International shipping is a significant contributor to Global Greenhouse Gas (GHG) emissions, responsible for approximately 3% of global CO 2 emissions. The International Maritime Organization is currently working to establish GHG regulations for international shipping and a cost effectiveness approach has been suggested to determine the required emission reductions from shipping. To achieve emission reductions in a cost effective manner, this study has assessed the cost and reduction potential for present and future abatement measures based on new and unpublished data. The model used captures the world fleet up to 2030, and the analysis includes 25 separate measures. A new integrated modelling approach has been used combining fleet projections with activity-based CO 2 emission modelling and projected development of measures for CO 2 emission reduction. The world fleet projections up to 2030 are constructed using a fleet growth model that takes into account assumed ship type specific scrapping and new building rates. A baseline trajectory for CO 2 emission is then established. The reduction potential from the baseline trajectory and the associated marginal cost levels are calculated for 25 different emission reduction measures. The results are given as marginal abatement cost curves, and as future cost scenarios for reduction of world fleet CO 2 emissions. The results show that a scenario in which CO 2 emissions are reduced by 33% from baseline in 2030 is achievable at a marginal cost of USD 0 per tonne reduced. At this cost level, emission in 2010 can be reduced by 19% and by 24% in 2020. A scenario with 49% reduction from baseline in 2030 can be achieved at a marginal cost of USD 100 per tonne (27% in 2010 and 35% in 2020). Furthermore, it is evident that further increasing the cost level beyond USD 100 per tonne yield very little in terms of further emission reduction. The results also indicate that stabilising fleet emissions at current levels is obtainable at moderate costs, compensating for fleet growth up to 2030. However, significant reductions beyond current levels seem difficult to achieve. Marginal abatement costs for the major ship types are also calculated, and the results are shown to be relatively homogenous for all major ship types. The presented data and methodology could be very useful for assisting the industry and policymakers in selecting cost effective solutions for reducing GHG emissions from the world fleet.

International shipping is a significant contributor to global greenhouse gas (GHG) emissions, and is under mounting pressure to contribute to overall GHG emission reductions. There is an ongoing debate regarding how much the sector could be expected to reduce emissions and how the reduction could be achieved. This paper details a methodology for assessing the cost-effectiveness of technical and operational measures for reducing CO 2 emissions from shipping, through the development of an evaluation parameter called the Cost of Averting a Tonne of CO 2 -eq Heating, CATCH, and decision criterion, against which the evaluation parameter should be evaluated. The methodology is in line with the Intergovernmental Panel on Climate Change (IPCC) and with regulatory work on safety and environmental protection issues at the International Maritime Organization (IMO).The results of this study suggest that CATCH 550 $/tonne of CO 2 -eq should be used as a decision criterion for investment in emission reduction measures for shipping. In total, 13 specific measures for reducing CO 2 emissions have been analysed for two selected case ships to illustrate the methodology. Results from this work shows that several measures are cost effective according to the proposed criterion. The results suggest that cost effective reductions for the fleet may well be in the order of 30% for technical measures, and above 50% when including speed reductions. The results of this study show that the cost effectiveness approach for the regulation of shipping emissions is viable and should be pursued in the ongoing regulatory process.

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This article examines the quest for data in the negotiations on the reduction of greenhouse gases in the International Maritime Organization (IMO) from 2012 to 2020. We find that the collection of data was invoked in two different manners: holding back decision-making on emission-reduction regulations and helping the greenhouse gas negotiations move forward out of gridlock. We draw on insights from literature in science and technology studies on the politics of data and boundary objects to explore how these strategies are entangled over time. We argue that aligning around data collection and an ambiguous “three-step approach” to decision-making initially facilitated collaboration between IMO delegations despite disagreement on details. We examine how the three-step approach later morphs into what we call a mechanism for delay over the course of the negotiation period, challenging regulatory development at the pace required by opening for continuous calls for more data.