Third IMO Greenhouse Gas Study 2014

Inventories of CO2 emissions from international shipping 2007–2012 49
dry bulk fleet, whereas the container ship fleet has seen a slight increase. Consistent with the results presented
in Table 17, more container ships adopted slow steaming operations. In other words, similar reductions in
average fuel consumption per ship over the study period were achieved through different combinations of
speed and days at sea.
The analysis of trends in speed and days at sea are consistent with the findings from Section 3 that the global
fleet is currently at or near the historic low in terms of productivity (transport work per unit of capacity).
(See Section 3.2.4 and related text and Annex 7, Figures 38–40, for further details.) The consequence is that
these (and many other) sectors of the shipping industry represent latent emissions increases, because the
fundamentals (number of ships in service, fleet total installed power and demand tonne-miles) have seen
upward trends. These upward trends have been controlled because economic pressures (excess supply of
fleet as demonstrated by the relative supply and demand growth in each plot), together with high fuel prices,
have acted to reduce productivity (reducing both average operating speeds and days spent at sea in both the
oil tanker and bulk carrier fleets, and only operating speeds in the container fleets). These two components
of productivity are both liable to change if the supply and demand differential returns to historical long-run
trends. Therefore, whether and when the latent emissions may appear is uncertain, as this depends on the
future market dynamics of the industry. However, the risk is high that fleet “potential to emit” (e.g. fleetaverage
installed power and design speeds) could encounter conditions favouring the conversion of latent
emissions to actual emissions; this could mean that shipping reverts to the trajectory estimated in the Second
IMO GHG Study 2009. The potential for latent emissions to be realized is quantified in the sensitivity analysis
in Section 3.3.4 (see Figure 88 and related text).