Long-term marginal abatement cost curves of non-CO2 greenhouse gases

The new MAC curves include current technology and costs information as well as estimates of technology development and removal of implementation barriers to capture long-term dynamics. Compared to earlier work, we find a higher projected maximum reduction potential (MRP) of nitrous oxide (N₂O) and a lower MRP of methane (CH₄).

The combined MRP for all non-CO₂ gases is similar but has been extended to also capture mitigation measures that can be realized at higher implementation costs. When applying the new MAC curves in a cost-optimal, integrated assessment model-based 2.6 W/m2 scenario, the total non-CO₂ mitigation is projected to be 10.9 Mt CO₂ equivalents in 2050 (i.e. 58% reduction compared to baseline emissions) and 15.6 Mt CO₂ equivalents in 2100 (i.e. a 71% reduction).

In applying the new MAC curves, we account for inertia in thline implementation speed of mitigation measures. Although this does not strongly impact results in an optimal strategy, it means that the contribution of non-CO₂ mitigation could be more limited if ambitious climate policy is delayed.