A new study has revealed that global efforts to reduce air pollution have inadvertently led to a sharp increase in methane emissions from wetlands, peatlands and swamps. The research shows that as sulfur pollution declines due to clean air policies methane production in natural wetlands has surged adding an estimated 20 to 35 million metric tons of methane to the atmosphere each year.
Published in Science Advances the study highlights the unintended consequences of reducing sulfur emissions. Sulfur previously helped limit methane release by supporting bacteria that outcompete methane-producing microorganisms for nutrients.
However as sulfur levels drop, methane-producing microbes have flourished, leading to higher emissions. Additionally, increased atmospheric carbon dioxide has boosted plant growth in wetlands, providing more organic material for methane-producing bacteria to consume.
The findings suggest that current climate policies may need to be more stringent. More than 150 countries signed the Global Methane Pledge at COP26, committing to a 30% reduction in anthropogenic methane emissions by 2030. However with natural emissions rising at an unexpected rate, meeting climate targets will require even greater reductions in human-caused methane sources.
The study also ties into broader concerns about the rapid pace of climate change. In 2020 stricter regulations on sulfur dioxide emissions from shipping were introduced to combat air pollution, but the resulting decline in atmospheric sulfur has been linked to faster-than-expected global warming. Scientists warn that the complexity of climate interactions such as the role of sulfur in suppressing methane, has not been fully accounted for in current climate models.
With wetlands acting as a major natural source of methane, researchers emphasize the need for a more comprehensive approach to methane reduction. Understanding these complex biogeochemical processes will be critical to refining climate projections and ensuring that global warming stays within safe limits as outlined in the Paris Agreement.
