Holocene deglaciation of the Scandinavian Ice Sheet and Implications for Late-Glacial Sea-Level Rise

Wednesday, 17 December 2014: 8:15 AM
Josh K Cuzzone1, Peter U Clark1, Shaun A Marcott2, Anders E Carlson3, David J Ullman1, Juha P Lunkka4, Barabara Wohlfarth5 and Marc W Caffee6, (1)Oregon State University, College of Earth, Ocean, and Atmospheric Sciences, Corvallis, OR, United States, (2)University of Wisconsin Madison, Madison, WI, United States, (3)COAS, Corvallis, OR, United States, (4)University of Oulu, Oulu, Finland, (5)Stockholm University, Stockholm, Sweden, (6)Purdue University, West Lafayette, IN, United States
Establishing records of past ice-sheet retreat provides a critical constraint in identifying sources of past sea-level rise while also providing insight into the possible responses of present-day ice sheets to a warming climate. Here we present 86 new 10Be cosmogenic exposure dates that constrain the final deglaciation of the Scandinavian Ice Sheet (SIS) during the latest Pleistocene and early Holocene. Our dates come from three transects spanning southern to northern Sweden and Finland. All transects begin around previously dated or inferred Younger Dryas ice margins and converge in northwestern Sweden, where ages suggest final deglaciation of the SIS at 10±0.3 ka. The individual transects reveal an asymmetric pattern for the deglaciation of the SIS, with near-instantaneous retreat occurring in southeastern Finland during the end of the Younger Dryas (ages range from 11.9±0.4 ka to 12.1±0.4 ka). Although not as rapid, deglaciation in northern Finland occurs during the later portion of the Younger Dryas (12.1±0.4 ka to 11.9±0.8 ka), with the majority of the retreat occurring in response to warming after the Younger Dryas. In southern Sweden, retreat during the Younger Dryas is much slower (~63 m/yr) than in Finland, but accelerates rapidly northward in response to warming out of the Younger Dryas (574 m/yr). As the ice margin retreated onto the Swedish highlands, retreat remains steady along transects at ~280 m/yr, before terminating at 10±0.3 ka. Combining this new chronology with existing ages constraining the deglaciation of the SIS from the Last Glacial Maximum position allows for a determination of SIS sensitivity to warming throughout the last deglaciation, while providing constraints on the SIS sea level rise contribution. When combined with recent constraints on Laurentide Ice Sheet retreat during the Holocene, we provide an estimate of residual sea-level rise as the difference between the combined SIS and LIS contributions and a new estimate of global mean sea-level rise. Results suggest a residual of ~24m of sea level rise exists from 13 to 11 ka, and then decreases to 0m by ~7 ka.