May 4 (UPI) -- For the month of April, carbon dioxide concentrations in Earth's atmosphere averaged more than 410 parts per million -- a distressing first.
Last year, a sensor at Hawaii's Mauna Loa Observatory recorded a CO2 reading above 410 ppm. It was the first time CO2 concentrations had been that high in millions of years.
Now, for the first time, CO2 concentration averaged above the 410 mark for an entire month.
Once again, the dubious honor of recording the milestone goes to the Keeling Curve detection system at the Mauna Loa Observatory, a program managed by the Scripps Institution of Oceanography at the University of California, San Diego.
"We keep burning fossil fuels. Carbon dioxide keeps building up in the air," Ralph Keeling, a geochemist, director the Scripps CO2 program and son of the late Keeling Curve creator Charles David Keeling, said in a news release. "It's essentially as simple as that."
This worrisome new normal means CO2 levels have increased 30 percent since scientists first began plotting the Keeling Curve in 1958.
While CO2 levels rise and fall annually, average concentrations continue to rise steadily each year.
"As a scientist, what concerns me the most is what this continued rise actually means: that we are continuing full speed ahead with an unprecedented experiment with our planet, the only home we have," Katharine Hayhoe, climate scientist at Texas Tech University, tweeted in response to the news.