Baltic's hidden peril: WWII chemical munitions threaten crisis

The depths of the sea, even in a relatively shallow stretch like the Baltic, are inhospitable to humans. For this reason, since time immemorial, people have pointed to the dangers lurking within: sea serpents, the Kraken, mermaids, Leviathan, Cthulhu, and others. Even if they referred to real threats, they were only mythical creatures.

Meanwhile, on the floor of the Baltic Sea lie truly dangerous barrels containing deadly substances. Recently, Professor Jacek Bełdowski from the Institute of Oceanology PAS sought to remind us of this issue in his lecture "Sunk Munitions in the Baltic - a Forgotten Problem" delivered at the Museum of the Second World War in Gdańsk.

The scientist is involved in, among other things, NATO and EU research programs related to monitoring the condition of chemical weapons stored on the Baltic Sea bottom. How did they end up there? They are remnants of the Second World War. During the war, the Third Reich produced chemical warfare agents on a massive scale, mainly gases. Although they did not use them extensively in combat, fearing Allied retaliation, the Germans did employ them during the genocide against Poles, Jews, and others.

A large portion of the German stockpile of mustard gas, sarin, tabun, hydrogen cyanide, etc., survived the war and was seized by the Allies. It shared the fate of other German weapons – during the Potsdam Conference, the so-called Big Three decided that German weapons were to be surrendered to the victors or destroyed. In the case of chemical weapons, two methods were considered: costly and difficult chemical disposal or deferring the problem over time. The latter method was chosen, explicitly sinking them in the Baltic.

Two main dump sites were selected: near the Gotland Deep (approximately 2,000 metric tonnes of chemical munitions) and the Bornholm Deep (approximately 38,000 metric tonnes). Another 150,000 metric tonnes of chemical warfare agents were sunk along with German ships in the Danish Straits, and 1,000 metric tonnes were sunk by the Germans themselves at the end of the war in Danish waters.

There are also much higher estimates: just in the central Baltic, there may be over 90,000 metric tonnes of chemical munitions. Most of the cargo was sunk in 1947 through the joint efforts of Britain, the USA, and the USSR, although, for instance, East Germany also carried out similar "disposals" in the Gulf of Gdańsk as late as 1954. Outside of the Baltic, chemical weapons were also sunk in the Bay of Biscay.

They were sunk in different ways: in the holds of sunken ships and, individually, in metal barrels. We are talking about agents where even the mildest is tear gas, and many are agents where a minimal amount (in the case of sarin, micrograms are sufficient) can kill an adult human. According to various estimates, their total mass ranges from 12,000 to 26,000 metric tonnes. Not all have been located, as some were sunk outside official storage sites - according to the HELCOM CHEMU report (an expert group operating under the auspices of the Helsinki Commission).

The first incidents did not take long to appear. In 1955, a barrel of mustard gas was washed ashore at Darłówko Beach – about 100 people, including children, suffered burns or even lost their sight. Barrels, canisters, etc., continued appearing on beaches, fishing nets, and elsewhere in subsequent years. In 1997, the crew of a fishing vessel was burned by mustard gas, and in 2012, white phosphorus contaminated a beach in the Czołpino area. In each of these incidents, relatively small amounts of agents caused serious injuries.

However, if larger quantities were released simultaneously, on the order of hundreds of metric tonnes, an ecological disaster would ensue. We do not truly know how much time we have left. Chemical weapons lie on the sea floor, primarily inside various kinds of missiles or metal containers. Meanwhile, salty water and sea life activity promote corrosion.

According to Professor Bełdowski's lecture, two views prevail: one suggests accelerated corrosion would occur after a relatively short period (60-120 years from sinking). In contrast, other studies suggest it could be up to 500 years. We do not even know whether this corrosion will breach the containers more or less simultaneously or gradually.

The second scenario is optimistic: only occasional local contamination occurs, and the long-term impact on the Baltic ecosystem is nearly negligible. The first scenario, however, could lead to the cessation of life in the Baltic and possibly also part of the North Sea. It is unnecessary to explain how this would affect human life around the Baltic, especially since we are part of the ecosystem.

The two scenarios may unfold somewhat simultaneously, as it is already known that containers of mustard gas or sarin are not airtight, and animals living near the dumping areas are noticeably less healthy than their counterparts living a bit farther away.

Of course, efforts are being made to reduce the threat. One of the latest is the EU's MUNIMAP program, which, unfortunately, has a small budget. This international program aims to monitor and conduct research on the state of chemical weapons dumped at sea. Interestingly, this poses a legal problem: currently, it is treated as a military threat rather than an environmental one, and attempts to retrieve it must address the issue of acquiring possession of chemical weapons.

The military is expected to eventually contribute to the civilian initiative by providing specialized equipment for monitoring underwater objects. The Polish Navy regularly participates in neutralizing underwater hazardous objects. Nevertheless, no remedial measures are apparent so far. For example, in 2020, Poland's Supreme Audit Office negatively assessed government actions in the report "Combating Threats Arising from the Presence of Hazardous Materials on the Bottom of the Baltic Sea."

For now, only Germany has invested slightly more funds - 112 million dollars (by comparison, efforts to combat the potential widespread leakage of chemical weapons could consume about 2.8 billion dollars annually) – in developing a system for the safe extraction and disposal of wartime deposits. However, as Prof. Bełdowski points out, the problem has outgrown German experts because contemporary German law has proven to be a more significant threat than the creations of past German engineers, preventing the extraction of munitions from the sea floor unless they pose a direct threat to people.

In other words, we are monitoring the situation. Still, neither engineers nor lawyers are ready to solve a problem that threatens the destruction of a key body of water for many countries.

Chemical weapons are just the tip of the iceberg. The Baltic was the scene of intense fighting during the Crimean War and both World Wars, as well as many maritime and aviation disasters were witnessed. Every sunken ship holds dozens, if not hundreds or even thousands of metric tonnes of fuel (the tanker T/S Franken sunk at the bottom of the Gulf of Gdańsk contains about 3,000 metric tonnes of fuel), as well as artillery shells, torpedoes, and often dangerous cargo (tonnes of medicines, reagents, etc.).

Marine mines are occasionally found in the Baltic, sometimes freely roaming the waters, threatening ships, and their oldest passengers may no longer remember the war that these mines are relics of. These further magnify the problem, and cleaning the Baltic of the lingering death is progressing rather ineffectively.