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Feedback between aeolian dust, climate, and atmospheric CO2 in glacial time
 

Summary: Feedback between aeolian dust, climate,
and atmospheric CO2 in glacial time
A. J. Ridgwell1
School of Environmental Sciences, University of East Anglia, Norwich, UK
Tyndall Centre for Climate Change Research, University of East Anglia, Norwich, UK
A. J. Watson
School of Environmental Sciences, University of East Anglia, Norwich, UK
Received 23 October 2001; revised 19 April 2002; accepted 17 June 2002; published 18 October 2002.
[1] Enhanced aeolian supply of iron to the biota of the Southern Ocean during glacial periods is suspected to be
an important contributory mechanism to the concurrently low observed mixing ratios of atmospheric CO2.
Declining rates of dust deposition prior to the glacial terminations may be critical in driving the initial deglacial
rise in CO2, but the reasons behind the dust decline itself are as yet unknown. Here we show that the dust record
from the Vostok ice core can be qualitatively derived from a few general assumptions regarding the formation
and aging of Patagonian sources of aeolian material and the efficiency with which it is transported through the
atmosphere. We suggest that during glacial periods this dust supply becomes particularly sensitive to changes in
global climate and that, in turn, climate is responsive to the dust due to iron fertilization. This positive feedback
may mean that during glacial periods the carbon cycle exhibits two quasi steady states, characterized by distinct
CO2 concentrations. Recognition of this ``glacial subcycle'' may help to account for the timing and sequence of
events at the terminations. INDEX TERMS: 1620 Global Change: Climate dynamics (3309); 3344 Meteorology and Atmospheric
Dynamics: Paleoclimatology; 4267 Oceanography: General: Paleoceanography; 4805 Oceanography: Biological and Chemical:

  

Source: Archer, David - Department of Geophysical Sciences, University of Chicago
Watson, Andrew - School of Environmental Sciences, University of East Anglia

 

Collections: Environmental Sciences and Ecology; Geosciences