Here's What Happens When Atmospheric CO2 Exceeds 400 PPM, Like It Just Did

Scariest thing that's happened to planet Earth this year?

By Reuben Brody

 
Here's What Happens When Atmospheric CO2 Exceeds 400 PPM, Like It Just Did
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28 September 2016

History is littered with apocalypse stories.

The Mayan Calendar. Revelations. Dante’s Peak. We love to envision the end of the world, and we tend to do so as hyperbolically as possible.

But aside from a nuclear war, it’s fairly safe to say we’ll never experience anything as catastrophic as what John foretold. The glacially slow, quiet, sneaky end of the world, though? That's happening as we speak.

Latest evidence: scientists at the Scripps Institution of Oceanography have announced that we’ve officially passed a dubious milestone — atmospheric carbon levels just exceeded 400 parts per million. More ominous than the milestone itself is the fact that that number is now permanent. The finding is based off of weekly carbon dioxide research dating back to 1958 from the Mauna Loa Observatory in Hawaii.  

Why is 400 ppm a scary number? It’s the number that triggers climatalogical imbalances, as occurred in 2012, when the Arctic was the first region to pass the threshold, causing temperatures to rise and lots of ice to begin melting. Carbon dioxide levels usually dip sharply toward the end of September, but this year CO2 remained above 401 ppm, and the folks at Scripps doubt they’ll be dipping anytime soon.

Speaking via email to Adventure Journal, Gavin Schmidt, a NASA chief climate scientist, said:  “At best [in that scenario], one might expect a balance in the near term, and so CO2 levels probably wouldn’t change much. In my opinion, we won’t ever see a month below 400 ppm.”

The good news is that awareness is up, and many countries are doing their best to curb carbon emissions, as evidenced by the Paris Climate Agreement, in which 60 countries pledged to halt temperature rises to pre-industrial levels of 1.5 degrees celsius. Downside: those 60 countries only account for 47.76 percent of the world’s emissions. And at least one current American presidential candidate won’t even admit that climate change is real.

It’s easy to understand why. You don't perceive its changes on a daily basis. You don’t witness firsthand the extinction of 10,000 species since 1980. You don’t notice sea algae dying. You don’t register water taking over cities until it's too late (but by 2100, the rising oceans are expected to displace 13 million people).

These things are happening, they're just doing so at a creep that will become more perceptible in time.

Heed the words of one T.S. Elliot the next time you reach for your car keys instead of hopping on your bike: “This is the way the world ends, not with a bang, but a whimper.”

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