Ice-marginal process and retreat dynamics of Norwegian plateau icefields
Student thesis: Doctoral Thesis
A significant portion of Norwegian glaciers are plateau icefields. These are highly sensitive to changes in climate because of their top-heavy hypsometry. A small rise in the equilibrium line altitude may cause the ablation area to expand significantly, leading to rapid icefield recession. This behaviour deserves particular research attention in light of the current warming of the Earth’s climate system. This doctoral thesis examines the response of the icefields Hardangerjøkulen in southern Norway, Svartisen just within the Arctic Circle, and Langfjordjøkelen in Arctic mainland Norway to climate warming since the Little Ice Age (LIA). These ice masses have been in retreat since they reached their maximum LIA positions between ~1750-1925. The glacial landform record of these icefields is used to reconstruct their maximum LIA extent. In addition, historical maps are used to reconstruct their ~1900 extent. These data sets are compared with data from available Norwegian glacier inventories of the present-day glacier extent, revealing substantial changes in icefield size. The greatest percentage decline occurred at Langfjordjøkelen in Arctic Norway, with an area reduction of 57 % between 1925 and 2018. Hardangerjøkulen in southern Norway lost 37 % of its original LIA area between 1750 and 2013, and the Vestre and Østre Svartisen icefields in northern Norway had lost 16 % and 23 % of their ~1900 areas by 2000, respectively. This research demonstrates how the LIA glacier extent can be employed as a valuable baseline to assess long-term glacier change.
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