After a bad 2024, carbon emissions in the box shipping sector have started to fall again, according to the latest data provided by Xeneta, after monitoring pollution produced by vessels on the 13 top global ocean trades.
In 2024, the escalation of Red Sea conflicts resulting in longer average shipping distances in the East-West trades caused a serious increase in CO2 emissions on routes connecting the Far East with ports in the Mediterranean, Northern Europe and, to a lesser extent, the North American East Coast. However, an opposite trend has been recorded so far in 2025.
Using its Carbon Emissions Index (CEI), the Danish consultancy firm shows how, in the second quarter of 2025, this index fell below 100 points to 97.4 for the first time in 12 months.
The CEI index is calculated based on the average CO2 emissions produced by ships per tonne of cargo. Q1 2018 is the benchmark against which any value below one hundred indicates an improvement in efficiency over the past five years.
Although the vast majority of containerships are still opting for the alternative Cape of Good Hope route instead of the Suez one, it is a fact that in the Q2 2025 carbon emissions dropped to the point where they were only 1.5 percentage points higher than in April-June 2023, when transiting Suez was not considered to put the safety of ships and crews at risk.
“This clearly demonstrates that, if there is a resolution to the conflict and the Red Sea opens up at large, carbon emissions performance at a global level would drop significantly below the levels seen in 2023,” says analyst, Emily Stausbøll.
The second-quarter score shows a 4.5% reduction compared to the first quarter of 2025 and a 7% one compared to the fourth quarter of 2024, when the average index had reached its all-time high at 104.8.
The Red Sea routes, which link the Far East with Northern Europe and the Mediterranean, generally remained above 100 points in Q2.
However, fronthaul routes to the Mediterranean fell by 4.3% to 126.3 year-on-year, while those to Northern Europe were down 0.2% to 107.5. On both routes, emissions fell year-on-year by 12.8% and 2.7% respectively.
The routes with the best CEI score are the ones connecting the Far East to the US East Coast (71.2 points) and the US West Coast (71.1 points)
Xeneta points out that in terms of carbon emissions reduction, the best Q2 results were achieved by backhaul traffic from the US West Coast to the Far East, down 28.2% on the previous quarter, to 72.2 points. The reduction in capacity on fronthaul traffic improved the filling factor on backhaul trips, partially offsetting the increase in emissions.
On the flipside, carbon emissions from traffic from Northern Europe to the US east coast have increased the most: up 10.9% to 92 points compared to Q1 2025,. This is probably due to the US trade policy, which has forced ships to sail at higher speeds across the Atlantic (resulting in greater fuel consumption) to meet tariff schedules.
Indeed, Xeneta points out that shipowners have been forced to increase vessel speed as a necessity for coping with the need to reallocate capacity as quickly as possible between routes, in response to the rise and fall in demand caused by the announcement of tariffs and the subsequent introduction of the 90-day tariff breaks.
The market analyst noted that the route between Northern Europe and the east coast of South America, which is not operationally affected by the Red Sea, recorded a CEI score of 114.4 in the second quarter of 2025, up 15% year-on-year.
The CEI score is based on emissions per tonne of cargo. This suggests that larger ships offer greater efficiency in relation to the amount of cargo they carry and pollution levels, having to make fewer voyages to satisfy demand than smaller vessels.
However, the ongoing trade war and the very highly fluctuating demand for shipping has led liners to frequently use smaller ships (7400 TEU or less), which are considered more versatile and easier to move from one trade to another. On the route between Northern Europe and South America’s east coast, for instance, the size of the vessels being used has been reduced by 14% year-on-year, negatively affecting carbon emissions per tonne of cargo.
Translation by Giles Foster
