Baltic Sea present climate

Has global warming affected the Baltic Sea? And if so, how? Some people say that the climate has deviated from the natural variation in the past 30 years. A recent study carried out within our research group (Omstedt and Nohr, 2004) recounts how various meteorological factors varied in the air above the Baltic Sea during this period. Air temperature and wind have increased; cloudiness and relative humidity have declined. Nevertheless, analysis of the sea’s heat balance shows that the Baltic Sea has not been appreciably affected – the trends cancel each other out. Locally, we can track trends in different parts of the Baltic Sea and at various depths, but the net effect does not yield a trend. The mean water temperature of the Baltic Sea is stable despite regional warming. The reason was explained by the heat balance that indicated no trend in the Baltic Sea net heat loss.


(Click image to enlarge)

Click image to enlarge


Figure 1. Observed (dashed line) and modelled (fully drawn line) annual variation of Baltic Sea mean water temperature. The BALTEX/BRIDGE period is marked. From Omstedt and Nohr (2004).



  • Omstedt, A. and C., Nohr (2004). Calculating the water and heat balances of the Baltic Sea using ocean modelling and available meteorological, hydrological and ocean data. Tellus 56A, 400-414.


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