Nice description of the “snowball earth” epoch some hundreds of millions of years ago.
Sometimes cited as “evidence” that co2 is not an important greenhouse gas, as I showed in this video, part of the Crock of the Week series where I debunked “Lord” Christopher Monckton. (starts at 2:04 if you’re rushed)
Sweet! PBS is still good for something after all!
Nice work, love your site!!