Carbon emissions from global shipping could almost double to two billion tonnes a year by 2020, according to new figures from Netherlands-based shipping technology specialist DK Group.

The estimate is some 500m tonnes higher than official International Maritime Organisation (IMO) projections, prompting DK Group chief executive Christian Eyde Moeller to warn that emissions from the sector are growing faster than expected.

DK Group specialises in so called air cavity systems that enhance the fuel efficiency of ships by reducing the frictional resistance of the hull's surface by directing air through the ship's hull, and as such has a vested interest in promoting emissions reduction measures for the shipping industry.

But Eyde Moeller stood by the company's calculations, insisting they were robust and accurate. "We undertook research last year since backed up by a similar report from [oil tanker association] Intertanko that suggested there was a substantial gap between official estimates of emissions and the actual situation," he explained. "If you take that base line and look at new build data and order pipelines for the ship building industry it is not complicated to conclude that the IMO estimates for 2020 are well below what emissions will actually be."

A spokesman for the IMO said that its most recent estimates for greenhouse emissions were undertaken in 2000 and as such were likely to be outdated. He added that the organisation was now working on fresh projections and was expected to publish new research on shipping's carbon footprint this October.

The DK Group figures come just days after the IMO announced a raft of plans designed to limit the shipping industry's environmental impact.

At a meeting in London last week the IMO's Marine Environment Protection Committee (MEPC) agreed a range of amendments to the MARPOL Annex VI regulations that will impose tough new air quality standards on ships.

Under the changes, which are expected to come into effect between 2010 and 2016, ship operators will be required to deliver progressive reductions in sulphur oxide emissions and nitrous oxide emissions. The moves are expected to impose major costs on ship operators and have a knock on impact on oil refiners who will be required to provide shipping firms with diesel containing lower sulphur content.

The London meeting also made progress towards developing a regulatory framework for curbing shipping's greenhouse gas emissions with delegates discussing a raft of proposals, including plans to impose a global levy on bunker fuels, promote increased use of wind power, improve traffic management to shorten journey distances, enforce speed reductions for vessels, introduce standardised emission reporting, and incorporate ship operators in emissions trading schemes.

The next round of talks of the IMO's GHG Working Group is now scheduled for Norway in June, where IMO Secretary-General Efthimios E. Mitropoulos expressed confidence further progress could be made. "As we look beyond Kyoto, we should be able to put in place a robust regime that will apply fairly to shipping while, at the same time, achieving our main objective of protecting the marine and atmospheric environment," he said.

DK Group's Eyde Moeller insisted that a robust regulatory regime would ultimately be required to curb shipping emissions, arguing that a voluntary approach would prove inadequate.

"There is a direct link between CO2 emissions and fuel consumption, yet despite the fact fuel represents around 50 per cent of ship operators costs they are still not making the transition to more fuel efficient approaches quick enough," he said. "Regulations will be needed to challenge operators to make the required changes."