Global breakthrough agreement to tackle shipping emissions

Shipping accounts for around 3% of global emissions. But unlike many other sectors it has struggled to reduce its carbon footprint over the last decade and is reliant on fossil fuels like diesel.

But the agreement means it is now the first industry in the world with internationally mandated targets to reduce emissions.

The agreement was passed at the UN's International Maritime Organisation (IMO) meeting.

It will require owners of large international vessels to increase their use of less carbon intensive fuels or face a penalty of up to $380 per tonne of carbon dioxide emissions they emit from burning fuel.

Although the final agreement was passed, it had to be put to a vote - an unusual move for UN bodies that usually agree measures by consensus.

The vote was requested by Saudi Arabia, who did not support the agreement, and this position was shared by a dozen other oil-producing nations, including Russia.

Although they opposed the proposal, they will be bound to implement it because they are members of the IMO.

There have been moves to improve the efficiency of ships, but emissions have continued to increase in line with global trade - 90% of which is carried by ships.

The most effective measure would be to switch ships away from fossil fuels to green fuels, but that would be very expensive.

"There is no fuel as cheap as diesel that ships use today because when we take crude oil out of the ground, we take out all the nice bits, that's the kerosene for aviation, diesel and petrol for cars," said Faig Abbasov, programme director for maritime transport at think tank Transport and Environment.

"Whatever is left at the bottom, that's what ships burn. So no fuel will be as cheap as this because not much energy goes into its production," he said.

In comparison, the most environmentally friendly fuels like e-kerosene and ammonia are created from initially splitting water atoms to obtain hydrogen, which is a very energy-intensive and costly process.

Figures vary depending on the fuel type but the World Economic Forum estimates that these green fuels are 3-4 times more expensive to produce.

"There's still a huge cost gap between the fossil fuels and the zero emission fuels and we need to close this gap. So you need carrots and sticks and in shipping the stick is not that big yet to use sustainable fuels," said Refke Gunnewijk, program manager for sustainable transport at the Port of Rotterdam.