Edwards, T. L., Fettweis, X., Gagliardini, O., Gillet-Chaulet, F., Goelzer, H., Gregory, J.M., Hoffman, M., Huybrechts, P., Payne, A. J., Perego, M., Price, S., Quiquet, A. and Ritz, C.
Effect of uncertainty in surface mass balance--elevation feedback on projections of the future sea level contribution of the Greenland ice sheet.
The Cryosphere, 8.
To link to this article DOI: 10.5194/tc-8-195-2014
We apply a new parameterisation of the Greenland
ice sheet (GrIS) feedback between surface mass balance
(SMB: the sum of surface accumulation and surface ablation)
and surface elevation in the MAR regional climate model
(Edwards et al., 2014) to projections of future climate change
using five ice sheet models (ISMs). The MAR (Modèle Atmosphérique
Régional: Fettweis, 2007) climate projections
are for 2000–2199, forced by the ECHAM5 and HadCM3
global climate models (GCMs) under the SRES A1B emissions
The additional sea level contribution due to the SMB–
elevation feedback averaged over five ISM projections for
ECHAM5 and three for HadCM3 is 4.3% (best estimate;
95% credibility interval 1.8–6.9 %) at 2100, and 9.6% (best
estimate; 95% credibility interval 3.6–16.0 %) at 2200. In all
results the elevation feedback is significantly positive, amplifying
the GrIS sea level contribution relative to the MAR
projections in which the ice sheet topography is fixed: the
lower bounds of our 95% credibility intervals (CIs) for sea
level contributions are larger than the “no feedback” case for
all ISMs and GCMs.
Our method is novel in sea level projections because we
propagate three types of modelling uncertainty – GCM and
ISM structural uncertainties, and elevation feedback parameterisation
uncertainty – along the causal chain, from SRES
scenario to sea level, within a coherent experimental design
and statistical framework. The relative contributions to uncertainty
depend on the timescale of interest. At 2100, the
GCM uncertainty is largest, but by 2200 both the ISM and
parameterisation uncertainties are larger. We also perform
a perturbed parameter ensemble with one ISM to estimate the
shape of the projected sea level probability distribution; our
results indicate that the probability density is slightly skewed
towards higher sea level contributions.
|Date Deposited:||26 Nov 2014 10:50|
|Last Modified:||07 Jun 2015 23:42|
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