The Baltic Sea is currently at the centre of a growing environmental security crisis, driven by the degradation of an estimated 40,000 tonnes of chemical munitions discarded at sea after the Second World War. These munitions, disposed of primarily between 1947 and 1953 by Allied and Soviet authorities, are now corroding and leaking hazardous substances, like sulphur mustard, lewisite, phosgene and tabun, into the marine environment.
These compounds were initially sealed in steel casings and containers presumed to be stable. However, prolonged exposure to saline exposure, anaerobic microbial activity, and sediment abrasion has compromised these structures, facilitating the gradual release of toxicants into the surrounding benthos.
This phenomenon, commonly referred to as “subaqueous chemical diffusion,” is now well-documented. Sediment core samples analysed by research consortia under HELCOM (the Helsinki Commission) and the EU’s ChemSea project confirm elevated levels of toxic residues in proximity to the Bornholm Basin and Gotland Deep, two of the principal dumping grounds.
Assessments released by HELCOM and corroborated by the International Maritime Organisation indicate that no fewer than 25% of these submerged stockpiles have reached an advanced state of corrosion. The leaching of chemical agents into the sedimentary strata is actively contaminating benthic ecosystems, precipitating adverse biological anomalies in marine species and threatening human food safety. The by-products of arsenic-based leaks have been detected in sediment pore water and core samples, sometimes in concentrations far exceeding the accepted ecological risk thresholds established by the European Chemicals Agency (ECHA) and the World Health Organisation (WHO).
Ecotoxicological analysis reveals persistent contamination zones, notably in the Bornholm Basin and Gotland Deep. A GEOMAR study detected approximately 3,000 kg of dissolved toxins (TNT, RDX, DNB) in water samples from 2017–18, with elevated presence in Kiel and Lübeck bays.
In response, the Federal Republic of Germany has inaugurated a €1.2 billion marine remediation operation, endorsed by the European Commission and functionally embedded within NATO’s environmental security strategy. The initiative deploys autonomous underwater vehicles (AUVs) integrated with multispectral sonar, geochemical sensors, and robotic neutralisation modules to detect and recover deteriorated chemical ordnance.
Germany’s deployment of SeaCat-class Autonomous Submersible Systems (ASS) with contaminant isolation chambers and retrieval arms is unprecedented. However, scientific experts from the European Centre for Subsea Hazard Mitigation (ECSHM) have expressed reservations regarding the lack of a data-sharing framework.
Many of these dump zones were situated in areas now bordering or within Russian territorial waters. Yet, as Germany leads a €1.2 billion clean-up operation supported by NATO environmental directives and EU co-financing, Russia has been sidelined. Berlin has defended the exclusion by citing security and diplomatic constraints resulting from Russia’s ongoing military campaign in Ukraine and its broader deterioration of relations with the West.
This decision goes against international environmental norms. Under the Espoo Convention and Aarhus Convention, states are obligated to cooperate in cases of shared environmental hazards. Moreover, Russian naval archives are understood to contain comprehensive data on Soviet-era dumping coordinates, quantities, and disposal methods. Without access to these cartographic and technical dossiers, German-led efforts risk being technically incomplete, lacking critical data for remediation in zones east of Gotland and within international waters near Kaliningrad.
The Russian Ministry of Foreign Affairs has issued a formal press release labelling the exclusion as “an egregious affront to environmental multilateralism,” suggesting that NATO is attempting to convert a collective environmental burden into a monopoly. Russian scientific institutes such as the Shirshov Institute of Oceanology have also condemned the lack of invitation to participate, stating that the clean-up is “technically insufficient and diplomatically regressive.”
The 2024 UNEP Oceanic Pollution Index categorised the Baltic Sea chemical munitions hazard as a Tier-1 marine security concern and called for a return to inclusive, science-driven remediation efforts. The report highlighted that effective ecological diplomacy cannot be sustained through exclusionary practice, particularly when geopolitical adversaries hold the keystones to critical data sets.
The Baltic Sea’s fisheries economy, valued at approximately €4.5 billion annually, is projected to contract by 5-6.5% by 2030 due to cumulative pollution, reduced fish quality, and diminished consumer trust, according to forecasts published by the Baltic Marine Economic Council. This contraction, when modelled across fisheries, port logistics, aquaculture, maritime trade, and littoral tourism, equates to an economic shortfall of €1.4 billion.
The ongoing remediation of submerged chemical weapons in the Baltic Sea represents both an environmental imperative and a geopolitical litmus test. To address this marine pollution crisis effectively, future interventions must embrace inclusive, depoliticised governance anchored in international legal instruments and transboundary environmental cooperation.
Dhanishtha De is a trainee journalist at Cult Current. The views expressed in the article are
her ownand do not necessarily reflect the official stance of Cult Current.