Over the past 500 million years, the earth has not had ice caps for longer than it has had ice caps. Average temperatures have peaked at 90 F [32 C ] 5 times and down to ~ 45 F [7 C] 7 times, that last time being relatively recent history We are actually on a warming trend from an ice age low with a range within periodic variations that lasted 100 million years from some 250 million years ago.
https://www.climate.gov/sites/default/files/graph-from-scott-wing-620px.png Preliminary results from a Smithsonian Institution project led by Scott Wing and Brian Huber, showing Earth's average surface temperature over the past 500 million years. For most of the time, global temperatures appear to have been too warm (red portions of line) for persistent polar ice caps. The most recent 50 million years are an exception. Image adapted from Smithsonian National Museum of Natural History. On Mon, Jan 18, 2021 at 4:42 PM Phil Morrison <[email protected]> wrote: > > The present global average temperature is above 2°C (based on > preindustrial 1750), heading for 3°C in the next few years. > > Humans go extinct at ~3°C, and all life on earth vanishes at 5°C. > > Please visit web site below for global average temperature studies. > > > http://arctic-news.blogspot.com/ >
