Five reasons why the climate benefits of Arctic shipping might be too good to be true

On Monday, the first vessel arrived in the UK as part of the China-Europe Arctic Express service. By travelling through the Arctic instead of using conventional shipping routes, the Istanbul Bridge cut its journey time, with reports that this led to reduced emissions. However, as our Scientific Officer James Kershaw investigates, the overall climate impact of Arctic shipping is more complicated than initial comparisons suggest.

The sight of a container ship coming into the Port of Felixstowe is hardly unusual – the port is Britain’s largest, with 2,000 ships calling at its docks every year. However, there was particular interest on Monday night, as the 300m long container vessel Istanbul Bridge sailed into port.

The vessel had travelled to the UK from Ningbo, China. Again, there’s nothing unusual about this – in 2024, the UK’s ports handled incoming main freight equivalent to roughly 5m 20 ft containers, of which by volume more than 30% came from China. However, the ship left China on the 22nd September, meaning it took just under 21 days to make a journey which, on average, usually takes somewhere between 30 to 50 days. The reason the Istanbul Bridge made this transit so quickly? She travelled through the Arctic, along what is known as the Northern Sea Route.

The Istanbul Bridge is not the first vessel to traverse the Northern Sea Route this year. However, the voyage is significant, marking the inaugural sailing of what is being marketed as the China-Europe Arctic Express service.

Various media outlets have picked up on this story, with some highlighting claims that this voyage through the Arctic reduces carbon emissions by more than 50%, compared with taking conventional routes. Other articles have alleged that the voyage aligns with "Britain’s broader decarbonisation and Net Zero targets", while some logistics companies are arguing the emissions reductions can help "businesses meet sustainability targets". But is Arctic shipping really more sustainable than conventional routes?

Three routes from China to the UK

Until recently, ships travelling from China to the UK and Europe usually did so by first travelling south and east through the Pacific and then Indian oceans, before using the Suez Canal to cut into the Mediterranean and head north through the Atlantic. From Ningbo to Felixstowe, that’s a journey of around 20,000km, which takes roughly 30 days at a reasonable average speed of 15 knots (for the landlubbers amongst us, that’s about 28km/h).

However, since November 2023, Houthi rebels have attacked commercial ships in the Gulf of Aden and the Red Sea. According to Lloyd’s List around 100 attacks have been reported in the region to date, with the most recent being a missile attack on a Dutch-flagged cargo vessel which injured two crew members.

Shipping route options between Ningbo, China, and Felixstowe, UK. Actual routes and distances may differ. Northern Sea Route traced using NGA Arctic Open Data, basemap uses Esri World Continents, map produced in QGIS version 3.34.13.  

As a result, many shipping companies have chosen to avoid the region altogether, instead diverting their ships around the southern tip of Africa. This adds around 6,500km to the total journey length – that’s another 10 days at a speed of 15 knots. This diversion adds costs to consumers, creates logistical challenges and adds emissions, but not everyone loses out: freight rates have soared, and big shipping companies have cashed in.

There is, however, another alternative. In the North Pacific, the Bering Strait provides passage into the Arctic Ocean. From here, vessels can follow the Northern Sea Route, tracking west along the northern coast of Russia, before heading south into the North Sea bound for the UK and Europe.

Historically, much of the Arctic Ocean was covered by sea ice year-round, making navigation along the Northern Sea Route challenging. The Arctic, though, is extremely sensitive to climate change, and has warmed nearly four times as much as the rest of the globe over the past 40 years, accompanied by significant loss of sea ice cover. As a result, the Northern Sea Route has become increasingly navigable, and by 2100 projections suggest that year-round navigation will be possible. This forms part of what is referred to by some as an “Arctic opening”, and is set to take place in the context of wider geopolitical motivations and tensions spanning the region. These issues are thrown into sharp relief along the Northern Sea Route, which the Russian state views as an integral piece of its political strategy.

From Ningbo to Felixstowe, the journey through the Arctic via the Northern Sea Route is around 15,000km in length, some 20% shorter by distance than travelling through the Suez Canal and 40% shorter than diverting around South Africa. At 15 knots, a vessel would theoretically make the journey in about 23 days. This is the route the Istanbul Bridge took, leaving Ningbo on September the 22 and arriving in Felixstowe 21 days later on Monday evening. The ship therefore travelled at an average speed of more than 16 knots, but faced slight delays given original expectations that the voyage would take 18 days.

But is sailing from China to the UK in half the time, with half the emissions, really possible? Here are 5 reasons why the climate benefits of Arctic shipping might be too good to be true…

1. We need more details about the route and journey

All else being equal, a ship’s greenhouse gas emissions will be proportional to the amount of fuel burned, and thus distance travelled. The Arctic route travelled by the Istanbul Bridge (~ 15,000km) is only about 20% shorter than the route through the Suez Canal (~ 19,000km) but is 40% shorter than the route via South Africa (~ 26,000km).

The claimed 50% carbon emissions reductions are therefore only possible when comparing to the longer conventional route. Our calculations are not based on the exact route the vessel took, meaning the distance reduction may be slightly more or less than we’ve calculated here. However, it appears additional factors are needed to explain a reduction in emissions of more than 50%, for example reduced time waiting to enter a port owing to the vessel arriving before heavy seasonal traffic.

2. Fuel is a factor

Another key factor determining any ship’s emissions is the fuel used.

Most vessels travelling on conventional routes use forms of Heavy Fuel Oil (HFO). The International Maritime Organization (IMO) introduced a ban on the use of HFO in the Arctic from July 2024, though loopholes on its use are set to persist until 2029. It is possible that for this voyage the Istanbul Bridge used a different fuel, perhaps resulting in emission reductions. The ship’s owners are yet to confirm which fuel was used, despite public calls to do so.

Considering only the factors in these first two reasons, the 50% emissions reductions claimed for this voyage might just be possible, though are far from guaranteed. However, it is also important to account for other factors which might increase the climate impact of using Arctic shipping routes.

3. Additional sources of emissions must be accounted for

For instance, safety regulations set out vessel ice-strengthening requirements. As a general rule, these add weight, increase required engine sizes and reduce cargo capacity, which can in turn increase fuel consumption, and therefore emissions, for some vessel types (though not all). Istanbul Bridge reportedly has a low 1C ice class, meaning that instead, it may have needed to be accompanied by an icebreaker escort if it encountered thicker ice along route. These icebreakers would not be required on a conventional route, and the emissions associated with their operation must also be accounted for.

4. Delays and diversions increase emissions

Ships traversing the Arctic may experience severe weather conditions such as fog, slowing their transit, or be diverted to avoid sea ice, increasing the distance travelled, fuel burn and emissions. Just over a month ago, a sanctioned Russian LNG tanker was reportedly diverted and delayed by sea ice on the Northern Sea Route. The Istanbul Bridge was originally scheduled to arrive in Felixstowe on the 10th October, but actually arrived 3 days later on the 13th, though we do not yet know the cause of this delay.

5. Black carbon tips the balance?

Perhaps the most important factor of all, though, is the impact of black carbon emissions. Black carbon – or soot – is a powerful, short-lived, climate pollutant, with a 100-year global warming potential (GWP) hundreds of times higher than CO2.

In the atmosphere, black carbon contributes to warming by absorbing incoming solar radiation, before it falls and is deposited on the Earth’s surface. This deposited soot reduces the reflectivity of the normally white surface of sea ice and snow, further increasing the absorption of solar radiation.

Because of the proximity to sea ice and snow, black carbon emitted in the Arctic – for instance due to Arctic shipping – has a particularly strong climate impact. One study found that, when considering climate impacts over the next 150 years and comparing Arctic and conventional shipping routes, the increased warming from Arctic shipping’s black carbon emissions would outweigh the cooling impacts of reduced CO2 emissions.

Other environmental and social impacts

Beyond climate impacts, there are also concerns that increased levels of commercial shipping in the Arctic will increase risks to Arctic ecosystems and indigenous communities. Oil spills represent a particular challenge, due to the hazardous nature of the route, cold temperatures, remoteness of the area and severity of conditions, which conspire to simultaneously increase the likelihood of a spill, while delaying and inhibiting clean-up operations. These same factors heighten safety risks for seafarers and coastal communities alike.

Other environmental risks include the introduction of invasive and non-native species and marine mammal disturbance due to increased underwater noise. These environmental impacts of increased Arctic shipping, coupled with increased infrastructure required to support the industry, could cause wide-ranging impacts on indigenous Arctic communities.

Arctic shipping, climate change and geopolitics

The Istanbul Bridge made the journey from China to the UK in (nearly) double-quick time, however, claims of climate or sustainability benefits from taking this route must account for a range of factors. Especially important is the impact of Arctic black carbon emissions, as are the wider environmental, social and safety impacts of Arctic shipping.

In response to these concerns, a number of major shipping companies, including both Maersk and Hapag-Lloyd, have signed the voluntary Arctic shipping pledge, committing to not sending vessels through the Arctic. More broadly, the case for increased protection of the Arctic from shipping activities has never been clearer, and the IMO must take action to strengthen regulations at its next round of meetings in early 2026.