Third IMO Greenhouse Gas Study 2014

Inventories of emissions of GHGs and other relevant substances 101
Table 38 – Global warming potential of refrigerants commonly used in ships. The GWP100 is described
relative to CO 2 warming potential (IPCC Fourth Assessment Report: Climate Change 2007)
Refrigerant
Warming potential
(relative to CO 2 )
R-22 1,810
R134a 1,430
R404a 3,260
The release of refrigerants from global shipping is estimated at 8,412 tons, which corresponds to 15 million
tons (range 10.8 million tons–19.1 million tons) in CO 2 e emissions. Inclusion of reefer container refrigerant
emissions yields 13.5 million tons (low) and 21.8 million tons (high) of CO 2 e emissions. If these numbers
are compared to CO 2 emissions of shipping during 2011 (top-down estimate of 794 million tons of CO 2 ),
refrigerant emissions constitute about 1.9% of the GHG emissions of shipping. Inclusion of the reefer TEU
increases this to 2.2% of the total GHG emissions from shipping.
Refrigerant emissions from ships 2007–2012
The emissions of refrigerants from ships are mainly affected by changes in the size and composition of the
global fleet. The methodology used to assess refrigerant emissions is driven by the age structure of each ship
type rather than the activity patterns of vessels. This assumption makes the annual emission changes small
(Figure 71) but nevertheless consistent with the UNEP report (2010). Also, the dominant substance is R-22
(70% share), which is in line with previous studies (UNEP 2010; DG ENV 2007).
Figure 71: Estimated refrigerant emissions of the global fleet 2007–2012
The slow decrease of R-22 share in ship systems (Table 39) means that R-22 will be present for a long time,
possibily decades, before it is replaced by other substances.