Container shipping 2-Year peak efficiency: How vessel size and carrier choice shape global carbon footprint

VesselBot’s latest quarterly analysis, Decoding Maritime Emissions Q4 2025 “Efficiency Peaks as Intensity Hits Yearly Low”, provides an unprecedented snapshot of how global container-shipping operations evolved at the end of the year. The report shows how vessel fleet composition, carrier deployment choices, and trade-route design translate into radically different emissions outcomes for shippers.

Based on high-quality, shipment-level emissions data from 79,438 containership voyages completed in Q4 2025, this analysis provides supply chain leaders with a granular view of the carbon performance of individual routes, fleets, and operators.

Among the report’s key findings:

• Carbon Intensity Hit a Yearly Low While Total Emissions Remained High. Average Well-to-Wake emissions intensity fell to 188.9 g CO₂e per TEU-km, the lowest level recorded in 2025. At the same time total Q4 emissions exceeded 52 million tons, underscoring how volume growth and network design shape outcomes.
• Carrier Performance Diverged on Identical Routes. On major Asia–Europe corridors, competing operators recorded materially different carbon profiles depending on vessel size, fleet age, and time in port.
• Fleet Age Drives Structural Differences. Voyages performed by vessels younger than 15 years were significantly more efficient (showing up to 164.8 g CO2e per TEU km WTW intensity), than those by older ships, which concentrated on shorter regional trades and produced far higher emissions per container.
• Supply-Chain Architecture Matters More Than Speed Alone. Highly efficient voyages combined long steaming times, high utilization, and large cargo volumes, delivering intensities nearly five times lower than quarter averages.

VesselBot surfaces these dynamics using real-time, shipment-level emissions data captured at the level of individual voyages, rather than relying on modeled estimates or historical averages.

Important yearly highlight: Across the full year 2025, VesselBot tracked 313,690 containership voyages operated by more than 5,800 vessels, generating a total of 208.8 million tons of CO₂e.

“If you measure emissions quarterly but operations change daily, you are managing the past” said Constantine Komodromos, CEO and Founder of VesselBot. “Ocean networks are constantly reshaped by schedule changes, vessel swaps, blank sailings, port disruptions, and geopolitics. Sustainability has to become an operational KPI, evaluated at the moment of planning and execution, alongside reliability and cost. And we should be honest about offsets and book and claim fuels. They may help close a gap in the short term, but they do not force the system to change. Real progress comes when shippers and carriers change how freight is moved, not just how emissions are accounted for.”

The report also examines how geopolitical volatility, fleet renewal, and regulatory expansion are reshaping emissions exposure heading into 2026.