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The World Meteorological Organization has released a statement on carbon dioxide in the atmosphere, and the results aren't pretty.
In April, the monthly average of carbon dioxide in the northern hemisphere passed 400 parts per million, a record high. The WMO says this statistic has "symbolic and scientific significance" for the Earth's future.
"This should serve as yet another wakeup call about the constantly rising levels of greenhouse gases which are driving climate change," said WMO chief Michel Jarraud in a statement. "Time is running out."