1. Dynamical response of Mediterranean precipitation to greenhouse gases and aerosols
- Author
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Olivier Boucher, Dagmar Fläschner, Jean-Francois Lamarque, Timothy Andrews, Apostolos Voulgarakis, Thomas Richardson, Piers M. Forster, Tao Tang, Alf Kirkevåg, Toshihiko Takemura, Viatcheslav Kharin, Gregory Faluvegi, Bjørn Hallvard Samset, Øivind Hodnebrog, Jana Sillmann, Trond Iversen, Gunnar Myhre, Drew Shindell, Camilla Weum Stjern, Matthew Kasoar, Dirk Jan Leo Oliviè, National University of Defense Technology [China], Duke University [Durham], Center for International Climate and Environmental Research [Oslo] (CICERO), University of Oslo (UiO), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of Leeds, Norwegian Meteorological Institute, Department of Physics [Imperial College London], Imperial College London, Department of Psychology [York, UK], University of York [York, UK], Department of Geosciences, University of Arizona, Atmospheric Chemistry Observations and Modeling Laboratory (ACOML), National Center for Atmospheric Research [Boulder] (NCAR), Kyushu University [Fukuoka], École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Norwegian Meteorological Institute [Oslo] (MET), Department of Geosciences [Tucson], École normale supérieure - Paris (ENS-PSL), Department of Geosciences [University of Arizona], and Kyushu University
- Subjects
Earth's energy budget ,Mediterranean climate ,Atmospheric Science ,010504 meteorology & atmospheric sciences ,Forcing (mathematics) ,HYDROLOGICAL CYCLE ,010502 geochemistry & geophysics ,Atmospheric sciences ,01 natural sciences ,lcsh:Chemistry ,BLACK CARBON AEROSOLS ,chemistry.chemical_compound ,FUTURE ,Meteorology & Atmospheric Sciences ,CMIP5 ,Sulfate aerosol ,Precipitation ,Water cycle ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Science & Technology ,EARTH SYSTEM MODEL ,15. Life on land ,TRENDS ,lcsh:QC1-999 ,CLIMATE RESPONSE ,Aerosol ,VARIABILITY ,0201 Astronomical And Space Sciences ,lcsh:QD1-999 ,chemistry ,[SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology ,[SDU]Sciences of the Universe [physics] ,13. Climate action ,PROJECTIONS ,Greenhouse gas ,Physical Sciences ,SIMULATION ,[SDE]Environmental Sciences ,Environmental science ,0401 Atmospheric Sciences ,lcsh:Physics - Abstract
Atmospheric aerosols and greenhouse gases affect cloud properties, radiative balance and, thus, the hydrological cycle. Observations show that precipitation has decreased in the Mediterranean since the beginning of the 20th century, and many studies have investigated possible mechanisms. So far, however, the effects of aerosol forcing on Mediterranean precipitation remain largely unknown. Here we compare the modeled dynamical response of Mediterranean precipitation to individual forcing agents in a set of global climate models (GCMs). Our analyses show that both greenhouse gases and aerosols can cause drying in the Mediterranean and that precipitation is more sensitive to black carbon (BC) forcing than to well-mixed greenhouse gases (WMGHGs) or sulfate aerosol. In addition to local heating, BC appears to reduce precipitation by causing an enhanced positive sea level pressure (SLP) pattern similar to the North Atlantic Oscillation–Arctic Oscillation, characterized by higher SLP at midlatitudes and lower SLP at high latitudes. WMGHGs cause a similar SLP change, and both are associated with a northward diversion of the jet stream and storm tracks, reducing precipitation in the Mediterranean while increasing precipitation in northern Europe. Though the applied forcings were much larger, if forcings are scaled to those of the historical period of 1901–2010, roughly one-third (31±17 %) of the precipitation decrease would be attributable to global BC forcing with the remainder largely attributable to WMGHGs, whereas global scattering sulfate aerosols would have negligible impacts. Aerosol–cloud interactions appear to have minimal impacts on Mediterranean precipitation in these models, at least in part because many simulations did not fully include such processes; these merit further study. The findings from this study suggest that future BC and WMGHG emissions may significantly affect regional water resources, agricultural practices, ecosystems and the economy in the Mediterranean region.
- Published
- 2018
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