Long-term Warming Raises Risks of Seasonal Seafloor Methane Release in the Coastal Baltic Sea

Strategic Insights -

Scientists have discovered that climate change driven ocean warming can significantly increase the risk of methane release into the atmosphere from sediments in the coastal Baltic Sea. According to research conducted by Songjun Li and colleagues at Linnaeus University, long-term warming of marine sediments can lead to a 50-fold increase in methane concentrations, posing a significant threat to the global environment.

Key Takeaways:

  • The research found that long-term warming of marine sediments can lead to a 50-fold increase in methane concentrations, posing a significant threat to the global environment.
  • The study, conducted by Songjun Li and colleagues, used sediments from two Baltic Sea bays with different temperature profiles: one had been heated by a nearby power plant for 50 years, resulting in a 5.1°C increase in annual average temperature.
  • The results showed that near-seafloor sediment methane concentrations were 50 times higher in the heated bay compared to the unheated control bay.
  • The sediment fluxes and microbial community composition changes suggested that long-term warming may thin the sulfate reduction zone, allowing methanotrophic archaea and sulfate-reducing bacteria to peak at shallower sediment depths in the heated bay.
  • The study concluded that future climate change warming may increase the risk of methane release to the water and eventually the atmosphere.
  • The research highlights the need for continued monitoring and studies on the effects of climate change on marine ecosystems.

Statistics:

  • 50-fold increase in methane concentrations in the heated bay compared to the unheated control bay.
  • 5.1°C increase in annual average temperature in the heated bay compared to the control bay.
  • 50 years of heating by a nearby power plant in the heated bay.
  • 50 times higher methane concentrations in the near-seafloor sediment of the heated bay.
  • 10% increase in sediment fluxes in the heated bay.

Sources:

  • Li, S., Ketzer, M., Chang, C., Rula, I., Seidel, L., Svendsen, I. K., Forsman, A., Hylander, S., Dopson, M. (2025). Long-term warming raises risks of seasonal seafloor methane release in the coastal Baltic Sea. Frontiers in Microbiology, 16.
  • NewsRx. (2025, October 20). New Climate Change Research from Linnaeus University Described (Long-term warming raises risks of seasonal seafloor methane release in the coastal Baltic Sea). Global Warming Focus. October 20, 2025; p 1884.