By Patrick Norén
The Baltic Sea is one of the most polluted bodies of water in the world, contaminated by hundreds of thousands of tons of munitions dating back as far as World War I. Patrick Norén investigates.
When one thinks of the Baltic Sea, images that come to mind might include the chaotic, scraggy beauty of the Finnish or Swedish archipelagos, the colorful maritime cities of Gdansk or Tallinn, or perhaps the sweeping sandy beaches of Latvia or Lithuania.
What may not come to mind, however, is the approximately 300,000 tons of bombs, torpedoes, rockets, mines, depth charges, artillery shells, explosives, propellants, and chemical warfare agents (CWAs) dumped at the sea’s bottom after World War II. Having sat there largely ignored for almost 80 years, these munitions have gradually degraded and leaked their toxic contents into the water, contributing to the Baltic Sea’s status as one of the most polluted bodies of water in the world.
History of Baltic Sea Contamination
The Baltic Marine Environment Protection Commission, known as the Helsinki Commission or HELCOM, estimates that approximately 160,000 mines were laid in the Baltic Sea and its approaches during World Wars I and II. Mine clearance between 1996-2022 showed that about 25% of contact mines remain in the area where they were sunk, while 75% of ground mines remain in the positions where they were laid.
However, it was after World War II that Allied powers inherited huge quantities of munitions from a defeated Nazi Germany and were in a hurry to dispose of them. While the U.S. and U.K. largely dumped their portion of seized munitions in the Skagerrak Strait, a large part of the munitions stock found in the Soviet occupation zone were dumped in designated sites in the Baltic Sea, mostly to the south-east of the Swedish island of Gotland, and east of the Danish island of Bornholm. The Gdansk Deep off the coast of Poland is also contaminated.
Time constraints and limited shipping capacity to complete Germany’s demilitarization on schedule also resulted in the practice of en route dumping. Therefore, areas of concern today also include the transport routes from the ports of Flensburg and Wolgast, Germany. Allied bombing raids also left an additional legacy of chemical munitions contamination in the region.
Sulfur Mustard
The wide variety of different munitions dumped in the Baltic has resulted in an equally wide variety of CWA pollution. These include vesicants such as sulfur mustard and Lewisite, irritants such as Adamsite, the lacrimator α-chloroacetophenone, lung agents such as phosgene and diphosgene, the nerve agent tabun, and the blood agent hydrogen cyanide.
HELCOM wrote in a 2013 report that sulfur mustard mixtures represented about 63% of dumped materials near the islands of Bornholm and Gotland. The overwhelming majority of sulfur mustard present in the Baltic Sea today is understood to have come from dumped aircraft bombs, with a whopping 5,920 tons of them dumped in the waters around Bornholm alone. Meanwhile, some 512 tons of sulfur mustard aircraft bombs were dumped south-east of Gotland and along the transport routes from Wolgast.
However, due to sulfur mustard’s tendency to clump together and get caught in fishing nets, it has been involved in as many as 88% of fishing incidents involving dumped chemical munitions in the Baltic. Over the years, such and similar incidents have resulted in large quantities of catch being destroyed because of potential chemical munition contamination.
Meanwhile, HELCOM reported no fewer than 106 incidents involving dumped chemical munitions in the Baltic between 1994 and 2012. With the agent payload being anything from only a few hundred grams to as much as 130kg, the overwhelming majority of these incidents involved sulfur mustard. More recently, the Royal Danish Navy reported 13 munitions bycatch incidents around Bornholm between 2010 and 2021.
White Phosphorous
Of particular concern along the beaches of Germany, Poland, and Latvia is white phosphorous, a highly toxic incendiary agent that can burn at temperatures of around 1,300°C. Contamination in these areas originates from both Allied bombing raids during World War II as well as post-war munitions dumping.
White phosphorous has a very low solubility rate in water and can often be yellow-orange in color due to the presence of impurities. This means it can easily be mistaken as amber by curious beachgoers before being pocketed, drying out, and spontaneously igniting.
In January 2014, a German pensioner walking along a beach near Kiel suffered third-degree burns after picking up a small piece of what he believed to be amber, and put it in his pocket. Then, in August 2017, a woman in Hamburg discovered a piece of what she believed to be amber in wet sand, only narrowly escaping severe injury once it spontaneously combusted.
However, given that white phosphorus’s destructiveness comes from its thermic rather than toxic properties, its use is not prohibited under the Chemical Weapons Convention. Despite this, it is still a major concern in the southern Baltic given its potential to cause serious harm to unwitting people.
Food Chain Contamination
While the immediate effects of chemical munition exposure will differ depending on the agent, one common thread is the risk of long-term illnesses such as cancer. This is particularly pertinent when considering the risk of biomagnification of CWAs and their degradation products in the marine food chain, potentially resulting in the ingestion of harmful compounds by humans.
In 2019, for example, exploratory fishing conducted by the Swedish Agency for Marine and Water Management detected low levels of Clark I, Clark II, and Arsine oil in cod fished off Gotland.
That said, research into explosive and CWA contamination in seafood has been limited. A HELCOM report from May 2024 wrote that the “effects and risks for human seafood consumers cannot be clearly denied or defined at the present time”, and that “there are no existing quality regulations for TNT and CWA-contaminated food.”
Open Spirit and BALTOPS
The problem of conventional and chemical munitions contamination in the Baltic Sea is thankfully – if perhaps in a somewhat piecemeal fashion – being addressed by national and international initiatives.
One of the more long-standing international initiatives to deal with explosive remnants of war in the Baltic Sea is Open Spirit. Held since the 1990s and on a rotational basis in any of the three Baltic States, operation Open Spirit is a NATO-led exercise dedicated to clearing shipping lanes and fishing areas of WWI and WWII-era ordnance to improve maritime safety. The 2024 exercise took place in April in Estonia and involved approximately 700 Estonian and Allied soldiers, 14 ships, 11 shore-based divers, as well as underwater drone crews, from a total of 16 countries. 43 historical ordnances were destroyed in the 2024 operation, totaling 11 tons across an area of nearly 300km2. More specifically, 37 mines, one torpedo, two other pieces of ordnance, and other previously discovered ordnances were countermined.
Only a few weeks after the conclusion of Open Spirit, the 53rd edition of NATO’s biggest Baltic Sea exercise took place from June 7-20, involving 19 NATO allies, more than 50 ships, more than 85 aircraft, and approximately 9,000 personnel. BALTOPS 24 included a broad spectrum of naval military operations such as maritime interdiction, medical evacuation, air defense, as well as mine countermeasures.
“While mine countermeasures has been a central part of the BALTOPS exercise for decades, we are continuously looking for opportunities to increase its involvement and to experiment with different capabilities,” said Capt. Scott Hattaway, Director of the Mine Countermeasures Division at the U.S. Navy’s Naval Surface and Mine Warfighting Development Center.
“This year’s expeditionary mine countermeasures contingent is the largest so far, combining the typical EOD/diver and unmanned underwater vehicle personnel with a command task unit to better support command and control over a complex water space.”
European Commission Projects
Away from military operations and exercises, the European Commission is also taking steps to begin addressing munitions contamination in the Baltic Sea. Ministers responsible for environment and agriculture from Baltic Sea countries convened at the second “Our Baltic” conference in Palanga, Lithuania, in September 2023, where they agreed on six actions and commitments before a stock-take of progress in 2027.
These included pursuing cooperation with existing regional fora such as HELCOM and the Council of the Baltic Sea States, bridging knowledge and legal gaps, developing the necessary technologies to tackle unexploded ordnance in the Baltic Sea, and “working towards a comprehensive mapping of submerged munitions and appropriate associated risk assessments”.
To help members states implement the above commitments, the European Commission has and will continue to invest over €16 million in funding three new projects – MUNIRISK, MUNIMAP, MMinE-SweEEPER – and one additional pilot project.
With the contract signed in June, MUNIRISK will increase awareness of the location and condition of unexploded ordnance in the Baltic Sea, and further promote international cooperation to deal with the problem. MUNIMAP will focus on mapping both chemical and conventional munitions contamination in the Baltic Sea to set up a “modular, adaptable roadmap towards Baltic Sea munitions remediation”. These projects have seen European Commission investments of €2 million and €3 million, respectively.
MMinE-SwEEPER – receiving an investment of €5 million from the European Commission – aims to complete the process from detecting to ultimately removing and disposing of dumped munitions in the Baltic and North Seas, while also improving detection, classification, inspection, assessment, and neutralization methods in different scenarios.
Finally, June 2024 also saw the European Commission issue a call for a €5.59 million pilot project aimed at developing and testing technologies and methodologies for naval explosive ordnance disposal. This call would “support a project that will develop the most environmentally friendly, comprehensive, and efficient technologies and methods for the removal, disposal, and/or neutralization of munitions dumped at sea”. It would first focus on the Baltic Sea before being rolled out to other European sea basins in the future.
In Germany, a €100 million project funded by the federal government has begun testing a combination of remote-controlled surface and seabed robots that scan the sea for munitions before safely removing them. With testing focusing on the Lübeck Bay, a long-term goal of the project is the construction of an offshore platform outfitted with a detonation chamber where retrieved munitions can be destroyed without further harming the marine environment.
While this project is currently focusing only on conventional munitions, researcher at the Institute of Oceanology at the Polish Academy of Sciences Jacek Bełdowski recently told the BBC that it could easily be adapted to tackle the more complex issue of chemical munitions.
Turning the Tide on Maritime Munitions Contamination
Shockingly, a 2008 Council of Europe resolution on chemical munitions in the Baltic Sea wrote that HELCOM believed that the dumped chemical munitions “should not be retrieved from the bottom of the sea and should remain where they are”. The resolution added the “majority of experts who have studied the issue also share this opinion”.
Just like munitions on terra firma, maritime munitions will remain a threat until they are dealt with once and for all. Indeed, the longer that both conventional and chemical munitions are quite literally left to rot at the bottom of the sea, the more critical the problem becomes.
Posing a multitude of risks to civilians, animals, the environment, and economies, munitions contamination in the Baltic Sea is rightly beginning to be taken more seriously than ever before.
Click here to read HELCOM’s 2024 report “Thematic assessment on Hazardous Submerged Objects in the Baltic Sea”, and here read more about Germany’s dumped munitions clearance projects.
Patrick Norén is the Editor of CBNW Magazine.
