The WMO found there was the biggest year-on-year jump in methane concentrations in 2020 and 2021 since systematic measurements began almost 40 years ago. Methane levels have risen rapidly in recent years, puzzling scientists. Some blamed it on an increase in fracking in the US but this came into doubt as industrial emissions were not showing a similarly sharp rise.
Now the theory is that the methane rise could be caused by activities of microbes in wetlands, rice paddies and the guts of ruminants. Rising temperatures have caused the ideal conditions for microbial methane production, as they enjoy warm, damp areas. Carbon dioxide levels are also soaring, with the jump from 2020 to 2021 larger than the annual growth rate over the past decade. Measurements from WMO’s global atmosphere watch network stations show these levels continue to rise. These greenhouse gases cause global heating, with the warming effect rising by 50% between 1990 and 2021. Carbon dioxide comprised about 80% of this increase. According to the WMO, carbon dioxide concentrations in 2021 were 415.7 parts per million, methane was 1908 parts per billion (ppb) and nitrous oxide was 334.5 ppb. These are respectively 149%, 262% and 124% of pre-industrial levels.