TY - JOUR
T1 - Twenty-First Century Drought Projections in the CMIP6 Forcing Scenarios
AU - Cook, B. I.
AU - Mankin, J. S.
AU - Marvel, K.
AU - Williams, A. P.
AU - Smerdon, J. E.
AU - Anchukaitis, K. J.
N1 - Funding Information:
All data from CMIP6 simulations used in our analyses are freely available from the Earth System Grid Federation (https://esgf-node.llnl.gov/search/cmip6/). B. I. Cook, K. Marvel, and A. P. Williams were all supported by the NOAA MAPP grant, “Integrating models, paleoclimate, and recent observations to develop process-level understanding of projected changes in U.S. drought.” This work benefited from participation by B. I. Cook, K. Marvel, and A. P. Williams in the NOAA CMIP6 Task Force. The authors thank Naomi Henderson and Haibo Liu at the Lamont-Doherty Earth Observatory for essential help organizing output from the CMIP6 models. HadCRUT data are freely available from this site (https://crudata.uea.ac.uk/cru/data/temperature/). The authors thank two anonymous reviewers for helpful comments that improved this manuscript. Lamont contribution #8405. J.E. Smerdon was supported in part by the National Science Foundation under grants AGS-1602581, OISE-1743738, and AGS-1805490
Funding Information:
All data from CMIP6 simulations used in our analyses are freely available from the Earth System Grid Federation ( https://esgf-node.llnl.gov/search/cmip6/ ). B. I. Cook, K. Marvel, and A. P. Williams were all supported by the NOAA MAPP grant, “Integrating models, paleoclimate, and recent observations to develop process‐level understanding of projected changes in U.S. drought.” This work benefited from participation by B. I. Cook, K. Marvel, and A. P. Williams in the NOAA CMIP6 Task Force. The authors thank Naomi Henderson and Haibo Liu at the Lamont‐Doherty Earth Observatory for essential help organizing output from the CMIP6 models. HadCRUT data are freely available from this site ( https://crudata.uea.ac.uk/cru/data/temperature/ ). The authors thank two anonymous reviewers for helpful comments that improved this manuscript. Lamont contribution #8405. J.E. Smerdon was supported in part by the National Science Foundation under grants AGS‐1602581, OISE‐1743738, and AGS‐1805490
Publisher Copyright:
©2020. The Authors.
PY - 2020/6/1
Y1 - 2020/6/1
N2 - There is strong evidence that climate change will increase drought risk and severity, but these conclusions depend on the regions, seasons, and drought metrics being considered. We analyze changes in drought across the hydrologic cycle (precipitation, soil moisture, and runoff) in projections from Phase Six of the Coupled Model Intercomparison Project (CMIP6). The multimodel ensemble shows robust drying in the mean state across many regions and metrics by the end of the 21st century, even following the more aggressive mitigation pathways (SSP1-2.6 and SSP2-4.5). Regional hotspots with strong drying include western North America, Central America, Europe and the Mediterranean, the Amazon, southern Africa, China, Southeast Asia, and Australia. Compared to SSP3-7.0 and SSP5-8.5, however, the severity of drying in the lower warming scenarios is substantially reduced and further precipitation declines in many regions are avoided. Along with drying in the mean state, the risk of the historically most extreme drought events also increases with warming, by 200–300% in some regions. Soil moisture and runoff drying in CMIP6 is more robust, spatially extensive, and severe than precipitation, indicating an important role for other temperature-sensitive drought processes, including evapotranspiration and snow. Given the similarity in drought responses between CMIP5 and CMIP6, we speculate that both generations of models are subject to similar uncertainties, including vegetation processes, model representations of precipitation, and the degree to which model responses to warming are consistent with observations. These topics should be further explored to evaluate whether CMIP6 models offer reasons to have increased confidence in drought projections.
AB - There is strong evidence that climate change will increase drought risk and severity, but these conclusions depend on the regions, seasons, and drought metrics being considered. We analyze changes in drought across the hydrologic cycle (precipitation, soil moisture, and runoff) in projections from Phase Six of the Coupled Model Intercomparison Project (CMIP6). The multimodel ensemble shows robust drying in the mean state across many regions and metrics by the end of the 21st century, even following the more aggressive mitigation pathways (SSP1-2.6 and SSP2-4.5). Regional hotspots with strong drying include western North America, Central America, Europe and the Mediterranean, the Amazon, southern Africa, China, Southeast Asia, and Australia. Compared to SSP3-7.0 and SSP5-8.5, however, the severity of drying in the lower warming scenarios is substantially reduced and further precipitation declines in many regions are avoided. Along with drying in the mean state, the risk of the historically most extreme drought events also increases with warming, by 200–300% in some regions. Soil moisture and runoff drying in CMIP6 is more robust, spatially extensive, and severe than precipitation, indicating an important role for other temperature-sensitive drought processes, including evapotranspiration and snow. Given the similarity in drought responses between CMIP5 and CMIP6, we speculate that both generations of models are subject to similar uncertainties, including vegetation processes, model representations of precipitation, and the degree to which model responses to warming are consistent with observations. These topics should be further explored to evaluate whether CMIP6 models offer reasons to have increased confidence in drought projections.
KW - CMIP6
KW - drought
UR - http://www.scopus.com/inward/record.url?scp=85086435715&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85086435715&partnerID=8YFLogxK
U2 - 10.1029/2019EF001461
DO - 10.1029/2019EF001461
M3 - Article
AN - SCOPUS:85086435715
VL - 8
JO - Earth's Future
JF - Earth's Future
SN - 2328-4277
IS - 6
M1 - e2019EF001461
ER -