EarthTalk® is a weekly environmental column made available to our readers from the editors of E/The Environmental Magazine
Dear EarthTalk: I read that CO2 in our atmosphere is now more than 300 parts per million. Doesn’t this mean that we’re too late to avoid the worst impacts of climate change? – Karl Bren, Richmond, VA
Actually the amount of carbon dioxide (CO2) in the atmosphere today is roughly 390 parts per million (ppm). And that’s not good news. “Experts agree that this level cannot be sustained for many decades without potentially catastrophic consequences,” reports the Geos Institute, an Oregon-based non-profit and consulting firm that uses science to help people predict, reduce and prepare for climate change.
While we’re unlikely to get atmospheric CO2 concentrations down as low as they were (275 ppm) before we started pumping pollution skyward during the Industrial Revolution, climate scientists and green leaders agree that 350 ppm would be a tolerable upper limit. Prior to 2007 scientists weren’t sure what emissions reduction goal to shoot for, but new evidence led researchers to reach consensus on 350 ppm if we wished to have a planet, in the words of NASA climatologist James Hansen, “similar to the one on which civilization developed and to which life on earth is adapted.”
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EarthTalk® is a weekly environmental column made available to our readers from the editors of 
EarthTalk® is a weekly environmental column made available to our readers from the editors of 
EarthTalk® is a weekly environmental column made available to our readers from the editors of 
