Our planet is getting warmer today, that’s a fact. But, this isn’t the hottest time in our planet’s history — far from it, in fact. At various points, millions or billions of years ago, Earth was much more toasty than it is now.
One of the most notable hot flashes came 56 million years ago, during the Paleocene-Eocene Thermal Maximum, or PETM. It was a relatively brief period of rapid, abnormal warming. During that time, temperatures that were already far above normal spiked by around nine degrees Fahrenheit (5 degrees Celsius) over a period of just a few thousand years. Tropical conditions prevailed far beyond the equator, and ice caps were entirely absent from the poles.
