UC Irvine

Located at the south pole, as the fifth continent in the world and covering 20 percent of the surface area of the southern hemisphere, the Antarctic Ice Sheet has 58 meters of sea level potential and is a natural indicator of climate change because of its sensitivity to changes in temperature. Changes in the ice sheet could influence the global energy balance through ice-albedo feedback, the circulation pattern of the ocean, exchanges of gases with the at- mosphere, the global water cycle, and sea level. To understand and accurately quantify the changes in ice in the Antarctic Ice Sheet and its direct contribution to global sea level, continuing to observe, measure, and estimate the mass balance of the Antarctic Ice Sheet is essential among all Antarctica research. Currently, the Antarctic Ice Sheet represents the largest uncertainty in predicting sea level changes independently from any Representative Concentration Pathway (RCP) scenarios. At present, large discrepancies remain in estimates from the three independent methods (the gravity measurement method, altimetry method, and mass budget method) of the Antarctic ice mass balance from observations, particularly in East Antarctica. In this thesis, we present state-of-art mass balance estimates of Antarc- tica using GRACE and GRACE-FO satellites. Using the same satellites, we also present the mass balance estimates of Greenland and world glaciers and ice caps as well. Last but not least, we propose a novel algorithm that allows us to combine two independent methods (gravity measurement method and altimetry method) to improve the Antarctic mass bal- ance and glacial isostatic adjustment by deriving an analytical solution of GIA and ice mass balance. We are also able to give a GIA estimate and quantify an associated GIA uncer- tainty due to limited observations. This GIA uncertainty is likely applicable to all current GIA research as our approach allows us to quantify unaccounted uncertainties in traditional methods in a rigorous fashion. Our algorithm would also allow us to make suggestions to future GPS placements.Accurately quantifying the mass balance of Antarctica could not only help us understand its evolution under climate change and its contribution to global sea level but could also further inform global climate models and give information to world governments and communities to better prepare and adapt to a rising sea level and implement feasible and evidence-based decarbonization pathways.