Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica

Earth and Planetary Science Letters, Vol. 260, No. 1-2, p. 340-354, 2007

H. Fischer, F. Fundel, U. Ruth, B. Twarloh and A. Wegner
Alfred-Wegener-Institute for Polar and Marine Research, Columbusstrasse, D-27568 Bremerhaven, Germany.
R. Udisti, S. Becagli, E. Castellano, A. Morganti and M. Severi
Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino (Florence), Italy.
E. Wolff, G. Littot, R. Röthlisberger and R. Mulvaney
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
M.A. Hutterli, P. Kaufmann, U. Federer and F. Lambert
Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstr.5, 3012 Bern, Switzerland.
M. Hansson and U. Jonsell
Department of Physical Geography and Quaternary Geology Stockholm University, 106 91 Stockholm, Sweden.
M. de Angelis and C. Boutron
Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE), CNRS-UJF, BP96 38402 Saint-Martin-d'Hères Cedex, France.
M. Bigler, M.-L. Siggaard-Andersen and J.P. Steffensen
Ice and Climate, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark
C. Barbante and V. Gaspari
Department of Environmental Sciences, University Ca' Foscari of Venice, Dorsoduro 2137, 30123 Venice, Italy.
P. Gabrielli
Institute for the Dynamics of Environmental Processes-CNR, Dorsoduro 2137, 30123 Venice, Italy.
D. Wagenbach
Institute for Environmental Physics, University of Heidelberg, INF229, 69120 Heidelberg, Germany.

Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European Project for Ice Coring in Antarctica) deep ice cores. The joint use of these records from opposite sides of the East Antarctic plateau allows for an estimate of changes in dust transport and emission intensity as well as for the identification of regional differences in the sea salt aerosol source. The mineral dust flux records at both sites show a strong coherency over the last 150 kyr related to dust emission changes in the glacial Patagonian dust source with three times higher dust fluxes in the Atlantic compared to the Indian Ocean sector of the Southern Ocean (SO). Using a simple conceptual transport model this indicates that transport can explain only 40% of the atmospheric dust concentration changes in Antarctica, while factor 5-10 changes occurred. Accordingly, the main cause for the strong glacial dust flux changes in Antarctica must lie in environmental changes in Patagonia. Dust emissions, hence environmental conditions in Patagonia, were very similar during the last two glacials and interglacials, respectively, despite 2-4 oC warmer temperatures recorded in Antarctica during the penultimate interglacial than today. 2-3 times higher sea salt fluxes found in both ice cores in the glacial compared to the Holocene are difficult to reconcile with a largely unchanged transport intensity and the distant open ocean source. The substantial glacial enhancements in sea salt aerosol fluxes can be readily explained assuming sea ice formation as the main sea salt aerosol source with a significantly larger expansion of (summer) sea ice in the Weddell Sea than in the Indian Ocean sector. During the penultimate interglacial, our sea salt records point to a 50% reduction of winter sea ice coverage compared to the Holocene both in the Indian and Atlantic Ocean sector of the SO. However, from 20 to 80 ka before present sea salt fluxes show only very subdued millennial changes despite pronounced temperature fluctuations, likely due to the large distance of the sea ice salt source to our drill sites.