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Climate changes and human activities recorded in the sediments of Lake Estanya (NE Spain) during the Medieval Warm Period and Little Ice Age |
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| Authors: | Mario Morell??n Blas Valero-Garc??s Pen??lope Gonz??lez-Samp??riz Teresa Vegas-Vilarr??bia Esther Rubio Maria Rieradevall Antonio Delgado-Huertas Pilar Mata ??scar Romero Daniel R Engstrom Manuel L??pez-Vicente Ana Navas Jes??s Soto |
| Institution: | 1. Departamento de Procesos Geoambientales y Cambio Global, Instituto Pirenaico de Ecolog??a (IPE)??CSIC, Campus de Aula Dei. Avda Monta?ana 1005, 50059, Zaragoza, Spain 2. Departament d??Ecologia, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 645, Edf. Ram??n Margalef, 08028, Barcelona, Spain 3. Estaci??n Experimental del Zaid??n (EEZ)??CSIC, Prof. Albareda 1, 18008, Granada, Spain 4. Facultad de Ciencias del Mar y Ambientales, Universidad de C??diz, Pol??gono R??o San Pedro s/n, 11510, Puerto Real (C??diz), Spain 5. Facultad de Ciencias, Instituto Andaluz de Ciencias de la Tierra (IACT)??CSIC, Universidad de Granada, Campus Fuentenueva, 18002, Granada, Spain 6. St. Croix Watershed Research Station, Science Museum of Minnesota, Marine on St. Croix, MN, 55047, USA 7. Departamento de Suelo y Agua, Estaci??n Experimental de Aula Dei (EEAD)??CSIC, Campus de Aula Dei, Avda. Monta?ana 1005, 50059, Zaragoza, Spain 8. Departamento de Ciencias M??dicas y Quir??rgicas, Facultad de Medicina, Universidad de Cantabria Avda. Herrera Oria s/n, 39011, Santander, Spain |
| Abstract: | A multi-proxy study of short sediment cores recovered in small, karstic Lake Estanya (42°02?? N, 0°32?? E, 670 m.a.s.l.) in the Pre-Pyrenean Ranges (NE Spain) provides a detailed record of the complex environmental, hydrological and anthropogenic interactions occurring in the area since medieval times. The integration of sedimentary facies, elemental and isotopic geochemistry, and biological proxies (diatoms, chironomids and pollen), together with a robust chronological control, provided by AMS radiocarbon dating and 210Pb and 137Cs radiometric techniques, enabled precise reconstruction of the main phases of environmental change, associated with the Medieval Warm Period (MWP), the Little Ice Age (LIA) and the industrial era. Shallow lake levels and saline conditions with poor development of littoral environments prevailed during medieval times (1150?C1300 AD). Generally higher water levels and more dilute waters occurred during the LIA (1300?C1850 AD), although this period shows a complex internal paleohydrological structure and is contemporaneous with a gradual increase of farming activity. Maximum lake levels and flooding of the current littoral shelf occurred during the nineteenth century, coinciding with the maximum expansion of agriculture in the area and prior to the last cold phase of the LIA. Finally, declining lake levels during the twentieth century, coinciding with a decrease in human pressure, are associated with warmer climate conditions. A strong link with solar irradiance is suggested by the coherence between periods of more positive water balance and phases of reduced solar activity. Changes in winter precipitation and dominance of NAO negative phases would be responsible for wet LIA conditions in western Mediterranean regions. The main environmental stages recorded in Lake Estanya are consistent with Western Mediterranean continental records, and show similarities with both Central and NE Iberian reconstructions, reflecting a strong climatic control of the hydrological and anthropogenic changes during the last 800 years. |
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