Researchers at UCL (University College London) estimate that 10% of international shipping's greenhouse gas emissions occur within port areas — a share they argue could be reduced using electrification technology that already exists.

International shipping is generally estimated to account for around 3% of global greenhouse gas emissions, based on IMO assessments, giving port-area activity a meaningful absolute volume.

The finding comes from the university's Shipping and Oceans Research Group, which built its analysis on AIS (Automatic Identification System) data — the position and movement signals transmitted by ships — covering 1.2 million voyages undertaken by more than 43,000 vessels over one year, with total emissions of 575 million mt of CO2e.

According to the group, port-area emissions could be addressed through shore power at berth, battery-electric propulsion while idling or manoeuvring, and converting short-sea vessels to run on batteries — measures it describes as mature technologies. Shore power in particular is already shifting from voluntary practice to mandate in some jurisdictions: the EU's FuelEU Maritime regulation requires container and passenger ships to connect to onshore power at berth in major ports from 2030, and California has long required qualifying vessels to use shore power at its principal ports.

The analysis has been published alongside an interactive tool, the Shipping GHG Emissions Explorer, which the group says is intended to improve the evidence base for IMO negotiations on the Net-Zero Framework (NZF), due to resume next week. The NZF, which combines a global fuel standard with a greenhouse-gas pricing mechanism to implement the IMO's 2023 goal of net-zero shipping emissions by or around 2050, was approved in principle at the IMO's Marine Environment Protection Committee in April 2025 but not adopted after the vote fell short of unanimity, leaving final sign-off pending at a later extraordinary session. The tool allows IMO delegations to view the shipping activity and emissions attributed to their own country's trade, broken down by vessel type, port, and trading partner, and by whether emissions arose in port or on voyage.

"Although imperfect, AIS-centred big data approaches have revolutionised our ability to understand key trends in the energy demands and GHG emissions associated with international shipping activity," said James Stewart, research fellow at the group, in a statement.

The group's analysis points to small island nations as having the highest in-port emission shares.

"7 out of 10 countries in Latin America/Caribbean and 8 out of 10 in East Asia Pacific that have the highest in-port emissions are small island nations," said research assistant Yoseph Ismail, adding that these countries' in-port shares are often above 20%.

The release does not address the cost or practicalities that such electrification efforts would require.

An update planned for September is set to add state-level seaborne trade volumes and estimates of the economic impact of the proposed NZF amendments, ahead of the framework's potential adoption later this year.

The Shipping GHG Emissions Explorer is free to use on the group's website:

Source: Ship & Bunker