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Atmospheric CO2 from Flask Air Samples at the South Pole

graphics Graphics   data Data

C.D. Keeling and T.P. Whorf

Carbon Dioxide Research Group, Scripps Institution of Oceanography, University of California, La Jolla, California 92093-0444, U.S.A.

Period of Record



Atmospheric CO2 samples were collected at approximately bi-weekly intervals. Samples are collected in 5-L evacuated glass flasks, and then returned to the Scripps Institution of Oceanography (SIO) where CO2 concentrations have been determined using an Applied Physics Corporation (APC) nondispersive infrared gas analyzer. Further information on measurements, calibration procedures and analysis is available in the references listed below.

Map showing location of the South Pole, Antarctica

South Pole, Antarctica
Ice- and snow-covered plateau
89°59' S, 24°48' W
2810 m above MSL


The average of unflagged data for the first full year of measurements (1961) was 318.1 ppmv; values for 2001 averaged 368.1 ppmv, for an upward trend of 1.25 ppmv/year. Graphics here show the first and last year of data, to display the change in mean over time and the annual amplitudes. Long term trend curves are better displayed using SIO's PDF monthly averaged data.


CITE AS: Keeling, C.D. and T.P. Whorf. 2004. Atmospheric CO2 concentrations derived from flask air samples at sites in the SIO network. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, U.S.A.