Carbon Dioxide Levels this High Pre-Date Humanity

Dan Upham

Kevin Walsh/Flickr

To borrow the title of a 2004 Modest Mouse album, here’s some “good news for people who love bad news”: As Treehugger reported on Monday, 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.”

The folks at Mauna Loa have been recording atmospheric CO2 levels since 1958, and as the “Keeling Curve” below shows, we’ve been on a collision course with 400 ppm for some time.

From the Scripps Institution of Oceanography


The Keeling Curve gets its name from Charles David Keeling, and it’s maintained today by his son Ralph F. Keeling at the Scripps Institution of Oceanography. If you want to be one of the first to know when we cross the 400 ppm threshold, follow the Keeling Curve on Twitter @Keeling_curve

Update: We’ve arrived at 400ppm

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