GR:  Readers should think about what this means: “408 Parts per million CO2. 490 parts per million CO2e. This is the amount of heat-trapping CO2 and total CO2 equivalent for all heat-trapping gasses now in the Earth’s atmosphere. Two measures representing numerous grave potential consequences.

We’re Locking in 120-190 Feet of Sea Level Rise Long Term

Looking at the first number — 408 parts per million CO2 — we find that the last time global levels of this potent heat-trapping gas were so high was during the Middle Miocene Climate Optimum of 15-17 million years ago. During this time, the Greenland Ice Sheet did not exist. East Antarctic glacial ice was similarly scarce. And the towering glaciers of West Antarctica were greatly reduced. Overall, global sea levels were 120 to 190 feet higher than they are today. Meanwhile, atmospheric temperatures were between 3 and 5 degrees Celsius hotter than those experienced during the late 19th Century.”