Carbon-C02 threshold of 400ppm passed March 2015, researchers say
New and troubling carbon threshold passed, researchers say Scott Sutherland Meteorologist, theweathernetwork.com Friday, May 8, 2015, 8:26 AM - Global carbon dioxide concentrations have reached a new "benchmark" of 400 parts per million, a level unprecedented in at least a million years. "Reaching 400 parts per million as a global average is a significant milestone," Pieter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network, said in a press release this week. "This marks the fact that humans burning fossil fuels have caused global carbon dioxide concentrations to rise more than 120 parts per million since pre-industrial times. Half of that rise has occurred since 1980." Unprecedented in millions of years These values aren't just high when compared to recent history, or even human history. The release of tens of billions of metric tons of CO 2 into the atmosphere every year, through the burning of fossil fuels, has increased ca...