Global Cooling Scare
The left/media/polemics of today will pretend this didn't exist, or it was just a few outlets that were claiming it, and there was no science or momentum behind it. That's a lie. Paul R. Ehrlich, Watermelon environmentalist of the 1960's, not only wrote the discredited The Population Bomb, but he also started another Tragedy of the commons based chicken little disaster: the Global Cooling Scare. In 1968 he claimed fossil fuels had raised CO2 levels 15% which was causing clouds to block out the sun and causing the global cooling they had been observing (a minute fraction of a degree). He was wrong, warming had caused CO2 to go up (not fossil fuels), and it wasn't causing the cooling. But all the watermelon sources bought in: NCAR, CRU, NAS, NASA, NYT, Science, CIA, and so on. We needed big government authoritarianism to fix it, or we we're doomed. This was all the rage until something bad happened... and they realized that despite the 40 year drop in temperatures (due to mans minuscule contribution to CO2), that we were actually warming again. Reverse engines, nothing to see here. Time for the next theory/excuse why we needed centralized Marxism to cure what ails us: this time it was Global Warming. (And when that paused, they changed the term to Climate Change: so that they could use up or down trends as an excuse to prove themselves right).
When proposals such as melting the Arctic ice cap by covering it with black soot were common. "The world is cooling. We have about 10 years until cold temperatures and lack of sunlight inhibit adequate food production. The resulting hunger famine will be catastrophic. The evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it."