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Published September 2023 | Version Published
Journal Article Open

Resolving the Carbon-Climate Feedback Potential of Wetland CO₂ and CH₄ Fluxes in Alaska

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Abstract

Boreal-Arctic regions are key stores of organic carbon (C) and play a major role in the greenhouse gas balance of high-latitude ecosystems. The carbon-climate (C-climate) feedback potential of northern high-latitude ecosystems remains poorly understood due to uncertainty in temperature and precipitation controls on carbon dioxide (CO₂) uptake and the decomposition of soil C into CO₂ and methane (CH₄) fluxes. While CH₄ fluxes account for a smaller component of the C balance, the climatic impact of CH₄ outweighs CO₂ (28–34 times larger global warming potential on a 100-year scale), highlighting the need to jointly resolve the climatic sensitivities of both CO₂ and CH₄. Here, we jointly constrain a terrestrial biosphere model with in situ CO₂ and CH₄ flux observations at seven eddy covariance sites using a data-model integration approach to resolve the integrated environmental controls on land-atmosphere CO₂ and CH₄ exchanges in Alaska. Based on the combined CO₂ and CH₄ flux responses to climate variables, we find that 1970-present climate trends will induce positive C-climate feedback at all tundra sites, and negative C-climate feedback at the boreal and shrub fen sites. The positive C-climate feedback at the tundra sites is predominantly driven by increased CH₄ emissions while the negative C-climate feedback at the boreal site is predominantly driven by increased CO₂ uptake (80% from decreased heterotrophic respiration, and 20% from increased photosynthesis). Our study demonstrates the need for joint observational constraints on CO₂ and CH₄ biogeochemical processes—and their associated climatic sensitivities—for resolving the sign and magnitude of high-latitude ecosystem C-climate feedback in the coming decades.

Copyright and License

© 2023 Jet Propulsion Laboratory, California Institute of Technology and The Authors. Government sponsorship acknowledged. 

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Acknowledgement

This article also appears in: Understanding Carbon-Climate Feedbacks.

Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Part of the funding for this study was provided through a NASA Terrestrial Ecology Grant NNH21ZDA001N-TE, and NASA Carbon Monitoring System Grants NNH16ZDA001N-CMS and NNH20ZDA001N-CMS. Funding for J.D.W was provided by NASA Terrestrial Ecology Grant 80NSSC22K1245, NNH17ZDA001N and the Gordon and Betty Moore Foundation. Funding for ESE was provided by NSF Grants DEB-1636476, AON 856864, 1304271, 0632264, and 1107892, and the US Geological Survey. Funding for D.Z. was provided by the Office of Polar Programs of the National Science Foundation (NSF) (award numbers 2149988 and 1932900) with additional support by the NASA ABoVE (80NSSC21K1350) Program.

Data Availability

Eddy covariance observation data are available at https://ameriflux.lbl.gov/. Model results are available in a public repository (Ma et al., 2021a, 2021b) (https://doi.org/10.5281/zenodo.6339769). Figures were made with R version 4.2.0 (R Core Team, 2021) (https://www.R-project.org/). Model driver files are derived from the European Centre for Medium-Range Weather Forecasts (ECMWF, 2011) Reanalysis Interim (Berrisford et al., 2011) (https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era-interim) and are available at https://github.com/CARDAMOM-framework/CARDAMOM_v2.2".

Conflict of Interest

The authors declare no conflicts of interest relevant to this study.

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Global Biogeochemical Cycles - 2023 - Ma - Resolving the Carbon‐Climate Feedback Potential of Wetland CO2 and CH4 Fluxes in.pdf

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Additional details

Identifiers

ISSN
1944-9224

Funding

Earth Sciences Division
NNH21ZDA001N‐TE
Earth Sciences Division
NNH16ZDA001N‐CMS
Earth Sciences Division
NNH20ZDA001N‐CMS
Earth Sciences Division
NNH17ZDA001N
Earth Sciences Division
80NSSC22K1245
National Aeronautics and Space Administration
NNH17ZDA001N
Gordon and Betty Moore Foundation
Division of Environmental Biology
DEB‐1636476
National Science Foundation
DEB-1636476
National Science Foundation
DEB-1636476
National Science Foundation
OPP-1304271
National Science Foundation
OPP-0632264
National Science Foundation
OPP-1107892
United States Geological Survey
National Science Foundation
OPP-2149988
National Science Foundation
OPP-1932900
Earth Sciences Division
80NSSC21K1350