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Effects of Topographic and Climatic Controls on 19th and 20th Century Glacier Changes in the Lyngen and Bergsfjord Areas, North Norway

1989; Springer Nature (Netherlands); Linguagem: Inglês

10.1007/978-94-015-7823-3_10

0924-5006

W. Brian Whalley, John E. Gordon, Anne F. Gellatly,

Climate change and permafrost

Evidence of glacier extent and retreat in two areas of mountain plateaus in north Norway (70°N) are described. Glaciers on the Bergsfjord Peninsula are on rock plateaus about 900 m a.s.l. with a maximum summit altitude of 1200 m and ice thickness believed to be at least 100 m over substantial areas. The outlet glaciers flow down to about 400 m a.s.l., are receding at present and have been since the turn of the century. The southern Lyngen Alps lie 100 km to the southwest of Bergsfjord. Three plateau areas with glaciers are ca. 1700 m, 1600 m and 1450 m a.s.l. respectively. Depths of ice vary across each plateau with greatest thickness reaching 70–150 m. Glaciers on the highest summits are roughly in equilibrium but below 1500 m are rapidly receding. Although less extensive in area than the Bergsfjord group, the two higher plateau ice caps in Lyngen nourish valley glaciers which descend to similar altitudes (i.e. ca. 400 m). In both regions, some high plateau summits do not support permanent ice, reflecting the control of a threshold topographic area necessary for glacier growth. There is a distinct relationship between altitude and thermal regime of the glaciers; of the main glaciers it appears that the two highest ice caps are certainly cold-based. Climatic data available for three stations in the study which suggest that there have been higher temperatures since about 1910 and increased precipitation from about 1930 than during the late 19th and early 20th centuries. Photographic and sketched records show positions of both plateau ice caps and valley glaciers which can be related to present day ice limits and the positions of Neoglacial moraines. Where surface lowering of Øksfjordjøkelen is shown at the northern edge of the plateau, bedrock topography may be influential in shifting the location of the ice-divides. Hence the complexity of valley terminal moraine sequences is a response to both topographic and climatic controls at higher altitudes.