Scripps Institution of Oceanography / University of California, San Diego: “For the first time in human history, concentrations of the greenhouse gas carbon dioxide (CO2) could rise above 400 parts per million (ppm) for sustained lengths of time throughout much of the Northern Hemisphere as soon as May 2013. To provide a resource for understanding the implications of rising CO2 levels, Scripps Institution of Oceanography at UC San Diego is providing daily updates of the “Keeling Curve,” the record of atmospheric CO2 measured at Hawaii’s Mauna Loa. These iconic measurements, begun by Charles David (Dave) Keeling, a world-leading authority on atmospheric greenhouse gas accumulation and Scripps climate science pioneer, comprise the longest continuous record of CO2 in the world, starting from 316 ppm in March 1958 and approaching 400 ppm today with a familiar saw-tooth pattern. For the past 800,000 years, CO2 levels never exceeded 300 parts per million. “I wish it weren’t true, but it looks like the world is going to blow through the 400-ppm level without losing a beat,” said Scripps geochemist Ralph Keeling, who has taken over the Keeling Curve measurement from his late father. “At this pace we’ll hit 450 ppm within a few decades.” The website keelingcurve.ucsd.edu offers background information about how CO2 is measured, the history of the Keeling Curve, and resources from other organizations on the current state of climate.”