Climatic conditions shift gradually over millennia, altering the rates at which carbon (C) is fixed from the atmosphere and stored in the soil. However, legacy impacts of past climates on current soil C stocks are poorly understood. We used data from more than 5000 terrestrial sites from three global and regional data sets to identify the relative importance of current and past (Last Glacial Maximum and mid-Holocene) climatic conditions in regulating soil C stocks in natural and agricultural areas. Paleoclimate always explained a greater amount of the variance in soil C stocks than current climate at regional and global scales. Our results indicate that climatic legacies help determine global soil C stocks in terrestrial ecosystems where agriculture is highly dependent on current climatic conditions. Our findings emphasize the importance of considering how climate legacies influence soil C content, allowing us to improve quantitative predictions of global C stocks under different climatic scenarios.
Bibliographical noteFunding Information:
We thank T. Hengl (ISRIC’s WoSIS, Wageningen, Netherlands) for his helpful comments on a previous version of this manuscript. We acknowledge the use of data from ISRIC’s WoSIS, which are made available subject to the ISRIC data policy (www.isric.org/data/wosis). We also thank all the members of the EPES-BIOCOM network for providing the Global-Drylands data. Funding: This study was supported by the European Research Council (ERC) under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant Agreement 242658 (BIOCOM), by the Australian Research Council (projects DP13010484, DP 15010419, and DP 170104634), and by the Grains Research and Development Corporation (UWS00008). F.T.M. acknowledges support from the ERC Grant Agreement 647038 (BIODESERT). D.J.E. was supported by a grant from the Hermon-Slade Foundation. M.D.-B. acknowledges support from the Marie Sklodowska-Curie Actions of the Horizon 2020 Framework Programme (H2020-MSCA-IF-2016) under a Research Executive Agency grant agreement (no. 702057).
© 2017 The Authors.