Climate change and the hydrological situation

Climate change will bring higher temperatures and increased precipitation. How will this affect the hydrological situation of lakes and rivers, and how soon will we see these changes?

Global climate models predict that rainfall amounts in Finland will increase by at least 5%, but possibly as much as 30%.

Winter rains, in particular, will increase. Except in the northernmost areas of Finland, this will not mean a thicker snow cover, however, as the climate is also warming up. The winter season will be shorter, most of the precipitation will fall as rain, and rainstorms may become more common.

The increased precipitation will make the rivers run more swiftly and exacerbate the flood risk, also in mid-winter, whereas spring flooding may become less severe at least in some parts of Finland.

When rain falls on bare and unfrozen ground, soil particles can be easily carried along with water. Mineral soils, humus and plant nutrients are washed into rivers and lakes, making them cloudier and driving eutrophication. Salinity in the Baltic Sea is expected to decrease as a result of the increasing influx of fresh water.

These changes will not be immediately visible, and some may also initially be concealed by natural variations. Earlier springs and milder winters in Finland show, however, that the change is already under way.