From June 9 to 13, 2025, the city of Nice will become the global epicenter of marine governance. It will host the third United Nations Conference on the Ocean. Co-organized by France and Costa Rica, this event will bring together more than 70 heads of state, 4,000 government representatives, and 6,000 members of civil society, with the aim of addressing what the UN calls the “global ocean crisis.”
Why are we talking about an ocean crisis?
An unprecedented rise in temperature
The oceans have absorbed more than 90% of the excess heat generated by human activities since the 1970s, according to the IPCC. As a result, the average surface water temperature has reached record levels in recent years. This is disrupting marine ecosystems. In 2023, UNESCO warned of the alarming acceleration of global warming and rising sea levels. The organization points out that certain regions, such as the tropics and the poles, are seeing massive coral bleaching or rapid melting of sea ice.
Plastic Pollution: An Invisible but Persistent Tide
Every year, between 9 and 14 million tons of plastic end up in the seas, according to the United Nations Environment Programme (UNEP). This plastic never truly disappears: it fragments into nanoparticles that contaminate the entire marine food chain, from plankton to fish… all the way to humans. Scientists are now finding it in drinking water, sea salt, and even in human blood.
In the heart of the oceans lies a disturbing creation of our own making: the so-called “seventh continent.” This vast accumulation of plastic waste, drifting over an area three times the size of France, is not a solid island but a dense soup of debris and microplastics. Carried by currents, it traps millions of tons of waste that slowly degrade, poisoning marine ecosystems. The seventh continent is both a symptom and a warning: a mirror reflecting our consumption patterns, and a call to urgently rethink our relationship with plastic.
Overfishing is depleting fisheries resources
According to the Food and Agriculture Organization of the United Nations (FAO), more than a third of the world’s fish stocks are overexploited. Entire species such as bluefin tuna, cod, and grouper are becoming increasingly rare. Illegal, unregulated, and unreported fishing accounts for up to 30% of global catches, undermining sustainable management efforts.
Ocean Acidification: A Silent Threat
The ocean acts as a buffer against climate change by absorbing atmospheric carbon dioxide. But this absorption comes at a cost: it alters the chemistry of marine waters. Ocean pH has already dropped by 30% since the pre-industrial era. This acidification particularly affects organisms with shells or calcareous skeletons, which struggle to thrive in a more acidic environment.
Deoxygenation: Expanding Dead Zones
As the oceans warm and become more polluted, their capacity to store oxygen diminishes. We are seeing an increasing number of dead zones—marine regions where oxygen levels are so low that complex life cannot survive. These zones have quadrupled since the 1950s, according to a study published in Science in 2018.
Why ocean health is vital for humanity
The oceans play a fundamental role in sustaining life on Earth:
- Human health: Many medicines are derived from marine organisms, offering prospects for treating various diseases.
- Climate regulation: They absorb about a third of global CO₂ emissions, thus helping to mitigate climate change.
- Oxygen production: Thanks to phytoplankton, the oceans generate more than half of the oxygen we breathe.
- Food resources: They provide essential proteins to more than 3 billion people worldwide.
- Economy and employment: The maritime sector supports millions of jobs, particularly in fishing, tourism, and transport.
What political actions can be taken to preserve the oceans?
In light of this alarming situation, several measures could be considered at UNOC 2025:
- Extension of marine protected areas: Achieve 30% ocean protection by 2030, drawing inspiration from successful initiatives such as those in the Galapagos Islands.
- Fighting plastic pollution: Implementing action plans to significantly reduce marine waste, such as the Zero Plastic Action Plan at Sea (2020-2025) in France.
- Sustainable fishing: Encouraging ecosystem-friendly practices, particularly by banning bottom trawling in sensitive areas.
- Decarbonizing maritime transport: Reducing the sector’s greenhouse gas emissions by promoting clean technologies.
- Strengthening scientific research: Supporting research programs to better understand the oceans and develop innovative solutions.
One of the major objectives of the conference is also to promote the ratification of the treaty on biodiversity in the high seas adopted in 2023, in order to protect areas located beyond national jurisdictions.
Conclusion: A Decisive Moment for the Future of the Oceans
The 2025 UN Summit in Nice represents a unique opportunity to mobilize the international community around ocean conservation. The decisions taken at this conference will have lasting impacts on the health of our planet and the well-being of future generations. It is imperative that commitments translate into concrete and ambitious actions.
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