1University of Aberdeen, Institute of Biological and Environmental Sciences, School of Biological Sciences, 23 St Machar Drive, Aberdeen, AB24 3UU, UK
2Potsdam Institute for Climate Impact Research, Telegrafenberg, 14473 Potsdam, Germany
3German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
4Netherlands Environmental Assessment Agency, Antonie van Leeuwenhoeklaan 9, 3721 MA Bilthoven, The Netherlands
5Walker Institute for Climate System Research, University of Reading, Earley Gate, Reading, UK
6Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich, RG6 6AR, UK
7Hadley Centre, Met Office, Exeter, EX1 3PB, NR4 7TJ, UK
Received: 15 Nov 2011 – Discussion started: 13 Jan 2012
Abstract. We use a soil carbon (C) model (RothC), driven by a range of climate models for a range of climate scenarios to examine the impacts of future climate on global soil organic carbon (SOC) stocks. The results suggest an overall global increase in SOC stocks by 2100 under all scenarios, but with a different extent of increase among the climate model and emissions scenarios. The impacts of projected land use changes are also simulated, but have relatively minor impacts at the global scale. Whether soils gain or lose SOC depends upon the balance between C inputs and decomposition. Changes in net primary production (NPP) change C inputs to the soil, whilst decomposition usually increases under warmer temperatures, but can also be slowed by decreased soil moisture. Underlying the global trend of increasing SOC under future climate is a complex pattern of regional SOC change. SOC losses are projected to occur in northern latitudes where higher SOC decomposition rates due to higher temperatures are not balanced by increased NPP, whereas in tropical regions, NPP increases override losses due to higher SOC decomposition. The spatial heterogeneity in the response of SOC to changing climate shows how delicately balanced the competing gain and loss processes are, with subtle changes in temperature, moisture, soil type and land use, interacting to determine whether SOC increases or decreases in the future. Our results suggest that we should stop looking for a single answer regarding whether SOC stocks will increase or decrease under future climate, since there is no single answer. Instead, we should focus on improving our prediction of the factors that determine the size and direction of change, and the land management practices that can be implemented to protect and enhance SOC stocks.
Revised: 23 Jun 2012 – Accepted: 25 Jun 2012 – Published: 14 Aug 2012
Gottschalk, P., Smith, J. U., Wattenbach, M., Bellarby, J., Stehfest, E., Arnell, N., Osborn, T. J., Jones, C., and Smith, P.: How will organic carbon stocks in mineral soils evolve under future climate? Global projections using RothC for a range of climate change scenarios, Biogeosciences, 9, 3151-3171, doi:10.5194/bg-9-3151-2012, 2012.