Scientists trace Covid era methane surge to shifts in air chemistry and wetlands

by Robert Schreiber
Berlin, Germany (SPX) Feb 08, 2026
With fewer cars on the road, planes in the air and factories running during the Covid 19 pandemic, skies over many regions appeared cleaner even as a key greenhouse gas unexpectedly accelerated. Methane concentrations in the atmosphere surged between 2020 and 2022 at the fastest pace ever recorded, reaching an annual growth peak of about 16.2 parts per billion before easing to around 8.6 parts per billion per year by 2023.

Methane is the second largest contributor to climate warming after carbon dioxide and packs a much stronger punch per tonne. Over a century, a tonne of methane can trap roughly 30 times more heat than a tonne of carbon dioxide, even though methane typically remains in the atmosphere for only about a decade.

An international team has now reconstructed what drove this abrupt rise and partial slowdown in the early 2020s using a suite of satellite observations, ground based measurements, atmospheric chemistry records and advanced numerical models. Applying methodologies developed in the European Space Agency Climate Change Initiative's RECCAP 2 project, the researchers built a global methane budget covering the period from 2019 to 2023.

The study, published in the journal Science, points first to a temporary weakening in the atmosphere's capacity to cleanse itself of methane. Central to this process are hydroxyl radicals, highly reactive molecules often described as the atmosphere's detergent because they break down methane and other trace gases and control how long these gases persist.

Hydroxyl radicals form through chains of reactions involving sunlight, ozone, water vapour and gases such as nitrogen oxides, carbon monoxide and volatile organic compounds. During 2020 and 2021, emissions of several of these precursor gases dropped as human activity slowed under Covid 19 restrictions, which in turn reduced the production of hydroxyl radicals worldwide.

With fewer hydroxyl radicals available, methane molecules stayed in the atmosphere longer and accumulated more quickly than usual. The analysis indicates that this chemical slowdown in the atmosphere's oxidising capacity explains roughly 80 percent of the year to year variation in methane growth over this period.

At the same time, the climate system delivered conditions that amplified natural methane emissions, particularly from wetlands and inland waters. An extended La Nina episode from 2020 through 2023 brought wetter than average weather to large parts of the Tropics, expanding flooded areas and waterlogged soils that favour methane producing microbes.

These microbial communities thrived in expanded tropical wetlands, boosting emissions across regions such as tropical Africa and Southeast Asia. Arctic wetlands and lakes also released more methane as temperatures rose, adding to the global increase linked to natural sources.

Not all wetland regions responded in the same way. South American wetlands showed a sharp drop in methane emissions in 2023 that the study associates with severe El Nino related drought, underlining how sensitive these natural sources are to shifts between wetter and drier climate phases.

The research team found that fossil fuel operations and wildfires played only a minor role in the overall methane spike during the early 2020s. Isotopic fingerprints measured in atmospheric methane over this period point strongly toward microbial sources, including wetlands, inland waters and agriculture, as the dominant contributors to the observed changes.

These findings expose important shortcomings in many current methane emission models, which significantly underestimated wetland emissions during this episode. The authors argue that models must better capture the behaviour of flooded ecosystems, including soil and water processes that control microbial methane production and release.

Improving the integration between atmospheric chemistry, such as variations in hydroxyl radicals, and climate variability is another priority highlighted by the study. Combining these elements in models is essential for explaining past methane fluctuations and for narrowing uncertainties in projections of future trends.

The work underscores the growing role of satellite missions in tracking greenhouse gases and probing the subtle atmospheric processes that regulate them. Space based sensors complement ground networks by providing near global coverage and by helping to pinpoint regional changes in both emissions and atmospheric chemistry.

The analysis provides the most up to date global methane budget through 2023 and clarifies why methane growth accelerated so rapidly in the early 2020s before slowing more recently. It also shows that unexpected climate signals can arise not only from changes in what societies emit directly but from how the atmosphere and natural systems respond to altered conditions.

Looking ahead, the authors conclude that future methane trajectories will depend on a combination of human control over emissions, air quality policies that influence key chemical precursors and climate driven shifts in the planet's natural methane cycle. Reducing anthropogenic methane remains vital, but tracking and understanding natural feedbacks will be just as important for managing the gas's impact on global warming.

Research Report:Why methane surged in the atmosphere during the early 2020s