Monthly atmospheric CO2 record from Niwot Ridge, Colorado, U.S.A.

Graphics Digital Data

Pieter P. Tans and Thomas J. Conway

NOAA Climate Monitoring and Diagnostics Laboratory, Boulder, Colorado 80305, U.S.A.

Period of Record


Niwot Ridge, Colorado, U.S.A.
Alpine mountain
40°05' N, 105°58' W
3523 m above MSL


The sampling site at Niwot Ridge is operated in cooperation with the Institute of Arctic and Alpine Research (INSTAAR), University of Colorado. The NOAA/CMDL flask data from Niwot Ridge show an increase in the annual atmospheric CO2 mixing ratio from 323.11 parts per million (ppm) in 1968 to 374.24 ppm in 2002.

CITE AS: Tans, Pieter P. and T.J. Conway, 2005. Monthly Atmospheric CO2 Mixing Ratios from the NOAA CMDL Carbon Cycle Cooperative Global Air Sampling Network, 1968-2002. 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, Tenn., U.S.A.

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