Saharan aeolian input and effective humidity variations over western Europe during the Holocene from a high altitude record

Abstract

Saharan dust inputs affect present day ecosystems and biogeochemical cycles at a global scale. Previous Saharan dust input reconstructions have been mainly based on marine records from the African margin, nevertheless dust reaching western-central Europe is mainly transported by high-altitude atmospheric currents and requires high altitude records for its reconstruction. The organic and inorganic geochemical study of sediments from a southern Iberia alpine lacustrine record has provided an exceptional reconstruction of Saharan dust impact and regional climatic variations during the Holocene. After the last deglaciation, results indicate that Saharan dust reached Western Europe in a stepwise fashion from 7.0 to 6.0cal.kyrBP and increased since then until present, promoting major geochemical changes in the lacustrine system. Effective humidity reconstruction indicates wetter conditions during the early Holocene and progressive aridification during middle–late Holocene time, boosting abrupt changes in the lacustrine system. Cyclostratigraphic analyses and transport mechanisms both point to solar irradiance and aridity as major triggering factors for dust supply over Western Europe during the Holocene.