Twenty-first century hydroclimate: A continually changing baseline, with more frequent extremes
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- Univ. of California, Santa Barbara, CA (United States)
- Univ. of Hawaii at Manoa, Honolulu, HI (United States)
- Univ. of Michigan, Ann Arbor, MI (United States)
- Cornell Univ., Ithaca, NY (United States); National Center for Atmospheric Research (NCAR), Boulder, CO (United States); Eidgenoessische Technische Hochschule (ETH), Zurich (Switzerland)
- Cornell Univ., Ithaca, NY (United States)
Variability in hydroclimate impacts natural and human systems worldwide. In particular, both decadal variability and extreme precipitation events have substantial effects and are anticipated to be strongly influenced by climate change. From a practical perspective, these impacts will be felt relative to the continuously evolving background climate. Removing the underlying forced trend is therefore necessary to assess the relative impacts, but to date, the small size of most climate model ensembles has made it difficult to do this. Here we use an archive of large ensembles run under a high-emissions scenario to determine how decadal “megadrought” and “megapluvial” events—and shorter-term precipitation extremes—will vary relative to that changing baseline. When the trend is retained, mean state changes dominate: In fact, soil moisture changes are so large in some regions that conditions that would be considered a megadrought or pluvial event today are projected to become average. Time-of-emergence calculations suggest that in some regions including Europe and western North America, this shift may have already taken place and could be imminent elsewhere: Emergence of drought/pluvial conditions occurs over 61% of the global land surface (excluding Antarctica) by 2080. Relative to the changing baseline, megadrought/megapluvial risk either will not change or is slightly reduced. However, the increased frequency and intensity of both extreme wet and dry precipitation events will likely present adaptation challenges beyond anything currently experienced. In many regions, resilience against future hazards will require adapting to an ever-changing “normal,” characterized by unprecedented aridification/wetting punctuated by more severe extremes.
- Research Organization:
- Georgia Institute of Technology, Atlanta, GA (United States); University Corporation for Atmospheric Research, Boulder, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF); National Aeronautics and Space Administration (NASA); Swiss National Science Foundation (SNSF)
- Grant/Contract Number:
- SC0019418; SC0022070; AGS 1243125; 80NSSC17K0565; 80NSSC22K0046; AGS-1419571; IA 1947282
- OSTI ID:
- 1904229
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Vol. 119, Issue 12; ISSN 0027-8424
- Publisher:
- National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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