UN Conference: How to Protect the Oceans?

To protect the oceans, the international community has gathered in Nice, France, for the UN Ocean Conference (09.06 - 13.06.2025). UN Secretary-General Antonio Guterres has called on the international community to better protect the oceans. At the opening of the third UN Ocean Conference in Nice, Guterres said that heads of state and government should sign a treaty that would allow countries to create marine protected areas in international waters. Illegal fishing, plastic pollution and rising sea temperatures threaten fragile ecosystems and the people who depend on them. Fish stocks are collapsing, sea levels are rising and the oceans are becoming more acidic.

The seas and oceans are home to over 250,000 species – from microscopic plankton to giant coral reefs and the blue whale, the largest animal on the planet. For more than a billion people, the sea is the most important source of food. What are the most important problems facing the oceans?

Warmer seas mean fewer living things

Large parts of underwater life are at risk because the Earth is warming. As temperatures continue to rise, corals are breaking down and dying. Around 84% of all coral reefs worldwide are affected. If the seas warmed by 1.5 degrees compared to pre-industrial times, most corals would be wiped out. "Warming by 2 degrees Celsius would mean irreversible destruction," says Katja Matthes, who heads the GEOMAR Research Center in Kiel.

Since warm water can absorb less oxygen, many living things are at risk.

The results of new studies show that the sea is warming up to a depth of 2,000 meters. "As a result, oxygen is decreasing for plankton, fish and marine mammals. We are seeing dead zones in the Baltic Sea in Germany where there is practically no life left."

Overfishing creates stress on marine systems

Marine ecosystems are also threatened by uncontrolled fishing. The environmental organization WWF estimates that the number of species affected by uncontrolled fishing has tripled in the last 50 years. If too much is fished, stocks cannot be sufficiently replenished.

The problem is particularly evident in the Mediterranean. In this region, almost half of the species are affected by overfishing. Sardines are among the species most often caught in fishing nets. "As a result, the food chain for marine mammals and the entire ecosystem are disrupted," analyzes Matthes. This also affects the basis of our existence. Fish are the most important source of protein for billions of people.

Worldwide, about 600 million people, mainly in China, Indonesia and India, are economically dependent on the sea.

By 2050 there will be more plastic than fish in the ocean

By 2050, the weight of all fish will be surpassed by something else. Every year, 8 to 10 million tons of plastic waste enters the oceans, the World Resources Institute estimates. It can take hundreds of years for this waste to decompose. Long-lived plastic debris and particles are increasingly threatening the lives of marine life.

Sea temperature also influences the weather

Sea temperature also affects weather and atmospheric temperature. The monsoon season in South America and Asia or the relatively mild weather in Europe is influenced by global ocean currents.

The Gulf Stream, as part of the Atlantic overturning circulation, brings warm water from the Tropics to the North Atlantic Ocean. This influences the usually mild air temperatures and thus the high agricultural yields in Europe.

Rising temperatures, according to researchers, could change the ocean circulation system. There are already signs that the Gulf Stream is slowing down. Without it, northern Europe would be five to 15 degrees colder, the Federal Environment Agency in Germany estimates.

Sea surface temperatures set new records in 2023 and 2024, according to the latest Copernicus-Report. The warmer the water, the more it expands. This is why sea levels are constantly rising.

The sea warms because it absorbs carbon dioxide and other gases that are emitted - almost a third of human-caused emissions. This stabilizes the climate. "Without this absorption function, the temperature in the atmosphere would already be unbearable," explains Carlos Duarte. He studies the ocean at King Abdullah University in Saudi Arabia.

"The ocean is our ally in the fight against climate change," explains Matthes, "but this will only be the case as long as its function is maintained." Because as the water temperature rises, it can absorb less and less carbon dioxide.

How are the seas currently protected?

To counter the threat, states are creating so-called marine protected areas. Most of these areas are located off the coast of the US state of Hawaii.

These protected areas take different forms in different countries. They often prohibit offshore wind farms or fishing. There are currently less than nine percent of marine protected areas worldwide – but only three percent of them prohibit fishing.

Less plastic in the sea

"We can't solve all the problems with marine protected areas. Climate change or plastic in the sea have nothing to do with these areas," says expert Duarte. To avoid plastic pollution, the UN has been trying to establish an international agreement for years. Negotiations on this recently failed due to resistance from major oil countries such as Saudi Arabia and Russia. In August 2025, discussions will continue in Switzerland./ DW (A2 Televizion)