Publication Abstracts

Ullman et al. 2015

Ullman, D.J., A.E. Carlson, A.N. LeGrande, F.S. Anslow, A.K. Moore, M. Caffee, K.M. Syverson, and J.M. Licciardi, 2015: Southern Laurentide ice-sheet retreat synchronous with rising boreal summer insolation. Geology, 43, no. 1, 23-26, doi:10.1130/G36179.1.

Establishing the precise timing for the onset of ice-sheet retreat at the end of the Last Glacial Maximum (LGM) is critical for delineating mechanisms that drive deglaciations. Uncertainties in the timing of ice-margin retreat and global ice-volume change allow a variety of plausible deglaciation triggers. Using boulder 10Be surface exposure ages, we date initial southern Laurentide ice-sheet (LIS) retreat from LGM moraines in Wisconsin (USA) to 23.0±0.6 ka, coincident with retreat elsewhere along the southern LIS and synchronous with the initial rise in boreal summer insolation 24-23 ka. We show with climate-surface mass balance simulations that this small increase in boreal summer insolation alone is potentially sufficient to drive enhanced southern LIS surface ablation. We also date increased southern LIS retreat after ca. 20.5 ka likely driven by an acceleration in rising isolation. This near-instantaneous southern LIS response to boreal summer insolation before any rise in atmospheric CO2 supports the Milankovč hypothesis of orbital forcing of deglaciations.

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BibTeX Citation

  author={Ullman, D. J. and Carlson, A. E. and LeGrande, A. N. and Anslow, F. S. and Moore, A. K. and Caffee, M. and Syverson, K. M. and Licciardi, J. M.},
  title={Southern Laurentide ice-sheet retreat synchronous with rising boreal summer insolation},

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RIS Citation

ID  - ul02000c
AU  - Ullman, D. J.
AU  - Carlson, A. E.
AU  - LeGrande, A. N.
AU  - Anslow, F. S.
AU  - Moore, A. K.
AU  - Caffee, M.
AU  - Syverson, K. M.
AU  - Licciardi, J. M.
PY  - 2015
TI  - Southern Laurentide ice-sheet retreat synchronous with rising boreal summer insolation
JA  - Geology
VL  - 43
IS  - 1
SP  - 23
EP  - 26
DO  - 10.1130/G36179.1
ER  -

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