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https://doi.org/10.5194/egusphere-2023-383
https://doi.org/10.5194/egusphere-2023-383
24 Mar 2023
 | 24 Mar 2023

Simulated responses of soil carbon to climate change in CMIP6 Earth System Models: the role of false priming

Rebecca M. Varney, Sarah E. Chadburn, Eleanor J. Burke, Andy J. Wiltshire, and Peter M. Cox

Abstract. Reliable estimates of soil carbon change are required to determine the carbon budgets consistent with the Paris climate targets. This study evaluates projections of soil carbon during the 21st century in CMIP6 Earth System Models (ESMs) under a range of atmospheric composition scenarios. In general, we find a reduced spread of changes in global soil carbon (ΔCs) in CMIP6 compared to the previous CMIP5 model generation. However, similar reductions were not seen in the derived contributions to ΔCs due to both increases in plant Net Primary Productivity (NPP, named ΔCs,NPP) and reductions in the effective soil carbon turnover time (τs, named ΔCs,τ). Instead, we find a strong relationship across the CMIP6 models between these NPP and τs components of ΔCs, with more positive values of ΔCs,NPP being correlated with more negative values of ΔCs,τ. We show that this emergent relationship is the result of 'false priming', which leads to a decrease in the effective soil carbon turnover time as a direct result of NPP increase and occurs when the rate of increase of NPP is relatively fast compared to the slower timescales of a multipool soil carbon model. The inclusion of more soil carbon models with multiple pools in CMIP6 compared to CMIP5, therefore seems to have contributed towards the reduction in the overall model spread in future soil carbon projections.

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Journal article(s) based on this preprint

19 Sep 2023
Simulated responses of soil carbon to climate change in CMIP6 Earth system models: the role of false priming
Rebecca M. Varney, Sarah E. Chadburn, Eleanor J. Burke, Simon Jones, Andy J. Wiltshire, and Peter M. Cox
Biogeosciences, 20, 3767–3790, https://doi.org/10.5194/bg-20-3767-2023,https://doi.org/10.5194/bg-20-3767-2023, 2023
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

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This study evaluates soil carbon projections during the 21st century in CMIP6 Earth System...
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