Hawaii’s Mauna Loa observatory recently measured carbon dioxide (CO2) levels in the air of 398.36 parts per million (ppm). It’s looking likely that soon, for the first time in human existence, CO2 levels will hit 400 ppm. CO2 is one of the main gasses driving global warming, and the last time levels exceeded 400 ppm was roughly 2-3 million years ago.
That’s not just a long time ago. In human terms it’s essentially “all the time” ago. We’ve simply never lived in a world with CO2 concentrations so high. As Environmental Defense Fund land use and climate scientist Jason Funk explained, 2-3 million years ago:
Australopithecines were struggling to become bipedal
It would be more than a million years before their descendants would master the control of fire
There were at least eight glacial periods still to come
The rise and demise of Neanderthals was still in the future
A crafty little species called Homo sapiens had yet to arise and apply the use of fire to fossil fuels, launching us on an uncontrolled planetary climate experiment.
“Basic human systems we take for granted and depend on today, like agriculture and urban civilization, were developed in an entirely different climate regime than the one we're entering,” Funk said. “Our species and those systems may have a lot of difficulty enduring in the new climate regime. That's the magnitude of what we're talking about."http://tinyurl.com/q3w7u5l