Jökull - 01.06.2000, Page 16

Mackintosh, Dugmore and Jacobsen
Elevation (m)
Distance (km)
Figure 4. Our surveyed ice elevation (1996/1997) versus DMA map 1812 (pre-1980?). Note the difference
between the profiles, especially near the snout, where the glacier advanced by 482 m between 1970 and 1995.
- Samanburður á yfirborði Sólheimajökuls samkvœmt mœlingum með GPS-tœki 1996-1997 og korti Landmœl-
inga íslands (DMA 1812) sem sennilega er byggt á flugmyndum sem teknar voru fyrir 1980. Jökullinn hefur
þykknað og gengið fram 482 metra á árunum 1970-1995.
Sólheimajökull flows regularly. We found no evidence
in support of Sólheimajökull exhibiting surge-type
behaviour, although a velocity monitoring programme
is needed to be certain.
Finally, the relatively simple geometry of the sub-
glacial topography and surface profile are character-
istics of a glacier that is sensitive to climatic change.
Specifically, this includes a wide flat accumulation
area, long narrow confined snout, a lack of sub-glacial
undulations and a gently inclined bed (Oerlemans,
1989). These characteristics mean that changes in
equilibrium-line altitude will be effective over a large
area of the glacier, and topographic barriers will not
inhibit the dynamic response. In addition, Sólheima-
jökull has a high mass balance gradient (Björnsson,
1979) that results in the glacier snout reaching to low
altitude where ablation rates are high. The net result
is that Sólheimajökull is active and is likely to have
a short response time (Jóhannesson et al., 1989), and
experience large changes in extent for small changes
in mass balance. The present glacial advance is likely
to represent a simple response to changing mass bal-
ance conditions over the last few decades, in line
with other maritime glaciers in the North Atlantic
(Dowdeswell et al., 1997). Similarly, other Holocene
fluctuations might reflect a simple climate response.
14 JÖKULLNo. 48