“Last year, atmospheric carbon dioxide briefly crossed 400 parts per million for the first time in human history. However, it didn’t cross that threshold until mid-May. This year’s first 400 ppm reading came a full two months earlier this past week and the seeming inexorable upward march is likely to race past another milestone next month.

“We’re already seeing values over 400. Probably we’ll see values dwelling over 400 in April and May. It’s just a matter of time before it stays over 400 forever,” said Ralph Keeling in a blog post.

Keeling runs a carbon dioxide monitoring program for Scripps Institute of Oceanography, a position he took over from his father who started it. The program takes daily measurements from the Mauna Loa Observatory in Hawaii, which sits at 11,141 feet on a volcano’s northern flank.”* The Young Turks host Cenk Uygur breaks it down.

*Read more here from Brian Kahn / Climate Central:
http://www.climatecentral.org/news/co2-on-path-to-cross-400-ppm-threshold-for-a-month-17189