Play Live Radio
Next Up:
Available On Air Stations

Greenhouse Gas Levels Surpass Troublesome Milestone

Scripps Institution of Oceanography
A daily record of atmospheric carbon dioxide using from Scripps Institution of Oceanography at UC San Diego shows levels of CO2 have surpassed the 400 parts per million, March 17, 2014.

Greenhouse gas carbon dioxide (CO2) is continuing to increase at a steep rate in the Earth's atmosphere. The heat-trapping gas hit a troublesome milestone last year at its peak in May when it reached levels of 400 parts per million of carbon dioxide. But this year, two months earlier, those levels are already being seen.

Greenhouse gas is the main global warming pollutant caused by the burning of fossil fuels, such as coal for electricity and oil for gasoline.

Scripps Institution of Oceanography researcher Ralph Keeling is tracking daily CO2 measurements at Mauna Loa, Hawaii using the Keeling Curve founded by his late father, Charles David (Dave) Keeling, a world-leading authority on atmospheric greenhouse gas accumulation and Scripps climate science pioneer.


“We’re already seeing values over 400. Probably we’ll see values dwelling over 400 in April and May. It’s just a matter of time before it stays over 400 forever,” said Ralph Keeling in a blog post.

Measurements at Mauna Loa comprise the longest continuous record of CO2 in the world, starting from 316 ppm in March 1958.

Scripps Institution of Oceanography is providing a website,, to offer daily updates on CO2 levels and to provide background information about how CO2 is measured, the history of the Keeling Curve, and resources from other organizations on the current state of climate. An accompanying Twitter feed, @keeling_curve, also provides followers with the most recent Keeling Curve CO2 reading in a daily tweet.

Keeling tweeted a CO2 reading of 401.19 ppm on March 18, 401.34 ppm on March 17, 400.2 ppm on March 13 and 401.62 ppm on March 12.

Keeling recently told KPBS there is a time lag for the global temperature to catch up with the CO2 that humans have already added to the atmosphere, so temperatures will continue to rise for many years after the atmospheric CO2 amount is stabilized.


He said it’s increasingly doubtful warming temperatures can be limited to the 2-degree Celsius threshold to avoid climate change’s catastrophic effects, including rising sea levels, droughts, floods and heat waves.

"I think the opportunity to achieve that was more or less in the past decade and now it's probably not really realistic that we'll get there," said Keeling.