The shipping sector, like aviation, was excluded from any target cuts under last year's Paris climate deal, which set a goal of restricting the rise in global average temperature to less than 2 degrees Celsius.
Shipping now makes up around 2.2 percent of world emissions of carbon dioxide, the main greenhouse gas responsible for global warming, and that share is forecast to rise dramatically if nothing is done to slow it.
The International Maritime Organization, the U.N. agency responsible for regulating pollution from ships, forecasts CO2 emissions from vessels rising anywhere between 50 percent and 250 percent by 2050 in its "business as usual" case, as economies grow and trade increases.
So far, specific targets to curb emissions growth have been blocked by emerging countries like India and Brazil, which expect their shipping volumes to increase over the next decades.
But some shipping companies, especially ones that have invested in newer, more fuel-efficient ships, say the IMO should take action to limit emissions, before regulation is imposed by regional blocs like the European Union or individual states.
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