Neal Boortz has a collection of "predictions" from Earth Day 1970. Some personal favorites:

By...[1975] some experts feel that food shortages will have escalated the present level of world hunger and starvation into famines of unbelievable proportions. Other experts, more optimistic, think the ultimate food-population collision will not occur until the decade of the 1980s.
Paul Ehrlich, Stanford University biologist

Scientists have solid experimental and theoretical evidence to support...the following predictions: In a decade, urban dwellers will have to wear gas masks to survive air pollution...by 1985 air pollution will have reduced the amount of sunlight reaching earth by one half....
Life Magazine, January 1970

Dr. S. Dillon Ripley, secretary of the Smithsonian Institute, believes that in 25 years, somewhere between 75 and 80 percent of all the species of living animals will be extinct.
Sen. Gaylord Nelson

The world has been chilling sharply for about twenty years. If present trends continue, the world will be about four degrees colder for the global mean temperature in 1990, but eleven degrees colder in the year 2000. This is about twice what it would take to put us into an ice age.
Kenneth Watt, Ecologist

None of this nonsense came to pass. None of it!!! So when today's Earth Day practitioners predict their own brand of doom and gloom, color me skeptical.