ICOS

A network of networks

European countries had measured greenhouse gases and carbon exchange for decades, but national networks used different methods, calibrations and data formats, and could not be combined without effort. ICOS, the Integrated Carbon Observation System, was founded in 2008 to harmonise them. It was granted the legal status of a European Research Infrastructure Consortium, the ICOS ERIC, in November 2015, and has its head office in Helsinki.

ICOS covers three domains: the atmosphere, with towers that measure greenhouse gases; ecosystems, with towers that measure the exchange of carbon between land and air; and the ocean, with ships and moorings that measure carbon dioxide at the sea surface.

Labelling

A station joins ICOS by passing a labelling process: its instruments, siting, sampling and data processing must meet the common specifications. Thematic centres provide calibration gases, run the instrument tests and process the data, so that every station's data are produced the same way. By the end of 2024, 138 of 179 stations had been labelled.

The stations remain owned and operated by national institutions. ICOS sets the standard and runs the common services. Its data are open under a Creative Commons licence.

What it is used for

The harmonised data allow scientists to follow how forests, soils, oceans and the atmosphere exchange carbon, check national greenhouse gas inventories independently, and detect changes after events such as droughts and heatwaves.

Standardising what is already there

ICOS did not create most of its stations: it took stations that existed and brought them to a standard, with calibration, siting rules and data processing. That path, harmonisation rather than replacement, is slower than building a new network but retains the long records of existing sites. The labelling process shows its cost in time: it takes years for a station to be labelled, and not all do. The result is that data from different countries can be combined with confidence, and that governments and researchers can use them to check emission inventories independently. Another design choice matters here: ICOS publishes the rules for labelling, so a station operator outside the consortium can see what would be required to join, and countries can plan the investment before they apply. The same approach, applied one thematic centre at a time, is also what lets the infrastructure grow without a rebuild: a new country adds stations, and the centres already know how to calibrate, check and process them.

Instruments and technologies

• Tall atmospheric towers Towers of 100 metres or more, with air inlets at several heights feeding gas analysers, to sample air from a wide footprint.
• Eddy covariance towers Fast sonic anemometers and gas analysers measure the vertical flux of carbon dioxide between an ecosystem and the air.
• Ship and mooring systems Equilibrator systems on ships and buoys measure the partial pressure of CO2 in surface water.

Timeline

• 2008 ICOS founded.
• 2015 Granted ERIC legal status in November.
• 2024 138 of 179 stations labelled by year end.

Key lessons for observation today

• Label every station to one standard Common specifications make a patchwork into a network. Qualification is the heart of federation.
• Central calibration, local ownership Thematic centres calibrate and process; institutes run stations. A federation works when the shared part is small and clear.
• Open data by default ICOS data are open. Open licences let third parties build services without negotiation.

Sources

• ICOS, About
• ICOS, ICOS ERIC
• Wikipedia, Integrated Carbon Observation System