What Role Do the Impacts from High Emissions and High Temperatures Have on Choosing Optimal Mitigation Targets?

When choosing among emission trajectories that lead to final expected temperatures between 2 and 4 °C, society needs to weigh the extra mitigation cost of each strategy against the extra benefit (additional reduced damage). The damage associated with high emissions that lead to high temperatures play no role in this calculation. With uncertainty about the link between emissions and temperature, high temperatures can play a role in desired near term mitigation but it will generally be a modest effect. We need to focus scientific attention on policy relevant emission paths and their consequences and pay much less attention to what happens in high emission scenarios.