Clean Air, Dirty Seas: The Biodiveristy Cost of Scrubbers in the Mediterranean

Scrubbers are marketed as a cleaner alternative to traditional fuels, while in fact they discharge polluted washwater directly into the ocean, often near densely populated coastal areas and shallower sea areas.

Through original fieldwork and interviews with scientists, activists, government officials, and port authorities across Spain, Italy and France, this investigations reveals the scale of this underreported threat to marine biodiversity and coastal communities, particularly in the Mediterranean.

The team conducted over 20 in-depth interviews with sources across different sectors, including researchers involved in European scientific consortia, institutional voices at the IMO, national and port maritime authorities, port workers and fishermen, industry representatives and leading environmental NGOs.

Legal frameworks governing scrubber discharge were cross-checked across France, Spain, and Italy to identify both best practices and enforcement gaps.

The investigation also analysed scientific literature, leaked documents, and obtained exclusive visual materials, such as photos from lab research and videos showing black wastewater discharged near recreational waters.

This allowed the team to trace how scientific concerns have been downplayed in international policymaking and reveal a troubling governance vacuum in some of Europe's most vulnerable marine zones.

Overall, the investigation showcases a systemic failure to prevent marine pollution under the guise of air quality improvement, calling into question the maritime industry's decarbonisation claims. Findings point to the urgent need for region-wide, coordinated bans on scrubber discharges, robust monitoring, and a shift to cleaner fuels.

Photo: Samples of closed-loop washwater sludge from different cruise liners, at a MARPOL waste processing plant in the Port of Barcelona. (c) Helena Rodríguez Gómez