Shipping’s carbon footprint has fallen over 20% over the past decade, but the industry still has some way to go to meet IMO targets, according to Clarksons Research analyst Trevor Crowe.

“The world fleet’s ‘footprint’ is estimated at 819 million tonnes of CO2 this year, and IMO targets aim for a 50% reduction by 2050 compared with the 1bn tonnes in 2008,” Crowe said.

“This total is similar in size to the overall annual CO2 output of Germany, but it is also worth noting that shipping’s CO2 total last year was equivalent to only 2% of total world CO2 emissions.”

Crowe said that with shipping’s cargo base amounting to about 60,000 bn tonne-miles of seaborne trade this year, the world fleet’s CO2 output equates to an estimated ‘intensity’ of 14t of CO2 per million tonne-mile transported.

In contrast, he said historical estimates for rail range between 16-190t per million tonne-mile, while those for road transport of between 128-290t and for air cargo it is anywhere between 700t and 2,900t per tonne-mile highlighting shipping’s relative “carbon efficiency”.

But of course, Crowe said shipping accounts for around 85% of all international trade, so the absolute total “remains a challenge”.

However, the industry has seen a reduction in its carbon footprint over the last decade, according to Crowe.

“In 2008 the world fleet’s total CO2 output measured an estimated 1bn tonnes, and had dropped by 19% by 2018,” he said.

“Growth in trade, up 37% in tonnes, and the fleet, up 74% in gross tonnage terms has been outweighed by the impact of more fuel efficient ‘eco’ vessels and reductions in average speed, down an estimated 16% across the world fleet since 2008.

“But of course the decarbonisation targets are still daunting, and ‘business as usual’ is not an option. Changes in trading patterns, speed and vessel technology may all be needed to meet the goals,” he said.

Containerships, with their generally higher speeds, account for 182 million tonnes of CO2 output annually, or 22%. Bulkers come a close second at 158 million tonnes, or 19%, while tankers account for 114 million tonnes, or 14%.

Vessel size also has an impact. A VLCC based on a standard ‘modern’ ship operating for a year has an output of 187 tonnes per day (tpd) of CO2, 66% more than a suezmax which has an output of 113 tpd.

“But, on a CO2 per cargo tonne-mile basis, the larger ship is 55% more carbon efficient,” said Crowe.

“Whether a focus on larger ships is the clear answer when pressures might point towards more regional trading, is a significant debate,” he adds.

In conclusion, Crowe said that across transport modes, shipping looks like a “positive option” on a per tonne-mile basis, and its CO2 output has already dropped by almost 20% since 2008.

“However, carbon targets are still tough, and owners, shippers and participants across the industry spectrum still have plenty of debate and challenging decisions ahead of them yet,” he added.