17 January 2018

Precipitation Variability Increases in a Warmer Climate

Science

Understanding changes in precipitation variability is essential for a complete explanation of the hydrologic cycle’s response to warming and its impacts. While changes in mean and extreme precipitation have been studied intensively, precipitation variability has received less attention, despite its theoretical and practical importance. In this study, we examine single- and multi-model ensembles of climate simulations as well as station records of daily precipitation observations going back to 1950. We show that precipitation variability in most climate models increases over a majority of global land area in response to warming. Comparing simulations of recent decades to simulations forced with higher greenhouse gases, in the global, multi-model mean, precipitation variability increases 3–4% K−1 globally, and is remarkably robust on a range of timescales from daily to decadal. Precipitation variability increases by at least as much as mean precipitation and less than moisture and extreme precipitation for most models, regions, and timescales. We interpret this as being related to an increase in moisture which is partially mitigated by weakening circulation. We show that changes in observed daily variability in station data are consistent with increased variability. 

Impact

Understanding changes in precipitation variability is essential for a complete explanation of the hydrologic cycle’s response to warming and its impacts. While changes in mean and extreme precipitation have been studied intensively, precipitation variability has received less attention, despite its theoretical and practical importance. In this study, we examine single- and multi-model ensembles of climate simulations as well as station records of daily precipitation observations going back to 1950. We show that precipitation variability in most climate models increases over a majority of global land area in response to warming. Comparing simulations of recent decades to simulations forced with higher greenhouse gases, in the global, multi-model mean, precipitation variability increases 3–4% K−1 globally, and is remarkably robust on a range of timescales from daily to decadal. Precipitation variability increases by at least as much as mean precipitation and less than moisture and extreme precipitation for most models, regions, and timescales. We interpret this as being related to an increase in moisture which is partially mitigated by weakening circulation. We show that changes in observed daily variability in station data are consistent with increased variability.

Summary

Understanding changes in precipitation variability is essential for a complete explanation of the hydrologic cycle’s response to warming and its impacts. While changes in mean and extreme precipitation have been studied intensively, precipitation variability has received less attention, despite its theoretical and practical importance. In this study, we examine single- and multi-model ensembles of climate simulations as well as station records of daily precipitation observations going back to 1950. We show that precipitation variability in most climate models increases over a majority of global land area in response to warming. Comparing simulations of recent decades to simulations forced with higher greenhouse gases, in the global, multi-model mean, precipitation variability increases 3–4% K−1 globally, and is remarkably robust on a range of timescales from daily to decadal. Precipitation variability increases by at least as much as mean precipitation and less than moisture and extreme precipitation for most models, regions, and timescales. We interpret this as being related to an increase in moisture which is partially mitigated by weakening circulation. We show that changes in observed daily variability in station data are consistent with increased variability.

Contact
Angeline Pendergrass
National Center for Atmospheric Research (NCAR)
Publications
Pendergrass, A.  2017.  "Precipitation variability increases in a warmer climate."  Scientific Reports 7(1), doi:10.1038/s41598-017-17966-y.