A Potential Disintegration of the West Antarctic Ice Sheet: Implications for Economic Analyses of Climate Policy

Key objectives of international greenhouse gas (GHG) policy are to (i) “prevent dangerous anthropogenic interference with the climate system” and (ii) “enable economic development to proceed in a sustainable manner” (UNFCCC, 1992). One common interpretation of “dangerous anthropogenic interference” is to trigger a climate threshold or “tipping point” response – a nonlinear shift in the Earth system with the potential for abrupt, irreversible, or hysteresis effects (e.g., Alley et al., 2003). Examples of possible threshold responses include a disruption of the oceanic thermohaline circulation, sudden methane releases from the oceans or permafrost, or disintegrations of the Greenland or Antarctic ice sheets. The geological record shows that the Earth system can show such threshold responses, but the mechanisms, dynamics, and sensitivities are deeply uncertain (Alley et al., 2003).