The 8.2 ka event and Early–Mid Holocene forests,fires and flooding in the Central Ebro Desert,NE Spain |
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| Institution: | 1. Departament de Prehistòria, Universitat Autònoma de Barcelona, Edifici B Facultat de Filosofia i Lletres, 08193, Bellaterra, Barcelona, Spain;2. Laboratorio de Evolución Humana, Departamento Ciencias Históricas y Geografía, Universidad de Burgos, Plaza Misael Bañuelos, Edificio I+D+i, 09001 Burgos, Spain;3. Institut Català de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain;4. Institut Català de Paleoecologia Humana i Evolució Social (IPHES), Zona Educacional 4 - Campus Sescelades URV (Edifici W3), 43007 Tarragona, Spain;5. Universitat Rovira i Virgili, Carrer de l''Escorxador, s/n, 43003 Tarragona, Spain;6. Department of Paleoecology and Landscape Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands;7. GI Arqueobiología, Instituto de Historia, Centro de Ciencias Humanas y Sociales - Consejo Superior de Investigaciones Científicas (CCHS-CSIC), C/Albasanz 26–28, 28037 Madrid, Spain;8. Escuela Española de Historia y Arqueología en Roma, Consejo Superior de Investigaciones Científicas (CSIC), Via Sant''Eufemia 13, 00187 Rome, Italy;9. Archaeology of Social Dynamics, Institución Milà y Fontanals, Consejo Superior de Investigaciones Científicas (IMF-CSIC), C/Egipcíaques, 15, 08001 Barcelona, Spain |
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| Abstract: | The impact of the 8.2 ka cooling event during the Early–Mid Holocene has not been widely observed in Southern Europe, which in contrast to Northern Europe, was already experiencing a cooler than present climate at this time. Multi-proxy analysis of sediment cores from two closed-basin saline lakes in the Central Ebro Desert (NE Spain) has allowed us to investigate the impact of climatic changes around the time of this event in more detail. Long-term changes in climate between the Early and Mid Holocene indicate a shift in winter to a more positive NAO, resulting in declining lake levels in one lake sensitive to winter groundwater recharge, and cooler winter temperatures reconstructed from pollen–climate analysis. Reconstructed summer temperatures also declined over this period while annual precipitation and forest cover increased, interpreted as a result of enhanced convection-driven summer precipitation association with a northward displacement of the sub-tropical high pressure. Around 8.2 ka, a marked increase in fire frequency is shown between ca 8.8 and 8.0 ka BP, along with an expansion of fire-tolerant evergreen oak and peak in water levels in a second storm run-off fed lake. A maximum in fire intensity occurred with the deposition of a charcoal layer at both lake sites dated to 8150±130 and 8285±135 cal BP, respectively. The increase in fire is largely attributed to a temporary return southward of the summer sub-tropical high pressure over the Mediterranean, which not only increased summer aridity, but also caused a contradictory regional warming before Hemispheric cooling set in. |
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