The Antarctic Ice Sheet and sea level: contemporary changes and future projections

Abstract

Antarctica holds Earth’s largest ice sheet, which is slowly shrinking in response to climate warming. Over the coming decades to centuries, the loss of ice will likely continue and accelerate, potentially contributing several metres to global sea level rise. How fast and how much the Antarctic Ice Sheet (AIS) will continue to shrink is subject to “deep uncertainty”, which includes how rapid deglaciation can be triggered by feedback related to fracturing processes and vulnerabilities with regions grounded below sea level. In this chapter, we review our understanding of the key processes and potential feedback that can accelerate AIS retreat, and summarise its recent changes. We discuss future projections and what is understood by deep uncertainty in this context and then examine the consequences of AIS loss on global and regional sea level change. We close with a brief discussion of future research directions that will reduce gaps in our understanding of key ice-sheet processes and how these processes contribute to ice-sheet evolution, risks of rapid ice loss and implications for the research and planning needed to adapt to a changing sea level and climate.