Browsing UAF Graduate School by Author "Radic, Valentina"
Modeling Future Sea Level Rise From Melting GlaciersRadic, Valentina; Hock, Regine (2008)Melting mountain glaciers and ice caps (MG&IC) are the second largest contributor to rising sea level after thermal expansion of the oceans and are likely to remain the dominant glaciological contributor to rising sea level in the 21st century. The aim of this work is to project 21st century volume changes of all MG&IC and to provide systematic analysis of uncertainties originating from different sources in the calculation. I provide an ensemble of 21st century volume projections for all MG&IC from the World Glacier Inventory by modeling the surface mass balance coupled with volume-area-length scaling and forced with temperature and precipitation scenarios from four Global Climate Models (GCMs). By upscaling the volume projections through a regionally differentiated approach to all MG&IC outside Greenland and Antarctica (514,380 km 2) I estimated total volume loss for the time period 2001-2100 to range from 0.039 to 0.150 m sea level equivalent. While three GCMs agree that Alaskan glaciers are the main contributors to the projected sea level rise, one GCM projected the largest total volume loss mainly due to Arctic MG&IC. The uncertainties in the projections are addressed by a series of sensitivity tests applied in the methodology for assessment of global volume changes and on individual case studies for particular glaciers. Special emphasis is put on the uncertainties in volume-area scaling. For both, individual and global assessments of volume changes, the choice of GCM forcing glacier models is shown to be the largest source of quantified uncertainties in the projections. Another major source of uncertainty is the temperature forcing in the mass balance model depending on the quality of climate reanalysis products (ERA-40) in order to simulate the local temperatures on a mountain glacier or ice cap. Other uncertainties in the methods are associated with volume-area-length scaling as a tool for deriving glacier initial volumes and glacier geometry changes in the volume projections. Nevertheless, the lack of more detailed knowledge of global ice volume constrains the estimates of the potential and projected sea level rise from melting MG&IC. Any progress in this field is limited without a more complete glacier inventory database.