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Keeling Curve
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Line graph showing the Keeling Curve, which tracks atmospheric carbon dioxide (CO2) levels at Mauna Loa from 1965 to 2025. The graph shows a steady upward trend from about 320 to over 420 parts per million, with seasonal fluctuations. An inset highlights the annual cycle of CO2, demonstrating both the short-term oscillations and the long-term increase. Infographic showing a timeline of major climate change milestones from 1896 to 2025, with key events listed on the left. Insets on the right display a graph of rising atmospheric carbon dioxide levels, diagrams of ocean acidification due to carbon dioxide, and a world map highlighting countries that have signed or ratified the Paris Agreement.
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Combination shot of Grinnell Glacier taken from the summit of Mount Gould, Glacier National Park, Montana in the years 1938, 1981, 1998 and 2006.
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Archaea at Midway Geyser Basin in the Grand Prismatic Spring, Yellowstone National Park, Wyoming. Largest hot spring in Yellowstone, third largest in the world. Temp. 147-188F Dim. 250x380 ft. Archaeon, archeon, Yellowstone Geysers, algae
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Line graph showing the Keeling Curve, which tracks atmospheric carbon dioxide (CO2) levels at Mauna Loa from 1965 to 2025. The graph shows a steady upward trend from about 320 to over 420 parts per million, with seasonal fluctuations. An inset highlights the annual cycle of CO2, demonstrating both the short-term oscillations and the long-term increase.
Keeling Curve The Keeling Curve, named after American climate scientist Charles David Keeling, tracks changes in the concentration of carbon dioxide (CO2) in Earth's atmosphere at a research station on Mauna Loa in Hawaii. Despite small seasonal fluctuations in CO2 concentration, the overall trend shows that CO2 is increasing in the atmosphere.

Keeling Curve

atmospheric science
Written by
John P. Rafferty
John P. Rafferty writes about Earth processes and the environment. He serves currently as the editor of Earth and life sciences, covering climatology, geology, zoology, and other topics that relate to...
John P. Rafferty
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Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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History

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...

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