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May 8, 2015

Atmospheric Concentration of Co2 Tops 400 ppm for Longest Period on Record 
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The global level of carbon dioxide in the atmosphere has topped 400
parts per million for the longest time in recorded history. The National
Oceanic and Atmospheric Administration says the grim milestone was
reached on average for the entire month of March. The 400 parts per
million threshold has been an important marker in U.N. climate change
negotiations, widely recognized as a dangerous level that could
drastically worsen human-caused global warming. The environmentalist
group 350.org takes it name after the 350 parts per million threshold
that scientists say is the maximum atmospheric concentration of carbon
dioxide for a safe planet.

 

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