The world passes 400ppm carbon dioxide threshold. Permanently

We are now living in a 400ppm world with levels unlikely to drop below the symbolic milestone in our lifetimes, say scientists.

–Brian Kahn with Climate Central reports

The month of September usually marks the annual minimum for atmospheric carbon dioxide, after northern hemisphere plants have had a full summer to grow and absorb CO2 and before decomposing leaves release the stored carbon dioxide back into the atmosphere. This September, atmospheric carbon dioxide did not dip below 400ppm, causing scientists to to predict, “that 2016 will be the year that carbon dioxide officially passed the symbolic 400 ppm mark, never to return below it in our lifetimes.”

In this article, Brian Kahn explains why these September measurements are significant despite recent recognition that crossing the 400ppm mark had become more a question of “when” than “if”:

They’re a reminder that with each passing day, we’re moving further from the climate humans have known and thrived in and closer to a more unstable future.

You can read the full article here, and find more updates from Climate Central News through their RSS feed on the MAHB site.