Greenhouse gas level highest in two million years, NOAA reports

Greenhouse gas level highest in two million years, NOAA reports (Update 2)
Worldwide levels of the greenhouse gas that plays the biggest role in global warming have reached their highest level in almost 2 million years—an amount never before encountered by humans, U.S. scientists said Friday. http://phys.org/news/2013-05-carbon-dioxide-atmosphere-historic-high.html#nwlt

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