Quantifying climate and glacier mass balance in North Norway during the Younger Dryas

Brice Reid Rea, David J. A. Evans

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

Oksfjordjokelen is located at similar to 70 degrees N on the Troms-Finnmark border in North Norway. During the Younger Dryas, it was decoupled from and sat just beyond the margin of the Scandinavian Ice Sheet. At this time the major fjords in Troms and Finnmark were ice-free with outlet glaciers from the icefield filling a number of smaller side valleys. Only one outlet from the icefield, Sorfjorddalen, is temporally well-constrained by C-14 dating and association with the Main Shoreline (associated with a period of minimal crustal rebound dated to the Younger Dryas). Sorljorddalen is reconstructed using a valley centre-line iterative model and assuming a no-slip basal boundary condition. This assumption of cold-based ice is supported by the geomorphological evidence of angular bouldery fronto-lateral moraines formed during the Younger Dryas. The equilibrium line altitude for the Sorforddalen is calculated using both the Balance Ratio and Accumulation Area Ratio methods, and this is used to constrain the snout positions (generally to mapped moraines) of the other outlets. This approach assumes similarity of mass balance gradients and geometries of the outlet glaciers which is supported by present-day symmetry of the icefield. This method is extremely useful in such environments where dateable material is often difficult, if not impossible, to find. Some margins terminated in deep water where bathymetry was lacking, making calving quantification problematic with subsequent impacts on equilibrium line altitudes poorly constrained. These deep-water terminating snouts were discounted from subsequent palaeo-climate reconstructions. An empirical equilibrium line altitude temperature-precipitation relationship was used to define limits of climate change required to sustain the reconstructed icefield. Palaeo-precipitation estimates were refined using a palaeo-temperature estimate for the Younger Dryas from Andoya. Calculations of ice flux through the equilibrium line altitude were used to further constrain the mass balance characteristics of the reconstructed icefield and these suggest similarities with ice masses found in the northern (Nordaustlandet) regions of Svalbard.

Original languageEnglish
Pages (from-to)307-330
Number of pages24
JournalPalaeogeography Palaeoclimatology Palaeoecology
Volume246
Issue number2-4
Early online date5 Dec 2006
DOIs
Publication statusPublished - 6 Apr 2007

Keywords

  • Scandinavian Ice Sheet
  • equilibrium line altitude
  • ELA
  • balance ratio
  • accumulation area ratio
  • palaeoclimate
  • younger dryas
  • mass balance
  • plateau icefield
  • mass balance gradient
  • equilibrium-line altitudes
  • Southern-Norway
  • plateau icefields
  • late pleistocene
  • valley glaciers
  • Western Norway
  • New-Zealand
  • ice caps
  • holocene
  • geomorphology

Cite this

Quantifying climate and glacier mass balance in North Norway during the Younger Dryas. / Rea, Brice Reid; Evans, David J. A.

In: Palaeogeography Palaeoclimatology Palaeoecology, Vol. 246, No. 2-4, 06.04.2007, p. 307-330.

Research output: Contribution to journalArticle

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AU - Rea, Brice Reid

AU - Evans, David J. A.

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N2 - Oksfjordjokelen is located at similar to 70 degrees N on the Troms-Finnmark border in North Norway. During the Younger Dryas, it was decoupled from and sat just beyond the margin of the Scandinavian Ice Sheet. At this time the major fjords in Troms and Finnmark were ice-free with outlet glaciers from the icefield filling a number of smaller side valleys. Only one outlet from the icefield, Sorfjorddalen, is temporally well-constrained by C-14 dating and association with the Main Shoreline (associated with a period of minimal crustal rebound dated to the Younger Dryas). Sorljorddalen is reconstructed using a valley centre-line iterative model and assuming a no-slip basal boundary condition. This assumption of cold-based ice is supported by the geomorphological evidence of angular bouldery fronto-lateral moraines formed during the Younger Dryas. The equilibrium line altitude for the Sorforddalen is calculated using both the Balance Ratio and Accumulation Area Ratio methods, and this is used to constrain the snout positions (generally to mapped moraines) of the other outlets. This approach assumes similarity of mass balance gradients and geometries of the outlet glaciers which is supported by present-day symmetry of the icefield. This method is extremely useful in such environments where dateable material is often difficult, if not impossible, to find. Some margins terminated in deep water where bathymetry was lacking, making calving quantification problematic with subsequent impacts on equilibrium line altitudes poorly constrained. These deep-water terminating snouts were discounted from subsequent palaeo-climate reconstructions. An empirical equilibrium line altitude temperature-precipitation relationship was used to define limits of climate change required to sustain the reconstructed icefield. Palaeo-precipitation estimates were refined using a palaeo-temperature estimate for the Younger Dryas from Andoya. Calculations of ice flux through the equilibrium line altitude were used to further constrain the mass balance characteristics of the reconstructed icefield and these suggest similarities with ice masses found in the northern (Nordaustlandet) regions of Svalbard.

AB - Oksfjordjokelen is located at similar to 70 degrees N on the Troms-Finnmark border in North Norway. During the Younger Dryas, it was decoupled from and sat just beyond the margin of the Scandinavian Ice Sheet. At this time the major fjords in Troms and Finnmark were ice-free with outlet glaciers from the icefield filling a number of smaller side valleys. Only one outlet from the icefield, Sorfjorddalen, is temporally well-constrained by C-14 dating and association with the Main Shoreline (associated with a period of minimal crustal rebound dated to the Younger Dryas). Sorljorddalen is reconstructed using a valley centre-line iterative model and assuming a no-slip basal boundary condition. This assumption of cold-based ice is supported by the geomorphological evidence of angular bouldery fronto-lateral moraines formed during the Younger Dryas. The equilibrium line altitude for the Sorforddalen is calculated using both the Balance Ratio and Accumulation Area Ratio methods, and this is used to constrain the snout positions (generally to mapped moraines) of the other outlets. This approach assumes similarity of mass balance gradients and geometries of the outlet glaciers which is supported by present-day symmetry of the icefield. This method is extremely useful in such environments where dateable material is often difficult, if not impossible, to find. Some margins terminated in deep water where bathymetry was lacking, making calving quantification problematic with subsequent impacts on equilibrium line altitudes poorly constrained. These deep-water terminating snouts were discounted from subsequent palaeo-climate reconstructions. An empirical equilibrium line altitude temperature-precipitation relationship was used to define limits of climate change required to sustain the reconstructed icefield. Palaeo-precipitation estimates were refined using a palaeo-temperature estimate for the Younger Dryas from Andoya. Calculations of ice flux through the equilibrium line altitude were used to further constrain the mass balance characteristics of the reconstructed icefield and these suggest similarities with ice masses found in the northern (Nordaustlandet) regions of Svalbard.

KW - Scandinavian Ice Sheet

KW - equilibrium line altitude

KW - ELA

KW - balance ratio

KW - accumulation area ratio

KW - palaeoclimate

KW - younger dryas

KW - mass balance

KW - plateau icefield

KW - mass balance gradient

KW - equilibrium-line altitudes

KW - Southern-Norway

KW - plateau icefields

KW - late pleistocene

KW - valley glaciers

KW - Western Norway

KW - New-Zealand

KW - ice caps

KW - holocene

KW - geomorphology

U2 - 10.1016/J.PALAEO.2006.10.010

DO - 10.1016/J.PALAEO.2006.10.010

M3 - Article

VL - 246

SP - 307

EP - 330

JO - Palaeogeography Palaeoclimatology Palaeoecology

JF - Palaeogeography Palaeoclimatology Palaeoecology

SN - 0031-0182

IS - 2-4

ER -