Centennial mineral dust variability in high-resolution ice core data from Dome C, Antarctica

F Lambert,M Hutterli,M Bigler,J P Steffensen,H Fischer

doi:10.5194/cp-8-609-2012

Abstract

Abstract. Ice core data from Antarctica provide detailed insights into the characteristics of past climate, atmospheric circulation, as well as changes in the aerosol load of the atmosphere. We present high-resolution records of soluble calcium (Ca2+), non-sea-salt soluble calcium (nssCa2+), and particulate mineral dust aerosol from the East Antarctic Plateau at a depth resolution of 1 cm, spanning the past 800 000 years. Despite the fact that all three parameters are largely dust-derived, the ratio of nssCa2+ to particulate dust is dependent on the particulate dust concentration itself. We used principal component analysis to extract the joint climatic signal and produce a common high-resolution record of dust flux. This new record is used to identify Antarctic warming events during the past eight glacial periods. The phasing of dust flux and CO2 changes during glacial-interglacial transitions reveals that iron fertilization of the Southern Ocean during the past nine glacial terminations was not the dominant factor in the deglacial rise of CO2 concentrations. Rapid changes in dust flux during glacial terminations and Antarctic warming events point to a rapid response of the southern westerly wind belt in the region of southern South American dust sources on changing climate conditions. The clear lead of these dust changes on temperature rise suggests that an atmospheric reorganization occurred in the Southern Hemisphere before the Southern Ocean warmed significantly.

Highlights

Atmospheric aerosol production, mobilization, long-range aeolian transport, and deposition respond to past climatic changes (Fischer et al, 2007b; Legrand and Mayewski, 1997; Mahowald et al, 2006a)
In this study we present for the first time the complete datasets of Ca2+, nssCa2+, and insoluble dust records from the Dome C ice core at 1 cm resolution spanning the entire past 800 000 years, obtained in the frame of the European Project for Ice Coring in Antarctica (EPICA)
A clear change in dust composition has been derived from He isotope measurements on mineral dust aerosol from the EPICA Dronning Maud Land ice core between the last glacial period and the Holocene (Winckler and Fischer, 2006)

Summary

Introduction

Atmospheric aerosol production, mobilization, long-range aeolian transport, and deposition respond to past climatic changes (Fischer et al, 2007b; Legrand and Mayewski, 1997; Mahowald et al, 2006a). Dust and other aerosols affect radiative forcing, climate, through absorption and scattering of incoming shortwave radiation (Mahowald et al, 2006b; Miller and Tegen, 1998; Tegen et al, 1996) and play a role as condensation nuclei (Sassen et al, 2003; Schwartz, 1996). The total atmospheric dust load as well as physical (e.g. size, shape) and mineralogical characteristics are important factors for the radiative budget of the atmosphere (Tegen, 2003), and for the micronutrient supply to terrestrial and marine ecosystems (Martin et al, 1991). The hypothesis that a reduced supply of iron to the Southern Ocean could be responsible for a substantial part of the 80–100 ppmv CO2 increase from the Last Glacial Maximum (LGM) to the Holocene has been previously discussed (Martin et al, 1990; Watson et al, 2000). It is commonly believed that a combination of iron fertilization, carbonate compensation feedback, and Southern Ocean ventilation

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Conclusion