The ocean is getting out of breath. Like a patient showing signs of fever and gasping for air, the ocean presents symptoms of deepening stress. Since the mid-20th century, scientists have observed an average drop in its oxygen content by about 2%, a process known as ocean deoxygenation, and it is expected to fall as much as 3–4% by the end of the century. As warming waters hold less oxygen and excess nutrient input further fuels deoxygenation, the consequences might be severe.
Certain areas, the so-called dead zones, are already experiencing oxygen lows that make them uninhabitable for marine species. The Baltic Sea, for instance, hosts seven of the world’s ten largest marine dead zones, spanning over 70,000 km² – a surface approximately the size of Ireland. The Black Sea has seen a 36% decline in its oxygen inventory since the 1950s, with the oxygen-rich surface layer shrinking from 140 meters to 90 meters and displacing marine life. Along Canada's Atlantic coast, particularly in the Gulf of St. Lawrence, scientists have seen cod and other fish squeezed into ever-narrower oxygen-filled pockets, which interferes with their feeding, growth, and chances to reproduce. Even in well-oxygenated ocean areas, fast rates of oxygen loss have been reported at local scales, from the Norwegian fjords to the Irish lagoons.
Oxygen loss has repercussions on biodiversity, fisheries and climate, yet the issue remains poorly understood and vastly underrepresented in policy attention and funding agendas. That’s why JPI Oceans is currently exploring the possibility of launching a Joint Action on Ocean Oxygen Loss.
What began as an informal interest, identified through an open idea solicitation process launched by JPI Oceans in spring 2024, took on formal direction later that year when the Management Board gave it Scoping Action status. It is worth noting that a similar solicitation round is now open, inviting ideas to help us identify pressing or emerging marine challenges.
After months of preparatory work, on 5–6 May 2025, a group of experts from national and international institutions met in Brussels and online to define the potential shape and focus of such an initiative. The workshop, led by Karol Kulinski from the Institute of Oceanology of the Polish Academy of Sciences, aimed to define whether and especially how JPI Oceans could support coordinated research on this issue. To that effect, the group sketched out the direction and structure of a dedicated concept paper.
The topic is currently being scoped under the leadership of Poland, with Norway and Germany already on board, and further interest expressed from Sweden, Belgium, Ireland, Italy and Canada. The latter brings a much-welcome transatlantic perspective, expanding the initiative’s international reach. Representatives from IOC-UNESCO also participated and presented their two initiatives on the matter: GO2NE, the Global Ocean Oxygen Network, promoting collaboration on research and observation, and GOOD, the Global Ocean Oxygen Decade programme, which seeks to understand, attribute, and mitigate oxygen loss in coastal and open ocean systems.
Discussions revealed a preference for a joint call as the most effective format for a future Joint Action, complementing GO2NE’s role in coordinating global ocean oxygen observations, standardising data collection methods, and facilitating knowledge sharing among scientists and policymakers. Participants agreed that a joint call would help remediate the shortage in funding for research on ocean oxygen loss; they also determined that it should foresee an element of cooperation with citizens and the private sector to enhance ocean measurement practices and increase data accessibility.
The Joint Action would take a global perspective, complemented with case studies that range from the open ocean to local economic hotspots facing oxygen decline, such as fjords, bays, and lagoons, in addition to low-oxygen regions such as the Baltic, Adriatic, and Black Sea. The experts worked together to outline the main research priorities, from improving understanding of the drivers and consequences of deoxygenation to developing adaptation and mitigation strategies.
These will now feed into a concept paper, to be developed and submitted to the JPI Oceans Management Board in autumn 2025. If approved, a joint call could be launched in 2026, offering a much-needed breath of fresh air for ocean science and policy.