Almost exactly a year ago, the level of atmospheric carbon dioxide passed 400 parts per million (ppm) for
the first time in human history. In fact, the global atmosphere hadn't seen such a concentration of the greenhouse gas in
3 million years. It was a watershed moment, and a screaming alarm, yet the
White House Press Corps ignored it. As Pulitzer Prize-winning website
InsideClimate News reported:
"This is another global emissions target that we've blown past without doing anything," said Jim Butler, director of global monitoring at NOAA's Earth System Research Laboratory. "Stronger storms, droughts, rising seas. We are already seeing the impacts of increased CO2 in the atmosphere ... How much further can we really go?"
We now know:
The end of April has arrived, and with it, the record for the first month in human history with an average carbon dioxide level in Earth’s atmosphere above 400 parts per million has been set.
With a little more than 24 hours left in the month, the average for April can't slip below 400 ppm. “Every day in April has been over 400 ppm,” said Pieter Tans, a climate scientist with the National Oceanic and Atmospheric Administration.
The updated monthly record is charted at the top of this post.
The first measurement in excess of 400 ppm was made on May 9, 2013. This year, the level rose above that mark a full two months earlier, and has remained above 400 ppm steadily since the beginning of April. While the milestone is largely a symbolic one, it does illustrate how far emissions have risen from their preindustrial levels of 280 ppm.
To see graphs of atmospheric carbon dioxide since 1960, and since 1700, check the Scripps Institution of Oceanography's
Keeling Curve website. And keep in mind that the
target level for climate change mitigation is
350 ppm.
A year ago, we blew through 400 ppm for the first time in human history. Now we've seen our first month that averaged that level. What's next? We're drilling, mining, fracking, deforesting and even eating our way toward finding out. It won't be pretty.