Arctic wetlands, well-known as emitters of the potent greenhouse gas methane (CH4), may have a surprising ally in the fight against climate change: well-drained soils.
These soils, which cover more than 80 percent of the land area in Arctic and boreal biomes, remove methane from the atmosphere.
However, the underlying mechanisms, environmental controls, and even the magnitude of Arctic soil methane uptake have been a mystery.
A groundbreaking study led by the University of Eastern Finland and the University of Montreal suggests that Arctic soil methane uptake could be larger than previously estimated.
Moreover, the researchers found that methane uptake increases under dry conditions and with the availability of labile carbon substrates.
This research was primarily conducted at Trail Valley Creek, a tundra site in the Western Canadian Arctic, using a unique experimental set-up of 18 automated chambers for continuous methane flux measurements.
“No other automated chamber system exists this far North in the Canadian Arctic, and only few exist above the Arctic circle globally, most of which are installed at methane-emitting sites,” the researchers noted.
Over 40,000 flux measurements revealed previously unknown diurnal and seasonal dynamics in methane uptake.
While methane uptake in early and peak summer was largest during the afternoons, coinciding with maximum soil temperature, methane uptake during late summer peaked during the night.
The underlying biogeochemical mechanisms are complex, but the study shows that the strongest methane uptake coincided with peaks of ecosystem carbon dioxide (CO2) respiration.
Additionally, complementing flux measurements at Trail Valley Creek with measurements at other sites across the Arctic in Canada and Finland showed that the availability of labile carbon substrates and nutrients may promote methane consumption in Arctic soils.
These findings have significant implications for estimating the current Arctic methane budget and predicting the future response of Arctic soil methane uptake to a changing climate.
The study suggests that high-latitude warming, which is occurring up to four times faster in the Arctic than the rest of the world, will promote atmospheric methane uptake to a lesser extent than the associated large-scale drying.
The research was a collaborative effort between scientists from Canada, Finland, the United States, and Germany. The study is now published in the journal Nature Climate Change.
Arctic wetlands are a critical component of the global climate system. They are found in the Arctic region, which includes parts of Canada, Russia, Greenland, the United States (Alaska), and the Scandinavian countries.
These wetlands are unique ecosystems characterized by waterlogged soils and vegetation adapted to cold, water-saturated conditions.
Arctic wetlands are significant sources of methane (CH4), a potent greenhouse gas that has a warming potential many times greater than carbon dioxide (CO2) over a 100-year period.
Methane is produced in waterlogged soils by microbial activity under anaerobic (oxygen-deprived) conditions. The methane is then released into the atmosphere, contributing to the greenhouse effect and global warming.
Despite being a source of methane, Arctic wetlands also play a crucial role in carbon storage. They contain large amounts of organic carbon in the form of peat, which is partially decomposed plant material that accumulates over thousands of years.
This carbon is stored in the soil and vegetation of the wetlands, helping to reduce the overall amount of carbon in the atmosphere.
Arctic wetlands are home to a wide variety of plant and animal species specially adapted to the harsh conditions of the Arctic. These include various species of mosses, sedges, and shrubs, as well as migratory birds, insects, and mammals such as caribou and muskrats.
Wetlands play a vital role in regulating the water cycle. They store water during wet periods and slowly release it during dry periods, helping to regulate river flow and groundwater levels.
Arctic wetlands face numerous threats, including climate change, which is causing rising temperatures, melting permafrost, and changes in precipitation patterns. These changes can lead to the drying out of wetlands, increased wildfire frequency, and the release of stored carbon into the atmosphere. Other threats include oil and gas development, mining, and infrastructure development.
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