by By Gloria Dickie
BAKU (Reuters) – Research shows the world’s warming tropical wetlands are releasing more methane than ever before, an alarming sign that the world’s climate goals are slipping further out of reach.
A massive increase in methane in wetlands – which is not accounted for in national emissions plans and is not accounted for in scientific models – could increase pressure on governments to make deeper cuts in the fossil fuel and agricultural industries, researchers say.
Wetlands contain huge carbon stores in the form of dead plant matter that are slowly broken down by soil microbes. Rising temperatures are like accelerating this process, accelerating the biological interactions that produce methane. Meanwhile, heavy rainfall triggers flooding, which leads to the expansion of wetlands.
Scientists had long predicted that methane emissions from wetlands would rise as the climate warmed, but between 2020 and 2022 air samples showed the highest concentrations of methane in the atmosphere since reliable measurements began in the 1980s.
Four studies published in recent months say tropical wetlands are the most likely cause of the increase, with tropical regions contributing more than 7 million tons to methane increases in recent years.
“Methane concentrations are not only rising, but they are rising faster in the last five years than at any time in the instrumental record,” said environmental scientist Rob Jackson of Stanford University, chair of the group that released the most recent five-year global methane budget in September.
Satellite instruments showed that the tropics were the source of a sharp increase. Scientists also analyzed certain chemical signatures in the methane to determine whether it came from fossil fuels or a natural source – in this case wetlands.
According to researchers, the Congo, Southeast Asia, the Amazon and southern Brazil contributed most to the increase in the tropics.
Data published in March 2023 in Nature Climate Change shows that annual wetland emissions over the past two decades have been about 500,000 tons per year higher than scientists had predicted under worst-case climate scenarios.
Capturing emissions from wetlands is challenging with current technologies.
“We should probably be a little more worried than we are,” said Duke University climate scientist Drew Shindell.
The La Nina climate pattern, which causes heavier rainfall in parts of the tropics, appeared to be responsible for the increase, according to a study published in September in the journal Proceedings of the National Academy of Sciences.
But La Nina alone, which last ended in 2023, cannot explain the record-high emissions, Shindell said.
For countries seeking to combat climate change, “this has significant implications for planning reductions in methane and carbon dioxide emissions,” said Zhen Qu, an atmospheric chemist at North Carolina State University who led the study of La Nina impacts.
If methane emissions in wetlands continue to rise, scientists say governments will need to take stronger action to limit warming to 1.5°C (2.7°F), as agreed to in the United Nations’ Paris climate accord.
WATER WORLD
Methane is 80 times more effective at trapping heat than carbon dioxide (CO2) over a 20-year period and is responsible for about a third of the 1.3 degrees Celsius (2.3 F) of warming the world has recorded since 1850. Unlike CO2, however, methane is washed out of the atmosphere after about a decade, so the long-term effects are smaller.
More than 150 countries have committed to achieving a 30% reduction from 2020 levels by 2030, closing the gap in oil and gas infrastructure.
However, scientists have not yet observed a slowdown, although technologies to detect methane leaks have improved. According to the International Energy Agency’s 2024 Global Methane Tracker report, methane emissions from fossil fuels have remained at a record high of 120 million tons since 2019.
Satellites have also detected more than 1,000 large plumes of methane from oil and gas operations over the past two years, but notified countries responded to only 12 leaks, according to a U.N. Environment Program report released Friday.
Some countries have announced ambitious plans to reduce methane.
China said last year that it would seek to curb flaring or burning emissions from oil and gas wells.
President Joe Biden’s administration passed a methane fee on major oil and gas producers last week, but it is likely to be eliminated under the new presidency of Donald Trump.
Democratic Republic of Congo Environment Minister Eve Bazaiba told Reuters on the sidelines of the UN climate summit COP29 that the country was working to assess methane emissions from the swampy forests and wetlands of the Congo Basin. In the 2024 methane budget report, Congo was the largest hotspot for methane emissions in the tropics.
“We don’t know how much [methane is coming off our wetlands]” she said. “So we bring in those who can invest in this way and also monitor the inventory of how much we have and how we can use it as well.”
(Reporting by Gloria Dickie in Baku; Additional reporting by Virginia Furness in Baku; Editing by Katy Daigle and Suzanne Goldenberg)
