Carbon dioxide at NOAA's Mauna Loa Observatory reaches new milestone: Tops 400 parts per million
Friday, May 10, 2013 - 17:30
in Earth & Climate
On May 9, the daily mean concentration of carbon dioxide in the atmosphere of Mauna Loa, Hawaii, surpassed 400 parts per million (ppm) for the first time since measurements began in 1958. Independent measurements made by both NOAA and the Scripps Institution of Oceanography have been approaching this level during the past week. It marks an important milestone because Mauna Loa, as the oldest continuous carbon dioxide measurement station in the world, is the primary global benchmark site for monitoring the increase of this potent heat-trapping gas.