IMO's New GHG Study Identifies Troubles Ahead


Published May 7, 2015 7:16 PM by Wendy Laursen

The IMO has released the Third IMO Greenhouse Gas Study 2014 report saying emissions from shipping have dropped; that’s the good news.

IMO Secretary-General, Koji Sekimizu, says the mid-range forecasted scenarios presented in the report show that, by 2050, CO2 emissions from international shipping could grow by between 50 percent and 250 percent, depending on future economic growth and energy developments. 

“Therefore, if we are to succeed in further enhancing the sector’s energy efficiency, which is already the most energy-efficient mode of mass transport of cargo, the international community must deliver realistic and pragmatic solutions, both from a technical standpoint and a political perspective. I believe that 2015 will be a crucial year for progress on difficult and complex matters in the world’s climate change negotiations, culminating in the international conference to be convened in Paris in December 2015, which should identify the way forward for all sectors.

“IMO will bring the findings of the Study to the attention of Parties to the United Nations Framework Convention on Climate Change (UNFCCC) and I am confident that, in the light of the progress made by the Organization, both in gathering relevant information and in supporting implementation of the package of mandatory technical and operational measures, we have a positive message to convey to the global community.”


According to estimates presented in the report, international shipping emitted 796 million tons of CO2 in 2012, which accounts for no more than about 2.2 percent of the total emission volume for that year. By contrast, in 2007, before the global economic downturn, international shipping is estimated to have emitted 885 million tons of CO2, which represented 2.8 percent of the global emissions of CO2 for that year. 

SOx and NOx

The study estimates multi-year (2007–2012) average annual totals of 20.9 million and 11.3 million tonnes for NOx (as NO2) and SOx (as SO2) from all shipping, respectively (corresponding to 6.3 million and 5.6 million tonnes converted to elemental weights for nitrogen and sulphur respectively). Global NOx and SOx emissions from all shipping represent about 15 percent and 13 percent of global NOx and SOx from anthropogenic sources respectively.

Annually, international shipping is estimated to produce approximately 18.6 million and 10.6 million tonnes of NOx (as NO2) and SOx (as SO2) respectively. International shipping NOx and SOx represent approximately 13 percent and 12 percent of global NOx and SOx totals respectively.

Fuel Consumption

The total fuel consumption of shipping was dominated by three ship types: oil tankers, container ships and bulk carriers. Consistently for all ship types, the main engines (propulsion) were the dominant fuel consumers. These three most significant sectors of the shipping industry from a CO2 perspective experienced different trends over the period of the study (2007–2012). All three contain latent emissions increases (suppressed by slow steaming and historically low activity and productivity) that could return to activity levels that create emissions increases if the market dynamics that informed those trends revert to their previous levels.

The Future 

Maritime CO2 emissions are projected to increase significantly in the coming decades. Depending on future economic and energy developments, study scenarios project an increase by 50 percent to 250 percent in the period to 2050. Further action on efficiency and emissions can mitigate the emissions growth, although all scenarios but one project emissions in 2050 to be higher than in 2012.

Emissions projections demonstrate that improvements in efficiency are important in mitigating emissions increase. However, even modelled improvements with the greatest energy savings could not yield a downward trend. Compared to regulatory or market-driven improvements in efficiency, changes in the fuel mix have a limited impact on GHG emissions, assuming that fossil fuels remain dominant.


“I trust that the Third IMO GHG Study 2014 will become the paramount reference for the Organization’s Marine Environment Protection Committee as it continues its consideration of further appropriate measures as part of a robust regime to regulate international shipping emissions at the global level,” says Sekimizu.

The MEPC will consider the report of a correspondence group established to develop draft text for a data collection system for fuel consumption of ships that can be used for voluntary or mandatory application of the system. 

The European Parliament recently adopting a regional EU Regulation on the Monitoring, Reporting and Verification (MRV) of individual ship emissions of CO2, to the disappointment of the International Chamber of Shipping (ICS), BIMCO and Intercargo. 

The organizations believe the EU is pre-empting the current IMO negotiations on a global data collection system on shipping’s CO2 emissions by adopting a unilateral, regional Regulation on the Monitoring, Reporting and Verification of individual ship emissions – which will also apply to non-EU flag ships trading to Europe – in advance of IMO completing its work.

The EU Regulation includes controversial elements, such as the publication of commercially sensitive data on individual ships, an idea which had previously been rejected by the majority of IMO governments during a meeting of the MEPC in October 2014.

The full report is available here.