As has been reported everywhere, one earthly species has changed the climate here on earth, driving warming CO2 levels (briefly) to 400 parts per million. When was the last time this happened?
As Climate Central reported on May 3, there is no single, agreed-upon answer to when CO2 concentrations were last at this level, as studies show a wide date range from between 800,000 to 15 million years ago. The most direct evidence comes from tiny bubbles of ancient air that act as time capsules, sealing ancient air in the vast ice sheets of Antarctica and Greenland. By drilling for ice cores and analyzing the air bubbles, scientists have found that, at no point during at least the past 800,000 years have atmospheric CO2 levels been as high as they are now.
A 2011 study in the journal Paleoceanography found that atmospheric CO2 levels may have been comparable to today’s as recently as sometime between 2 and 4.6 million years ago, during the Pliocene epoch, which saw the arrival of Homo habilis, a possible ancestor of modern homo sapiens, and when herds of giant, elephant-like Mastadons roamed North America. Modern human civilization didn’t arrive on the scene until the Holocene Epoch, which began 12,000 years ago.
Best reporting on this may come from National Geographic, fittingly. Can we leave aside the politics and the science for a moment? Just a moment. Put ourselves in this moment, approx 3 million years ago. Ask what it felt like outside:
What was Earth like then? In Africa, grasslands were replacing forests and our ancestors were climbing down from the trees. (See related: "The Evolutionary Road.") On Ellesmere, there were no longer alligators and cypress trees, but there were beavers and larch trees and horses and giant camels—and not much ice. The planet was three to four degrees Celsius warmer than it was in the 19th century, before man-made global warming began.
If anything, those numbers understate how different the Pliocene climate was. The tropical sea surface was about as warm as it is now, says Alexey Fedorov of Yale University, but the temperature gradient between the tropics and the poles—which drives the jet streams in the mid-latitudes—was much smaller. The east-west gradient across the Pacific Ocean—which drives the El Niño-La Niña oscillation—was almost nonexistent. In effect, the ocean was locked in a permanent El Niño. Global weather patterns would have been completely different in the Pliocene.
Above we see an imagined day from an unimaginably vast plain of time. But looking at that illustration, and seeing but one of those creatures still around, the condor, on a day like today, when the afternoon temp reached 102 in Upper Ojai, a day after 106 in Ojai, twenty degrees over the average temperature, and one can't help but think of what the experts say, the sheer variability of the climate.
The changes we've experienced, the big storms, the heat waves, the Santa Anas, have been so little as compared to what could be.
Related articles
Kit Stolz 