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- Oh, Youmi, et al.
(författare)
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Reduced net methane emissions due to microbial methane oxidation in a warmer Arctic
- 2020
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Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 10:4, s. 317-321
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Tidskriftsartikel (refereegranskat)abstract
- Methane emissions from organic-rich soils in the Arctic have been extensively studied due to their potential to increase the atmospheric methane burden as permafrost thaws(1-3). However, this methane source might have been overestimated without considering high-affinity methanotrophs (HAMs; methane-oxidizing bacteria) recently identified in Arctic mineral soils(4-7). Herein we find that integrating the dynamics of HAMs and methanogens into a biogeochemistry model(8-10) that includes permafrost soil organic carbon dynamics(3) leads to the upland methane sink doubling (similar to 5.5 Tg CH4 yr(-1)) north of 50 degrees N in simulations from 2000-2016. The increase is equivalent to at least half of the difference in net methane emissions estimated between process-based models and observation-based inversions(11,12), and the revised estimates better match site-level and regional observations(5,7,13-15). The new model projects doubled wetland methane emissions between 2017-2100 due to more accessible permafrost carbon(16-18). However, most of the increase in wetland emissions is offset by a concordant increase in the upland sink, leading to only an 18% increase in net methane emission (from 29 to 35 Tg CH4 yr(-1)). The projected net methane emissions may decrease further due to different physiological responses between HAMs and methanogens in response to increasing temperature(19,20).
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| 2. |
- Treat, Claire C., et al.
(författare)
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Permafrost Carbon : Progress on Understanding Stocks and Fluxes Across Northern Terrestrial Ecosystems
- 2024
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Ingår i: Journal of Geophysical Research - Biogeosciences. - : American Geophysical Union (AGU). - 2169-8953 .- 2169-8961. ; 129:3
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Tidskriftsartikel (refereegranskat)abstract
- Significant progress in permafrost carbon science made over the past decades include the identification of vast permafrost carbon stocks, the development of new pan-Arctic permafrost maps, an increase in terrestrial measurement sites for CO2 and methane fluxes, and important factors affecting carbon cycling, including vegetation changes, periods of soil freezing and thawing, wildfire, and other disturbance events. Process-based modeling studies now include key elements of permafrost carbon cycling and advances in statistical modeling and inverse modeling enhance understanding of permafrost region C budgets. By combining existing data syntheses and model outputs, the permafrost region is likely a wetland methane source and small terrestrial ecosystem CO2 sink with lower net CO2 uptake toward higher latitudes, excluding wildfire emissions. For 2002–2014, the strongest CO2 sink was located in western Canada (median: −52 g C m−2 y−1) and smallest sinks in Alaska, Canadian tundra, and Siberian tundra (medians: −5 to −9 g C m−2 y−1). Eurasian regions had the largest median wetland methane fluxes (16–18 g CH4 m−2 y−1). Quantifying the regional scale carbon balance remains challenging because of high spatial and temporal variability and relatively low density of observations. More accurate permafrost region carbon fluxes require: (a) the development of better maps characterizing wetlands and dynamics of vegetation and disturbances, including abrupt permafrost thaw; (b) the establishment of new year-round CO2 and methane flux sites in underrepresented areas; and (c) improved models that better represent important permafrost carbon cycle dynamics, including non-growing season emissions and disturbance effects.
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