- New international research shows sulfur emissions from ships have fallen sharply since the 2020 global fuel regulation.
- The average sulfur content in marine fuel is now nearly ten times lower in open-ocean waters.
- The results confirm significant air quality benefits for coastal regions and port cities.
A newly published international study has confirmed that sulfur emissions from ships have fallen dramatically since the International Maritime Organization reduced the global sulfur cap in marine fuel to 0.5% in 2020. Measurements taken between 2019 and 2023 show a near tenfold decline in sulfur content across open-ocean shipping routes.
Before the rule change, many vessels operated well above the previous limit. After 2020, only a small number were found exceeding the new standard, indicating strong industry compliance.
Cleaner Air Beyond Control Zones
The study also found very low sulfur levels in designated emission control areas in Europe, where stricter limits apply. Surprisingly, ports outside these zones also recorded lower emissions, partly due to European requirements for cleaner fuel when vessels remain alongside for extended periods.
This research is the first to use aircraft-based measurements combined with emissions modelling to assess ship emissions beyond coastal control zones since the regulation took effect, offering rare insight into real mid-ocean conditions.
Health, Climate and the Next Phase of Regulation
Researchers say the reduction will improve air quality for coastal communities and port regions. However, they also noted that less sulfur in the atmosphere may affect cloud formation, with potential climate interactions still needing further study.
While overall compliance is strong, a small number of vessels were still detected above the sulfur limit. The study suggests more monitoring is needed to understand these outliers and ensure the trend continues.
A Step Forward But Not the End of the Journey
The findings support the conclusion that the 2020 sulfur cap is delivering meaningful results for environmental health. The next question for policymakers will be how to expand monitoring, ensure consistent global compliance, and balance air-quality goals with wider climate impacts linked to changing emissions.
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Source: NCAS UK
