"For the first time since humans have been monitoring, atmospheric concentrations of carbon dioxide have exceeded 410 parts per million averaged across an entire month, a threshold that pushes the planet ever closer to warming beyond levels that scientists and the international community have deemed “safe.”

The reading from the Mauna Loa Observatory in Hawaii finds that concentrations of the climate-warming gas averaged above 410 parts per million throughout April. The first time readings crossed 410 at all occurred on April 18, 2017, or just about a year ago.

Carbon dioxide concentrations — whose “greenhouse gas effect” traps heat and drives climate change — were around 280 parts per million circa 1880, at the dawn of the industrial revolution. They’re now 46 percent higher."

Chris Mooney reports for the Washington Post May 3, 2018. [2]