The monthly global average concentration of carbon dioxide in the atmosphere has surpassed 400 parts per million for the first time, according to the U.S. National Oceanic and Atmospheric Administration.
“This isn’t good,” writes the Washington Post’s Justin Wm. Moyer. “In fact, the last time it happened was up to five million years ago.”
“It’s both disturbing and daunting,” NOAA’s Pieter Tans told the Associated Press. “Daunting from the standpoint of how hard it is to slow this down.”
CO2 concentrations above 400 ppm were first recorded in the Arctic in 2012, and at NOAA’s Mauna Loa Observatory in Hawaii in 2013. This is the first time the monthly average has passed the threshold.
“Reaching 400 ppm doesn’t mean much in itself,” climate scientist Ed Hawkins told The Guardian. “But the steady increase in atmospheric greenhouse gases should serve as a stark reminder of the task facing politicians” at UN climate talks in Paris at the end of the year.
“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,” Tans said. “Half of that rise has occurred since 1980.”