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| Titel |
Could vegetation feedbacks determine whether the Greenland ice sheet regrows after deglaciation? |
| VerfasserIn |
E. J. Stone, D. J. Lunt, P. J. Valdes |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250021672
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| Zusammenfassung |
| The importance of vegetation feedbacks for the process of ice sheet regrowth have largely
been neglected from previous studies (e.g. Lunt et al. 2004; Toniazzo et al., 2004) but could
be potentially important in realistically modelling the past and future evolution of the
Greenland ice sheet. This work focuses on modelling the regrowth of the Greenland ice sheet
if it completely melted and CO2concentrations returned to pre-industrial levels
(280ppm).
We have used the fully coupled atmosphere-ocean model, HadCM3, to assess the
response of the climate when the Greenland ice sheet is replaced with a number of fixed
vegetation types. An ensemble of 100 year simulations have been performed with the
Greenland ice sheet replaced with bare soil and five plant functional types (PFT): broadleaf
and needleleaf trees, c3 and c4 grasses and shrubs. Sensitivity studies with respect
to the surface roughness length and change in orographic height have also been
carried out. The summer temperature change relative to an ice sheet being present,
ranges from 1˚ C for bare soil to almost 16˚ C for needleleaf trees. Furthermore,
snow cover diagnostics indicate almost snow free summers for all fixed vegetation
with only significant coverage occurring in high altitude eastern regions for bare
soil.
HadCM3 also includes a coupled vegetation model, TRIFFID. We present results where
dynamic vegetation is turned on for the initial conditions of bare soil and needleleaf coverage.
Simulations were run as extensions from the fixed vegetation experiments until the vegetation
was found to be in equilibrium.
Finally, in addition to using the snow diagnostic to predict regrowth we present results
where the ice sheet model, GLIMMER, is forced offline using climate input from the
ensemble of vegetation experiments. Initial results indicate that there is a threshold over
which ice regrowth can occur between bare soil and the PFT fixed vegetation experiments.
This work highlights that in order to model reglaciation it is necessary to take vegetation
feedbacks into account. |
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