Context of Transport Climate Action

The world’s key ports have committed themselves to reducing greenhouse gas (GHG) emissions while continuing their role as transportation and economic centers. This commitment is called the World Ports Climate Initiative (WPCI). This initiative seeks to implement the principle of sustainability in supply chains, taking into account local circumstances and varying port management structures. The initiative also supports seagoing ships taking measures to reduce ship to air GHG emissions.

One of the projects within WPCI is the Environmental Ship Index (ESI). The ESI identifies seagoing ships that perform well in reducing more air emissions than required by the current emission standards of the International Maritime Organization (IMO). The ESI evaluates the amount of nitrogen oxide (NOX), and sulphur oxide (SOX) that are released by a ship and measures the increase in the efficiency of ships regarding their fuel consumption, (with a view to CO2 reduction) and the reduction achieved in the release to the atmosphere of greenhouse gases.

The ESI is a good indication of the environmental performance of ocean -going vessels and will assist in identifying cleaner ships in a general way.


The ESI is used by some ports as an incentive for providing financial support to suitable ships commensurate with the level of their ESI score . It can also be used by shippers and ship owners as their own promotional instrument. The program is completely voluntary and WPCI hopes that the global port community will assume its role in improving the maritime and port environment. Finally all stakeholders in maritime transport can use the ESI as a means to improve their environmental performance and as an instrument to reach their sustainability goals.

The ESI measurements include the levels of emission pollutants: NOx, SOx and CO2. A bonus may be awarded if the ship can be connected to an electricity supply from the shore. The ESI score ranges from 0 for a ship that just meets the environmental performance regulations in place to 100 for a ship that emits zero levels of SOX and NOX and reports or monitors its energy efficiency; thus a ship with a score of 0 points may be considered to conform with the minimum requirements in force and the ship with 100 points with emissions, far exceeds these current minimum requirements.


The ESI had six founding ports that, together with IAPH (International Association of Ports and Harbors), provided the set up funds.

The main challenge was to keep the participants convinced of the positive outcome of the project during the initial setting up period of the project that took about three years; this was crucial to ensure continued financing.

After the start in 2011, another key challenge was to convince ship owners to participate; more importantly that it was necessary to convince ports of the benefits the index could provide to the environment and climate so that they were willing to provide financial incentives for ships participating with high ESI Scores.

These problems have not been overcome and efforts are constantly needed to keep ports convinced of the reasons for continuing their financial support.

The ESI has now been in operation for nearly five years. Some 4000 ships are registered in the database and 40 ports and organizations provide financial incentives.


In summary, ESI

  • is a voluntary system designed to improve the environmental performance of sea going vessels;
  • gives a numerical representation of the environmental performance of ships regarding air pollutants and CO2;
  • scores NOX and SOX emissions directly and proportionally and recognises increases in energy efficiency;
  • only includes ships that perform over and above current international legislation (IMO);
  • enables ports and other interested parties to stimulate ships to improve their environmental performance;
  • is straightforward and simple in approach and presentation;
  • can be applied to all types of seagoing ships;
  • is automatically calculated and maintained;
  • is free of charge for ship owners.

Potential for scaling up

The following ports/organizations are already participating:

Port of Amsterdam, Port of Rotterdam, Port of Oslo, Hamburg Port Authority, Ports of Bremen/Bremerhaven, Jade Weser Port, Port of Antwerp, Groningen-Seaports, Green Award Foundation, Seehafen Kiel, Autorità Portuale di Civitavecchia, Port of Zeebrugge, Port of Le Havre, Brunsbüttel Ports, Port of Ashdod, Tata Steel IJmuiden Terminals, Port of Los Angeles, Rightship Pty Ltd, The Port Authority of New York & New Jersey, Prince Rupert Port Authority, Ghent Port Company, Zeeland Seaports, Port Metro Vancouver, Ports of Paris, Port Authority of Setúbal and Sesimbra, Port of Rostock, Port of Sohar, Port of Rouen, Niedersachsen Ports, Busan Port Authority, Atlantic Port La Rochelle, Norwegian Coastal Administration (Kystverket), Port of Göteborg, Port of Tokyo, Port Nelson NZ, Port of Stavanger, Port of Bergen, Port Authority of Barcelona, Port of Flåm and Gudvangen.

There is also a long list of shippers that are participating.

Scaling up of the ESI can be increased as more members (both ships and ports) join.

Selected references











Global, Mitigation, Freight, Passenger, Policy, Awareness, Partnerships, Finance


International Association of Ports & Harbors IAPH World Ports Climate Initiative (WPCI)