Selcuk Uysal
22 January 2026•Update: 22 January 2026
ANKARA
The global reduction in sulphur content in ship fuels has inadvertently worsened coral bleaching events on Australia's Great Barrier Reef, according to a study that was published Thursday by researchers from the University of Melbourne, led by Dr. Robert Ryan, in the journal Nature.
The International Maritime Organization's (IMO) 2020 regulation, which slashed the maximum sulphur content in marine fuels from 3.5% to 0.5%, significantly improved air quality by cutting harmful emissions.
The Guardian reported that the “cleaner” shipping has removed a previously overlooked cooling effect in the atmosphere.
The removal of sulphur from shipping fuels caused “a lot of extra sunlight” to get through the atmosphere and hit the reef.
The research team used real ship traffic data and wind patterns to model how sulphur particles from thousands of vessels normally drift over the Reef, providing localized cooling.
The Great Barrier Reef has already suffered multiple severe bleaching episodes in recent years, driven primarily by rising ocean temperatures from climate change.
Experts stress that while cutting sulphur pollution remains essential for human health and the environment, it cannot substitute for urgent reductions in greenhouse gas emissions to protect vulnerable coral reefs.
