Erasing history is dangerous business, as is rewriting it. For instance the whole issue of the cooling scare of the 1970s that we’re now told didn’t happen. And the natural variability of the climate over hundreds, thousands and hundreds of millions of years that has also been stuffed down the memory hole. Mallen Baker, who has done unusually thoughtful if slightly patronizing YouTube videos on how to think about the issue (not entirely sharing our perspective, we might add) mentions in “The climate always changes!” that in 1974 then U.S. Secretary of State Henry Kissinger gave a speech to the UN warning of climate change, after which Congress passed a 1978 law declaring the 1980s and 1990s as “International Climate Decades” and mandating a major research effort. But before you pounce and say “Shell knew” or some such, remember that Kissinger was worried about natural climate change including cooling.
In his 2019 book Geoengineering, the Anthropocene and the End of Nature, Jeremy Baskin says “In April 1974, in a speech to the United Nations, US Secretary of State Henry Kissinger, pushed for increased research to counter the newly-voiced threat of climate change” and footnoted this claim to “Beheringer 2010 : 188).” And indeed Wolfgang Beheringer, in A Cultural History of Climate, had written that “In a speech to the United Nations on April 15 1974, the US Secretary of State Henry Kissinger, pushed for increased research to meet the threat of climate change”. But Beheringer concedes that the consensus back then was that catastrophic cooling loomed, and prompted serious discussion of recklessly unserious projects like damming the Bering Strait, actually discussed by Gerald Ford and Leonid Brezhnev at Vladivostok in 1974. But Beheringer says by 1977 the consensus had reversed its polarity and was now about man-made warming. Which tells you how solid and lasting a scientific consensus can be.
Of course the question whether people once thought the planet was cooling has no logical connection with whether it currently is warming or, if it is, whether humans are largely responsible. Nor indeed has the question whether the Earth is warming, for whatever reason, any logical connection with whether warming is liable to cause negative consequences, even disastrous ones, whatever polemical links may be drawn.
On the other hand, the question whether there was once a cooling consensus is relevant to the warming debate in several ways. First, it sheds some light on whether there might be a tendency to rush in panic or sensationalism from one extreme to another over climate. And second, subsequent discussions of the phenomenon sheds some light on whether there might be a tendency in certain quarters to suppress inconvenient truths like that we were wrong last time. Hence the desire to go back and revise the past so we always knew humans were causing warming and oil companies suppressed the knowledge and still are na na boo boo.
So here’s what Kissinger actually said in 1974. “The poorest nations, already beset by man-made disasters, have been threatened by a natural one: the possibility of climatic changes in the monsoon belt and perhaps throughout the world. The implications for global food and population policies are ominous. The United States proposes that the International Council of Scientific Unions and the World Meteorological Organization urgently investigate this problem and offer guidelines for immediate international action.”
Again he may have been right and he may have been wrong. He was not, after all, a “climate scientist”. But for better or worse he clearly identified the threat as “a natural one”. And in his video Baker agrees that looking backward from 1974 one sees persistent climate instability and chides alarmists who deny its existence.
One can accept this point of view and still believe there is now human influence, and indeed fear that it may become catastrophically worse. But one cannot accept models that say that all 20th-century warming was man-made and, on that basis, devise some estimate of the warming impact of human GHGs and the cooling impact of human aerosols that give you a hockey stick in the 21st century.
Climate science is really easy. First, you plot a graph of how you imagine anthropogenic CO2 causes catastrophic warming, all other things being equal. Second, you plot a graph showing the actual temperature observations over the relevant period of time - say, 1900 to present. Third, you produce a graph showing the discrepancies between graph #1 and graph #2, and deduce that this must be the result of natural variability. Fourth, you search for conjectures that "explain" the deduced natural variability retrospectively: Milankovitch cycles, ocean currents sequestering heat in the deep trenches, unknown underwater volcanic activity, aerosols, etc. Now you have it all: catastrophic alarmism, "supported" by observation, that takes into account "natural variability."