The Greenland ice sheet during LGM – a model based on field observations

TY - ABST

T1 - The Greenland ice sheet during LGM – a model based on field observations

AU - Funder, Svend Visby

AU - Kjeldsen, Kristian Kjellerup

AU - Kjær, Kurt H.

AU - O'Cofaigh, Colm

PY - 2011

Y1 - 2011

N2 - In the light of recent years¿ intense discussion on the role of Greenland Ice Sheet in global warming its reaction to past climatic change can contribute valuable information. We have updated the evidence for LGM (c. 23-20 kaBP) icesheet coverage. previous reviews An important part of the main The issue is complicated by the circumstance that during LGM (Last glacial maximum) the ice sheet margins around the whole perimeter stood on the shelf and “classical” evidence, such as large moraine belts, extensive sandurs and major drainage diversions do not apply. The first estimates were therefore based on observations on land, such as weathering limits on coastal mountains, major moraine belts, and altitudes of marine limits. Extrapolation from this gave estimates of LGM ice cover on the shelf ranging from inner to outer shelf, often under the assumption that it had to be either or, and not in between. Also, it was often assumed that if it could be demonstrated that the margin reached the shelf edge in one area, this should apply to the whole perimeter. Modelling, mainly on the basis of palaeoclimatic data, have presented a similar disparity between maximum and minimum estimates, assessing the Greenland ice sheet¿s contribution to Holocene sea level rise to between 0.3 and 2.6 m. Recent years have given spectacular new insight into shelf-ice distribution and behaviour - especially by detailed seismic surveys on the shelf and cosmogenic isotope surface exposure dating on coastal mountains. We combine this new evidence with the older observations. This model is conservative because it is, as far as possible, based on tangible evidence minimising the amount of speculation. The LGM ice sheet in this model covered c. 2.7 mio km2, 65% more than the present. Two thirds of this excess relative to the present was on the shelf beyond the coast, and only one third on land and in fjord basins. The evidence also indicates that the glacial regimes varied between regions.

AB - In the light of recent years¿ intense discussion on the role of Greenland Ice Sheet in global warming its reaction to past climatic change can contribute valuable information. We have updated the evidence for LGM (c. 23-20 kaBP) icesheet coverage. previous reviews An important part of the main The issue is complicated by the circumstance that during LGM (Last glacial maximum) the ice sheet margins around the whole perimeter stood on the shelf and “classical” evidence, such as large moraine belts, extensive sandurs and major drainage diversions do not apply. The first estimates were therefore based on observations on land, such as weathering limits on coastal mountains, major moraine belts, and altitudes of marine limits. Extrapolation from this gave estimates of LGM ice cover on the shelf ranging from inner to outer shelf, often under the assumption that it had to be either or, and not in between. Also, it was often assumed that if it could be demonstrated that the margin reached the shelf edge in one area, this should apply to the whole perimeter. Modelling, mainly on the basis of palaeoclimatic data, have presented a similar disparity between maximum and minimum estimates, assessing the Greenland ice sheet¿s contribution to Holocene sea level rise to between 0.3 and 2.6 m. Recent years have given spectacular new insight into shelf-ice distribution and behaviour - especially by detailed seismic surveys on the shelf and cosmogenic isotope surface exposure dating on coastal mountains. We combine this new evidence with the older observations. This model is conservative because it is, as far as possible, based on tangible evidence minimising the amount of speculation. The LGM ice sheet in this model covered c. 2.7 mio km2, 65% more than the present. Two thirds of this excess relative to the present was on the shelf beyond the coast, and only one third on land and in fjord basins. The evidence also indicates that the glacial regimes varied between regions.

M3 - Conference abstract for conference

T2 - Quaternary Glacial and Climate Extremes,

Y2 - 1 June 2011 through 4 June 2011

ER -