KIEL, July 27 — Against this backdrop of rising geopolitical tensions and climate-driven instability, a comprehensive international study published in the journal Science in February 2025 has sharpened the focus on an overlooked crisis: the steady suffocation of the world’s oceans.
Led by scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel, the University of Washington, and the U.S. National Oceanic and Atmospheric Administration, the study synthesises decades of data and projections from the Intergovernmental Panel on Climate Change, including its 2019 Special Report on the Ocean and Cryosphere in a Changing Climate. The warning is blunt: the ongoing loss of dissolved oxygen is approaching what the researchers call an “unsafe space” beyond which irreversible ecosystem collapse and severe socioeconomic consequences become unavoidable.
Since the 1950s, the global ocean has lost about 2% of its dissolved oxygen, while oxygen minimum zones—vast stretches of water where oxygen levels are too low to support most marine life—have expanded by roughly 4.5 million square kilometres. By 2100, under a high-emissions scenario, the ocean could lose another 3–4% of its oxygen content, and coastal dead zones could triple in extent. These are not abstract numbers.
They represent the slow dismantling of marine food webs, the foundation upon which the livelihoods and protein supply of more than 3 billion people depend.
The Science of Suffocation
The study does not treat oxygen loss in isolation. It explicitly links the trend to two other well-documented disturbances: marine heatwaves, which have increased in frequency by 50% over the past century, and ocean acidification, which has risen by 30% since the Industrial Revolution. Together, these three stressors compound one another, creating conditions that push marine ecosystems past tipping points.
In the corridors of European marine research institutes, the term “dead zone” is no longer a distant phenomenon confined to the Gulf of Mexico or the Baltic Sea—it is a creeping reality for shelves and basins worldwide. What is at stake goes beyond the environmental.
The researchers note that these trends could trigger transboundary resource conflicts over dwindling fish stocks, particularly in the tropical Pacific and Indian Oceans, where coastal nations already clash over maritime boundaries. For a European audience, the wider picture includes the Mediterranean, where the combination of warming, acidification, and deoxygenation is already reshaping fish distribution and testing the cooperative frameworks of the European Union’s Common Fisheries Policy.
The study’s authors do not name specific countries at risk, but the geography is unmistakable: the same regions where the European Union and its member states have invested in fishery access agreements and development aid are precisely those where fish stocks are most vulnerable.
A Geopolitical Time Bomb
In the halls of international diplomacy, the study’s timing is significant. It arrives as the United Nations Sustainable Development Goal 14—Life Below Water—faces repeated delays and underfunding, and as the Paris Agreement of 2015 struggles to maintain its credibility amid uneven national commitments. The researchers call for immediate implementation of the Paris targets and stronger commitments to SDG 14 to halt further oxygen decline.
Yet the political will required to curb greenhouse gas emissions, reduce agricultural runoff that feeds coastal dead zones, and manage fisheries sustainably remains fragmented. The United States, under President Donald Trump, has pursued an energy policy that prioritises fossil fuel production, a stance that sits at odds with the emissions reductions necessary to slow ocean deoxygenation.
While the administration has not formally withdrawn from the Paris Agreement during this term, its regulatory rollbacks and minimal engagement with multilateral climate finance have left European allies to shoulder much of the burden. In the corridors of Brussels, there is growing frustration that the U.S. is not pulling its weight on an issue that directly affects European fleets fishing in the Atlantic, the Indian Ocean, and the Pacific.
What Must Be Done
The study offers no easy prescriptions, but it underscores the urgency of action. Cutting greenhouse gas emissions in line with the Paris Agreement remains the most direct lever, because warming water holds less oxygen. Reducing nutrient pollution from agriculture and wastewater is equally critical to prevent coastal dead zones from expanding.
The authors also call for stronger marine protected areas and more robust monitoring networks to track oxygen levels in real time. For now, the warning sits on the desks of policymakers in Berlin, Brussels, Washington, and Tokyo.
Whether it will galvanise the kind of coordinated, long-term response that ocean systems require—or whether it will join the stack of unheeded scientific reports—remains an open question. What is certain, the researchers conclude, is that the window for action is narrowing. And in the global contest for dwindling marine resources, the next conflict may not start over oil or land, but over the fish that once seemed inexhaustible.
