North Atlantic Oscillation recorded in carbonate δ18O signature from Lagunillo del Tejo (Spain)

Oxygen (δ18O) and carbon (δ13C) isotope compositions of authigenic carbonates measured in Lagunillo del Tejo sediment document precipitation variability during the last millennium in the Iberian Range. Modern water samples show that Lagunillo δ18O and δD plot below the Global Meteoric Water Line (GMWL). Sediment samples show a covariant trend between carbonate δ18O and δ13C, indicating that the precipitation/evaporation ratio has largely controlled the isotopic composition of this lake. This covariant trend is used to extract information about past lake level changes. Humid periods occurred around AD 1300-1450, AD 1620-1775 and AD 1950-1980, while the driest periods were concentrated around AD 1200, AD 1500 and especially around the transition between the 19th and 20th centuries. We compared these inferences with previous studies in this lake and with NAO index and discovered strong correspondence of signals. This sensitive site can be used to extent records of NAO back in time, providing a framework for climatic modeling and ecological management.