hidden among bold headings like “Concoction Of ‘Consensus’ Achieved Via Exclusion” and “83% Global Cooling/Weak CO2 Influence Scientific ‘Consensus’ During 1960s, ’70s”.

The Denial Trick: Part 3

For the coup de grace, the article claims climatologists fraudulently erased the global cooling period from history, by showing this graph from NASA:

But this is just cherry picking “meteorological stations”. On NASA’s data page you’ll see that same graph alongside others that clearly show cooling from 1945 to 1975, mainly in northern latitudes but also globally:

You can see 0.3°C of cooling if you’re looking for it

(Note: don’t be surprised if the GISS record for this time period is revised in the future to reduce the suddenness of cooling after World War 2, caused by a recently-discovered bias in ocean readings.)

The Denial Trick: Part 4

Note: Part 4 is a late addition to this page, inspired by a post on SkepticalScience.

The author actually published his list of 285 “cooling” papers. To get this list, the author started by casting a much wider net than Connolley. Connolley reviewed a limited selection of peer-reviewed papers up to 1979, but the 285 “cooling” papers included non-peer reviewed papers and papers from the 1980s. Despite the author’s expansive search, he managed not to find even a single new “warming” paper beyond what Connolley already discovered.

Next have a look at paper #6, Benton 1970:

Climate is variable. In historical times, many significant fluctuations in temperature and precipitation have been identified. In the period from 1880 to 1940, the mean temperature of the earth increased about 0.6°C; from 1940 to 1970, it decreased by 0.3–0.4°C. Locally, temperature changes as large as 3–4°C per decade have been recorded, especially in sub-polar regions. … The drop in the earth’s temperature since 1940 has been paralleled by a substantial increase in natural volcanism. The effect of such volcanic activity is probably greater than the effect of manmade pollutants.

Naturally, it’s talking about past cooling. But look what was left out:

Recent numerical studies have indicated that a 10% increase in carbon dioxide should result, on average, in a temperature increase of about 0.3°C at the earth’s surface. The present rate of increase of 0.7 ppm per year would therefore (if extrapolated to 2000 A.D.) result in a warming of about 0.6°C — a very substantial change.

So much for being a “cooling” paper. Another trick in the list is to mention irrelevant topics. For example, standard climate science tells us that Milankovich cycles drive patterns of insolation change that lead to warming or cooling over cycles lasting tens of thousands of years. So here’s paper #1 on the list:

Climatic changes result from variables in planetary orbits which modulate solar energy emission and change seasonal and latitudinal distribution of heat received by the Earth. Small insolation changes are multiplied by the albedo effect of the winter snow fields of the Northern Hemisphere, by ocean-atmosphere feedbacks, and, probably, by the stratospheric ozone layer. The role of volcanic explosions and other aperiodic phenomena is secondary. The immediate climate response to insolation trends permits astronomic dating of Pleistocene events. A new glacial insolation regime, expected to last 8000 years, began just recently. Mean global temperatures may eventually drop about 1oC in the next hundred years. A refinement of the Milankovitch theory in terms of the lunar orbit and more data on solar periodicities are needed for reliable long range predictions.

Obviously, the mere existence of slow change over thousands of years says nothing about whether humans can cause fast change with CO2.

The most obvious trick, though, is the use of color and boldface to highlight “cooling” phrases while ignoring “warming” phrases. Have a look at paper #2. This text is shown in boldface:

None of the calculations of which I am aware found that the man augmented CO2 could have contributed more than a small fraction of the warming up to 1940.

But this other text is shown without boldface:

There is essentially universal agreement that atmospheric CO2 is increasing, increasing as a result of the consumption of fossil fuels and that this should enhance the “greenhouse” effect leading to a warming of the planetary surface.

Kenneth Richard

The article was written by Kenneth Richard, who posts an article every 3–4 days or so. Just by looking at the headlines, we can see that each one “teaches” one of about 200 popular myths (compare the headlines with the myth list on SkepticalScience). Who is Kenneth Richard? I haven’t been able to figure that out, and he is not among the hundreds of names in DeSmogBlog’s disinformation database. He started publishing at NoTricksZone on August 11, 2016. He didn’t introduce himself on the site, but simply dived right in with a highly misleading headline claiming “35 New Scientific Publications Confirm Ocean Cycles, Sun Are Main Climate Drivers”.

The Washington Connection

Of course, an anti-science argument is useless if no one reads it. While NoTricksZone has a sizeable audience, the article got a search-engine boost when it was reposted by ClimateDepot. ClimateDepot is “a project of CFACT”, a political Washington, D.C. organization that originally advocated free-market solutions to environmental issues, but now mainly promotes climate change denial. Their promotion makes it reach Google’s first page:

In this case, they chose a headline so long that Google cut off the phrase “Robust Cooling Consensus”. Oops.

Naturally, James Delingpole of Brietbart also used Kenneth Richard’s post as the basis to claim that “Lying Alarmists Rebranded 70s Global Cooling Scare as a Myth.” When asked how long he spent researching the piece, he boasted proudly that he’d done as little research as possible.

As I investigated climate change science I did hundreds of Google searches, and I noticed that in many cases Google gives me an even split between mainstream and denial web sites. In this particular case, though, they weren’t terribly successful.

Peterson, Connolley and Fleck’s review of the 1970s climate change literature concludes by pointing out that Jule Charney, one of the pioneers of climate modeling, brought together a panel of experts under the U.S. National Research Council to sort out the state of the science. The panel’s 1979 report said nothing of potential global cooling; instead it expressed concern that warming from doubled CO2 of 1.5° to 4.5°C was possible. Clearly, the consensus of the 70s was not for more global cooling.

Interestingly, the IPCC’s latest estimate is identical, and most climate scientists say that doubling CO2 is most likely to raise global temperatures by 2.5° to 3.5°C (source: Verheggen 2014, 4a), though uncertainty remains. So what’s changed from then to now? Our confidence and level of detail: more scientists have investigated the matter from more perspectives; more issues have been examined and modeled (clouds, carbon uptake and release by forests, permafrost, clathrates, glacier melt, etc.); far more detailed observations have been gathered; and unlike in the 1970s, the predicted warming has now been observed very clearly.