Future Climate Change in the Baltic Sea Region and Environmental Impacts
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Climate Science. Please check back later for the full article.
The warming of the global climate is expected to continue in this century, although the magnitude of change will depend on future anthropogenic greenhouse gas emissions and the sensitivity of climate to them. The regional characteristics and impacts of future climate change in the Baltic Sea countries have been explored since at least the 1990s. Later research has supported many findings from these early studies, but advances in understanding and improved modeling tools have made the picture gradually more comprehensive and more detailed. Nevertheless, many uncertainties remain.
In the Baltic Sea region, warming is likely to exceed its global average, particularly in winter and in the northern parts of the area. The warming will be accompanied by a general increase in winter precipitation, but in summer precipitation may either increase or decrease, with a larger chance of drying in the southern than in the northern parts of the region. Despite the increase in winter precipitation, the amount of snow is generally expected to decrease, because a smaller fraction of the precipitation will fall as snow, and mid-winter snow melt episodes will become more common. Changes in windiness are very uncertain, although most projections suggest a slight increase in average wind speed over the Baltic Sea. Climatic extremes are also projected to change, but some of their changes will differ from the corresponding change in mean climate. For example, the lowest winter temperatures are expected to warm even more than the winter mean temperature, and short-term summer precipitation extremes are likely to become more severe, even in those areas where the mean summer precipitation does not increase.
The projected atmospheric changes are accompanied by an increase in Baltic Sea water temperature, reduced ice cover, and according to most studies, reduced salinity due to increased precipitation and river runoff. The seasonal cycle of runoff is modified by changes in precipitation and earlier snowmelt. Global-scale sea level rise also affects the Baltic Sea, but is counteracted by glacial isostatic adjustment. In the northern parts of the Baltic Sea, the latter will still dominate according to most projections, leading to a continued although decelerated decrease in relative sea level. These changes in the physical environment and climate will have a number of environmental impacts: related, for example, to atmospheric chemistry, freshwater and marine biogeochemistry, ecosystems, and coastal erosion. However, future environmental change in the region will be affected by several interrelated factors. Climate change is only one of them, and in many cases its effects may be exceeded by other anthropogenic changes.