JPI Oceans has released the State of Europe’s Surface Ocean CO₂ Observations – Audit 2026, the first assessment that examines Europe’s ability to observe, steward, and interpret surface ocean carbon records on several levels: the global system, Europe as a whole, its regional seas, and individual countries. The audit, drafted under JPI Oceans’ Knowledge Hub on Ocean Carbon Capacities, provides a consolidated picture of Europe’s strengths and weaknesses along the surface ocean carbon value chain.
Rationale
The ocean absorbs over a quarter of all human-generated CO₂ emissions each year, making surface ocean CO₂ observations essential for quantifying the global carbon sink and informing climate assessments. These measurements underpin major processes such as the Global Carbon Budget, IPCC reporting, and the UNFCCC.
Europe’s contribution to this system has traditionally been strong, particularly in the development of global ocean carbon data products and biogeochemical models. However, until now, Europe’s reporting consistency and long-term stewardship capacity had not been evaluated using defined metrics. This audit fills that gap by reviewing observational coverage, data continuity, and national and regional contributions.
Key findings
The audit shows that European teams produce more than half of the data products used in the Global Carbon Budget and seven of the ten biogeochemical models included in the 2025 edition, which has traditionally positioned Europe as a leader in efforts to quantify air–sea CO₂ exchange. Yet this leadership rests on an increasingly fragile and uneven observational base. Reassuringly, the Baltic Sea recorded a particularly strong rise in measurements, with observation volumes rising by 165% compared with the 2015–2019 baseline, and the North-East Atlantic region saw a moderate increase of about 15%. In contrast, other European seas remain less covered. The Mediterranean Sea continues to be relatively under-sampled, with comparatively few medium- or high-quality observations, and in the Black Sea no surface ocean CO₂ measurements have been reported since 2016. In the Southern Ocean, one of the world’s largest ocean carbon sinks, European observations have declined by about 53% relative to the baseline period and represent only a small share of the total, increasing reliance on non-European partners.
In a country-by-country analysis, it was observed that the number of European countries providing medium- to high-quality observations has almost halved, from nine in the period 2015-19 to five in 2022-23. Monitoring efforts are now concentrated in a small group of countries, which undermines regional balance and long-term resilience. Nonetheless, it should be noted that Belgium, France, Germany and Norway have not only maintained but also improved their efforts.
At the same time, the closure of the European Surface Ocean CO2 Atlas (SOCAT) hub in 2022 has left the global SOCAT release reliant on a single operational hub located in the United States. With no dedicated hub in place, Europe no longer contributes to SOCAT's operational backbone, a role it had fulfilled since 2007. This increases the risk of delays, bottlenecks, and reduced resilience in the global data workflow and creates a single point of failure for a dataset central to global carbon assessments.
Conclusions
The audit makes clear that Europe’s world-class modelling and data product capacity is supported by an observational system that is uneven and increasingly vulnerable. Strengthening this foundation is essential for reliable carbon uptake estimates, for Europe’s science diplomacy and strategic autonomy, and for supporting the ambitions of the European Ocean Pact, the European Digital Twin Ocean, and now also the OceanEye.
Main recommendations and priorities derived from the audit include restoring observations in under-sampled regions, securing continuous data flows, broadening national participation, and re-establishing the European SOCAT hub.