Summary/Abstract
Melting of the Antarctic Ice Sheet (AIS) could contribute metres to global sea level rise (SLR) in the long run. The authors couple models of AIS melting due to rising temperatures, SLR, and economic impacts of SLR on coastlines worldwide. The authors report SLR projections close to the latest literature. Coastal impacts of AIS melting are very heterogeneous: they are large as a share of GDP in one to two dozen countries, primarily Small Island Developing States. Costs can be reduced dramatically by economically efficient, proactive coastal planning: relative to a no adaptation scenario, optimal adaptation reduces total costs by roughly an order of magnitude. AIS melting increases the social cost of carbon by an expected 7% on low to medium emissions scenarios and with moderate discounting. The authors conclude that, based on this projection, there is a tail risk of very large increases in the social cost of carbon, particularly on a high emissions scenario.