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April S DALTON

North American Ice Sheet Evolution Over the Last Glacial Cycle: Data and Preliminary Data-model Comparisons

Abstract
The North American ice sheet complex (including the Laurentide, Cordilleran and Innuitian ice sheets) was the largest global ice mass to grow and decay during the last glacial cycle (ie. from initiation at ~115 ka to remnant ice masses in the late Holocene). Because this ice complex held globally significant ice volume, understanding its evolution through time is critical for refining estimates of global sea level change along with various elements of earth system evolution. I will overview recent efforts to reconstruct and refine North American ice sheet dynamics through this whole interval. This work involved compiling and interpreting various empirical data sources (ie. stratigraphic data, geomorphic records, chronology data). Ice sheet evolution from the last glacial maximum (~25 ka) to present-day is relatively well understood owing to an abundance of sediments and landforms that remain on the land surface; however, reconstructing ice sheet evolution prior to the last glacial maximum is a particular challenge owing to limited data. The end results are a fully documented series of maps showing the evolution of the ice margin through the entire last glacial cycle, with uncertainties quantified as minimum and maximum bounds on the ice margin isochrones. These minimum and maximum uncertainty bounds are contributing to a History Matching exercise for the last glacial cycle combining glaciological modelling with a wide array of data constraints. To that end, we present some preliminary data-model comparisons for key regions of the ice sheet.




April S DALTON
Charles University, Czech Republic

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