From blue to green: The global shipping industry charts a path to decarbonisation

As environmental concerns become increasingly pressing for governments and businesses, the shipping industry is taking steps to reduce its carbon footprint. As part of global sustainability trends, companies around the world are shifting to more environmentally friendly processes in their operations and investment programmes. Shipping firms are no different, and many are working to lower their carbon footprint. These efforts stand to have an outsized impact once they are realised, especially given that maritime shipping is responsible for more than 80% of global trade by volume.


Indeed, the industry is responsible for around 940m tonnes of CO a year, or roughly 2.5% of the total. While it accounts for a relatively small percentage of total emissions, some scientists estimate it may be responsible for as much as 17% of total emissions by 2050. Shipping is difficult to decarbonise, as zero-carbon fuels and technologies are not available on the scale that is needed to maintain global logistics networks, according to a 2021 report from Standard & Poor’s Global.

The difficulty of decarbonising international maritime shipping was underscored by the fact that the industry was not included in the Paris Agreement. Even so, some players in the international community are working to lower the industry’s carbon emissions. In April 2018 the 178 member states of the International Maritime Organisation (IMO), a UN agency that acts as a regulator, announced a target of least halving shipping’s carbon emissions by 2050 when compared to 2008. However, the plan has been criticised by some – including António Guterres, secretary-general of the UN – as not going far enough, as it falls short of what is necessary to meet the goals of the Paris Agreement.

Building on Momentum

The IMO has implemented changes in recent years aimed at reducing maritime transport’s impact on the environment. It implemented regulations effective January 1, 2020 that reduced the limit of sulphur dioxide in marine fuel from 3.5% to 0.5%. This change resulted in a 70% reduction in total shipping-related sulphur dioxide emissions – equivalent to 8.5m tonnes a year. Sulphur dioxide has been linked to cases of lung cancer, cardiovascular and pulmonary disease, and asthma, as well as acid rain and ocean acidification.

Industry bodies such as Europe-based Transport & Environment have outlined a number of ways in which shipping companies could reduce their environmental impact. These include engine improvements, propeller optimisation, and the use of zero-carbon fuels such as e-hydrogen and e-ammonia. Another simpler solution is the introduction of speed limits for large container vessels. According to a 2019 report compiled by Transport & Environment and environmental group Seas at Risk, a 20% reduction in the speed of ships could cut sulphur and nitrogen oxides by 24%, as well as reduce underwater noise by 66% and minimise the risk of colliding with whales by 78%.

Private Push

As the international community works to implement long-term plans, global shipping firms are also taking steps to reduce emissions. In late August 2021 Danish shipping company Maersk, the world’s largest container shipping line, announced that it had invested $1.4bn in eight new vessels to be powered by methanol rather than traditional oil-based fuels. The ships, set to be delivered in 2024, represent 3% of the company’s total container capacity. They will replace older ships in the fleet and are expected to save up to 1m tonnes of CO year. Under the terms of the deal with South Korean manufacturer Hyundai Heavy Industries, Maersk has the option to secure four more ships in 2025.

The decision represents the latest step in Maersk’s efforts to improve its environmental footprint. In February 2021 the company said that its newbuild vessels would be able to use carbon-neutral fuels, and that a new, smaller container vessel capable of running on clean versions of methanol is expected to be operational as soon as 2023.

In addition to exploring new sources of maritime fuel, the company has implemented a series of engineering upgrades to improve the efficiency of its fleet. In 2013 Maersk undertook a programme of retrofitting its container ships. This included a “nose job” on 12 of its New Panamax vessels, which involves replacing a ship’s bulbous bow with a more streamlined design, as well as the introduction of a new propeller and propeller boss cap fin.

The changes helped to reduce fuel emissions by more than 10%, and also led to unexpected benefits with regard to sound pollution. The new designs resulted in a reduction of 6-8 decibels in sound pressure, which translated to a 75% drop in acoustic energy. The cut was regarded as having a positive impact on endangered killer whale populations off Canada’s south-west coast, as ship noise is a major obstacle to whales’ ability to hunt and communicate.

New Technologies

In a similar vein, in July 2021 Belgian shipping company Euronav finalised a joint development programme with Hyundai Heavy Industries, as well as classification groups Lloyd’s Register and DNV, for two ships capable of running on ammonia or liquefied natural gas, before announcing the establishment of a programme to speed up the rollout of tankers that can be powered by duel-fuel ammonia systems.

Experimentation with green transport technologies is also taking place in other industries that rely heavily on maritime transport. In October 2020 US agricultural firm Cargill, one of the world’s largest charterers of ships and tankers, announced that it was working on a plan to fit wind sails to its 600-vessel fleet to minimise their environmental impact. The company said the sails will help to reduce carbon emissions by up to 30%, with the first vessels expected to be in the water in 2022.

Global energy giant Shell, for it part, launched a feasibility study in April 2021 to trial the use of hydrogen fuel cells for its ships in Singapore, the first such move for the company.


While measurable progress is being made to improve the environmental footprint of the shipping industry, there are hurdles to overcome in order for maritime transport to meet such ambitious targets. One relates to the supply of alternative fuels, with Maersk noting in August 2021 that despite its planned rollout of vessels powered by carbon-neutral methanol, sourcing sufficient supply of the fuel is likely to take time. Another hurdle is cost. While the aforementioned engineering retrofits can lead to meaningful efficiency gains, they are unaffordable for most companies, meaning that only the largest firms are able to carry out such plans.