A spatial emergent constraint on the sensitivity of soil carbon turnover time to global warming
- 1University of Exeter, Mathematics, United Kingdom of Great Britain and Northern Ireland (r.varney@exeter.ac.uk)
- 2Met Office Hadley Centre, United Kingdom of Great Britain and Northern Ireland
- 3Earth and Environmental Sciences Division, Lawrence Berkeley National Laboratory, United States of America
- 4Department of Physical Geography & Bolin Centre of Climate Research, Stockholm University, Sweden
Carbon cycle feedbacks represent large uncertainties on climate change projections, and the response
of soil carbon to climate change contributes the greatest uncertainty to this. Future changes in soil
carbon depend on changes in litter and root inputs from plants, and especially on reductions in the
turnover time of soil carbon (τs) with warming. The latter represents the change in soil carbon
due to the response of soil turnover time (∆Cs,τ), and can be diagnosed from projections made with
Earth System Models (ESMs). It is found to span a large range even at the Paris Agreement Target
of 2◦C global warming. We use the spatial variability of τs inferred from observations to obtain a
constraint on ∆Cs,τ . This spatial emergent constraint allows us to greatly reduce the uncertainty in
∆Cs,τ at 2◦C global warming. We do likewise for other levels of global warming to derive a best
estimate for the effective sensitivity of τs to global warming, and derive a q10 equivalent value for
heterotrophic respiration.
How to cite: Varney, R., Cox, P., Chadburn, S., Friedlingstein, P., Burke, E., Koven, C., and Hugelius, G.: A spatial emergent constraint on the sensitivity of soil carbon turnover time to global warming, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9866, https://doi.org/10.5194/egusphere-egu2020-9866, 2020.
