06 December 2016

Using GRACE and Climate Model Simulations to Predict Mass Loss of Alaskan Glaciers through 2100


Glaciers in Alaska are presently losing mass at a rate of about 52 Gt yr-1, the largest  ice loss rate of any regional collection of mountain glaciers on Earth. Existing projections of Alaska’s future sea-level contributions tend to be complex and are not tied directly to regional observations. Here we develop a simple, regional observation based prediction of Alaska’s future sea-level contribution. We compute a time series of recent Alaska glacier mass variability using monthly GRACE gravity fields from August, 2002 through December, 2014.  


We also construct a simple three-parameter model of Alaska mass variability based on monthly ERA-Interim snowfall and temperature fields.  When these three model parameters are fit to the GRACE time series, the model can explain 94% of the variance of the GRACE data. We apply this this same simple model, with these same parameter values, to  simulated fields of monthly temperature and snowfall from the Community Earth System Model,  to obtain predictions of mass variations through 2100.   


We conclude that mass loss rates would increase to between 80 and 110  Gt/yr by 2100, with a total sea level rise contribution of 19  4 mm during the twenty-first century.

Sean Swenson
National Center for Atmospheric Research (NCAR)