Abstract
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 Utqiaġvik (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.
| Original language | English |
|---|---|
| Article number | 0185 |
| Journal | Ecosystem Health and Sustainability |
| Volume | 10 |
| DOIs | |
| State | Published - 2024 |
Funding
We are grateful to R. A. Dahlgren from the University of California, Davis for his constructive suggestions in the early phase of this study. Funding: We are grateful for the financial and facility support from San Diego State University. Financial assistance was partially provided by the SPRUCE and NGEE Arctic projects, which are supported by the Office of Biological and Environmental Research in the Department of Energy Office of Science. This project is partially supported by the U.S. National Science Foundation (2145130, 1702797, and 2208656). Geospatial support for this work was provided by the Polar Geospatial Center under NSF OPP awards 1204263 and 1702797. W.O. and D.Z. have been supported by NASA ABoVE program (NNX15AT74A and NNX16AF94A) and the National Oceanic and Atmospheric Administration NOAA/EPP Grant (NA22SEC4810016). Author contributions: X.X. conceived the idea. Y.W. carried out all modeling experiments. L.H. and J.L. contributed to model forcing data. K.A., D.Z., D.L., and W.O. contributed observational data. J.L.R., D.M.R., and S.D.W. contributed to the interpretation of the results. Y.W. and X.X. led the writing of the early draft. All authors contributed to the manuscript revision. Competing interests: The authors declare that they have no competing interests.