Recent and near-term future changes in impacts-relevant seasonal hydroclimate in the world's Mediterranean climate regions

Seager, Richard, Wu, Yutian, Cherchi, Annalisa, Simpson, Isla R., Osborn, Timothy J. ORCID: https://orcid.org/0000-0001-8425-6799, Kushnir, Yochanan, Lukovic, Jelena, Liu, Haibo and Nakamura, Jennifer (2024) Recent and near-term future changes in impacts-relevant seasonal hydroclimate in the world's Mediterranean climate regions. International Journal of Climatology, 44 (11). pp. 3792-3820. ISSN 0899-8418

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Abstract

Change over recent decades in the world's five Mediterranean Climate Regions (MCRs) of quantities of relevance to water resources, ecosystems and fire are examined for all seasons and placed in the context of changes in large-scale circulation. Near-term future projections are also presented. It is concluded that, based upon agreement between observational data sets and modelling frameworks, there is strong evidence of radiatively-driven drying of the Chilean MCR in all seasons and southwest Australia in winter. Observed drying trends in California in fall, southwest southern Africa in fall, the Pacific Northwest in summer and the Mediterranean in summer agree with radiatively-forced models but are not reproduced in a model that also includes historical sea surface temperature (SST) forcing, raising doubt about the human-origin of these trends. Observed drying in the Mediterranean in winter is stronger than can be accounted for by radiative forcing alone and is also outside the range of the SST-forced ensemble. It is shown that near surface vapour pressure deficit (VPD) is increasing almost everywhere but that, surprisingly, this is contributed to in the Southern Hemisphere subtropics to mid-latitudes by a decline in low-level specific humidity. The Southern Hemisphere drying, in terms of precipitation and specific humidity, is related to a poleward shift and strengthening of the westerlies with eddy-driven subsidence on the equatorward side. Model projections indicate continued drying of Southern Hemisphere MCRs in winter and spring, despite ozone recovery and year-round drying in the Mediterranean. Projections for the North American MCR are uncertain, with a large contribution from internal variability, with the exception of drying in the Pacific Northwest in summer. Overall the results indicate continued aridification of MCRs other than in North America with important implications for water resources, agriculture and ecosystems.

Item Type:	Article
Additional Information:	Data availability statement: The data that support the findings of this study are available from the corresponding author upon reasonable request. Funding information: RS, YW and YK were supported by NSF award AGS-2127684. IRS acknowledges support from the NSF National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation under the Cooperative Agreement 1852977. AC acknowledges support from the OptimESM project, European Union's Horizon Europe Research and Innovation Programme under GA number 101081193.
Uncontrolled Keywords:	sdg 13 - climate action ,/dk/atira/pure/sustainabledevelopmentgoals/climate_action
Faculty \ School:	Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups:	Faculty of Social Sciences > Research Centres > Water Security Research Centre Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences Faculty of Science > Research Groups > Climatic Research Unit
Depositing User:	LivePure Connector
Date Deposited:	08 Jul 2024 11:33
Last Modified:	25 Sep 2024 17:55
URI:	https://ueaeprints.uea.ac.uk/id/eprint/95820
DOI:	10.1002/joc.8551

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