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Scripps Institute for Oceanography

2016 will go down in history as the first year of the rest of our lives — not in a good way.

It’s the year we finally crossed a threshold we won’t be able to un-cross in a hurry: The concentration of CO2 in the atmosphere exceeded 400 parts per million and stayed there. We may not see it drop below that level again before we, too, go the way of Bowie.

September is the month when the concentration of carbon dioxide in the atmosphere tends to hit its lowest point, thanks to the trees of the Northern Hemisphere that have been sucking up CO2 all summer long and storing it for us. As the autumn sets in, those trees drop their leaves again and exhale a global gust of CO2.

But this fall, that process begin without atmospheric CO2 levels ever falling below 400 ppm, Climate Central reported. In fact, the iconic CO2 monitoring station on Mauna Loa, Hawaii, hasn’t seen monthly average carbon dioxide below that threshold in all of 2016.

And because CO2 hangs around for decades, even as whatever Taylor really said to Kanye fades like so many fallen leaves, the atmosphere remembers.

Climate Central