Improved Sea Level Change Predictions through Advanced Postglacial Rebound Modeling

Accurate measurements of melting of land ice in Greenland and Antarctica are vital for predicting future sea level rise. However, measurements of land ice melt in these regions are masked by land rising and sinking due to growth and melt of past ice sheets. This process is called Glacial Isostatic Adjustment (GIA). Without quantitative knowledge of GIA we can not reliably estimate land ice melt rates. The geophysical models that are currently used to correct for GIA in Greenland and Antarctica are overly simplistic and leave out information from other branches of Earth science. In preliminary studies for North America and Scandinavia, these simplifications were shown to have a large influence on GIA predictions. This proposal aims to address the shortcomings of the current GIA models for Greenland and Antarctica by three novel contributions. (i) Results from laboratory experiments will form the basis for more realistically describing deformation of mantle rocks in the GIA models. This requires the development of a new method to incorporate background stresses resulting from mantle convection. (ii) For the first time, regional information on the structure of the Earth will be integrated in the models. (iii) The models will be extended to include ice thickness fluctuations in the last millennium. The proposed developments pave the way for a wealth of data from laboratory experiments, seismology and surface geology as well as historic sea level data to contribute to GIA models in Greenland and Antarctica. Thus, this project marks a leap forward for GIA modeling for regions where accurate predictions are crucial for monitoring the effects of climate change. Expected project results will lead to high-impact scientific publications on the interaction between mantle convection and GIA, new GIA models for Greenland and Antarctica and improved estimates of present-day ice mass changes and corresponding sea level change.