April 2014 First Month In History Of Homo Sapiens With CO2 Levels Over 400 ppm
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 levels of carbon dioxide in the atmosphere are monitored from a site atop Hawaii’s Mauna Loa volcano, where they have been measured continuously since 1958. The long record has charted the steep rise of the greenhouse gas — the most prevalent in Earth’s atmosphere — as a result of human emissions.
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.
The last time atmospheric carbon dioxide levels were this high consistently was anywhere from 800,000 to 15 million years ago, various studies have estimated, and the world was a very different places then, with much warmer temperatures and extremely higher seas.
EDIT
http://www.climatecentral.org/news/april-becomes-first-month-with-co2-levels-above-400-ppm-17367
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