Harlow Shapley was interesting. Here is a nyt article about his theory that solar systems drifted through murk which caused climate change. 1921 was a time of lots of theories now GHG theory is only one?
AGES OF COLD DUE TO BIG DUST CLOUDS; Dr. Harlow Shapley, Harvard Observatory Director, Discusses Climate Changes.THE EARTH ONCE LIFELESS What Will Happen When the SunPasses Through the Orion Nebulae. An Age of Murk. Effect of Dust Clouds. Cold Caused by Volcanic Action. No Life on Earth at Periods.
A new theory relating to one of the greatest mysteries about the past of the earth has been offered by Dr. Harlow Shapley, the measurer of the universe, whose appointment as Director of the Harvard Observatory was announced on Thursday.
From NYT archive 1921