Not sure why I was reminded of this today, but here’s a John von Neumann quote from 1955:

The carbon dioxide released into the atmosphere by industry’s burning of coal and oil — more than half of it during the last generation — may have changed the atmosphere’s composition sufficiently to account for a general warming of the world by about one degree Fahrenheit.

(I’ve seen this collected in The Neumann Compendium and The Fabulous Future: America in 1980.)

This is not new knowledge.