Some readers of the Keeling Curve website have asked us about the graphs that show carbon dioxide concentrations since 1700 and over the past 800,000 years, which use a combination of data derived from analysis of the gas contained in ice cores and that obtained from air sampled at Mauna Loa Observatory in Hawaii. Continue reading How are ice-core data and Mauna Loa atmospheric data made comparable?
Instruments at the Mauna Loa Observatory in Hawaii recorded atmospheric levels of carbon dioxide greater than 400 parts per million on March 12, 2014 nearly two months earlier than the date on which the milestone was passed in 2013. Continue reading Comment on Recent Readings in Excess of 400 ppm
A daily record of atmospheric carbon dioxide from Scripps Institution of Oceanography at UC San Diego