The European Parliament commissioned study analyses which targets would be compatible with the global long-term goal of keeping the temperature increase below 2°C compared to pre-industrial levels. The analysis supports the view that it is important to establish targets for both sectors that clearly indicate that emissions cannot grow in an unlimited and unregulated way.

The IPCC finds that the growth of global transport demand could pose a significant challenge to the achievement of potential emission reduction goals. Due to strong growth in transport demand, CO₂ emissions of international aviation and maritime transport were and are constantly growing despite considerable efficiency improvements. In 2012, both sectors together account for about 3 % to 4 % of global emissions depending on whether global GHG or only CO₂ emissions are considered. Initiatives and actions taken by ICAO and IMO to address GHG emissions started late and have been insufficient from an environmental perspective to date: they do not take appropriate account of global decarbonisation requirements. In the long run, measures proposed by IMO and ICAO will mitigate growth of the sectoral CO₂ emissions but not lead to absolute emission reductions.

If, as in the past, the ambition of these sectors continues to fall behind efforts in other sectors and if action to combat climate change is further postponed, their CO₂ emission shares in global CO₂ emissions may rise substantially to 22 % for international aviation and 17 % for maritime transport by 2050, or almost 40 % of global CO₂ emissions if both sectors are considered together. Establishing reduction targets for both sectors would provide clear signals for all actors in these sectors and thus contribute to improving investment perspectives in both sectors with their long investment cycles.

Based on several criteria, potential mitigation targets for the aviation and shipping sectors were developed. They range from a somewhat reduced increase of future emissions over stabilisation at 2020 levels to a full decarbonisation of those sectors by 2050. While full decarbonisation within only 30 years is rather unrealistic, stabilising emissions at 2020 levels (carbon neutral growth) is clearly not enough. To stay below 2°C, the target for aviation for 2030 should not exceed 39 % of its 2005 emission levels (50 % below the baseline) and should be ‑41 % compared to its 2005 emission levels in 2050. The respective targets for shipping are ‑13 % and ‑63 % compared to its 2005 emissions in 2030 and 2050, respectively. If non-CO₂ impacts are taken into account, these targets would need to be even more stringent.

Taking into account the estimated mitigation potential within the sectors, it is unlikely that targets which are compatible with the below 2°C objective can be achieved only with technological and operational improvements within the sectors. Thus, these potential targets indicate the extent to which both sectors could contribute adequately to global GHG mitigation efforts. Achieving these targets may require both encouraging behavioural change which leads to reduced demand for international transport services and enabling the offsetting of climate impacts by financing emission reductions in other sectors. Moreover, it needs to be taken into account that particularly the non-CO₂ climate impacts of aviation will not be reduced if fossil fuels are replaced by hydrocarbons extracted from renewable energies. Only electrical propulsion, demand reduction or offsetting remaining emission will enable full decarbonisation of the aviation sector.

These considerations support the view that it is important to establish targets for international aviation and maritime transport which clearly indicate that emissions cannot grow unlimited and unregulated. Enhancing the stringency of the targets can be aimed at in a second step. Yet, aiming for ambitious targets in line with the approaches outlined above should not prevent agreement on targets which will trigger emission reductions sooner rather than later. 

The full study can be downloaded here.