The Trump administration is shutting down the Ocean Observatories Initiative, a National Science Foundation programme that has operated a network of more than 900 deep-sea instruments across four major ocean arrays for over a decade. The initiative announced earlier in June that recovery of in-water equipment at four of five operating arrays has already begun, a process expected to take approximately 15 months. Scientists are calling the closure a significant blow to long-term ocean and climate monitoring.

The Ocean Observatories Initiative, known as OOI, was established with federal funding to maintain continuous, real-time observation of the ocean’s deep layers — regions critical to understanding how heat, carbon dioxide, and nutrients move through the global ocean system. The network has tracked everything from underwater volcanic activity and seafloor earthquakes to changes in ocean chemistry associated with carbon absorption and warming temperatures.

The programme’s data feeds directly into climate models used by researchers to project sea level rise, predict extreme weather patterns, and monitor the AMOC — the Atlantic Meridional Overturning Circulation, a vast system of ocean currents that moves warm water from the tropics toward Europe and cold water back south in the deep ocean. Scientists studying AMOC have already raised alarms about observational gaps created by the Trump administration’s broader cuts to federal science infrastructure.

The OOI’s closure fits within a pattern of science programme cuts across federal agencies since the beginning of Trump’s second term. NOAA, NASA’s Earth science division, and the US Geological Survey have all seen budget reductions that researchers say are degrading the United States’ ability to track environmental changes in real time. Critics argue the cuts are being made with no private-sector replacement in sight, meaning the data will simply stop being collected.

The NSF said in a statement that budget constraints required prioritisation across its programme portfolio and that the OOI was among those deemed lower priority. No alternative funding source has been identified to continue the deep-ocean measurements, and researchers who depend on OOI data are scrambling to document the existing archive before the network is fully decommissioned.

International scientific organisations have responded with concern. Several European research institutes have expressed interest in potentially taking over parts of the network’s observational mandate, though the technical and financial barriers to doing so quickly are significant. The instruments are spread across remote locations in the Atlantic and Pacific, and maintaining them requires specialised ships and engineering teams.

The OOI shutdown arrives as climate scientists are warning about elevated risks to Atlantic circulation patterns and the potential for accelerating sea level rise along the US East Coast if AMOC weakens as some models project. Without the continuous deep-ocean data the OOI provides, those projections become harder to validate or refine. The climate science community’s response has been sharp and immediate. The Ocean Observatories Initiative website carries the programme’s data archive and the latest operational updates.