30 September 2022 | Stockholm | WWF raises concern over the environmental impacts of the Nord Stream pipelines leaks. Whilst it currently seems that the environmental consequences may be greater in terms of the climate than nature, the potential effect of this unprecedented event on the Baltic Sea environment and marine life must urgently be assessed.
At present, it is difficult to say what impact the four leakages from the damaged pipelines may have on the environment. While most gas is expected to be released into the atmosphere , the exact volume of which is still unclear. Firstly, the total amount of leaked natural gas is currently unknown, and secondly, there is insufficient knowledge of the composition of the gas and how its components are behaving in this particular situation – how much dissolves in water, how much escapes into the atmosphere, and how much may concentrate in marine waters or be consumed by microorganisms.
As natural gas primarily consists of methane, a highly potent driver of climate change, we expect that the massive gas release adds to the global climate crisis. However, to what extent depends on the total amount of gas eventually released to the atmosphere. According to an estimate made by Danish authorities, approximately 778 million standard cubic meters of gas will be released, which corresponds to approximately 14.6 million tons CO2-equivalent (CO2e). In comparison, this corresponds to 32% of Danish annual CO2e emissions .
Aside from the potential climate impacts, there are varying opinions on the potential effects on the Baltic Sea marine environment. Whilst Swedish authorities expect no significant impact on marine life in the area , voices of concern have been raised by others, highlighting that methane in high concentrations, combined with the already low oxygen levels in the Baltic, may be dangerous to marine life such as fish . This is particularly concerning as the leaks have occurred off the island of Bornholm close to the only spawning ground for the Eastern Baltic cod, a fish population which has seen a dramatic decline in recent years. The underwater explosions and gas plumes will likely have posed a threat to nearby marine organisms. Even at greater distances the blasts may have negatively impacted individuals of the critically endangered Baltic harbour porpoise, which uses echolocation and is highly sensitive to high, impulsive noise .
WWF considers it crucial that any further harm is averted and potential damage to the marine environment is urgently assessed as soon as conditions allow. We call for timely action from the Swedish and Danish governments in collaboration with other European member states around the Baltic Sea, to assess and monitor any impact on marine life and water quality in the perimeter of the leaks and in downstream ecosystems. It is crucial to swiftly identify possible direct and long-term effects, as this incident is unprecedented in the Baltic Sea. Shifts in water chemistry and changes in biota of the entire water column need to be considered with special emphasis on microorganisms that consume methane, but also potential changes in fish, bird and marine mammal populations. It is particularly important to assess any consequences for the critically endangered Baltic harbour porpoise, the Baltic cod and its spawning area.
Despite uncertainties surrounding the impact on climate and the Baltic Sea, this incident highlights the fragility of fossil energy systems and the need to transition toward safe, sustainable, renewables-based energy.
 Aarts G, von Benda-Beckmann AM, Lucke K, Sertlek HÖ and others (2016) Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions. Mar Ecol Prog Ser 557:261-275. https://doi.org/10.3354/meps11829
WWF Baltic Ecoregion Programme
Hannah Griffiths Berggren
WWF Baltic Ecoregion Programme