J. Murray Mitchell

In 1976 he described the conjecture of global cooling as irresponsible, and around that time supported other scientists in warning of the damaging effects of increasing CO2 in the atmosphere.

[3] Mitchell's investigation of Arctic haze in the 1950s found aerosol particles which apparently originated from industrial areas of Europe and China.

[1] Using studies of nuclear fallout from bomb tests which showed how aerosols moved in the upper atmosphere, he compared global temperature statistics with the record of volcanic eruptions in a 1961 paper which put forward his view that large eruptions had significantly affected temperatures at a hemispherical scale.

Average temperatures had fallen since 1940 despite a lack of eruptions, and he thought this an "enigma" which might indicate a long term "rhythm" or cycle.

[5] He continued his statistical investigations, and in a 1969 paper calculated that about two-thirds of Northern Hemisphere cooling since 1940 had been caused by a few recent volcanic eruptions, leading him to conclude that "man has been playing a very poor second fiddle to nature as a dust factory", though he thought that human influence could increase.

[4][6] As research developed, he drew attention to increasing evidence that warming climate, particularly in polar regions, was due to human caused greenhouse gas emissions and could change weather patterns to the detriment of agriculture.