Large underestimations of warming-induced soil carbon emissions from oversimplistic Q10 indicator
Moinet, Gabriel Y.K. | Morán-Rivera, Karen | Moinet, Antoine | Wadoux, Alexandre M.J.C.
The sensitivity of soil microbial respiration to climate warming is a major source of uncertainty in predicting soil carbon (C) emissions to the atmosphere and their feedback to climate change. One key issue is the persistent misuse of Q10, the factor by which respiration rate is multiplied for a 10 °C increase in temperature, as an indicator of the temperature sensitivity. Despite ample empirical and theoretical evidence that Q10 is temperature-dependent, most publications on the topic continue to measure and conceptualise Q10 as being independent of temperature. Here, we analyse a published dataset of temperature incubations of soil microbial respiration across a global latitudinal gradient and project the resulting sensitivities onto global maps under four climate change scenarios. We reveal that omitting to account for the temperature dependence of Q10 leads to an underestimation of global soil C emissions from 2015 to 2100 ranging from 5.5 ± 2.4 PgC to 10.4 ± 6.9 PgC across different climate change scenarios. Moreover, beyond uncertainties in predictions of global soil C emissions, modelling inaccuracies are geographically skewed, with large underestimations at high latitudes (of up to 34 MgC ha−1) and overestimations in warmer regions (of up to 12 MgC ha−1). The disparate regional patterns have large implications for land stewardship, as management efforts could overlook soil C losses in vulnerable septentrional areas while unnecessary interventions could be recommended in tropical regions where soil C sequestration may not be as pressing.
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