Global warming and warning

Rising temperatures were noted in the arctic in the early 1920s. The phenomenon got play in the press of the era.

There were also efforts to explain scientifically what was happening.

An article in the New York Times in 1921 theorized space dust was responsible.

New York Times, November 20, 1921

Seems that bouts of warming and cooling have been going on as long as the Earth's been around.

The difference between now and in the past is that in the past, scientific theory was presented as theory, and wasn't designed or exploited as an excuse to control or manipulate people or whole populations for political purposes as it is now.