Summary/Abstract
For the second year in a row, NOAA scientists observed a record annual increase in atmospheric levels of methane, a powerful, heat-trapping greenhouse gas that’s the second biggest contributor to human-caused global warming after carbon dioxide.
NOAA’s preliminary analysis showed the annual increase in atmospheric methane during 2021 was 17 parts per billion (ppb), the largest annual increase recorded since systematic measurements began in 1983. The increase during 2020 was 15.3 ppb. Atmospheric methane levels averaged 1,895.7 ppb during 2021, or around 162% greater than pre-industrial levels. From NOAA’s observations, scientists estimate global methane emissions in 2021 are 15% higher than the 1984-2006 period.