Atmospheric carbon dioxide recorded at Mauna Loa Observatory in Hawaii peaked at 417.1ppm in May – the highest monthly reading ever.

Scientists from NOAA and Scripps Institution of Oceanography at the University of California San Diego said this year’s peak was 2.4ppm higher than the 2019 peak in May last year.

They also explained that the sharp economic slowdown caused by Covid-19 has not affected CO2 levels in the same way that pollution levels have reduced because the drop isn’t large enough to stand out from natural CO2 variability.

Ralph Keeling, a geochemist who runs the Scripps Oceanography program at Mauna Loa, said, “The build-up 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.”

The rate of CO2 increasing in the atmosphere has accelerated from 0.8ppm per year in the 1960s to 2.4ppm per year in the last decade.