Earth's atmospheric carbon levels pass milestone threshold 'permanently'

By Hunter
Tuesday Sep 27, 2016 · 11:01 PM EDT

It's all but official now: 400 ppm is the new normal.

“Is it possible that October 2016 will yield a lower monthly value than September and dip below 400 ppm? Almost impossible,” Ralph Keeling, the scientist who runs the Scripps Institute for Oceanography’s carbon dioxide monitoring program, wrote in a blog post. “Brief excursions toward lower values are still possible, but it already seems safe to conclude that we won’t be seeing a monthly value below 400 ppm this year – or ever again for the indefinite future.”

We may get a day or two reprieve in the next month, similar to August when Tropical Storm Madeline blew by Hawaii and knocked carbon dioxide below 400 ppm for a day. But otherwise, we’re living in a 400 ppm world. Even if the world stopped emitting carbon dioxide tomorrow, what has already put in the atmosphere will linger for many decades to come.

“At best (in that scenario), one might expect a balance in the near term and so CO2 levels probably wouldn't change much — but would start to fall off in a decade or so,” Gavin Schmidt, NASA’s chief climate scientist, said in an email. “In my opinion, we won’t ever see a month below 400 ppm.”
CO2 levels above 400 ppm were first measured at Mauna Loa, Hawaii in 2013. Earth’s atmosphere had not previously reached that concentration of carbon dioxide in the last 4 million years.

http://www.dailykos.com/stories/2016/9/27/1575176/-Open-thread-for-night-owls-Earth-s-atmospheric-carbon-levels-pass-milestone-threshold-permanently