The Importance of Strong Regulations in Sustainable Shipping

A lot is expected of global trade nowadays when it comes to sustainability. That said, heavy freight is still widely regarded as a hard-to-abate sector.

Air and sea shipping are the main culprits here. While lorries are able to carry just a fraction of the loads of planes and boats, there are readily available electric alternatives to old school, fossil fuel-powered road vehicles.

Progress is well underway though, whether that's the development of sustainable aviation fuel or the kinds of biofuel or hydrogen that boats are experimenting with.

Regulations are being written to reflect and encourage this gradual transition too. When it comes to ships specifically, a new piece of research by the International Maritime Organization has sought to examine just how effective legislation is at the moment when it comes to nautical sustainability. 

Published by the Royal Society of Chemistry, the IMO's study is full of data that could prove crucial for how supply chain professionals understand the day-to-day impact of global fuel rules.

The report, which is titled SO₂ and NOₓ emissions from ships in North‑East Atlantic waters, sets out to measure sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) directly, using aircraft and onshore sensors to sample exhaust plumes from 2019 to 2022.

This approach offers a more precise picture of emissions for a sector that operates largely beyond easy observation.

What kind of impact is tighter regulation having on shipping?

The research shows a dramatic fall in pollution since the 2020 fuel sulphur limit came into effect. Before the rule change in 2019, the average apparent fuel sulphur content (aFSC) across open Atlantic waters was around 3.03%.

By 2021, this had dropped to roughly 0.31%, and further declined to 0.25% by 2022.

Researchers concluded that “a nearly 10-fold decrease in the mean aFSC demonstrates the strong impact the International Maritime Organization regulation change in 2020 had on sulphur emissions from ships.”

The findings underline a smooth transition toward lower-sulphur fuels across the sector.

The study also gauged nitrogen oxide emissions, finding that the NOₓ/CO₂ ratio was significantly lower in ports than at sea, probably because ships rely on smaller auxiliary engines when docked – an operational factor with implications for port logistics and emission tracking.

How are companies complying with sustainable shipping restrictions?

The researchers from the Royal Society of Chemistry also looked at how shipping companies were adhering to new limits.

In 2019, before the new restrictions, eight of the 19 ships sampled surpassed the 3.5% sulphur threshold then in force.

By contrast, during 2021–2022, only five of the 78 ships tested were non‑compliant under the tougher 0.5% cap. This high level of compliance demonstrates the regulation’s effectiveness, although a small proportion of breaches remains.

Failure to comply still poses risks for supply chain stakeholders, ranging from shipment delays to reputational repercussions.

Collecting this evidence required complex operations, including flying an aircraft at altitudes as low as 30 metres to capture and analyse 130 ship exhaust plumes.

The finer details of the study

Within special environmental zones like the European Sulphur Emission Control Area (SECA), stretching across the English Channel, the limits are even stricter. Average sulphur content in these waters was measured at around 0.04%, well below the 0.1% ceiling.

Direct measurements enabled scientists to flag non‑compliant ships that computer models might miss. For example, one container vessel exceeded sulphur limits on the open sea but switched to cleaner fuel closer to shore within SECA boundaries.

This illustrates the intricate fuel‑switching routines global shipping lines must manage, which impact both operational planning and cost efficiency.

When will the shipping sector actually become sustainable?

All in, the shipping sector accounts for about 13% of global sulphur emissions and 15% of NOₓ emissions, much of it within just 400km of coastlines.

The steep drop in sulphur pollution offers clear proof that the IMO’s rules are delivering on their environmental goals.

That said, the tanking of negotiations for a new piece of worldwide sustainability legislation at the IMO earlier this year was a huge blow for establishing an industry-wide consensus on decarbonisation.

Nevertheless, the IMO is ploughing ahead with its mission. Negotiations for the global accord are expected to restart next year, while many more local enforcements are being prepared all the time.