Alpine ice core record of large changes in dust, sea-salt, and biogenic aerosol over Europe during deglaciation

Aerosol radiative forcing is an important but often poorly understood component of regional climate. While glacier ice contains the most detailed archives of past atmospheric aerosol composition and temperature, no well-preserved ice records extending into the last climatic transition have been reported for the historically important European region. Here, we use an Alpine ice core to document changes in European aerosols and climate from the end of the last glacial age (LGA) through the Holocene. The core was drilled on a glacier dome in the French Alps called the Dôme du Goûter (DDG), and it provides a stratigraphically intact record of aerosol and climate extending to at least 12 kyears (ky) before present. Although dating near the base of the glacier is not well constrained, the oldest DDG ice layers reflect glacial conditions in western Europe during the LGA. In addition to changes in atmospheric transport, increased sea-salt and dust deposition in western Europe recorded in the LGA ice suggest enhanced westerly winds and more active dust sources, possibly including North Africa. Deposition of terrestrial biogenic indicators during the cold LGA climate was lower, however, consistent with strongly reduced European vegetation. The DDG record of terrestrial biogenic emissions also suggests a decline of European forests throughout the Holocene, resulting from deterioration of climatic conditions and more recently from establishment of the first agricultural societies. The pronounced changes in atmospheric aerosol recorded in Alpine ice imply large variations in aerosol radiative forcing in western Europe during the last 12 ky.