Climate projections1,2,3 and observations over recent decades4,5 indicate that precipitation in subtropical latitudes declines in response to anthropogenic warming, with significant implications for food production and population sustainability. However, this conclusion is derived from emissions scenarios with rapidly increasing radiative forcing to the year 21001,2, which may represent very different conditions from both past and future ‘equilibrium’ warmer climates. Here, we examine multi-century future climate simulations and show that in the Southern Hemisphere subtropical drying ceases soon after global temperature stabilizes. Our results suggest that twenty-first century Southern Hemisphere subtropical drying is not a feature of warm climates per se, but is primarily a response to rapidly rising forcing and global temperatures, as tropical sea-surface temperatures rise more than southern subtropical sea-surface temperatures under transient warming. Subtropical drying may therefore be a temporary response to rapid warming: as greenhouse gas concentrations and global temperatures stabilize, Southern Hemisphere subtropical regions may experience positive precipitation trends.
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The authors declare that the data supporting the findings of this study are available within the article and its Supplementary Information files. The CMIP5 model data used in this study are available in public repositories (for example, at https://esgf-node.llnl.gov/projects/esgf-llnl/). The model data used here were stored on the Australian node of the Earth System Grid (the National Computational Infrastructure). Data associated with the CanESM1 simulation used in this study are available at http://crd-data-donnees-rdc.ec.gc.ca/CCCMA/CanESM1_zero_emission.
Journal peer review information: Nature Climate Change thanks Jie He, Hanh Nguyen, Caroline Ummenhofer and other anonymous reviewer(s) for their contribution to the peer review of this work.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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We thank P. Hope, L. Ashcroft, B. Timbal and R. Colman for comments on versions of the manuscript, and P. Whetton for discussions about this study. This research programme was supported by Australian Research Council grants DP0985214 and FL160100028 (to J.D.W.), DP130101829 (to J.D.W. and R.N.D.), DE120102530 (to J.M.K.S.), FT130100801 (to J.H.) and DE180100638 (to A.D.K.). We acknowledge the World Climate Research Programme’s Working Group on Coupled Modelling, which is responsible for CMIP5, and we thank the climate modelling groups (listed in Supplementary Table 1) for producing and making available their model output. For CMIP5, the US Department of Energy’s Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led the development of software infrastructure in partnership with the Global Organization for Earth System Science Portals.
Supplementary Figures 1–16, Supplementary Table 1