High-resolution ensemble projections of near-term regional climate over the continental United States

Moetasim Ashfaq, Deeksha Rastogi, Rui Mei, Chieh Shih-Kao, Sudershan Gangrade, Bibi S. Naz, Danielle Touma

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

We present high-resolution near-term ensemble projections of hydroclimatic changes over the contiguous U.S. using a regional climate model (RegCM4) that dynamically downscales 11 global climate models from the fifth phase of Coupled Model Intercomparison Project at 18 km horizontal grid spacing. All model integrations span 41 years in the historical period (1965-2005) and 41 years in the near-term future period (2010-2050) under Representative Concentration Pathway 8.5 and cover a domain that includes the contiguous U.S. and parts of Canada and Mexico. Should emissions continue to rise, surface temperatures in every region within the U.S. will reach a new climate norm well before mid 21st century regardless of the magnitudes of regional warming. Significant warming will likely intensify the regional hydrological cycle through the acceleration of the historical trends in cold, warm, and wet extremes. The future temperature response will be partly regulated by changes in snow hydrology over the regions that historically receive a major portion of cold season precipitation in the form of snow. Our results indicate the existence of the Clausius-Clapeyron scaling at regional scales where per degree centigrade rise in surface temperature will lead to a 7.4% increase in precipitation from extremes. More importantly, both winter (snow) and summer (liquid) extremes are projected to increase across the U.S. These changes in precipitation characteristics will be driven by a shift toward shorter and wetter seasons. Overall, projected changes in the regional hydroclimate can have substantial impacts on the natural and human systems across the U.S.

Original languageEnglish
Pages (from-to)9943-9963
Number of pages21
JournalJournal of Geophysical Research: Biogeosciences
Volume121
Issue number17
DOIs
StatePublished - 2016

Funding

We thank three anonymous reviewers for their constructive and insightful comments. This study was funded by the Regional and Global Climate Modeling Program within the Office of Science and the Wind and Water Power Technologies Office within Office of Energy Efficiency and Renewable Energy of the U.S. Department of Energy (DOE), and also the Oak Ridge National Laboratory (ORNL) Laboratory Directed Research and Development Program. This paper was authored by employees of the ORNL, managed by UT Battelle, LLC, under contract DE-AC05- 00OR22725 with the U.S. DOE. Accordingly, the publisher, by accepting the article for publication, acknowledges that the United States government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States government purposes. Support for RegCM4 simulations, data storage, and analysis is provided by the Oak Ridge Leadership Computing Facility, and this data can be obtained by contacting M. Ashfaq ([email protected]) at ORNL Climate Change Science Institute. We also thank U.S. DOE's Program for Climate Model Diagnosis and Intercomparison for providing coordinating support and leading development of software infrastructure in partnership with the Global Organization for Earth System Science Portals for CMIP.

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