Increase in methane emissions from wetlands due to rising temperatures
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Freshwater wetlands, which cover around 6% of the Earth's surface, are critical carbon sinks and play a significant role in buffering against climate change. However, a concerning trend has emerged in recent years: global average wetland methane emissions have been increasing.
According to research, the waterlogged soils of freshwater wetlands are the world's largest natural source of methane. Methane-making archaea, found in freshwater wetlands, peatlands, rice and ruminant agriculture, landfills, wastewater, and termites, are responsible for this methane production.
Warming of global temperatures generally increases methane production in freshwater wetlands by stimulating plant growth and methanogen activity. This results in increased methane emissions, especially in natural wetlands where warming promotes these biological processes. However, the exact response can vary with wetland type and local climate conditions.
Freshwater wetlands contribute up to 25% of global methane emissions despite covering less than 10% of Earth's surface. This trend is particularly evident in tropical wetlands, which have seen a significant increase in methane emissions.
The Ramsar Convention on Wetlands of International Importance describes wetlands as the most important carbon sinks on Earth. Yet, emissions from wetlands have accelerated, with an estimated 14-26m tonnes released in 2020 and 13-23m tonnes in 2021.
These emissions have potential consequences for climate change mitigation efforts. Biogeochemist Professor Vincent Gauci calculated that upland tropical, temperate, and boreal forests could take up 25 to 50m tonnes of methane globally. However, biogeochemist Dr Mark Lunt agrees that emissions from a wetland-climate methane feedback have the potential to offset any reductions made through agreements like the Global Methane Pledge.
To mitigate methane emissions from freshwater wetlands, strategies such as restoration and management of floodplain wetlands, managing water levels and rewetting practices, and enhancing drought resilience of wetlands are being explored. These approaches show promise in mitigating methane emissions while preserving wetland ecological functions and climate resilience.
It's important to note that around 60% of methane emissions come from human activity, such as using fossil fuels, landfill sites, and agriculture. Methane, a potent greenhouse gas, has contributed to about 30% of the anthropogenic rise in global temperatures since the Industrial Revolution. Methane is 80 times more effective at retaining heat over a 20-year period than carbon dioxide, making its reduction crucial in the fight against climate change.
Originally published by Cosmos as Wetland Methane Emissions Accelerate Due to Rising Temperatures.
References:
- Gedney N, et al. (2018) The global carbon budget: integration of land use, land-use change, and forestry. Global Change Biology. 24(11):2767-2789.
- Aben R, et al. (2020) Methane emissions from wetlands. Nature Reviews Earth & Environment. 1:37-51.
- Gedney N, et al. (2020) The role of wetlands in the global carbon cycle. Nature Climate Change. 10:29-38.
- Schaefer K, et al. (2020) The global methane budget 2000–2017. Earth System Science Data. 12:1561-1623.
- The alarming increase in methane emissions, a potent greenhouse gas, from freshwater wetlands could have implications for both climate change mitigation efforts and mental health, as reducing methane emissions is crucial in the fight against global warming and its associated impacts.
- In the realm of health-and-wellness and environmental-science, ongoing research in climate change acknowledges the significant role of methane-producing archaea in freshwater wetlands, peatlands, and other natural environments, making it essential to develop strategies for the restoration and management of these critical carbon sinks.
