Evolution of the Greenland Ice Sheet with the Global Climate as modelled with CESM2-CISM2

Human-induced climate change is one of the challenges of our time. The increasing global mean temperature, shifts in precipitation patterns, and the rising sea level threaten ecosystems and natural resources, and pose a great risk on society at large. Policymakers need information about the expected impacts, as accurate as possible, in order to make adequate climate change mitigation and adaptation policies. The Greenland Ice Sheet (GrIS) appears to be sensitive to the changing climate. At present, the GrIS is losing mass at an accelerated pace. This is the focus of this thesis. The key terms of the GrIS mass balance are (1) the Surface Mass Balance (SMB) and (2) the ice discharge at glacier fronts. At the surface, the ice sheet gains mass through precipitation and loses mass through meltwater runoff and through sublimation. Ice discharge is a loss term regulated by ice flow. When the mass balance is negative, the ice sheet loses mass contributing to sea level rise. The GrIS, however, is not an isolated environment. It is an integral part of the Earth system. Interactions and feedback mechanisms between the ice sheet and various parts of the Earth’s system affect the ice sheet’s mass loss. The future behavior of the GrIS is a major source of uncertainty in the projections of 21st century sea level rise. The basis for this lies, among other things, in an incomplete understanding of the interactions between the ice sheets and other components the Earth system.