Hotter Temperatures Threaten Wetlands' Methane Controls

New research highlights how rising temperatures are causing wetlands to emit increased levels of methane as the delicate microbial balance in wetland soils shifts. Wetlands are both carbon sinks and the largest natural sources of methane, a greenhouse gas with about 80 times the warming power of carbon dioxide over 20 years. In wetland soils, specialized microbes compete to produce and consume methane, regulating the gas's release into the atmosphere.

According to a recent study, when temperatures rise, the activity of methane-producing microbes accelerates, while the microbes that consume methane struggle to keep pace. This imbalance leads to a spike in methane emissions from wetlands. The findings were demonstrated in field experiments where soil temperatures were increased, mimicking projected global warming scenarios, and indicated a dramatic boost in methane output under hotter conditions.

Researchers observed that microbes capable of removing methane could reduce its emissions by only about 12% under normal conditions, but their efficiency dropped as temperatures climbed. In particularly warm and low-salinity environments, methane emissions from wetlands surged the most, suggesting that freshwater wetlands under hotter and wetter conditions are especially prone to higher methane release.

This emerging trend is significant since methane accounts for nearly 19% of global warming. The study underscores the importance of understanding natural methane sources when setting emissions targets to address climate change. Without accurate accounting of these rising natural emissions, climate mitigation strategies may fall short of their goals.