A warming climate changes the Baltic Sea, and impacts underwater life in many ways. Climate change also further accelerates the eutrophication of the Sea. The consequences of climate warming are already evident in the Baltic Sea. The period when the Sea is covered with ice has become shorter, and a smaller section of the Sea is now covered by ice in the winter. The surface water of the Sea is less salty than it used to be, and sea water temperature records are being broken both on the surface and in the depths.
The nature of the Baltic Sea is changing
As a result of climate change, rainfall volumes are expected to grow. When more fresh waters flow into the Baltic Sea, the species that require salty water will be in trouble. The habitats of marine species are in fact expected to become smaller. The key species of the Baltic Sea’s coastal habitats, i.e. bladderwrack, eelgrass, and blue mussel, are all originally from the oceans, and now, as a result of climate change, their future in the Nordic Baltic Sea is threatened.
Warming seawater also changes the food chains of the Baltic Sea, and impacts underwater life in its entirety in many ways. Some of the northern species that are well-adjusted to the conditions in the Baltic Sea cannot adapt to the speedily advancing changes. In the future, southern, non-indigenous species will have an easier time of making the Baltic Sea their home, and some of the newcomers may pose a threat to the indigenous species of our Sea. Loss of biodiversity weakens the ability of marine nature to adjust to the changes brought about by warming.
Climate change accelerates eutrophication
With more rainfall and mild winters without snow, runoff and discharge loads from land to the Baltic Sea increase, and accelerate eutrophication in the Sea. As the climate heats up, seawater, too, will become warmer, boosting algae growth. Warmer waters mean that more oxygen is consumed in the Sea, which may further worsen the anoxia of the seabed, and lead to more nutrients being released from the seabeds for the use of the algae.
The impact of climate change has benefitted those species for whom the eutrophication of the Sea is not a major problem. Cyprinids, for example, have become more abundant in coastal waters, and pike-perch is also a species that thrives in murky and warm waters. By contrast, the species that need clean and cool waters, such as salmon and whitefish, suffer from the changes in the Sea, brought about by both eutrophication and climate change.
Combating climate change will help the Baltic Sea
The small and shallow Baltic Sea is particularly vulnerable to discharge loads and the impacts of climate change. The Baltic Sea, with its low water mass, is a unique, cold and northern brackish sea, with a fragile and vulnerable nature. Climate warming and eutrophication have already changed the Baltic Sea, and the inhabitants of the sea are challenged by the need to adjust to the fast-advancing changes. A diverse, healthy community of species is, however, more resistant to the coming environmental changes, which is why protection work is worthwhile.
By combating climate change, we can at the same time help the Baltic Sea, and slow down the impact the changes will have on marine nature and the status of the sea.