Permafrost Region Greenhouse Gas Budgets Suggest a Weak CO2 Sink and CH4 and N2O Sources, But Magnitudes Differ Between Top‐Down and Bottom‐Up Methods
Résumé
Large stocks of soil carbon (C) and nitrogen (N) in northern permafrost soils are vulnerable to remobilization under climate change. However, there are large uncertainties in present-day greenhouse gas (GHG) budgets. We compare bottom-up (data-driven upscaling and process-based models) and top-down (atmospheric inversion models) budgets of carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) as well as lateral fluxes of C and N across the region over 2000-2020. Bottom-up approaches estimate higher land-to-atmosphere fluxes for all GHGs. Both bottom-up and top-down approaches show a sink of CO 2 in natural ecosystems (bottom-up: 29 ( 709, 455), top-down: 587 ( 862, 312) Tg CO 2 -C yr 1 ) and sources of CH 4 (bottom-up: 38 (22, 53), top-down: 15 (11, 18) Tg CH 4 -C yr 1 ) and N 2 O (bottom-up: 0.7 (0.1, 1.3), top-down: 0.09 ( 0.19, 0.37) Tg N 2 O-N yr 1 ). The combined global warming potential of all three gases (GWP-100) cannot be distinguished from neutral. Over shorter timescales (GWP-20), the region is a net GHG source because CH 4 dominates the total forcing. The net CO 2 sink in Boreal forests and wetlands is largely offset by fires and inland water CO 2 emissions as well as CH 4 emissions from wetlands and inland waters,
Fichier principal
Global Biogeochemical Cycles - 2024 - Hugelius - Permafrost Region Greenhouse Gas Budgets Suggest a Weak CO2 Sink and CH4.pdf (2 Mo)
Télécharger le fichier
| Origine | Fichiers éditeurs autorisés sur une archive ouverte |
|---|