The Sentinel-6B sea level rise satellite has been launched into orbit to measure global ocean levels with millimetre precision, giving Europe new tools to track climate change and strengthen its space autonomy in a rapidly changing geopolitical environment.
A new European satellite to measure sea level rise
Sentinel-6B is the latest satellite in the European Union’s Copernicus Earth observation programme, dedicated to monitoring sea level rise as a key indicator of global warming. Launched on 17 November aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California, the satellite will orbit the planet and map the height of the oceans with unprecedented accuracy every ten days.
Together with its twin satellite Sentinel-6A, which has been in orbit since 2020, Sentinel-6B extends a three-decade record of sea-surface height measurements that began in the early 1990s with the Topex-Poseidon and Jason missions. This long, consistent time series allows scientists to detect changes of just a few millimetres per year in the average height of the oceans.
According to climate scientists, global mean sea level has risen by around 3.3 millimetres per year since 1993, and the rate has accelerated to about 4.2 millimetres per year over the past decade. Even small annual increases translate into significant long-term changes for coastal regions, deltas and low-lying islands. Up to 900 million people worldwide live in coastal areas that are increasingly exposed to flooding, storm surges and coastal erosion.
The Sentinel-6 mission is designed as the gold-standard reference for satellite sea-level measurements. Its radar altimeter sends pulses towards the ocean surface and measures the time they take to return, while other instruments correct for atmospheric effects such as water vapour. Combined with precise positioning data, these measurements provide a highly accurate picture of how the oceans are responding to melting ice sheets, shrinking glaciers and the thermal expansion of seawater.
Swedish technology at the heart of Sentinel-6B
The new satellite also highlights how Nordic technology is embedded in Europe’s space infrastructure. Sentinel-6B is controlled by an onboard computer built by Beyond Gravity in Gothenburg, one of Sweden’s key players in the space hardware sector. The same company supplied the antenna system that relays data back to Earth.
Once in orbit, Sentinel-6B will transmit its data to ground stations in Kiruna, in northern Sweden, and Fairbanks in Alaska. From there, the measurements are processed and made available to researchers, meteorological agencies and public authorities around the world.
The mission’s data are freely accessible, in line with the Copernicus open-data policy. This means that climate scientists, weather services and even private companies can use Sentinel-6B observations to improve weather and storm forecasts, monitor extreme events and refine long-term projections of sea level rise.
For Sweden and the broader Nordic region, the satellite underlines a long-standing contribution to Earth observation and Arctic research. Data from Sentinel-6B will be particularly relevant for monitoring changes in the North Atlantic and Arctic Ocean, where warming, sea ice loss and shifting ocean currents are reshaping ecosystems and sea conditions.
Copernicus, climate data and Europe’s strategic autonomy
Sentinel-6B is part of a wider effort by the European Union and the European Space Agency (ESA) to build independent space capabilities that support climate policy, security and economic resilience. The Copernicus programme already includes missions dedicated to land, ocean, atmosphere and climate monitoring, and Sentinel-6 is its dedicated ocean altimetry component.
In March 2023, the EU adopted its first Space Strategy for Security and Defence, which recognises space as a strategic domain and stresses the need to protect European space infrastructure and ensure strategic autonomy in orbit. Within this framework, Copernicus is not only a scientific tool but also a pillar of Europe’s ability to take decisions based on its own data and monitoring systems.
The Sentinel-6 partnership itself illustrates this balance between autonomy and cooperation. The mission is implemented and co-funded by the European Commission, ESA and EUMETSAT in close collaboration with NASA, the US National Oceanic and Atmospheric Administration (NOAA) and the French space agency CNES. Europe retains control over the Copernicus programme, while sharing responsibilities and data with international partners.
By investing in high-precision climate satellites such as Sentinel-6B, the EU strengthens its capacity to monitor sea level rise, inform coastal adaptation policies and support global climate negotiations with reliable evidence. At the same time, it reduces its dependence on data from non-European systems that may be subject to commercial, political or security constraints.
Private mega-constellations, China and the new space race
The launch of Sentinel-6B takes place against the backdrop of a new global space race, driven not only by states but increasingly by large private companies. In the United States, SpaceX’s Starlink constellation and Amazon’s Project Kuiper are deploying thousands of satellites into low Earth orbit to provide broadband connectivity. China is accelerating its own plans for large constellations, adding to the growing number of spacecraft crowding key orbital regions.
These mega-constellations offer clear benefits for connectivity, especially in remote or underserved areas. However, they also raise concerns about orbital congestion, space debris, radio-frequency interference and the environmental impact of frequent rocket launches and satellite re-entries. Scientists and regulators warn that without stronger international rules, low Earth orbit risks becoming a congested and contested environment.
For Europe, this evolution has a double significance. On the one hand, European research, telecommunications and navigation depend on safe and sustainable access to space. On the other, European governments want to avoid over-reliance on privately owned foreign infrastructures that operate under different regulatory regimes and commercial priorities.
Alongside Copernicus and the Galileo navigation system, the EU is therefore developing IRIS², a secure connectivity constellation designed to provide government, defence and critical infrastructure users with resilient satellite communications under European control. Together, these programmes form the backbone of an emerging European space ecosystem that combines public missions such as Sentinel-6B with regulated commercial services.
Implications for Nordic and European climate policy
The precise sea level measurements delivered by Sentinel-6B are expected to feed directly into Nordic and European climate adaptation strategies. Coastal cities around the Baltic Sea, the North Sea and the North Atlantic are planning new flood defences, updated building codes and revised risk maps as sea levels rise and extreme weather events become more frequent.
In the Nordic countries, where long coastlines, fjords and low-lying urban areas meet sensitive Arctic and sub-Arctic ecosystems, even a few centimetres of additional sea level can change erosion patterns, storm surge reach and saltwater intrusion into freshwater systems. For local authorities, access to reliable, high-resolution data is essential to design cost-effective and proportionate protection measures.
Sentinel-6B’s data will also support shipping, offshore energy and fisheries, sectors that are particularly exposed to changing sea conditions and wave patterns. By improving forecasts of waves, winds and currents, the mission can contribute to safer operations at sea and more resilient maritime infrastructure.
More broadly, the new satellite reinforces Europe’s role as a key provider of global public goods in the climate field. Open access to Copernicus data enables researchers and decision-makers far beyond Europe to monitor sea level trends, assess local vulnerabilities and plan adaptation strategies.
A strategic investment in Europe’s future in space
The launch of Sentinel-6B is a reminder that space policy and climate policy are increasingly intertwined. High-precision satellites are indispensable for tracking how the planet is changing, and they are also central to debates about who controls critical infrastructure in orbit.
By expanding its Copernicus constellation with Sentinel-6B, Europe is investing in long-term climate monitoring, scientific excellence and strategic autonomy. The mission complements, rather than replaces, cooperation with partners such as NASA, but it ensures that European governments and societies have direct access to the data they need to respond to sea level rise.
As private mega-constellations proliferate and new space powers emerge, Europe’s choice to prioritise open, science-driven Earth observation missions stands out. Sentinel-6B embodies this approach: a satellite designed to measure the oceans down to the millimetre, and at the same time a symbol of Europe’s determination to remain an autonomous, responsible actor in the new space age.
