At the first Earth Day celebration, in 1969, environmentalist Nigel Calder warned, "The threat of a new ice age must now stand alongside nuclear war as a likely source of wholesale death and misery for mankind." C.C. Wallen of the World Meteorological Organization said, "The cooling since 1940 has been large enough and consistent enough that it will not soon be reversed." In 1968, Professor Paul Ehrlich, Vice President Gore's hero and mentor, predicted there would be a major food shortage in the U.S. and "in the 1970s ... hundreds of millions of people are going to starve to death." Ehrlich forecasted that 65 million Americans would die of starvation between 1980 and 1989, and by 1999 the U.S. population would have declined to 22.6 million.

In 1975, the Environmental Fund took out full-page ads warning, "The World as we know it will likely be ruined by the year 2000."