Fróðskaparrit - 01.01.1998, Blaðsíða 314

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CLIMATE INDUCES TWENTIETH-CENTURY GLACIER FLUCTUATIONS
IN SOUTHEASTICELAND
Figurel: Location map showing the study area and
neighbouring glaciers (modified from Thompson,
1988).
Mynd 1: Støðukort, sum vísir rannsóknarøkið og
grannajøklar (broytt úr Thompson, 1988).
to its position in the north-eastern Atlantic
Ocean. The warm North Atlantic surface
waters and Norwegian Sea deepwater cur-
rents strongly influence the location of both
the atmospheric and oceanic polar fronts.
Studies have shown (Boyle and Keigwin,
1987; Broecker et al., 1988; Veum et ai,
1992; Bjorck etal, 1997; Hald and Aspeli,
1997) that ocean currents around Iceland
and the Faeroe Islands may hold the key to
climatic change in this area since the Last
Glacial Maximum (LGM). Evidence is
mounting to suggest a causal link between
ocean circulation patterns and climatic
change.
It has been shown that temperate glaciers
and small ice-caps are sensitive indicators
of climatic change (Nye, 1965; Rosqvist
and Østrem, 1989; Grudd, 1990). Particular
ice-bodies can be seen to reflect the pattern
of climate change over relatively short
timescales (Suggate, 1950; Bjornsson,
1979; Gordon, 1981; Woo and Fitzharris,
1992; Bickerton and Matthews, 1993; Nes-
je et al, 1995).
Short-term fluctuations of glacier termi-
ni are essentially a climatically dependent
phenomenon (Hoinkes, 1968; Oerlemans,
1989; Nesje, 1989; Paterson, 1994). How-
ever, due to glacier dynamics, the response
of the glacier margin to any such climatic
change may be delayed or become diffuse
(Nye, 1960; Johannesson et al, 1989; Pa-
terson, 1994). It is proposed that rates of
snout movement during the last century or
so are seen largely as a direct response to
fluctuations in local air temperature rather
than the product of more complex mass-
balance adjustments. A comparison be-
tween the known record of mean air tem-
perature over the last ninety years in south-
east Iceland and the nearby glacier front
fluctuations, should allow the validity of
this relationship to be tested.
Aims
This study aims to test two main hypothe-
ses:
1. That glacier-front movements can be
viewed as a đirect response to local cli-
matic change, in particular variations in
mean air temperature.