The Baltic
Here is what is happening to it, and what we can do. No panic, with numbers and sources.
The Baltic is a brackish, semi-enclosed and shallow sea, on average about 54 metres deep. It connects to the ocean only through the narrow Danish straits, so it takes around thirty years for its water to fully exchange. Whatever enters it stays for decades. That makes it unusually fragile, and makes the state of the Baltic a matter for everyone who lives around it.
What threatens the Baltic
Nitrogen and phosphorus from farming and wastewater fuel algal blooms. As these sink and decompose, they use up oxygen near the seabed and create anoxic "dead zones" where life disappears. The Baltic holds the largest human-induced dead zone in the world. According to HELCOM's 2023 assessment, eutrophication still affects almost the entire sea, with no clear improvement over 2016–2021.
Source: HELCOM, State of the Baltic Sea 2023 →Microplastic in the water and in marine life, debris on the beaches and the seabed. Most litter comes from land, and as a semi-enclosed sea the Baltic accumulates it more than the open ocean. HELCOM runs a regional action plan to cut marine litter.
Source: HELCOM, Marine Litter →The eastern Baltic cod stock has collapsed. In 2019, acting on alarming ICES assessments, the European Commission banned targeted cod fishing. Scientists also regularly warn that herring and sprat quotas are set too high. The result is a broken food chain and lower biodiversity.
Source: European Commission, ICES →Heavy metals, persistent pollutants and pharmaceutical residues. On top of that, around 40,000 tonnes of chemical weapons were dumped after the Second World War, including some 13,000 tonnes of chemical warfare agents, mostly east of Bornholm and near Gotland. The containers corrode, slowly releasing their contents.
Source: HELCOM →The Baltic is warming faster than almost any sea on Earth; since the 1980s it has warmed fastest of all the world's coastal seas. The effects are more frequent marine heatwaves, less winter ice, a shifting mix of species, and a rising sea level that threatens coastlines, including Poland's.
Source: HELCOM, Baltic Earth →The Baltic is one of the busiest seas in the world: up to around 15% of global maritime transport passes through it, with about 2,000 ships at sea at any moment. That means spill risk and emissions. Since 2015 a stricter limit on sulphur in fuel applies (SECA), and since 2021 a nitrogen oxide control area (NECA) as well.
Source: HELCOM →The Baltic in numbers
Figures straight from scientific assessments, not from our imagination.
Sources: HELCOM, State of the Baltic Sea 2023, HELCOM (chemical munitions), IMO. Figures are approximate, based on the latest available assessments.
What you can do
What we are doing in response
We run lessons and events, build a network of young leaders, and work with scientific partners so that what we say is true and what we do does not stop.
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