What does Earth Day teach us about supply?

Around the time of the first Earth Day (1970), Environmentalists were making dire predictions (via Mark Perry): 

• ...world famines of unbelievable proportions.
• some 4 billion people, including 65 million Americans, would perish in the “Great Die-Off.”
• By the year 2000, … there won’t be any more crude oil.
• Lead, zinc, tin, gold, and silver would be gone before 1990.

Why were these predictions so spectacularly wrong? 

ANSWER: If prices increase, producers find more supply or develop alternatives. For example, oil reserves are much bigger now due to technological innovations like directional drilling and shale oil extraction. 

• In 1980, Paul Ehrlich, a Stanford biologist (author of "The Population Bomb,") bet Julian Simon, a Maryland Economist, that prices of five metals (chromium, copper, nickel, tin, and tungsten) would rise due to increased demand from population growth. 
• In 1990, the prices of all five metals had fallen, and Ehrlich lost $1,000.

BOTTOM LINE:  Don't underestimate supply.