Economics of the disintegration of the Greenland ice sheet

Abstract

Concerns about the impact on large-scale earth systems have taken center stage in the scientific and economic analysis of climate change. The present study analyzes the economic impact of a potential disintegration of the Greenland ice sheet (GIS). The study introduces an approach that combines long-run economic growth models, climate models, and reduced-form GIS models. The study demonstrates that social cost-benefit analysis and damage-limiting strategies can be usefully extended to illuminate issues with major long-term consequences, as well as concerns such as potential tipping points, irreversibility, and hysteresis. A key finding is that, under a wide range of assumptions, the risk of GIS disintegration makes a small contribution to the optimal stringency of current policy or to the overall social cost of climate change. It finds that the cost of GIS disintegration adds less than 5% to the social cost of carbon (SCC) under alternative discount rates and estimates of the GIS dynamics.

Keywords: DICE model; Greenland ice sheet; climate change; economics; optimization.

Fig. 1.

Alternative specifications of GIS equilibrium. A is reversible; B displays hysteresis; C is effectively irreversible because rebuilding requires ice age conditions.

Fig. 2.

Estimated equilibrium relationship between temperature change and equivalent sea level rise (SLRe) for the GIS. Data from ref. . The original figure is annual temperature over the GIS, and this is converted to global annual temperature using a ratio of 1.5:1 for GIS to global. The four points from Left to Right are modern (1960), the Holocene Thermal Maximum (HTM), the Eemian, and full ice sheet loss of MIS 11 or earlier, while the arrow suggests the impact of the glacial maximum, as discussed by Alley et al. This source also provides error bars on the estimates for the upper three points (from Left to Right) for temperature ±0.7, ±2.4, and ±2.5 °C and for sea level rise of ±0.5, ±2.0, and ±0.7 m.

Fig. 3.

Alternative estimates of initial melt rate from different studies. Estimates are provided in SI Appendix, parts A and C. The arrow shows the range of studies for the Bindschadler et al. (12) model-comparison study for the 500-y horizon. [Legend: “Apple,” Applegate et al. (13); “Bind,” Bindschadler et al. (12); “Furst,” Furst et al. (14); “Ridley,” Ridley et al. (4); “Rob,” Robinson et al. (3). “DICE” is the results of the GIS estimates in the DICE-GIS model.]

Fig. 4.

Volume of GIS under different global temperature regimes from calculations in Robinson et al. (3). Data provided by A. Robinson (Complutense University of Madrid, Madrid, Spain).

Fig. 5.

The evolution of the GIS under optimal and baseline (no-policy) cases plus a geoengineering scenario. See text for discussion. The arrow is the range of model estimates from different ISMs for a high warming scenario from IPCC (1), p. 1191, table 13-8, and has comparable forcings as the DICE-GIS baseline run. The optimal policy stays above the upper instability for the GIS found in studies discussed in text, whereas the baseline declines below the upper threshold. The run labeled “Base-geo” shows the result for a no-policy run followed by a geoengineering experiment after year 500 (see Geoengineering to Limit Temperature for details).