In 1972, a report was written for the Club of Rome warning the world would run out of gold by 1981, mercury and silver by 1985, tin by 1987 and petroleum, copper, lead and natural gas by 1992. Gordon Taylor, in his 1970 book "The Doomsday Book," said Americans were using 50 percent of the world's resources and "by 2000 they [Americans] will, if permitted, be using all of them." 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."

Harvard University biologist George Wald in 1970 warned, "... civilization will end within 15 or 30 years unless immediate action is taken against problems facing mankind." That was the same year that Sen. Gaylord Nelson warned, in Look Magazine, that by 1995 "... somewhere between 75 and 85 percent of all the species of living animals will be extinct."