Climate and Human impact synergies in Mediterranean Mountains: The Late Holocene records of the Iberian Range karstic lakes (NE Spain)

Abstract

Available paleohydrological reconstructions in the Iberian Peninsula from the Pyrenees (Arreo, Montcortés, Estanya Lakes), the Iberian Range (La Cruz Lake) and Andalucía (Zoñar Lake) have identified several climatic fluctuations during the last millennia, particularly, the arid 4 ka BP crisis, the Iberian-Roman Humid Period (IRHP), the Medieval Climatic Anomaly (MCA) and the Little Ice Age (LIA). Although the timing of these climate fluctuations is similar, the data show regional differences and suggest a NS moisture variability.We have chosen two karstic lakes located to test the regional extent of climate variability and to evaluate the human and climate interplay in the Iberian Range (central-eastern Spain): La Parra, a holomictic, freshwater lake with a small watershed (1 ha) and El Tobar, a meromictic, saline lake with a larger (20 ha) watershed.Sedimentological and geochemical (XRF-scanner) high resolution data of long sediment cores (two of 6.93 m and 5,24 m long respectively from La Parra and 4 cores about 18 m from El Tobar) were used to reconstruct the depositional environments, particularly, clastic input, endogenic carbonate deposition, redox evolution and organic productivity. The preliminary chronological model is based on 14C AMS dates of terrestrial macrorests and 210Pb/137Cs dating. The hydrological and geochemical evolution demonstrates a rapid response of the lacustrine systems to anthropogenic and climate forcing during the last 4000 years while highlights differences due to the limnological properties of each lake (holomictic and freshwater versus meromictic and hypersaline) and the importance of the historical uses of the watershed during the MCA and the LIA. The results allow to evaluate the interplays and feedbacks of climate variability in the context of variable human landscapes and activities and enhance our ability to predict the environmental consequences of climate change in Mediterranean mountain areas.