There was a paper by Rasool and Schneider in 1971 that was behind this, I think. "Our ways" would've been industrial particulate pollution, where a 4x increase,

There was a paper by Rasool and Schneider in 1971 that was behind this, I think. "Our ways" would've been industrial particulate pollution, where a 4x increase, sustained, risked kicking off a new ice age. Schneider later retracted the findings in 1974.