Third IMO Greenhouse Gas Study 2014

144 Third IMO GHG Study 2014
Table 79 – Emissions of CO 2 and other substances in 2012, 2020 and 2050 (million tonnes)
Greenhouse
gases
Other
relevant
substances
Scenario 2012 2020 2050
index (2012 = 100) index (2012 = 100) index (2012 = 100)
CO 2 Low LNG 100 108 (107–112) 183 (105–347)
High LNG 100 106 (105–109) 173 (99–328)
CH 4 Low LNG 100 1,600 (1,600–1,700) 10,500 (6,000–20,000)
High LNG 100 7,550 (7,500–7,900) 32,000 (19,000–61,000)
N 2 O Low LNG 100 108 (107–112) 181 (104–345)
High LNG 100 105 (104–109) 168 (97–319)
HFC 100 106 (105–108) 173 (109–302)
PFC – – –
SF 6 – – –
NO x Constant ECA 100 107 (106–110) 161 (93–306)
More ECAs 100 99 (98–103) 130 (75–247)
SO x Constant ECA 100 64 (63–66) 30 (17–56)
More ECAs 100 55 (54–57) 19 (11–37)
PM Constant ECA 100 77 (76–79) 84 (48–159)
More ECAs 100 65 (64–67) 56 (32–107)
NMVOC Constant ECA 100 108 (107–112) 183 (105–348)
More ECAs 100 106 (105–110) 175 (101–333)
CO Constant ECA 100 112 (111–115) 206 (119–392)
More ECAs 100 123 (122–127) 246 (142–468)
3.3.4 Sensitivity to productivity and speed assumptions
The scenario approach to these results allows an evaluation of the sensitivity of maritime transport emissions
to economic growth, fossil fuel energy use, marine fuel mix, market-driven or regulatory efficiency changes
and maritime emissions regulation.
This section discusses the most important remaining sensitivity: the impact of productivity and speed
assumptions on emissions projections.
All the projections presented here assume that the productivity of the fleet returns to long-term average values
without increasing the emissions of individual ships. This is possible if the cause of the current low productivity
is a low cargo load factor of ships. If, however, fleet productivity has decreased because ships have been laid
up or have slowed down, a return to long-term average productivity levels would result in higher emissions.
There are no data that enable the evaluation of whether cargo load factors are below their long-term average
levels and if so by how much. The data on speed and days at sea do show that ships have slowed down and
reduced their number of days at sea since 2007. Productivity of container ships and bulk carriers in 2007 was
at or near a 15-year maximum, while for tankers it was declining but still above the long-term average. Hence,
these factors have contributed to a reduction in productivity.
Figure 88 shows the impact of our assumption that the productivity of different ship types will return to its
long-term average values on the emissions projections. For reasons of clarity, the figure shows the impact
on one scenario; however, the impact on other scenarios is similar. If it is assumed that the productivity of
the fleet will remain at its 2012 level, CO 2 emissions will be 12% higher. This means that if the response to a
transport demand increase is to add proportionately more ships to the fleet, rather than to increase the cargo
load of ships, emissions will be 12% higher.