Record Details
Laurentide ice-sheet instability during the last deglaciation
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Laurentide ice-sheet instability during the last deglaciation |
| Names |
Ullman, David J.
(creator) Carlson, Anders E. (creator) Anslow, Faron S. (creator) LeGrande, Allegra N. (creator) Licciardi, Joseph M. (creator) |
| Date Issued | 2015-07 (iso8601) |
| Note | To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Nature Publishing Group and can be found at: http://www.nature.com/ngeo/index.html |
| Abstract | Changes in the amount of summer incoming solar radiation (insolation) reaching the Northern Hemisphere are the underlying pacemaker of glacial cycles. However, not all rises in boreal summer insolation over the past 800,000 years resulted in deglaciation to present-day ice volumes, suggesting that there may be a climatic threshold for the disappearance of land-based ice. Here we assess the surface mass balance stability of the Laurentide ice sheet—the largest glacial ice mass in the Northern Hemisphere—during the last deglaciation (24,000 to 9,000 years ago). We run a surface energy balance model with climate data from simulations with a fully coupled atmosphere–ocean general circulation model for key time slices during the last deglaciation. We find that the surface mass balance of the Laurentide ice sheet was positive throughout much of the deglaciation, and suggest that dynamic discharge was mainly responsible for mass loss during this time. Total surface mass balance became negative only in the early Holocene, indicating the transition to a new state where ice loss occurred primarily by surface ablation. We conclude that the Laurentide ice sheet remained a viable ice sheet before the Holocene and began to fully deglaciate only once summer temperatures and radiative forcing over the ice sheet increased by 6–7 °C and 16–20 W m⁻², respectively, relative to full glacial conditions. |
| Genre | Article |
| Identifier | Ullman, D. J., Carlson, A. E., Anslow, F. S., LeGrande, A. N., & Licciardi, J. M. (2015). Laurentide ice-sheet instability during the last deglaciation. Nature Geoscience, 8(7), 534-540. doi:10.1038/NGEO2463 |
