Scrubbers, used to reduce sulfur oxides in a ship's exhaust, have been identified as one of the most harmful shipping-related pressures on the marine environment. With a pH around 3, these systems discharge large volumes of acidic, polluted effluent, containing a mix of metals and organic contaminants.
In 2020, in response to the lack of legislation, ICES published a Viewpoint on Scrubbers. This was developed by a collaboration between members of our expert groups on Shipping Impacts in the Marine Environment (WGSHIP), Marine Chemistry (MCWG), Biological Effects of Contaminants (WGBEC), and Marine Sediments in Relation to Pollution (WGMS).
Since then, the scientific consensus on the environmental risks of scrubber discharges has only grown stronger. WGSHIP addresses the ecological impacts of shipping on the global coastal marine environment, and members of the group have been at the forefront of advancing scientific understanding of the issue. Their work has contributed to a reinforced consensus that scrubber discharges pose serious risks to marine ecosystems.
Over the past five years, WGSHIP members have actively contributed to this body of evidence through multiple research projects. Recent publications by WGSHIP members span topics such as the transport of pollutants, microparticulate contamination, economic drivers of pollution, and cumulative risk assessments in coastal areas and ports, as well as contributing to major research projects like H2020 EMERGE and ImpEx.
Policy change
This work is creating real change as an increasing number of countries are moving to restrict scrubber effluent discharges in their territorial waters.
In the Baltic Sea, Denmark, Finland, and Sweden will enforce bans on discharges from open-loop scrubbers (the most common type) from land and 12 nautical miles off the coast( i.e. territorial waters). This, a significant policy shift, entering into force on 1 July 2025, is directly linked to the scientific leadership and sustained efforts of WGSHIP and its network of experts.
On 26 June 2025, OSPAR agreed on binding regulations to restrict shipping pressures across the northeast Atlantic. Under this agreement, discharges from open-loop scrubbers will be banned in internal waters and port areas by July 2027.
“Since the launch of the WGSHIP Viewpoint on scrubbers, the evidence from additional ecotoxicological studies has continued to pile up, supporting the recommendation by WGSHIP to restrict discharge of scrubber effluent to the marine environment", states Ida-Maja Hassellöv, co-chair of WGSHIP, "In addition,
our continued research has concluded that scrubbers are lucrative for the ship owners, saving many billions of Euros at the expense of degradation of the marine environment. Hence, we are happy to see that an increasing number of countries have decided to ban scrubber discharges in their territorial waters, and we hope that more countries will follow to meet the general wish from the shipping industry to have harmonized regulations.”
ICES Working Group on Shipping Impacts in the Marine Environment (WGSHIP) addresses the ecological impacts of shipping on the global coastal marine environment. Topics addressed by the working group include reviews of knowledge on shipping interactions with the environment and trends in current and future global shipping activity.
