Antarctica reaches historic, troubling CO2 high

Jun 17, 2016, 3:15 PM EDT
Antarctica. (Source: Andreas Kambanis/flickr)
Antarctica. (Source: Andreas Kambanis/flickr)

The South Pole Observatory in Antarctica has marked readings below the symbolic carbon dioxide threshold of 400 parts per million (ppm) since humans have been recording CO2 levels. But the National Oceanic and Atmospheric Administration announced this week that the Observatory cleared 400 ppm on May 23, marking the first time Antarctica has experienced that level of CO2 in 4 million years. Scientific American reports:

There’s a lag in how carbon dioxide moves around the atmosphere. Most carbon pollution originates in the northern hemisphere because that’s where most of the world’s population lives. That’s in part why carbon dioxide in the atmosphere hit the 400 ppm milestone earlier in the northern reaches of the world.
 
But the most remote continent on earth has caught up with its more populated counterparts.
 
“The increase of carbon dioxide is everywhere, even as far away as you can get from civilization,” Pieter Tans, a carbon-monitoring scientist at the Environmental Science Research Laboratory, said. “If you emit carbon dioxide in New York, some fraction of it will be in the South Pole next year.”
 
 
Over the course of the year, CO2 levels rise during fall and winter and decline during the Northern Hemisphere's summer as terrestrial plants consume CO2 during photosynthesis. But plants only capture  a fraction of annual CO2 emissions, so for every year since observations began in 1958, there has been more CO2 in the atmosphere than the year before. 
 
Last year's global CO2 average reached 399 ppm, meaning that the global average in 2016 will almost certainly surpass 400 ppm. The only question is whether the lowest month for 2016 will also remain above 400.
 
 
And the annual rate of increase appears to be accelerating. The annual growth rate of atmospheric CO2 measured at NOAA’s Mauna Loa Observatory in Hawaii jumped 3.05 ppm during 2015, the largest year-to-year increase in 56 years of monitoring. Part of last year’s jump was attributable to El Nino, the cyclical Pacific Ocean warming that produces extreme weather across the globe, causing terrestrial ecosystems to lose stored CO2 through wildfire, drought and heat waves.
 
Last year was the fourth consecutive year that CO2 grew more than 2 ppm – which set another record. This year promises to be the fifth.
 
“We know from abundant and solid evidence that the CO2 increase is caused entirely by human activities,” Tans said. “Since emissions from fossil fuel burning have been at a record high during the last several years, the rate of CO2 increase has also been at a record high. And we know some of it will remain in the atmosphere for thousands of years.”
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