Greenhouse gas emissions from international shipping

The International Maritime Organization (IMO) has developed global measures to improve energy efficiency and reduce greenhouse emissions from international shipping.

Measures to reduce the carbon intensity of shipping

In 2018 the IMO adopted the Initial IMO strategy on reduction of greenhouse gas emissions from ships. The strategy commits the IMO to reduce emissions from international shipping and to decarbonise the industry as soon as possible this century. 

The strategy includes a series of short-, mid- and long-term candidate measures, building on the already adopted mandatory energy efficiency requirements for ships.

In 2021 the IMO adopted a new short-term measure for existing ships engaged on international voyages. This measure builds on the emissions improvements already made by the shipping sector to reduce the carbon intensity of international shipping by at least 40% by 2030, compared to 2008 levels, as outlined in the Initial IMO strategy. 

Commencing 1 January 2023, the new measure will require ships to make technical improvements under the Energy Efficiency Existing Ship Index (EEXI) framework and operational improvements under the Carbon Intensity Indicator (CII) framework.

Regulations to enhance the energy efficiency of ships

In 2011 the IMO adopted mandatory energy efficiency measures to reduce greenhouse gas emissions from international shipping under the International Convention for the Prevention of Pollution from Ships (MARPOL). The energy efficiency measures located in a chapter 4 of MARPOL Annex VI (air pollution) —Regulations on energy efficiency for ships—require ships to comply with the following:

These regulations entered into force on 1 January 2013 and apply to ships of 400 gross tonnage (GT) and above. 

In 2016 the IMO adopted amendments to MARPOL that require ships of 5,000 GT and above undertaking international voyages, to collect and submit fuel consumption data  to their flag State from 1 January 2019. The flag State is required to verify and aggregate the data and submit it to the IMO data collection system (DCS), where it is used to track the success of existing emission reduction measures and to inform future requirements. 

Alternative fuels and propulsion systems

To meet the 2050 levels of ambition in the initial greenhouse gas strategy and decarbonise international shipping as soon as possible, the adoption and use of alternative low-carbon and zero-carbon fuels and energy efficient technologies is required.

In the shorter term, considerable emission reductions are possible by transitioning to lower-carbon fuels such as LNG, until zero-carbon fuels become readily available to cut emissions in the long term. Promising candidates for zero-carbon fuels include green ammonia, hydrogen, methanol, biofuels and batteries.

For the effective uptake of alternative low-carbon and zero-carbon fuels, there is a need to consider a range of issues such as safety to the ship, crew and environment, pollution-response requirements and infrastructure availability.

The IMO is developing lifecycle guidelines for maritime fuels, which will measure the greenhouse gas emissions across a fuel's production and usage. A first interim version of the guidelines is expected to be finalised for adoption at MEPC 78 in mid-2022. 
Different propulsion systems and aids are also being investigated, including electric, hybrid drives, fuel cell, wind power and solar power. 

The role of AMSA in reducing GHG emissions from shipping

The Australian Maritime Safety Authority (AMSA) leads Australia’s interests at the IMO on behalf of the Australian Government and works with other government agencies, Australian stakeholders and international administrations to develop internationally consistent greenhouse gas measures for shipping. The Department of Infrastructure, Transport, Regional Development and Communications leads policy development for greenhouse gas emission reduction for shipping

Through AMSA’s rigorous flag State control (FSC) and port State control (PSC) programs, we are also responsible for ensuring Australian-flagged ships and foreign-flagged ships operating in Australian waters comply with international shipping standards, including the greenhouse gas reduction measures adopted by the IMO.

Last updated: 

Thursday 24 March 2022