Details

Autor(en) / Beteiligte

• Wernecke, Andreas
• Edwards, Tamsin L.
• Holden, Philip B.
• Edwards, Neil R.
• Cornford, Stephen L.

Titel

Quantifying the Impact of Bedrock Topography Uncertainty in Pine Island Glacier Projections for This Century

Ist Teil von

• Geophysical research letters, 2022-03, Vol.49 (6), p.n/a

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2022

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• 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 projected 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 spatially dependent uncertainties and avoids unnecessary smoothing from spatial averaging or interpolation. A set of topography realizations is generated representing our best estimate of the topographic uncertainty in ice sheet model simulations. The bedrock uncertainty alone creates a 5%–25% uncertainty in the predicted sea level rise contribution at year 2100, depending on friction law and climate forcing. Pine Island Glacier simulations on this new set are consistent with simulations on the BedMachine reference topography but diverge from Bedmap2 simulations. Plain Language Summary We investigate the impact of uncertainties in the elevation of the bedrock underneath the ice of a particularly vulnerable glacier in Antarctica. We propose a new approach to better estimate how much future projections depend on knowledge of bedrock elevation. The main focus of this study is to represent the current understanding of the bedrock elevation as closely as possible so that our simulations accurately reflect the extent of our knowledge of the future glacier behavior. In summary, we find that the mass of ice lost in simulations for year 2100, which contributes to the global mean sea level, can be affected by up to 25%. This highlights the value of closely‐spaced bedrock measurement and of careful consideration of related uncertainties in ice‐sheet simulations. Key Points Uncertainty in topography estimates has a significant impact on predictions for all tested friction laws Simulations with BedMachine and statistically generated topographies are more sensitive to upper‐end climate forcing than with Bedmap2 Pine Island Glacier is likely to transition into a more unstable state late mid‐century for upper‐end climate forcing