Keeling Curve

Keeling Curve, graph showing seasonal and annual changes in atmospheric carbon dioxide (CO₂) concentrations since 1958 at the Mauna Loa Observatory in Hawaii. The graph, which was devised by American climate scientist Charles David Keeling of the Scripps Institution of Oceanography, charts the buildup of CO₂ in the atmosphere. It is the longest uninterrupted instrumental record of atmospheric CO₂ in the world, and it is commonly regarded as one of the best and most recognizable products of a long-term scientific study. The curve is considered by many scientists to be a trustworthy measure of CO₂ in the middle layers of the troposphere, and it has been interpreted by many climate scientists as a warning signal for global warming.