Atmospheric carbon dioxide reached a seasonal peak of 417.1 parts per million (ppm) for 2020 in May, the highest monthly reading ever recorded, according to scientists from the National Oceanic and Atmospheric Administration (NOAA) and Scripps Institution of Oceanography at the University of California San Diego, who used measurements at Mauna Loa Observatory.
That’s a carbon dioxide level not experienced by the atmosphere in at least several million years, according to the scientists’ press release.
This year’s peak value was 2.4 ppm higher than the previous peak of 414.7 ppm recorded in May 2019. Monthly carbon dioxide values at Mauna Loa first topped the 400 ppm mark in 2014.
The peak comes despite worldwide government policies during the coronavirus pandemic that have drastically altered patterns of energy demand, according to a recent study in the journal Nature Climate Change.
The study estimates daily global CO2 emissions decreased by 17 percent by early April because of stay-at-home orders, reductions in transportation and changing consumption patterns. Emissions in individual countries decreased by 26 percent on average at their peak, the study notes.
“People may be surprised to hear that the response to the coronavirus outbreak hasn’t done more to influence CO2 levels,” said geochemist Ralph Keeling in the release. Keeling runs the Scripps Oceanography program at Mauna Loa. “But the buildup of CO2 is a bit like trash in a landfill. As we keep emitting, it keeps piling up.
“The crisis has slowed emissions, but not enough to show up perceptibly at Mauna Loa. What will matter much more is the trajectory we take coming out of this situation,” Keeling said.