A Hidden Atmospheric Shift Let Methane Surge Worldwide

Atmospheric methane rose faster than ever in the early 2020s, driven less by fossil fuels and more by changes in nature itself.

Methane levels in Earth’s atmosphere climbed at an unprecedented pace in the early 2020s due to a mix of weaker natural removal and rising emissions from warming wetlands, rivers, lakes, and agricultural land. An international team of scientists reports these findings today (February 5) in the journal Science, pointing to a convergence of atmospheric chemistry changes and climate-driven shifts on the ground.

Researchers found that the atmosphere temporarily lost much of its ability to break down methane. During 2020–2021, levels of hydroxyl radicals, the main chemical responsible for removing methane from the air, dropped sharply. According to the research team, including Boston College Earth and Environmental Science Professor Hanqin Tian, this decline explains about 80 percent of the year-to-year changes in how quickly methane built up.

La Niña and Expanding Wetlands Boost Emissions

At the same time, a prolonged La Niña event from 2020 to 2023 brought unusually wet conditions across much of the tropics. These wetter landscapes expanded flooded areas, creating ideal conditions for microbes that produce methane. This effect intensified emissions of methane, the second-most important greenhouse gas after carbon monoxide.

Between 2019 and 2023, atmospheric methane increased by 55 parts per billion, reaching a new record of 1921 ppb in 2023. The fastest rise occurred in 2021, when methane levels jumped by nearly 18 ppb, representing an 84 percent increase compared with 2019.

“As the planet becomes warmer and wetter, methane emissions from wetlands, inland waters, and paddy rice systems will increasingly shape near-term climate change,” said Tian. “Our findings highlight that the Global Methane Pledge must account for climate-driven methane sources alongside anthropogenic controls if its mitigation targets are to be achieved.”

Managed Landscapes Play a Bigger Role Than Expected

The methane response was not limited to natural wetlands. Managed environments such as paddy rice fields and inland waters also contributed substantially, according to Tian, who serves as Director of the Center for Earth System Science and Global Sustainability in the Schiller Institute for Integrated Science and Society. These sources are often underestimated or missing in global methane models.

The largest emission increases were detected in tropical Africa and Southeast Asia. Arctic wetlands and lakes also showed notable growth as rising temperatures boosted microbial activity. In contrast, methane output from South American wetlands fell in 2023 during an extreme El Niño–related drought, underscoring how sensitive methane emissions are to climate extremes, the report notes.

How Scientists Tracked the Methane Surge

Tian and his colleagues played a key role in measuring how wetlands, rivers, lakes, reservoirs, and global paddy rice farming contributed to the rapid increase in methane. By combining land, freshwater, and atmospheric processes in advanced Earth system models, the Boston College team demonstrated how climate variability amplified emissions across connected ecosystems.

Importantly, the study found that fossil fuel use and wildfires were not major contributors to the recent methane surge. Chemical fingerprinting shows that microbial sources, including wetlands, inland waters, and agriculture, were responsible for most of the observed increase.

“By providing the most up-to-date global methane budget through 2023, this research clarifies why atmospheric methane rose so rapidly,” said lead author Philippe Ciais of the University of Versailles Saint-Quentin-en-Yvelines. “It also shows that future methane trends will depend not only on emission controls, but on climate-driven changes in natural and managed methane sources.”

Key Findings From the Study

• The rapid rise in methane during the early 2020s was driven mainly by a temporary weakening of atmospheric chemistry, rather than a surge in emissions alone.
• A short-term decline in hydroxyl (OH) radicals during 2020–2021 accounts for roughly 80-85 percent of the year-to-year changes in methane growth.
• COVID-19–related shifts in air pollution played an important role. Lockdowns reduced nitrogen oxides (NOₓ), which in turn lowered OH levels and allowed methane to accumulate more quickly.
• Climate-driven emissions from wetlands and inland waters further amplified the increase. Exceptionally wet conditions during La Niña (2020–2023) boosted methane output in tropical Africa and Southeast Asia, with additional increases seen in Arctic regions.
• Changes in fossil fuel and biomass-burning emissions were relatively small and cannot explain the global spike in methane.
• Finally, the study highlights gaps in current bottom-up emission models. Many widely used models underestimated emissions from wetlands and inland waters during this period, revealing the need for better monitoring of flooded ecosystems and microbial methane production.

Reference: “Why methane surged in the atmosphere during the early 2020s” by P. Ciais, Y. Zhu, Y. Cai, X. Lan, S. E. Michel, B. Zheng, Y. Zhao, D. A. Hauglustaine, X. Lin, Y. Zhang, S. Sun, X. Tian, M. Zhao, Y. Wang, J. Chang, X. Dou, Z. Liu, R. Andrew, C. A. Quinn, B. Poulter, Z. Ouyang, W. Yuan, K. Yuan, Q. Zhu, F. Li, N. Pan, H. Tian, X. Yu, G. Rocher-Ros, M. S. Johnson, M. Li, M. Li, D. Feng, P. Raymond, X. Yang, J. G. Canadell, R. B. Jackson, X. Yu, Y. Li, M. Saunois, P. Bousquet and S. Peng, 5 February 2026, Science.
DOI: 10.1126/science.adx8262

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