Published on Australian Maritime Safety Authority (

Short-term measure to reduce greenhouse gas emissions from existing ships

The short-term measure under the MARPOL Convention requires ships engaged on international voyages to make improvements to deliver a reduction in their carbon intensity by an average of at least 40% by 2030 (compared to 2008 levels), in line with the target set by the International Maritime Organization (IMO).

In June 2021, the IMO adopted a short-term measure under the MARPOL Convention that requires certain international ship types to take technical and operational measures to reduce their carbon intensity across the global fleet by an average of at least 40% by 2030 (compared to 2008 levels). This measure became mandatory for the relevant ship types internationally and in Australia, on 1 January 2023.

The short-term measure requires operational improvements under a Carbon Intensity Indicator (CII) framework and technical improvements under an Energy Efficiency Existing Ship Index (EEXI) framework.

The Energy Efficiency Existing Ship Index (EEXI)

The EEXI promotes the adoption of technical measures to improve the energy efficiency of ships globally.

The EEXI is a companion to the Energy Efficiency Design Index (EEDI), which has applied to new build ships or ships undergoing a major conversion since 2015. For ships that have been designed to meet the EEDI requirements, the EEDI can be used instead of the EEXI, where it is equal to, or lower than, the EEXI target.

Under the EEXI framework, a required energy efficiency target is set by the IMO for each ship by type and size. The EEXI level that is attained by the ship is then calculated and compared to the target.

The EEXI attained by the ship should be equal to, or lower than, the required EEXI target. Where this is not the case, technical adjustments must be made to improve the energy efficiency of the ship so that it meets the target. These might include engine power limitation, new antifouling coatings, modified bulbous bows, new propellers or retrofitting energy-saving devices.

Information necessary for the calculation of the ship’s attained EEXI, including the calculation process, must be detailed in an EEXI technical file.

Survey and certification of the EEXI requirements

For ships delivered before 1 January 2023, the certification of EEXI will take place at the first annual, intermediate or renewal survey of the International Air Pollution Prevention (IAPP) certificate after that date.

For ships delivered on or after 1 January 2023, the verification of EEXI shall be completed during the initial survey.

After certification, the required and attained EEXI values for the ship will be detailed in the ship's International Energy Efficiency (IEE) Certificate.

Owners and operators of Australian-flagged ships that operate on international voyages can approach their classification society to calculate their EEXI, develop their technical file and issue an IEE Certificate. 

Carbon Intensity Indicator (CII) and rating system

The CII requires changes to the way ships are operated to improve energy efficiency and reduce carbon intensity.

A ship’s carbon intensity is the greenhouse gas emissions relative to the amount of cargo carried over the distance travelled. The less fuel used by the ship for a given distance travelled, the lower the ship's carbon intensity. The CII framework sets an annual carbon intensity limit for ships by size and type, which builds on the already achieved carbon intensity reduction by the global fleet. This limit is adjusted annually in three phases for the period 2020-30. These annual reductions are cumulative, that is, they build on the reductions achieved in previous years, to achieve the 40% reduction by 2030 target.

PhaseYearsReduction rate
One2020 to 20221% per annum, which is similar to  business as usual carbon intensity improvement
Two2023 to 20262% per annum
Three2027 to 2030To be further strengthened and developed taking into account the review of the measure

The ship owner, operator and Master must decide on the operational modifications that will be adopted to ensure a ship achieves its CII target, such as voyage planning or speed optimisation.

At the end of each calendar year, the CII achieved by the ship (attained CII) must be calculated and compared to the required CII target. Within three months after the end of each calendar year, the ship’s attained CII must be reported to its flag State or any authorized organisation for verification.

The ship is then assigned a rating from ‘A’ to ‘E’ by the flag State administration (where A is the best) based on its performance against the annual CII target.

Ships rated as meeting their annual CII performance requirements (those rated A to C), will be issued with a Statement of Compliance (SoC).

Ships rated as D for three consecutive years or E once, are considered to be underperforming and must develop a corrective action plan before they can be issued with a SoC.

Governments, port authorities and other stakeholders, are encouraged to provide incentives to ships rated as A or B.

Corrective action plan

A corrective action plan must be developed for ships underperforming against their annual CII target. This includes ships that are rated D three years in a row or E once.

The corrective action plan should outline what actions will be taken to ensure the ship meets its required CII target and how long it will take to bring the ship back into compliance.

Once this plan has been developed and verified by the ship's flag State, the ship will be issued with a SoC.

The corrective action plan must be included in the ship's energy efficiency management plan (SEEMP)

Owners and operators of Australian-flagged ships that undertake international voyages must report their attained CII to their Recognised Organisation (RO) —also known as a classification society.

RO’s can also assist owners and operators to calculate their CII, develop their SEEMP and corrective action plan, if required. 

RO’s are also responsible for issuing the SoC related to fuel oil consumption reporting and annual operational carbon intensity rating to Australian-flagged ships.

Application of the new short-term measure

The EEXI and CII requirements apply to ships engaged in international voyages of the following type and size.

Ship typeCalculation of attained EEXICalculation of required EEXICII requirements
Bulk carrieri400 gross tonnage and above10,000 dryweight tonnage and above5,000 gross tonnage and above
Gas carrier (other than an LNG carrier)ii2,000 dryweight tonnage and above
Tankeriii4,000 dryweight tonnage and above
Containershipiv10,000 dryweight tonnage and above
General cargo ship (other than livestock carriers, barge carriers, heavy load carriers, yacht carriers, nuclear fuel carriers)v3,000 dryweight tonnage and above
Refrigerated cargo carriervi3,000 dryweight tonnage and above
Combination carriervii4,000 dryweight tonnage and above
LNG carrierviii10,000 dryweight tonnage and above
Ro-ro cargo ship (vehicle carrier)ix10,000 dryweight tonnage and above
Ro-ro cargo shipx1,000 dryweight tonnage and above
Ro-ro passenger shipxi250 dryweight tonnage or 400 gross tonnage and above
Cruise passenger ship having non-conventional propulsionxii25,000 Gross tonnage and above

Review of the measure

Both the CII and EEXI requirements will be subject to review by the IMO to ensure the new measure will meet the 2030 target outlined in the IMO’s Initial GHG Strategy. This review will occur before 1 January 2026.

Following the review, the IMO will determine if any amendments to the measure are required.

IMO resources

For further information on the EEXI and CII, please refer to MARPOL Annex VI and the technical guidelines adopted by the IMO to support implementation of the short-term measure. requirements.



Bulk carrier means a ship which is intended primarily to carry dry cargo in bulk, including such types as ore carriers as defined in regulation 1 of chapter XII of SOLAS 74 (as amended) but excluding combination carriers.

ii Gas carrier means a cargo ship, other than a liquefied natural gas (LNG) carrier constructed or adapted and used for the carriage in bulk of any liquefied gas.

iii Tanker means an oil tanker as defined in regulation 1 of Annex I of MARPOL or a chemical tanker or an NLS tanker as defined in regulation 1 of Annex II of MARPOL.

iv Containership means a ship designed exclusively for the carriage of containers in holds and on deck.

General cargo ship means a ship with a multi-deck or single deck hull designed primarily for the carriage of general cargo. This definition excludes specialised dry cargo ships, which are not included in the calculation of reference lines for general cargo ships, namely livestock carrier, barge carrier, heavy load carrier, yacht carrier, nuclear fuel carrier.

vi Refrigerated cargo carrier means a ship designed exclusively for the carriage of refrigerated cargoes in holds.

vii Combination carrier means a ship designed to load 100% deadweight with both liquid and dry cargo in bulk.

viii LNG carrier means a cargo ship constructed or adapted and used for the carriage in bulk of liquefied natural gas (LNG).

ix Ro-ro cargo ship (vehicle carrier) means a multi deck roll-on-roll-off cargo ship designed for the carriage of empty cars and trucks.

Ro-ro cargo ship means a ship designed for the carriage of roll-on-roll-off cargo transportation units.

xi Ro-ro passenger ship means a passenger ship with roll-on-roll-off cargo spaces.

xii Non-conventional propulsion means a method of propulsion, other than conventional propulsion, including diesel-electric propulsion, turbine propulsion, and hybrid propulsion systems.

Last updated: 13 December 2023