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132 Third IMO GHG Study 2014
In all cases of ship-transported products, the non-linear Verhulst regression model (with S-shaped curve) is
used to reflect more realistic market behaviour rather than continued linear relationships. The historical data
on transport work (by type) and demand and GDP are shown in Figure 79.
Figure 79: Historical data on world coal and oil consumption, coal and oil transported (upper panel),
total (non-coal) bulk dry goods, other dry cargoes and global GDP (lower panel)
Predicted proxy data of (separate) coal and oil demand and GDP were provided by the RCP/SSP scenarios and
the associated underlying IAMs. In one case (RCP6.0), fossil energy demand data could not be obtained and
data from the IAM GCAM were used.
3.2.4 Fleet productivity
For the emissions projection, the development of the tonnage of the different ship types is determined by a
projection of the ships’ productivity, defined as transport work per deadweight tonne. More precisely, the fleet