Still Rising After All These Years: CO2 Levels Increase for 51st Straight Year

Atmospheric CO2 reached 387.81 parts per million (ppm) in July 2009 up from 386.38ppm this time last year according to data released by the National Oceanic Atmospheric Administration (NOAA) earlier this month. Atmospheric CO2 has been rising since Charles Keeling started taking measurements with high precision instruments at the remote Mauna Loa Observatory in 1958. (The graph of rising CO2 is known as the Keeling Curve). These levels are significantly higher than the range of CO2 levels (average 280 ppm) experienced on the planet for the 2.1 million years prior to the industrial revolution.

CO2 Levels Over the Past Half Century (Image: CO2Now. Data: NOAA)
CO2 Levels Over the Past Half Century (Image: CO2Now. Data: NOAA)

The rate of increase is accelerating as well.Since the beginning of the 21st century, CO2 level have increased at an average rate of 1.87 ppm/year. This is greater than the previous decade rate of 1.53 ppm/year and more than twice the rate of increase when measurements began in the 1960’s. The rate of increase has risen steadily:

July 2000 – July 2009:  1.87 ppm (average increase per year)
July 1990 – July 1999:  1.53 ppm
July 1980 – July 1989:  1.62 ppm
July 1970 – July 1979:  1.17 ppm
July 1960 – July 1969:  0.93 ppm

Many scientists believe that the safe upper limit for atmospheric CO2 is 350ppm, a level we have already exceeded.Climate scientists James Hansen and his colleagues state unequivocally:

If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm.”*

Current CO2 data, as published by NOAA, is available on the CO2Now website

What can you do?

  • Climate activist and writer Bill MCKibben called 350 “the most important number on the planet” and has started a ‘people-powered movement’ called
  • The nifty CO2 widget at right is available for your website at at

Check them out!

*Hansen, J., Mki. Sato, P. Kharecha, D. Beerling, R. Berner, V. Masson-Delmotte, M. Pagani, M. Raymo, D.L. Royer, and J.C. Zachos, 2008: Target atmospheric CO2: Where should humanity aim? Open Atmos. Sci. J., 2, 217-231, doi:10.2174/1874282300802010217.

Climate scientists James Hansen and his colleagues state uneqiuvocally in their paper

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