Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening
During the first half of the Holocene (11 000 to 5000 years ago), the Northern Hemisphere experienced a strengthening of the monsoonal regime, with climate reconstructions robustly suggesting a greening of the Sahara region. Palaeoclimate archives also show that this so-called African humid period (...
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Uppsala universitet, Luft-, vatten- och landskapslära
2024
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ftuppsalauniv:oai:DiVA.org:uu-537001 2024-09-15T18:21:50+00:00 Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening Gaetani, Marco Messori, Gabriele Pausata, Francesco S. R. Tiwari, Shivangi Castro, M. Carmen Alvarez Zhang, Qiong 2024 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-537001 https://doi.org/10.5194/cp-20-1735-2024 eng eng Uppsala universitet, Luft-, vatten- och landskapslära Univ Sch Adv Studies IUSS, Dept Sci Technol & Soc, Pavia, Italy. Uppsala Univ, Swedish Ctr Impacts Climate Extremes climes, Uppsala, Sweden.;Stockholm Univ, Bolin Ctr Climate Res, Dept Meteorol, Stockholm, Sweden. Univ Quebec Montreal, ESCER Ctr Etud & simulat climat echelle regionale, Dept Earth & Atmospher Sci, Montreal, PQ, Canada.;Univ Quebec Montreal, GEOTOP Res Ctr Dynam Earth Syst, Dept Earth & Atmospher Sci, Montreal, PQ, Canada. Univ Pablo Olavide, Dept Phys Chem & Nat Syst, Seville, Spain. Stockholm Univ, Bolin Ctr Climate Res, Dept Phys Geog, Stockholm, Sweden. Climate of the Past, 1814-9324, 2024, 20:8, s. 1735-1759 orcid:0000-0002-2032-5211 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-537001 doi:10.5194/cp-20-1735-2024 ISI:001284889500001 info:eu-repo/semantics/openAccess Climate Research Klimatforskning Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning Article in journal info:eu-repo/semantics/article text 2024 ftuppsalauniv https://doi.org/10.5194/cp-20-1735-2024 2024-09-03T23:45:25Z During the first half of the Holocene (11 000 to 5000 years ago), the Northern Hemisphere experienced a strengthening of the monsoonal regime, with climate reconstructions robustly suggesting a greening of the Sahara region. Palaeoclimate archives also show that this so-called African humid period (AHP) was accompanied by changes in climate conditions at middle to high latitudes. However, inconsistencies still exist in reconstructions of the mid-Holocene (MH) climate at mid-latitudes, and model simulations provide limited support in reducing these discrepancies. In this paper, a set of simulations performed using a climate model are used to investigate the hitherto unexplored impact of Saharan greening on mid-latitude atmospheric circulation during the MH. Numerical simulations show Saharan greening has a year-round impact on the main circulation features in the Northern Hemisphere, especially during boreal summer (when the African monsoon develops). Key findings include a westward shift in the global Walker Circulation, leading to modifications in the North Atlantic jet stream in summer and the North Pacific jet stream in winter. Furthermore, Saharan greening modifies atmospheric synoptic circulation over the North Atlantic, enhancing the effect of orbital forcing on the transition of the North Atlantic Oscillation phase from predominantly positive to negative in winter and summer. Although the prescription of vegetation in the Sahara does not improve the proxy-model agreement, this study provides the first constraint on the influence of Saharan greening on northern mid-latitudes, opening new opportunities for understanding MH climate anomalies in regions such as North America and Eurasia. Article in Journal/Newspaper North Atlantic North Atlantic oscillation Uppsala University: Publications (DiVA) Climate of the Past 20 8 1735 1759 |
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Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Climate Research Klimatforskning Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning |
spellingShingle |
Climate Research Klimatforskning Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning Gaetani, Marco Messori, Gabriele Pausata, Francesco S. R. Tiwari, Shivangi Castro, M. Carmen Alvarez Zhang, Qiong Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening |
topic_facet |
Climate Research Klimatforskning Meteorology and Atmospheric Sciences Meteorologi och atmosfärforskning |
description |
During the first half of the Holocene (11 000 to 5000 years ago), the Northern Hemisphere experienced a strengthening of the monsoonal regime, with climate reconstructions robustly suggesting a greening of the Sahara region. Palaeoclimate archives also show that this so-called African humid period (AHP) was accompanied by changes in climate conditions at middle to high latitudes. However, inconsistencies still exist in reconstructions of the mid-Holocene (MH) climate at mid-latitudes, and model simulations provide limited support in reducing these discrepancies. In this paper, a set of simulations performed using a climate model are used to investigate the hitherto unexplored impact of Saharan greening on mid-latitude atmospheric circulation during the MH. Numerical simulations show Saharan greening has a year-round impact on the main circulation features in the Northern Hemisphere, especially during boreal summer (when the African monsoon develops). Key findings include a westward shift in the global Walker Circulation, leading to modifications in the North Atlantic jet stream in summer and the North Pacific jet stream in winter. Furthermore, Saharan greening modifies atmospheric synoptic circulation over the North Atlantic, enhancing the effect of orbital forcing on the transition of the North Atlantic Oscillation phase from predominantly positive to negative in winter and summer. Although the prescription of vegetation in the Sahara does not improve the proxy-model agreement, this study provides the first constraint on the influence of Saharan greening on northern mid-latitudes, opening new opportunities for understanding MH climate anomalies in regions such as North America and Eurasia. |
format |
Article in Journal/Newspaper |
author |
Gaetani, Marco Messori, Gabriele Pausata, Francesco S. R. Tiwari, Shivangi Castro, M. Carmen Alvarez Zhang, Qiong |
author_facet |
Gaetani, Marco Messori, Gabriele Pausata, Francesco S. R. Tiwari, Shivangi Castro, M. Carmen Alvarez Zhang, Qiong |
author_sort |
Gaetani, Marco |
title |
Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening |
title_short |
Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening |
title_full |
Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening |
title_fullStr |
Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening |
title_full_unstemmed |
Mid-Holocene climate at mid-latitudes : assessing the impact of Saharan greening |
title_sort |
mid-holocene climate at mid-latitudes : assessing the impact of saharan greening |
publisher |
Uppsala universitet, Luft-, vatten- och landskapslära |
publishDate |
2024 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-537001 https://doi.org/10.5194/cp-20-1735-2024 |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_relation |
Climate of the Past, 1814-9324, 2024, 20:8, s. 1735-1759 orcid:0000-0002-2032-5211 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-537001 doi:10.5194/cp-20-1735-2024 ISI:001284889500001 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/cp-20-1735-2024 |
container_title |
Climate of the Past |
container_volume |
20 |
container_issue |
8 |
container_start_page |
1735 |
op_container_end_page |
1759 |
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1810460823523426304 |