Most other emissions increase in parallel with CO2
and fuel, with some notable exceptions. Methane
emissions are projected to increase rapidly (albeit
from a low base) as the share of LNG in the fuel
mix increases. Emissions of NOx
may increase at
a lower rate than CO2
emissions as a result of tier
II and tier III engines entering the fleet. Emissions
of PM show an absolute decrease until 2020, and
SOx
continue to decline through 2050, mainly
because of MARPOL annex VI requirements on
the sulphur content of fuels