Ice Core Archives of Mineral Dust - Mineral Dust: A Key Player in the Earth System - page 464

18.3.1.2 Southern Hemisphere Mountain Glaciers

Dust records are only available from a few mountain glaciers in the South American
Andes. The longest dust records have been produced from the Sajama ice core in
Bolivia (Thompson et al. 1998 ) and the Huascaran ice core in Peru (Thompson et al.
1995 ), covering the past 20-25 ka. Both records show synchronous temperature
changes, but opposing dust trends, to Greenland ice core records. The Andean dust
records show high concentrations during the Holocene and from 13 to 16 ka ago,
and eight-fold lower concentrations during the glacial. The dust record reflects local
hydrological conditions while the temperature record is a strong indication of fast-
reacting atmospheric teleconnections between high and low latitudes.

18.3.2 Northern Hemisphere Dust Records

18.3.2.1 Greenland

Hamilton and Langway ( 1967 ) were the first to demonstrate annual dust cycles in
polar ice using a central Greenland shallow ice core. Since then profiles of Green-
land ice core dust concentrations from over the last glacial cycle have been obtained
from all of the major Greenland ice coring sites (Fig. 18.1 ). Hammer et al. ( 1978 )
determined dust concentration profiles from sections of the 1,387 m long Camp Cen-
tury ice core from Northwestern Greenland that covers the entire last glacial period
(Dansgaard et al. 1969 ). A continuous dust concentration profile was obtained from
the 2,037 m long Dye-3 ice core from southern Greenland that continuously reaches
back some 40 ka (Hammer et al. 1985 ). In the early 1990s two deep ice cores were
retrieved from Summit, Greenland: the 3,053 m long American-led GISP2 ice core
(Grootes et al. 1993 ) and the 3,029 m long European-led GRIP ice core (Johnsen
et al. 1992 ). Both ice cores continuously cover the last 100 ka, although earlier
layering is folded and disturbed. Continuous dust records for the glacial section of
those ice cores are available (Ram and Koenig 1997 ; Svensson et al. 2000 ).
In Fig. 18.4 the high resolution dust concentration record from the 3,085 m long
Central Greenland NGRIP ice core (Ruth et al. 2003 ) is shown together with the
Greenland temperature proxy '• 18 O' from the same core (NGRIP members 2004 ).
During the present interglacial period, the Holocene covering the last 11.7 ka, and
the previous interglacial period, the Eemian about 130-115 ka, the average dust
content of the ice has been very low, around 45 mg of dust per kilo of ice (45 ng/g).
During the last glacial period the amount of dust that reached Greenland was much
greater than during the interglacials. Within the last glacial the dust concentration of
the ice is coupled to climate (Fig. 18.3 ) with the highest dust levels occurring during
the cold Marine Isotope Stages (MIS) 2 and 4 and lower levels during the milder
MIS3. On shorter time scales of centuries-to-millennium, the coupling to climate
is even stronger with high dust concentrations during the colder periods (so-called
stadials) and lower dust levels during the milder (so-called interstadial) periods. In