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For many years, marine scientists have known that methane (CH4) is generated in shallow seabed sediments,
especially where sedimentation of organic matter and nutrient inputs are high. Such locations occur at
continental margins, estuaries, harbors and river deltas. About 82% of globally buried organic carbon is stored in
coastal shelf sediment, 16% in continental slope sediments and only 2% of the organic carbon is buried in deep
sea sediments. Eutrophication can accelerate natural seabed gas generation by enhancing organic matter
deposition which upon burial is converted to methane. Gassy sediments occur widespread in the Baltic Sea but
their magnitude of gas storage and potential instability are not known. Hot-spots of shallow gas enhance
ebullition and, thus, emission of greenhouse gas and of toxic hydrogen sulphide. The consequences of
enhanced methane generation for future sustainable ecosystem functioning or for the potential degradation of
habitats in the Baltic Sea are currently not predictable. Furthermore, hot spots of shallow gas pose hazards to
seabed structures such as wind farms, pipelines, power or communications cables, and off-shore drilling
operations.

BALTIC GAS aims to understand how climate change and long-term eutrophication affect the accumulation of
shallow gas and the emission of methane and hydrogen sulphide from the seabed to the water column and
atmosphere. Will future climate-dependent changes in temperature and ventilation of the deep Baltic Sea,
combined with continued organic carbon loading, trigger a massive gas release from the seabed? The project
will bring together a multi- disciplinary team of scientists with the goal to:

- quantify and map the distribution and flux of methane in the Baltic Sea
- analyze the controls on the relevant key biogeochemical processes
- integrate seismo-acoustic mapping with geochemical profiling
- model the dynamics of Baltic Sea methane in the past (Holocene period), present (transport-reaction models),
and future (with predictive scenarios)
- identify hot-spots of gas and potential future methane emission in a Baltic database available for national
authorities and scientists.

BALTIC GAS is an EU founded project with collaboration of many different countries around the Baltic Sea.