Quantifying the impact of bedrock topography uncertainty on 100-year
Pine Island Glacier projections
Abstract
The predicted Antarctic contribution to global-mean sea-level rise is
one of the most uncertain among all major sources. Partly this is
because of instability mechanisms of the ice flow over deep basins.
Errors in bedrock topography can substantially impact the resilience of
glaciers against such instabilities. Here we analyze the Pine Island
Glacier topography to derive a statistical model representation. Our
model allows for inhomogeneous and statistically dependent uncertainties
and avoids unnecessary smoothing from spatial averaging or
middle-of-the-road interpolation. A set of topographic fields is
generated which properly represents the topographic uncertainty in our
ice sheet model simulations with lower and upper end climate forcings.
The bedrock uncertainty alone creates a 5% to 25% uncertainty in the
predicted 100-year sea level rise contributions. Ice sheet model
simulations on this new set are consistent with simulations on the
frequently used BedMachine topography but diverge from Bedmap2
simulations.