Concentrations of the powerful greenhouse gas methane in the atmosphere are rising at an accelerating pace, threatening efforts by countries to meet their climate targets, researchers warned Tuesday.
"Methane is rising faster in relative terms than any major greenhouse gas and is now 2.6-fold higher than in pre-industrial times," said an international group of researchers under the aegis of the Global Carbon Project in a study published in Environmental Research Letters.
Methane is the second-largest greenhouse gas produced by human activity after carbon dioxide, with agriculture, energy production and organic waste rotting in landfills the major sources.
In the first 20 years, its impact on the atmosphere is about 80 times that of carbon dioxide, but it breaks down quicker.
That opens a possibility to sharply reduce climate impact in the short term, but the researchers found that despite efforts to cut methane emissions atmospheric concentrations of the gas are still rising.
An average of 6.1 million tonnes of methane were added to the atmosphere per year in the 2000s. That rose to 20.9 million tonnes per in the 2010s. It hit 41.8 million tonnes in 2020.
"Anthropogenic emissions have continued to increase in almost every other country in the world, with the exception of Europe and Australia, which show a slow declining trend," Global Carbon Project executive director Pep Canadell, and one of the study's co-authors, told Agence France-Presse (AFP).
The largest increases have come from China and Southeast Asia and were primarily linked to coal extraction, oil and gas production and landfills, the researchers found.
The La Nina weather phenomenon has also led to an increase in methane from natural sources, they also found.
The drop in nitrogen oxide pollution in 2020 as transportation plunged due to the COVID-19 pandemic had a paradoxical impact: It is key in preventing methane from accumulating in the atmosphere.
Rising methane pollution is running at cross purposes of efforts to keep global warming under 2 degrees Celsius (2.6 degrees Fahrenheit).
A "Global Methane Pledge" was launched in 2021 by the European Union and the United States to cut global methane emissions by 30% from 2020 levels by 2030.
More than 150 countries have signed up, but not China, India or Russia.
"Right now, the goals of the Global Methane Pledge seem as distant as a desert oasis," said lead author of the Environmental Research Letters paper, Stanford University scientist Rob Jackson.
"We all hope they aren't a mirage."
China and the United States are preparing to host a summit on greenhouse gasses other than carbon dioxide later this year, raising the prospects for further pledges by governments.
