The fragile climatological niche of the Baltic Sea

The Baltic Sea is governed by the same physical laws as any other sea. Yet since it lies in a very different part of the temperature and salinity range than most other waters of the World Ocean, these laws result in dynamics that is not found elsewhere in the same extent. Here some consequences of this fact are discussed in light of recent observational and theoretical advances. We show that heat fluxes are almost negligible for restratification in this regime, and combine this idea with what is expected about the climatic warming to give a forecast of a substantial, non-linear change in the way the seasonal stratification and the vernal bloom in the Baltic Sea are formed. This discussion should also provide a conceptual framework for the discussion of the impacts of climate change on vernal bloom dynamics there, and in boreal estuaries in general.