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Methane Emissions from Nord Stream Leak Affect Southern Baltic Sea
A recent study conducted by researchers from the University of Gothenburg and the Voice of the Ocean research foundation highlights the extensive impact of methane released from the Nord Stream pipelines, which were compromised in late September 2022. The findings indicate that the methane spread over a significant area of the southern Baltic Sea, remaining detectable for several months.
While a large portion of the methane escaped directly to the atmosphere, some of it remained submerged and was subsequently distributed by ocean currents.
“Our measurements indicate that the methane contamination reached vast regions of the southern Baltic Sea, spanning from the coast of Danish Zealand in the west to the Polish Gulf of Gdansk in the east,” explained Martin Mohrmann, a researcher at Voice of the Ocean (VOTO).
Detailed Measurements Through Innovative Techniques
The research team utilized an underwater robot known as a glider, which was deployed just beyond the exclusion zone around the damaged pipelines. This advanced instrument facilitated comprehensive measurements of methane concentrations throughout various depths of the water. The researchers continued monitoring the area for three months post-incident, leading to the accumulation of high-resolution data surrounding the leak sites.
“To refine our estimations, we integrated data from our gliders with surface measurements gathered by colleagues at the German research institute IOW, who collected data from ferry routes. The correlation with results from the University of Gothenburg’s research vessel in the Nord Stream leak vicinity further enhances our certainty regarding the methane dispersion in the Baltic Sea, both temporally and spatially,” stated Bastien Queste, an oceanographer at the University of Gothenburg.
Extremely Elevated Methane Levels
In the immediate aftermath of the pipeline explosion, methane concentrations in certain areas reached levels over 1,000 times higher than normal. Elevated methane levels were recorded for several months following the leak before they diminished due to dilution, microbial consumption, or atmospheric release.
“Through our gliders and ocean models pertaining to the southern Baltic Sea, we obtained a comprehensive understanding of the affected areas. We estimate that over 14 percent of the Baltic Sea experienced methane concentrations at least five times higher than usual,” Mohrmann added.
Impact on Marine Protected Areas
The study, published in Nature Communications, alongside two complementary studies on the atmospheric impacts of the Nord Stream emissions, led to the formulation of a detailed dispersal model of the methane in the water. According to the research, ocean currents carried the methane to 23 designated marine protected areas.
“This research provides critical insights into the regions impacted by the methane emissions. It will aid in identifying potential links between future ecological issues in the Baltic Sea and the Nord Stream leak,” remarked Bastien Queste.
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