Report

Increased Dust Deposition in the Pacific Southern Ocean During Glacial Periods

Science  24 Jan 2014:
Vol. 343, Issue 6169, pp. 403-407
DOI: 10.1126/science.1245424

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Abstract

Dust deposition in the Southern Ocean constitutes a critical modulator of past global climate variability, but how it has varied temporally and geographically is underdetermined. Here, we present data sets of glacial-interglacial dust-supply cycles from the largest Southern Ocean sector, the polar South Pacific, indicating three times higher dust deposition during glacial periods than during interglacials for the past million years. Although the most likely dust source for the South Pacific is Australia and New Zealand, the glacial-interglacial pattern and timing of lithogenic sediment deposition is similar to dust records from Antarctica and the South Atlantic dominated by Patagonian sources. These similarities imply large-scale common climate forcings, such as latitudinal shifts of the southern westerlies and regionally enhanced glaciogenic dust mobilization in New Zealand and Patagonia.

Dust in the Sea

The effect of windblown dust on marine productivity in the Southern Ocean is thought to be a key determinant of atmospheric CO2 concentrations. Lamy et al. (p. 403) present a record of dust supply to the Pacific sector of the Southern Ocean for the past one million years, derived from a suite of deep-sea sediment cores. Dust deposition during glacial periods was 3 times greater than during interglacials, and its major source region was probably Australia or New Zealand.

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