Specifying the emission reduction and carbon intensity targets of the IMO’s short-term measures

The IMO’s initial strategy states that it will pursue “a pathway of CO2 reductions consistent with the Paris Agreement temperature goals”. However, we find a large gap between a 1.5 degree climate science derived pathway for CO2 reduction in international shipping, and the CO2 pathway for international shipping’s GHG emissions if a 40% carbon intensity improvement (2008-2030) is used to specify emission reduction targets for the IMO’s short-term measures. Because of steadily rising demand for shipping services, the IMO’s target of a 40% carbon intensity improvement by 2030 compared with 2008 is expected to result in constant or rising emissions from international shipping over that period. A Paris-aligned pathway, on the other hand, implies deep emission cuts in the 2020s. Crucially, delaying absolute CO2 reduction until 2030 would require an unfeasibly rapid 10 year transition to zero emissions (see Figure 1) thereafter. As temperature rises are correlated with cumulative emissions, the later the emissions peak, the more rapid the subsequent required rate of transition becomes.