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Emergent temperature sensitivity of soil organic carbon driven by mineral associations

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Peer-reviewed

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Abstract

jats:titleAbstract</jats:title>jats:pSoil organic matter decomposition and its interactions with climate depend on whether the organic matter is associated with soil minerals. However, data limitations have hindered global-scale analyses of mineral-associated and particulate soil organic carbon pools and their benchmarking in Earth system models used to estimate carbon cycle–climate feedbacks. Here we analyse observationally derived global estimates of soil carbon pools to quantify their relative proportions and compute their climatological temperature sensitivities as the decline in carbon with increasing temperature. We find that the climatological temperature sensitivity of particulate carbon is on average 28% higher than that of mineral-associated carbon, and up to 53% higher in cool climates. Moreover, the distribution of carbon between these underlying soil carbon pools drives the emergent climatological temperature sensitivity of bulk soil carbon stocks. However, global models vary widely in their predictions of soil carbon pool distributions. We show that the global proportion of model pools that are conceptually similar to mineral-protected carbon ranges from 16 to 85% across Earth system models from the Coupled Model Intercomparison Project Phase 6 and offline land models, with implications for bulk soil carbon ages and ecosystem responsiveness. To improve projections of carbon cycle–climate feedbacks, it is imperative to assess underlying soil carbon pools to accurately predict the distribution and vulnerability of soil carbon.</jats:p>

Description

Acknowledgements: K.G. was supported as a Lawrence Fellow at Lawrence Livermore National Laboratory (LLNL) by the LLNL-LDRD Program under Project No. 21-ERD-045 and 24-LW-053. J.P.-R. and E.W.S. were supported by the US Department of Energy (DOE) Office of Science, Office of Biological and Environmental Research, Genomic Science Program as part of the LLNL Microbes Persist Scientific Focus Area, SCW1632. Work at LLNL was conducted under the auspices of DOE Contract DE-AC52-07NA27344. W.R.W. was supported by National Science Foundation Grants 1926413 and 2031238 and by USDA NIFA-AFRI Grant 2020-67019-31395. C.D.K., W.J.R. and Q.Z. were supported by the US DOE Biological and Environmental Research (BER) Program at LBNL under DOE Contract DE-AC02-05CH11231 through the Regional and Global Model Analysis Program (RUBISCO SFA). N.J.B. was supported by the US DOE BER Early Career Research Program under Contract FP00005182. R.Z.A. and B.N.S. were supported by the US DOE BER at Oak Ridge National Laboratory under DOE Contract DE-AC05-00OR22725. A.A. acknowledges the research environment Biodiversity and Ecosystem Services in a Changing Climate (BECC) at Lund University and funding from the Swedish Research Council (2021-05344).

Keywords

37 Earth Sciences, 3709 Physical Geography and Environmental Geoscience, 13 Climate Action, 15 Life on Land

Journal Title

Nature Geoscience

Conference Name

Journal ISSN

1752-0894
1752-0908

Volume Title

17

Publisher

Springer Science and Business Media LLC
Sponsorship
DOE | LDRD | Lawrence Livermore National Laboratory (LLNL) (21-ERD-045)
DOE | Office of Science (SC) (DE-AC02-05CH11231, DE-AC02-05CH11231, SCW1632, FP00005182)
NSF | BIO | Division of Environmental Biology (DEB) (1926413)