U.S. government scientists warned Wednesday that despite temporary drops in planet-heating emissions due to shutdowns triggered by the ongoing coronavirus pandemic, "levels of the two most important anthropogenic greenhouse gases, carbon dioxide and methane, continued their unrelenting rise in 2020."

The National Oceanic and Atmospheric Administration (NOAA) also said that the global surface average for carbon dioxide (CO2) last year was 412.5 parts per million (PPM), among the highest rates of increase ever documented since the federal agency, started keeping records over six decades ago.

At the Mauna Loa Observatory in Hawaii, the annual mean was 414.4 ppm in 2020.

The figures likely would have been higher if the pandemic hadn't happened, according to Pieter Tans, senior scientist at NOAA's Global Monitoring Lab (GML), which measures carbon dioxide, methane, and nitrous oxide from observatories in Alaska, American Samoa, Hawaii, and the South Pole.

"The economic recession was estimated to have reduced carbon emissions by about 7% during 2020," the agency explained. "Without the economic slowdown, the 2020 increase would have been the highest on record."

According to NOAA, "Carbon dioxide levels are now higher than at any time in the past 3.6 million years."