The future sea-level contribution from Antarctica: Projections of solid ice discharge (Kumulative Dissertation)

• Main Author: Winkelmann, R.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Mathematisch-Naturwissenschaftlichen Fakultät, Universität Potsdam 2012
• Subjects: Antarc*; Antarctic; Antarctica; Ice Sheet
• Online Access: http://hdl.handle.net/21.11116/0000-000F-BE29-E; http://hdl.handle.net/21.11116/0000-000F-BE2B-C

Future sea level change has a strong impact on the livelihood of a large share of the world's population. Sea-level projections are thus of great importance with respect to an assessment of necessary mitigation and adaptation measures. The major uncertainty in state-of-the-art projections lies within the evolution of the solid ice discharge from Antarctica, the largest ice mass on Earth. To understand the physical mechanisms underlying a change in solid ice discharge and to quantify the uncertainties in future projections of the sea-level contribution from Antarctica, we have developed the Potsdam Parallel Ice Sheet Model, PISM-PIK, which consistently represents the ice ow in sheet, shelves and the transition zone. In a dynamic equilibrium simulation of the Antarctic Ice Sheet under present-day boundary conditions the model is able to reproduce large-scale geometric properties and the full range of ice velocities observed in Antarctica, from almost zero near the ice divides to a few kilometers per year in ice streams. With PISM-PIK, I investigate solid ice discharge for the years 1850 to 2500 under climate scenarios based on the Extended Concentration Pathways. I show that the uncertainties of the regional temperature projections and from unknown ice parameters used in PISM-PIK are of similar importance throughout the simulations. The maximum dynamic ice loss from Antarctica caused solely by surface warming within the time-period from 1850 to 2500 is 0.58 m. Additional ocean warming and the resulting increase in sub-shelf melting lead to almost a doubling of sea-level rise until the year 2500. However, the largest contribution to solid ice discharge turns out to be caused by the projected increase in precipitation, tripling the overall ice loss. This is due to a precipitation-induced steepening of the surface gradients across the grounding line which results in an increase in driving stress along almost the entire coastline of Antarctica. PISM-PIK is able to reproduce the recently observed rate of solid ice loss ...