We investigate changing precipitation patterns in the Kangerlussuaq region of western central Greenland during the Holocene thermal maximum (HTM), using a new chronology of ice sheet terminus position through the Holocene and a novel inverse modeling approach based on the unscented transform (UT). The UT is applied to estimate changes in annual precipitation in order to reduce the misfit between modeled and observed terminus positions. We demonstrate the effectiveness of the UT for time-dependent data assimilation, highlighting its low computational cost and trivial parallel implementation. Our results indicate that Holocene warming coincided with elevated precipitation, without which modeled retreat in the Kangerlussuaq region is more rapid than suggested by observations. Less conclusive is whether high temperatures during the HTM were specifically associated with a transient increase in precipitation, as the results depend on the assumed temperature history. Our results highlight the important role that changing precipitation patterns had in controlling ice sheet extent during the Holocene.
Department of Mathematical Sciences, University of Montana, Missoula, MT, United States; Department of Computer Science, University of Montana, Missoula, MT, United States; Department of Geology, University at Buffalo, Buffalo, NY, United States; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, United States; Department of Earth System Science, University of California, Irvine, Irvine, CA, United States
Recommended Citation:
Downs J.,Johnson J.,Briner J.,et al. Western greenland ice sheet retreat history reveals elevated precipitation during the holocene thermal maximum[J]. Cryosphere,2020-01-01,14(3)