Environmental impact of sabotage of the Nord Stream pipelines

Abstract Armed conflicts have, in addition to severe impacts on human lives and infrastructure, also impacts on the environment, which needs to be assessed and documented. On September the 26th 2022, unknown perpetrators deliberately ruptured the two gas pipelines Nord Stream 1 and 2 with four coordinated explosions near a major chemical munition dump site near the Danish island of Bornholm in the Baltic Sea. While the massive release of natural gas into atmosphere raised serious concerns for climate, this paper assesses the overlooked direct impact of this sabotage on marine ecosystem. Seals and porpoises within a radius of four km would be at high risk of being killed by the shockwave, while temporary impact on hearing would be expected up to 50 km away. As the Baltic Proper population of harbour porpoises (Phocoena phocoena) is critically endangered, the loss or serious injury of even a single individual is considered a significant impact on the population. The rupture resulted in the resuspension of 250.000 metric tons of heavily contaminated sediment from deep-sea sedimentary basin for over a week, resulting in unacceptable risks towards fish and other biota in 11 km3 water for more than a month.