Carbon Dioxide Levels Already In Danger Zone, Revised Theory Shows

Atmospheric carbon dioxide if coal emissions are phased out linearly between 2010 and 2030, calculated using a version of the Bern carbon cycle model.
(Credit: Hansen, et al/Open Atmospheric Science Journal)

From Science Daily:

ScienceDaily (Nov. 9, 2008) — If climate disasters are to be averted, atmospheric carbon dioxide (CO2) must be reduced below the levels that already exist today, according to a study published in Open Atmospheric Science Journal by a group of 10 scientists from the United States, the United Kingdom and France.

The authors, who include two Yale scientists, assert that to maintain a planet similar to that on which civilization developed, an optimum CO2 level would be less than 350 ppm — a dramatic change from most previous studies, which suggested a danger level for CO2 is likely to be 450 ppm or higher. Atmospheric CO2 is currently 385 parts per million (ppm) and is increasing by about 2 ppm each year from the burning of fossil fuels (coal, oil, and gas) and from the burning of forests.

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