We are fast approaching the centennial of what should have been the end of The Climate Wars. Although quantum mechanics was in its infancy in 1925, atmospheric optics and spectrophotometry were far enough advanced to ground basic calculations of the radiative equilibrium of climate relative to the concentration of CO2 in the air. As Arrhenius' contemporary Mellor noted in:
The bottom line can be fairly put as being that, today as in 1925, the blackboard calculations of Tyndall, Angstrom, Roentgen & Arrhenius remain basically right, and those of Kayser, Abbot and Fowle woefully wrong- their understanding of aerosol cooling did not translate into an equally coherent understanding of atmospheric radiation:
VOLCANOES AND CLIMATE
By C. G. ABBOT and F. E. FOWLE
During- the summer of 191 2 we were engaged, respectively, at Bassour, Algeria, and at Mount Wilson, California, in measuring with the pyrheliometer and spectrobolometer the intensity of the radiation of the sun. On June 19 Mr. Abbot began to notice in Bassour streaks resembling smoke lying along the horizon, as if there were a forest fire in the neighborhood of the station. These streaks continued all summer, and were very marked before sunrise and after sunset covering the sky then towards the sun nearly to
the zenith. After a few days the sky became mottled, especially near the sun. The appearance was like that of the so-called mackerel sky, although there were absolutely no clouds.
In the months of July, August, and so long as the expedition remained in September, the sky was very hazy, and it was found that the intensity of the radiation of the sun was greatly decreased by the uncommonly great haziness. Mr. Fowle noted similar appearances at Mount Wilson especially noting the streakiness beginning with June 21.
Publications in European Journals and elsewhere have indicated that this haziness was world-wide. We adopt the view expressed by Dr. Hellmann 1 that the haze in question was due to the eruption of the volcano of Mount Katmai in Alaska in June, 1912. In the present paper we give the effects of the haze on the quantity and quality of the solar radiation as determined by our measurements, and also the effect which the presence of the haze and that of similar occurrences in former years appear to have had on the climate of the earth. Before passing to the Numerical results it will be interesting to recall briefly the circumstances attending the eruption of Mount Katmai and of other extraordinary volcanic outbreaks which resulted in periods of prolonged haziness similar to that of the summer of 1912.
1 Zeitschrift fur Meteorologie, January, 1913. Smithsonian Miscellaneous Collections, Vol 60, No. 29
