Simulated retreat of Jakobshavn Isbræ during the 21st century
<p>The early 21st century retreat of Jakobshavn Isbræ into its overdeepened bedrock trough was accompanied by acceleration to unprecedented ice stream speeds. Such dramatic changes suggested the possibility of substantial mass loss over the rest of this century. Here we use a three-dimensional...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-11-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/13/3139/2019/tc-13-3139-2019.pdf |
| Summary: | <p>The early 21st century retreat of Jakobshavn Isbræ into its
overdeepened bedrock trough was accompanied by acceleration to
unprecedented ice stream speeds. Such dramatic changes suggested the
possibility of substantial mass loss over the rest of this century. Here we
use a three-dimensional ice sheet model with parameterizations to represent
the effects of ice mélange buttressing, crevasse-depth-based calving and
submarine melting to adequately reproduce its recent evolution. We are the
first study on Jakobshavn Isbræ that solves for three-dimensional ice
flow coupled with representations of hydro-fracturing-induced calving and
mélange buttressing. Additionally, the model can accurately replicate
interannual variations in grounding line and terminus position, including
seasonal fluctuations that emerged after arriving at the overdeepened basin
and the disappearance of its floating ice shelf. Our simulated ice viscosity
variability due to shear margin evolution is particularly important in
reproducing the large observed interannual changes in terminus velocity. We
use this model to project Jakobshavn's evolution over this century, forced by
ocean temperatures from seven Earth system models and surface runoff derived
from RACMO, all under the IPCC RCP4.5 climate scenario. In our simulations,
Jakobshavn's grounding line continues to retreat <span class="inline-formula">∼18.5</span> km by
the end of this century, leading to a total mass loss of <span class="inline-formula">∼2068</span> Gt (5.7 mm sea level rise equivalent). Despite the relative success of the
model in simulating the recent behavior of the glacier, the model does not
simulate winter calving events that have become relatively more important.</p> |
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| ISSN: | 1994-0416 1994-0424 |