In a coastal cave off Spain, scientists have found evidence showing that more than 3 million years ago, when temperatures were similar to those projected for the end of this century, sea levels were as much as 16 meters higher than they are now.
Pliocene Archives - State of the Planet
“Right now, we’re living in a world of a Pliocene atmosphere,” scientist Maureen Raymo of the Lamont-Doherty Earth Observatory tells the Yale Forum on Climate Change and the Media. “But the whole rest of the climate system — the oceans are trying to catch-up, the ice sheets are waning, and everything is trying to catch up to this Pliocene atmosphere.”
Why should society care that CO2 is now as high as 400 ppm? The reasons are multiple, but all trace back to the relationship between CO2 and temperature.