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| Titel |
Ensemble ice and sea-level change projections with the Earth system model of intermediate complexity LOVECLIM |
| VerfasserIn |
Heiko Goelzer, Philippe Huybrechts, Sarah Raper, Marie-France Loutre, Hugues Goosse, Thierry Fichefet |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250054428
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| Zusammenfassung |
| We present results from future ice-sheet evolution and sea-level change experiments with the
Earth system model of intermediate complexity LOVECLIM. The model includes fully
coupled three-dimensional thermomechanical models of the Greenland and Antarctic ice
sheets (GIS, AIS), a global glacier melt algorithm to account for the response of mountain
glaciers and small ice caps, and a diagnostic for oceanic thermal expansion. In the
present study a large range of the model’s sensitivity to greenhouse warming was
sampled by systematic parameter variations. This led to an ensemble of model
versions that simulate the present-day climate consistent with observations, while
producing contrasted results for the future period. We first discuss results for the best
validated model version under three different SRES forcing scenarios (B1, A1B and
A2) extended over the third millennium. The relatively low climate sensitivity in
this best model version combines with the relatively high polar amplification in
LOVECLIM to yield a polar temperature response that is in line with more comprehensive
models. Mountain glaciers are the fastest to disappear in all scenarios, followed
by small ice caps, both representing minor contributions to sea level changes on
longer time scales. Initially the strongest contribution, thermal expansion of the
world oceans decelerates on multi-centennial time scales and is outpaced by GIS
melting, the largest contribution to sea level rise at the end of the third millennium
in all scenarios. The AIS contribution remains negative for scenario B1, due to
increasing accumulation but is positive for the two other scenarios. Contributions
from both the GIS and AIS are still accelerating at the end of the third millennium,
demonstrating that they are far from equilibrium with the imposed warming and thus may
contribute to sea level rise for many more centuries thereafter. Finally, we analyze
sea-level contributions at the end of the third millennium of both ice sheets as a
function of local average warming for the entire ensemble of model versions and for
all three forcing scenarios. We find overlapping ranges of ice sheet response for
changing the forcing scenario and for changing the climate sensitivity of the model.
By 3000 AD, the GIS contribution to sea-level rise is more than one meter for a
local average warming of less than 2 Ë C and increases by more than one meter per
degree of additional warming limited by the total amount of Greenland ice. The
sea-level contribution of the AIS is negligible or negative for less than 5 Ë C local
warming and increases rapidly for an average warming above 8 Ë C. The volume
response follows from a balance between changes in surface accumulation, marginal
runoff, and dynamic changes of the grounding line driven by ice-shelf melting. |
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