Short answers, pulled from the story.
The Keeling Curve is a continuous record of atmospheric carbon dioxide concentrations measured at the Mauna Loa Observatory in Hawaii. Charles David Keeling began collecting the data in 1958, when CO2 stood at 315 parts per million; by 2005 it had reached 380 parts per million. The dataset is considered a reliable indicator of the global trend in the mid-level troposphere.
Charles David Keeling (the 20th of April 1928 - the 20th of June 2005) was an American scientist at the Scripps Institution of Oceanography. His measurements at Mauna Loa confirmed that atmospheric carbon dioxide was rising steadily due to fossil fuel emissions, providing empirical support for Svante Arrhenius's 1896 proposition about anthropogenic contributions to the greenhouse effect.
Keeling's primary measurement station was the Mauna Loa Observatory in Hawaii, situated two miles (3,000 meters) above sea level. He began collecting samples there in 1958 after receiving funding through the International Geophysical Year. The data collected at Mauna Loa form the longest continuous record of atmospheric carbon dioxide in the world.
By 1960, Keeling had established that carbon dioxide levels follow strong seasonal cycles, peaking in the late northern hemisphere winter and falling each spring and early summer. The decline occurs because vegetation in the land-rich northern hemisphere absorbs carbon dioxide during its growing season. This seasonal oscillation is layered on top of the long-term upward trend in the Keeling Curve.
Al Gore featured the Keeling Curve in the 2006 book and film An Inconvenient Truth. Gore had first seen the graph on the wall of a Harvard classroom in the 1960s, when Roger Revelle was teaching there, and later described marveling at it. In July 1997, Gore had also presented Keeling with a special achievement award at a White House ceremony.
Keeling received a special achievement award from Vice President Al Gore in July 1997. The Keeling Curve Prize has been awarded annually since 2018 by the Global Warming Mitigation Project. The Charles David Keeling apartments at Revelle College of the University of California San Diego opened in 2011. Memorial lecture series at Scripps and the University of Illinois both began in 2010, and a minor planet was named in his honor on the 11th of August 2025.