Regulating speed: a short-term measure to reduce maritime GHG emissions

Maritime shipping GHG emissions are projected to increase by 20-120% between 2012 and 2050. In fact, they have increased by 2.4% in the period 2013-2015.The Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) is working on a Comprehensive Strategy on the Reduction of Greenhouse Gas Emissions from Ships. Amongst others, the Strategy will contain a list of candidate short- medium- and long-term measures to reduce emissions.

One of the few measures that will deliver emission reductions in the short-term, is slower steaming.
This report shows that speed of ships can be regulated either globally, unilaterally as a condition of entry into a port or as a condition to navigate in coastal waters, or bilaterally between ports in two states. In order to effectively reduce emissions, speed regulations have to be mandatory and there has to be an enforcement system that deters ships from not complying. Speed regulations can best be differentiated to ship type and size so that ships do not have to operate at technically challenging low loads and in order not to disturb the competition between ship types. An issue that needs to be studied in more detail is whether it is more effective to regulate average or maximum speeds. Probably regulating maximum speeds is easier to implement, because it does not require regulation on how averages would be calculated. Requiring ships to slow down to such an extent that the idle and laid-up ships would be drawn back into the fleet would reduce emissions immediately by 4%. Further speed reductions of 20-30% would put shipping emissions on a declining pathway, thus contributing to reaching the goals of the Paris Agreement.