Polski
An infusion of salt water from the North Sea into the Baltic Sea is expected in late 2023 and early 2024. This water, thanks to winds and atmospheric pressure differences, will enter the Baltic Sea through the Danish Straits. Are salt water inflows necessary for the Baltic? What do they actually mean to him? Why do they occur so rarely?
The Baltic Sea and salt water infusion
The Baltic Sea is the youngest sea in the world. Due to the large influx of freshwater from the surrounding areas and its low salinity, it is classified as brackish water (it is also the largest body of brackish water in the world – it occupies approx. 420,000. km2). Thanks to its uniqueness, it is home to both freshwater and marine species.
The Baltic Sea ecosystem is exposed to natural and anthropogenic threats on a daily basis – it’s worth reading “What are we stressing to the Baltic residents?“. The organisms living in it need adequate oxygenation and nutrients for proper development. The infusion of saltwater from the North Sea is a response to their demand, as it brings in a huge amount of salt and fresh oxygen, delivering them to the deepest areas of the sea that are particularly vulnerable to deficits. Many fish species, such as cod, need salty and well-oxygenated areas for breeding – if these conditions are not maintained, cod will not survive. The inflows therefore have a direct and valuable impact on the health of the Baltic ecosystem.
Salt water infusion a guarantee for the health of the Baltic Sea
In addition to salt and oxygen, salt water infusion also introduces nutrients (i.e., nitrogen and phosphorus compounds), which increase the fertility of the waters and affect the growth of phytoplankton. Excess nutrients, in addition to rising water temperatures and pollution of various origins, lead to eutrophication of waters, i.e. algal blooms that produce toxic substances that affect water quality and the health of organisms living in it. This process leads in the long run to a significant reduction in the amount of oxygen, and life in these places dies. These areas, due to such a radical lack of habitat for marine organisms, are called dead zones. The long-term existence of an environment unfavorable to life can lead to significant changes in the Baltic ecosystem, including the reduction or destruction of biodiversity in it.
Rarity of salty inflows from the North Sea
Inflows are mainly recorded in winter, when prolonged and strong storms occur. In the Baltic, such inflows occur in smaller areas compared to other seas or oceans. They are divided into a smaller saltwater infusion, which is one that occurs more often but does not bring with it much salt and oxygen, and a larger saltwater infusion, which is one that happens much less often and brings with it a lot of good.
The larger and more valuable saltwater inflows from the North Sea are cyclical. They occur regularly – on average once every 10 years. In the past, large inflows of saltwater into the Baltic Sea, for example, occurred in 1993, then in 2003, and most recently in 2015. Today’s forecasts, focusing on predicting this nature-friendly phenomenon, speak of late 2023 and early 2024.
Favorable for the Baltic, large inflows occur sporadically and their arrival is difficult to predict. The reason for their lower numbers is climate change, which causes vagaries in atmospheric circulation. As a result, conditions are rarely favorable for fresh water to overflow from the North Sea into the Baltic.
The Baltic Sea is a delicate and complex ecosystem, and inflows of salty and oxygenated water from the North Sea depend mainly on atmospheric and climatic conditions. In order to maintain a properly functioning, healthy and unique biodiversity of the Baltic Sea, regularity and a large volume of inflows (at least 200-300 km3) are necessary. For this, it is essential to protect this unique body of water and ensure that the Baltic Sea environment is not further polluted and littered. Only by inhibiting the progressive climate change, or at least minimizing the harmfulness of the accompanying phenomena, are we able to maintain the frequency of fresh water flow to the Baltic Sea. A small infusion of salt water will not be able to guarantee the maintenance of biodiversity in its waters and will end in ecological disaster.
