The world relies on a modest number of countries to keep watch over the ocean. That arrangement is starting to fail. Europe and Asia must now decide whether to let the system unravel, or to take it up together.
Right now, in every ocean basin on Earth, a global network of instruments measures the state of the sea.
Research ships steam along oceanographic transects from surface to seafloor. Anchored buoys watch the tropical oceans for the first signs of El Niño or tropical cyclones and take the pulse of the thermohaline circulation. Some 4,000 autonomous floats sink every 10 days to 2,000 meters before rising to transmit temperature and salinity to ground stations via satellite. Underwater gliders patrol continental margins, and drifting buoys ride the surface in the most remote waters. Hundreds of elephant seals carry miniaturized sensors beneath the polar sea ice…
Together, this network produces invaluable information that allows societies to anticipate and respond to changing ocean and weather conditions, and protect the ocean in return.
It is also far more fragile than most people, and most governments, realize. A new study published in Nature Climate Change has measured for the first time just how fragile the ocean watch network is.
The result is alarming. If observations from a single major contributor, the United States, were withdrawn from the Global Ocean Observing System (GOOS), the errors in our estimate of how fast the ocean is warming would jump by 163%. That is worse than randomly losing 80% of all global ocean data. The reason is geographical: U.S. instruments cover every ocean basin and plug critical gaps that no other nation currently fills.
This is not a theoretical concern. Proposed cuts to National Oceanic and Atmospheric Administration and the National Science Foundation in the United States now threaten exactly this contribution. And the situation is barely better on the other side of the Atlantic.
The pressures are not confined to one side of the Atlantic, nor to the West. In China, scientists and policymakers are working to build a more resilient national contribution to ocean observation, but without the resources the moment requires. The marine monitoring system the world relies on is under strain almost everywhere.
Public conversations about ocean observations often focus on Argo floats.
Each Argo is essentially a sealed cylinder of pressurized electronics with a clever buoyancy chamber: It floods with seawater to sink and is evacuated to rise again. These autonomous robots have transformed ocean science this century.
However, Argo is just one component of GOOS, and the complementarity of its parts matters.
Argo profiles the upper 2 kilometers of the open ocean.
Research vessels go deeper: GO-SHIP cruises survey from surface to seafloor along long repeated transects, providing the high-precision reference measurements that calibrate every other instrument and help validate climate models.
Moored buoys deliver continuous time series critical for monitoring El Niño, the Atlantic Meridional Overturning Circulation, and the conditions in which tropical cyclones form.
Underwater gliders target coastal currents, eddies and continental margins that floats cannot resolve. (Phys Org)
Elephant seals carry sensors into under-ice regions of the polar oceans that no other instrument can reach.
Each platform answers questions the others cannot.
Remove any one of these ocean watch components, and the observing system’s ability to deliver reliable information degrades not in proportion to the volume of data lost, but in proportion to where the gaps appear.
The Global Ocean Observing System is too often described as “climate monitoring,” but it does so much more.
Every operational weather forecast is built on these data. The numerical weather prediction systems run by European Center for Medium-Range Weather Forecasts, by Météo France, and by every other major weather service ingest ocean observations many times a day.
Without them, forecasts drift quickly out of skill.
The new artificial intelligence-based forecast systems Pangu-Weather and GraphCast, despite their impressive performance, rely entirely on the same observational stream.
AI does not replace observations; it depends on them.
Subseasonal to seasonal forecasting, to help anticipate harvest seasons, energy demand and water availability weeks to months ahead, depends critically on knowledge about subsurface ocean heat and salinity.
Tropical cyclone track and intensity forecasts, central to early warning and evacuation decisions, depend on ocean heat content beneath the surface, not just sea surface temperature, because hurricanes draw their explosive energy from the warm layers down to at least 200 meters deep.
Marine heat wave warnings, now used routinely by fisheries managers worldwide, are impossible without sustained subsurface observation. (Phys Org)
