Strong El Niño events during the early Holocene: stable isotope evidence from Peruvian sea shells

International audience"Intrashell oxygen and carbon stable isotope profiles (δ18O,δ13C) were established for Mesodesma donacium shells from the preceramic archaeological site, Quebrada de los Burros in coastal southern Peru, to reconstruct the sea-surface temperature (SST) variations and to estimate changes of the El Niño-Southem Oscillation (ENSO) interannual variability from the early Holocene to the present. Very strong oxygen isotopic excursions attributed to El Niño events are evident in three shells dated between 9 and 7.9 ka. This indicates that short and strong warm events were breaking the mean cooler surface conditions (2-3°C cooler compared with today SSTs) in relation with an intense upwelling system. At 4.8 ka, slightly lower mean SST (cooler than today by 0.7°C) and a reduced seasonality confirms the previous hypothesis of a weak ENSO variability at this period." (source éditeur