Sunday, March 7, 2021

Thoughts on Climate Change -- Part 10: The Aerosol Excuse

Climate change advocates have been exceptionally ingenious in devising various ways to “cook” the raw data in such a manner as to fit their favored theory despite evidence to the contrary. For example, a common attempt to explain away the mid-twentieth century temperature hiatus is the frequently stated claim that an underlying warming trend was masked by industrial aerosols (i.e. pollutants) emitted, ironically enough, by the same process that also emitted large amounts of CO2.

The mid-century cooling appears to have been largely due to a high concentration of sulphate aerosols in the atmosphere, emitted by industrial activities and volcanic eruptions. Sulphate aerosols have a cooling effect on the climate because they scatter light from the Sun, reflecting its energy back out into space. (Climate myths: The cooling after 1940 shows CO2 does not cause warming.)

The effects of volcanic aerosols can be discounted as they are short-lived, no more than a blip on a typical graph. As for the effects of industrial pollution, they are indeed continuous -- but localized. Industrial aerosols are most heavily expelled in highly industrialized areas and since their lifetime is quite short, tend to remain in roughly the same area where they were released. The effects of CO2 emissions, on the other hand, are global. So if you want to argue that industrial aerosols were responsible for the global cooling evident from ca. 1940 to ca. 1979, you would need to produce evidence of the alleged underlying warming in undeveloped areas, relatively unaffected by industrial pollutants. Does such evidence exist? Let’s take a look:


No sign of underlying warming in the Arctic during the period in question (1940-1979). Instead we see a steady cooling trend followed by a brief period of stabilization. Not much sign of heavy industry in this region I’d say.

Gradual cooling in the Antarctic from 1945 through 1970. No sign of an upward trend until the early 80’s.

Gradual cooling in Africa from the late 30’s til the late 70’s. Not much industrial activity on this continent during the same period.

Following the red line representing Madagascar, we see no sign of warming until the 80’s.


Kirensk and Tura are located in Siberia, far from any industrial activity. No warming trend in either during the period in question.

Not much in the way of industrial activities in Afghanistan -- yet here too we see a clear cooling trend during the period in question.

More or less the same picture for Burundi.

Here's the data for Haiti.

Not much different in Kyrgistan.

No warming trend in New Caledonia.

Need I continue?

So! Where on Earth, pray tell, is all the warming that “would have” happened were it not for industrial aerosols?

. . . [F]or each accepted explanation of a phenomenon, there is always an infinite number of possible and more complex alternatives, because one can always burden failing explanations with ad hoc hypotheses to prevent them from being falsified . . .  This endless supply of elaborate competing explanations, called saving hypotheses, cannot be ruled out—but by using Occam's Razor. (Occam's Razor - Wikipedia)

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