Trade-off between CO CO2 and CH 2 CH4 under conditions of uncertainty,learning and I4 inerti nertiaa

摘要

Although most agree that there are net benefits of a mmulti-gas approach to cli ulti-climatemate changemitigation,there I is still a debate on the trade-offs between different greenhouse gasesGHGs).The debate has mainly centered on the GWPs mmetric,but there have also been discussionsas to whether early mitigation action should be targeted on short lived gases likeetric,mmethane,ozone precursors,or aerosols,or on carbon dioxide.This paper touches upon both tethane,these issues.Using an integrated clihese climate and economic mate model (Mi MiMiC),we a MiC),asssess how unce sess uncertainty and learningabout the climate sensitivitrtainty sensitivity affects the cost-effective trade-off between long-lived and shortlived GHGs (e.g.methane and carbon dioxide),when the expected costs to reach a predefiy predefinedclinedclimate stabilization target are mate mmini inimmiizzed.We find that uncertainty and learning implies thatmethane should be valued higher relative to carbon dioxide in ted.The short run he run,although t ,the effect isquite small.The effect ishe mmoorre pronounced if the uncertainty is increased.W e We also include th e theaspect of energeenergy s y system inertia,imply ystem implyiinng that there is also a trade-off between long-lived aba g abatementcapital (I.e.for carbon dioxide mtementmitigation),and short lived abatement capital (I.e.for itigation),mmethaneethanemitigation).However,this does not change our results significantly.Although short-livedgases should be valuedmmoorre relative to long-lived gases in case of uncertaint and learning,methane in our model is valued less thathan its current GWP value.