Life on the Ledge is Over

What happens when we wreck the platform on which civilization is built?

Photo by Yeshi Kangrang on Unsplash

Take a look at the right half of the chart below, which shows the estimated average temperatures on earth from one million years ago to the present. The rightmost box shows the temperatures during the last 20,000 years; the box to its left shows the period from one million years before the present until 20,000 years be…