The map on my computer screen shows most of the ocean between the Arctic and Antarctic circles swarming with tiny yellow dots. They look like a vast cloud of fireflies covering the globe, but each one represents the location of the more than 50,000 cargo ships currently at sea.
This map makes visible the enormous scale and never-ending nature of the global shipping industry. The backbone of international trade, it is responsible for transporting roughly 90 per cent of everything we buy. Although shipping is the least carbon-intensive form of mass transport per tonne, the huge amount of cargo that is shipped means the industry has an enormous carbon footprint. If it were a country, it would be the sixth biggest emitter on Earth, accounting for about a billion tonnes of greenhouse gas emissions every year – about 3 per cent of the global total.
Yet this industry is one that “nobody ever really thinks about”, according to Shane Keating, an oceanographer and associate professor of applied mathematics at UNSW Sydney. “It’s one of these invisible industries. It underpins the global economy but it’s out of sight and out of mind.”
Keating spends a lot of time thinking about this industry and, in particular, how to achieve the International Maritime Organization’s goal of net zero greenhouse gas emissions from international shipping by 2050. It’s going to be a challenge. Shipping is one of the most difficult industries to decarbonise, Keating says, because of the immense size of the existing fleet, which runs on dirty “bunker fuel”, and the performance constraints of currently available green technologies.
“You can’t electrify ships that cross the ocean,” Keating says. “Batteries don’t work that long.”
The scientist has, however, developed what he says is a simple method for significantly reducing emissions from shipping immediately, one that harnesses the immense and untapped power of the “storms of the ocean”: eddies.
Mariners have known about and utilised ocean currents for centuries.
In August 1785, while sailing back to North America from Europe aboard the London Packet, Benjamin Franklin wrote a long letter to a scientific colleague in Paris in which he detailed “sundry maritime observations” – including about the effect of major ocean currents such as the Gulf Stream on maritime journeys.
“Vessels are sometimes retarded, and sometimes forwarded in their voyages, by currents at sea, which are often not perceived,” Franklin wrote.
To help others perceive the powerful Gulf Stream, Franklin included in his letter the first known map of it. Since then – and especially since satellite observations of the ocean commenced in 1992 – large currents have become even more perceptible. Recently, so too have smaller ocean processes such as eddies.
There are thousands of these swirling, circular currents of seawater on Earth. They form by spinning off larger ones such as the East Australian Current, and range in diameter from 10 kilometres to up to 300 kilometres. They can flow in both clockwise and anticlockwise directions at a rate of up to four kilometres an hour.
Despite their slow speed, eddies contain more energy than tropical cyclones due to the fact that water is roughly 800 times denser than air. In fact, they contain about 90 per cent of the total amount of kinetic energy that exists in the ocean.
Improved ocean data collected from ships – including through the Ship of Opportunity Program, a partnership between the maritime industry and the National Oceanic and Atmospheric Administration – is one reason these energetic, albeit unpredictable, oceanic weather systems are better understood and able to be incorporated into ocean forecasts. Another is advancements in satellite technology, as exemplified by the Surface Water and Ocean Topography (SWOT) satellite.
Launched in December 2022 as part of a joint mission by NASA and the Centre National d’Études Spatiales, the French space agency, this satellite is fitted with an instrument called the Ka-band radar interferometer that can map, in unprecedented detail, the ocean’s topography. Scientists can then use this data to better understand the location and behaviour of eddies and currents, which slightly depress or raise the surface of the ocean.
SWOT is a “game changer”, says Nathan Bindoff, professor of physical oceanography at the University of Tasmania and a coordinating lead author on multiple Intergovernmental Panel on Climate Change (IPCC) reports.
“Instead of talking about ocean currents at a 100-kilometre scale, we’re now down to the 10-kilometre scale. That really is transformational.”
Keating, a principal investigator on the SWOT mission, started properly thinking last year about how this new and improved view of the ocean and its processes could be applied to reduce the emissions of the shipping industry.
His was an expanded and updated version of Benjamin Franklin’s idea from more than two centuries ago: combine artificial intelligence with state-of-the-art ocean forecasts to offer cargo ships optimised routes that go with the flow of eddies and therefore reduce fuel usage.
“It’s essentially Google Maps for the sea, which offers the most efficient route in real time based on the behaviour of ocean eddies,” Keating says.
Comparative hindcast modelling by Keating demonstrates this does not delay travel. Nor does it require a substantial deviation from existing routes, which follow a straight line between two ports but often go directly against the flow of regional eddies.
For example, if the 212-metre-long container ship Botany had followed Keating’s optimised route between Sydney and Wellington, it could have completed the 384 nautical mile-long journey in the same amount of time – just over 24 hours – but used roughly 17 per cent less fuel. This is because it would have tracked with the flow of a large anticlockwise eddy in the Tasman Sea.
Extrapolating from this and similar experiments, Keating believes the global shipping industry could cut its total fuel usage by 10 per cent with his route optimisation algorithm, which he is offering through his just-launched UNSW spin-off company named Ocean Intelligence. He estimates savings of nearly US$50 billion and 237 million tonnes of CO2 emissions every year.
Many of Keating’s colleagues are on board with his initiative and believe there are few challenges preventing it from being widely employed by the shipping industry. “I think it’s a beautiful application of the detailed oceanographic measurements that are actually being collected nowadays,” Bindoff says.
Peter Oke, a physical oceanographer at the CSIRO, agrees. “Clever ship routing can save fuel and save time. It can help a vessel meet a deadline, avoid a storm and, most importantly for our warming climate, reduce fuel emissions – an important step towards net zero.”
In August 2023, the Pyxis Ocean – a 229-metre-long cargo vessel partly powered by two large, rigid sails fitted to its hull – set out on its first voyage from China to Brazil. This marked the first real-world test of a wind-powered cargo ship. The following month, the shipping industry achieved another important milestone for its net zero future when the Laura Maersk, the world’s first green methanol container vessel, completed its maiden voyage from South Korea to Denmark.
However, even though these technologies are promising, they are, according to Keating, also very expensive and still a way from being implemented at scale. By contrast, he says, his solution is “available now and requires nothing more than modifying a ship’s route a little bit”. He hopes to build on the Ship of Opportunity Program and start attaching low-cost, easy-to-use sensors to cargo ships to transform even more of them into ocean weather stations and so improve the accuracy of the forecasts Ocean Intelligence delivers – and the extent of fuel savings for ships.
He has had moments worrying his invention might enable shipping companies to “kick the can down the road” and keep “gas-guzzling” ships in operation for longer, rather than shifting to net zero technologies. This concern is outweighed, however, by his belief in the importance of optimising shipping routes – both now and in the decades to come.
“I’m a scientist, an earth scientist. My number one concern is reducing emissions, as quickly as possible. And when ships do eventually move to green fuels, there will be an even greater need to improve their efficiency, because those fuels are so much more expensive.
“My hope is that this solution will get us part of the way to a sustainable future.”
This article was first published in the print edition of The Saturday Paper on
June 1, 2024 as “Going with the flow”.
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