In March, the monthly average of global carbon dioxide concentrations in the atmospherereached 400 parts per millionfor the first time,The Guardianreports. The National Oceanic and Atmospheric Administration released the figure on Wednesday, calling it a “significant milestone” for the planet’s changing climate. Scientists estimate that eliminating 80% of fossil fuel emissions would stabilize atmospheric carbon dioxide levels. Further reductions, however, would be needed to spur an actual decrease in the lingering gas and avert the worst effects of climate change, they warn.

From:http://news.sciencemag.org/sifter/2015/05/global-carbon-dioxide-levels-break-new-record