IMO Work on Greenhouse Gas Emissions Estimate

Work to update the greenhouse gas (GHG) emissions estimate for international shipping moved forward during an Expert Workshop at IMO Headquarters during 26 February to 1 March 2013. A final study is expected to be delivered in 2014. The second IMO GHG Study 2009 had estimated that international shipping emitted 870 million tonnes, or about 2.7% of the global man-made emissions of carbon dioxide (CO2) in 2007.

Exhaust gases are the primary source of GHG emissions from ships, with CO2 the most important GHG, both in terms of quantity and of global warming potential.

As the current estimate contained in the Second IMO GHG Study 2009 does not take account of the economic downturn experienced globally since 2008, an updated GHG emissions estimate should provide MEPC with reliable and up-to-date information to base its decisions on when considering further possible measures to address GHG emissions from international shipping.

An updated emissions estimate would also provide a baseline to enable the impact to be assessed of technical and operational energy efficiency measures for international shipping that entered into force on 1 January 2013 (refer to MARPOL Annex VI Requirements for Technical and Operational Measures).

The Expert Workshop agreed that the primary focus of the Update Study should be to update the CO2 emission estimates for international shipping. It recommended that the MEPC agree Terms of Reference for the update including the methodology, so that work could begin in 2013, with a view to the final report of the Update Study being submitted to the 66th session of the MEPC, to be held in 2014.

Noting that there have been improvements in both the availability and quality of data since the Second IMO GHG Study was published in 2009, the Expert Workshop recommended that the same approaches, both top-down (based on fuel sales data) and bottom-up (based on ship activity data), should be used in the Update Study to estimate GHG emissions for international shipping.

The Expert Workshop recommended also that should there be adequate resources then the same substances as those estimated by the Second IMO GHG Study 2009 should also be estimated.

In addition to CO2, a global estimate of emissions of other GHGs and relevant substances emitted from ships, engaged in international transport could include: