There had been articles in the press since the early 20th century that Earth was cooling and a new ice age was a possibility. In March 1970 as a nation prepared for the first Earth Day, evidence was published that this was being caused not by a natural event such as sunspots or changes in the rotation of the planet, but by man.

United Press International reports in newspapers of March 4, 1970 carried “Continued pollution of the atmosphere with smoke, dust and other small particles ‘may…