The Keeling Curve is a graph of the annual variation and overall accumulation of carbon dioxide in the Earth's atmosphere based on continuous measurements taken at the Mauna Loa Observatory on the island of Hawaii from 1958 to the present day.

[6][7] Charles David Keeling, of the Scripps Institution of Oceanography at UC San Diego, was the first person to make frequent regular measurements of atmospheric CO2 concentrations in Antarctica, and on Mauna Loa, Hawaii from March 1958 onwards.

[1] He observed strong diurnal behavior of CO2, with excess CO2 at night due to respiration by plants and soils, and afternoon values representative of the "free atmosphere" over the Northern hemisphere.

[1] In 1957–1958, the International Geophysical Year, Keeling obtained funding from the Weather Bureau to install infrared gas analyzers at remote locations, including the South Pole and on the volcano of Mauna Loa on the island of Hawaii.

Keeling and his collaborators measured the incoming ocean breeze above the thermal inversion layer to minimize local contamination from volcanic vents.

After reaching a minimum in September, the level rises again in the northern fall and winter as plants and leaves die off and decay, releasing CO2 back into the atmosphere.

[22] Along with more precise measurement materials and funds for the project of monitoring of the Earth's CO2 levels, Keeling wrote about his pride for his father's work and how he has continued it in his memory.

[25] This level of carbon dioxide, causing climate change, suggests a continued worsening in natural and ecological disasters, which increasingly threatens human and animal habitats on Earth, if greenhouse gas emissions are not significantly reduced.