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TitleA glacial isostatic adjustment model for the central and northern Laurentide Ice Sheet based on relative sea level and GPS measurements
AuthorSimon, K M; James, T S; Henton, J A; Dyke, A S
SourceGeophysical Journal International no. 205, issue 3, 2016 p. 1619-1636,
Alt SeriesEarth Sciences Sector, Contribution Series 20150224
PublisherOxford University Press
Mediapaper; on-line; digital
File formatpdf
ProvinceCanada; British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut
NTS1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
Lat/Long WENS-141.0000 -50.0000 90.0000 41.7500
Subjectsgeneral geology; sedimentology; surficial geology/geomorphology; ice retreat; ice thicknesses; ice flow; ice movement directions; glaciation; glaciers; glaciology; ice thicknesses; sea level changes; sea level fluctuations; paleo-sea levels; paleoclimatology; paleoenvironment; paleoclimates; paleotemperatures; paleohydrology; Laurentide Ice Sheet
Illustrationsmaps; location maps; icesheet maps; equations; graphs; charts; structural maps
ProgramCoastal Infrastructure, Climate Change Geoscience
AbstractThe thickness and equivalent global sea-level contribution of an improved model of the central and northern Laurentide Ice Sheet is constrained by 24 relative sea-level histories and 18 present-day GPS-measured vertical land motion rates. The final model, termed Laur15, is derived from the ICE-5G model by iteratively adjusting the thickness history in four regions of northern Canada. In the final model, the last glacial maximum (LGM) thickness of the Laurentide Ice Sheet west of Hudson Bay was ~3.4-3.6 km. Conversely, east of Hudson Bay, peak ice thicknesses reached ~4 km. The ice model thicknesses inferred for these two regions represent, respectively, a ~30% decrease and an average ~20-25% increase to the load thickness relative to the ICE-5G reconstruction, a result which is generally consistent with other recent studies that have focussed on Laurentide Ice Sheet history. The final model also features peak ice thicknesses of 1.2-1.3 km in the Baffin Island region, a modest reduction relative to ICE-5G, and unchanged thicknesses for a region in the central Canadian Arctic Archipelago west of Baffin Island. Vertical land motion predictions of the final model fit observed crustal uplift rates well, after an adjustment is made for the elastic crustal response to present-day ice mass changes of regional ice cover. The new Laur15 model provides more than a factor of two improvement of the fit to the RSL data (?2 measure of misfit) and a factor of nine improvement to the fit of the GPS data (mean squared error measure of fit), compared to the ICE-5G starting model. Laur15 also fits the regional RSL data better by a factor of two and gives a similar fit to GPS uplift rates when compared to the recent ICE-6G model. The volume history of the Laur15 reconstruction corresponds to an up to 8 m reduction in global sea-level equivalent compared to ICE-5G.
Summary(Plain Language Summary, not published)
This is a technical article that describes a new reconstruction of the Laurentide ice sheet from Last Glacial Maximum (about 21,000 years ago) to its disappearance about 8000 years ago. The Laurentide Ice Sheet covered much of Canada during the last ice age. The new model fits measurements of past sea-level changes and present-day vertical crustal motion better than a previous model called ICE-5G. The improved model gives a better understanding of vertical land motion and sea-level change across a large segment of northern Canada and will help give improved projections of future sea-level change.