Intensified Positive Arctic–Methane Feedback under IPCC Climate Scenarios in the 21st Century

Journal Article · 17 April 2024 · Ecosystem Health and Sustainability

DOI: https://doi.org/10.34133/ehs.0185 · OSTI ID:2439842

Wang, Yihui ^[1]; He, Liyuan ^[1]; Liu, Jianzhao ^[2]; Arndt, Kyle A. ^[3]; Mazza Rodrigues, Jorge L. ^[4]; Zona, Donatella ^[1]; Lipson, David A. ^[1]; Oechel, Walter C. ^[1]; Ricciuto, Daniel M. ^[5]; Wullschleger, Stan D. ^[5]; Xu, Xiaofeng  ^[1]

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1. San Diego State Univ., CA (United States)
2. Chinese Academy of Sciences (CAS), Changchun (China)
3. Woodwell Climate Research Center, Falmouth, MA (United States)
4. Univ. of California, Davis, CA (United States)
5. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

The positive Arctic–methane (CH₄) feedback forms when more CH₄ is released from the Arctic tundra to warm the climate, further stimulating the Arctic to emit CH₄. This study utilized the CLM-Microbe model to project CH₄ emissions across five distinct Arctic tundra ecosystems on the Alaska North Slope, considering three Shared Socioeconomic Pathway (SSP) scenarios using climate data from three climate models from 2016 to 2100. Employing a hyper-resolution of 5 m × 5 m within 40,000 m² domains accounted for the Arctic tundra’s high spatial heterogeneity; three sites were near $$Utqia\dot{g}vik$$ (US-Beo, US-Bes, and US-Brw), with one each in Atqasuk (US-Atq) and Ivotuk (US-Ivo). Simulated CH₄ emissions substantially increased by a factor of 5.3 to 7.5 under the SSP5–8.5 scenario compared to the SSP1–2.6 and SSP2–4.5 scenarios. The projected CH₄ emissions exhibited a stronger response to rising temperature under the SSP5–8.5 scenario than under the SSP1–2.6 and SSP2–4.5 scenarios, primarily due to strong temperature dependence and the enhanced precipitation-induced expansion of anoxic conditions that promoted methanogenesis. The CH₄ transport via ebullition and plant-mediated transport is projected to increase under all three SSP scenarios, and ebullition dominated CH₄ transport by 2100 across five sites. Projected CH₄ emissions varied in temperature sensitivity, with a Q₁₀ range of 2.7 to 60.9 under SSP1–2.6, 3.8 to 17.6 under SSP2–4.5, and 5.7 to 17.2 under SSP5–8.5. Compared with the other three sites, US-Atq and US-Ivo were estimated to have greater increases in CH₄ emissions due to warmer temperatures and higher precipitation. The fact that warmer sites and warmer climate scenarios had higher CH₄ emissions suggests an intensified positive Arctic–CH₄ feedback in the 21st century. Microbial physiology and substrate availability dominated the enhanced CH₄ production. The simulated intensified positive feedback underscores the urgent need for a more mechanistic understanding of CH₄ dynamics and the development of strategies to mitigate CH₄ across the Arctic.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); National Oceanic and Atmospheric Administration (NOAA); National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 2439842
• Journal Information: Ecosystem Health and Sustainability, Journal Name: Ecosystem Health and Sustainability Vol. 10; ISSN 2332-8878
• Publisher: Ecological Society of America (ESA)Copyright Statement
• Country of Publication: United States
• Language: English