Under most nations' Kyoto Protocol commitments, all industries have to reduce Co2 emissions by 50% by 2050 -- a target that would be hard for the shipping industry to meet on its own, Svenson said.
"With seaborne trade growing, it will be difficult for shipping to deliver an absolute reduction in CO2 emissions by 2050," he said. "However, it would be possible to remain at around 2008 levels," he added.
Svenson said the world's total man-made emissions of CO2 were estimated at 32 billion mt/year, 13% of which were contributed by the transport sector.
Shipping alone contributed close to 2-3% of the total, or 17% of the transport sector's.
However, shipping remained more energy-efficient than other forms of cargo transport, he noted.
"More shipping is part of the solution," Svenson said, adding that Japan was aiming to reduce the Co2 emissions of new-build ships by 30% by 2011.