CO2 Now

Mauna Loa CO2 PDF Print E-mail
  • Throughout this website, references to average or mean CO2 levels for any month or year since March 1958 means data collected by continuous atmospheric monitoring at the Mauna Loa Observatory in Hawaii, USA. At Mauna Loa, the remote location, undisturbed air, and minimal influences of human activity and vegetation are ideal for monitoring consituents in the atmosphere that can cause climate change.
  • The Mauna Loa Observatory is part of the National Oceanic and Atmospheric Administration (NOAA), Earth System Research Laboratory (ESRL), Global Monitoring Division (GMD) in the USA.  The continuous, high-precision measurement of changes in atmospheric CO2 concentrations was started in March 1958 at the Mauna Loa Observatory by Charles David Keeling.


  • The monthly CO2 reading is the most current and comprehensive indicator of how well we are doing, collectively, to address the root causes of global warming and climate change.


CO2 is well mixed in the atmosphere, so observations of concentrations from a single site like the Mauna Loa Observatory are an adequate indicator of world trends for atmospheric CO2. 




CO2 Acceleration  |

Mauna Loa Science and Wonder  |  CO2Now.orgMauna Loa Observatory, Hawaii  |  NOAA / ESRL

Monthly CO2 Data Since March 1958  |  NOAA / ESRL |  Scripps Data

About the Mauna Loa data  |  NOAA)

Why Mauna Loa data is important  |  NOAA

Atmospheric CO2 from continuous air samples at Mauna Loa Observatory, Hawaii  |  CDIAC 1958 - 2001)

Keelings' CO2 measurements as global warming's longest yardstick | San Diego UT 






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