The concentration of carbon dioxide in Earth’s atmosphere reached historic levels in May after emissions plunged in the first months of the coronavirus pandemic, according to data released Monday by the Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration (NOAA).
The annual peak reached 419 parts per million (PPM) in May, according to the research, with “no discernible signal in the data” from the reduced industrial activity in 2020. This is the highest level recorded in the 63 years concentration levels have been tracked, with researchers saying daily levels have surpassed 420 PPM on several occasions. It also represents an increase from 417 PPM in May 2020.
Annual carbon dioxide concentration values peak in May, the end of the period when plants in the northern hemisphere begin taking in large amounts of CO2 from the atmosphere. This trend is known as the Keeling Curve, after Charles David Keeling, the scientist who first observed the phenomenon.
"The ultimate control knob on atmospheric CO2 is fossil-fuel emissions,” Keeling’s son Ralph Keeling, who runs the Scripps program at the NOAA’s Mauna Loa observatory, said in a statement. “But we still have a long way to go to halt the rise, as each year more CO2 piles up in the atmosphere. We ultimately need cuts that are much larger and sustained longer than the COVID-related shutdowns of 2020."
Ralph Keeling told Axios the concentration will likely exceed 420 PPM in 2021, adding ,“We’re moving deeper and deeper into a territory we almost certainly never would have wanted to get to."
Although carbon emissions fell 17 percent globally in spring 2020, they were on the rise again by September, with research from the World Meteorological Organization indicating they fell only a net 6.4 percent last year.
Experts have said emissions will likely rebound as more people return to their daily automobile commutes and that reduced ridership for public transportation also has worrisome implications for emissions.