The 8.2 ka event and early-mid holocene forests, fires and flooding in the central Ebro desert, NE Spain

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 front 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 Lis 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. (C) 2007 Elsevier Ltd. All rights reserved.