Page Banner

Essential Climate Variables

Taking the pulse of the Earth

The ENVRI-Hub harmonises access to ENVRIs across different Earth domains, including Atmosphere, Ecosystem & Biodiversity, Marine and Solid Earth, through a federated and seamless access to data, services and assets, under the prism of Essential Variables.

The family of Essential Variables (EVs) consists of a set of variables that allows scientists, scientific and policy makers to monitor the health of our changing planet. This family spans four interconnected domains: Climate (ECVs), Oceans (EOVs), Biodiversity (EBVs), and Geodesy (EGVs). EVs are usually delivered as global gridded datasets, and illustrated on geographical maps. To construct them, several kinds of data are merged:

  • In-situ observations
  • Satellite data
  • Computer modeling and reanalysis

The complete family of Essential Variables, their governance, their definition and example variables are presented here-below. For more information about each framework, follow the indicated links.

Domain Governance Definition Example Variables

ECVs (Essential Climate Variables)

Global Climate Observing System (GCOS)

Link

“An Essential Climate Variable (ECV) is a physical, chemical or biological variable or a group of linked variables that critically contributes to the characterization of Earth’s climate.”

Surface temperature, carbon dioxide and methane levels, sea-ice extent, glacier mass, soil moisture.

Further described in the specification document GCOS-245.

EOVs (Essential Ocean Variables)

Global Ocean Observing System (GOOS)

Link

“GOOS EOVs are defined as the minimum set of ocean variables that are needed to assess ocean state and variability for important global ocean phenomena (see GOOS phenomena list), and to provide essential data for applications that support societal benefit.”

Ocean temperature, salinity, oxygen, marine debris/microplastics, fish abundance.

EBVs (Essential Biodiversity Variables)

Group on Earth Observations Biodiversity Observation Network (GEO BON)

Link

“Essential Biodiversity Variables (EBVs) are a set of standardized biological measurements that help scientists study, report and manage changes in biodiversity across time, space, and biological level.”

Species distribution, population abundance, genetic diversity, ecosystem structural traits.

EGVs (Essential Geodetic Variables)

Global Geodetic Observing System (GGOS)

Link Link

“Essential Geodetic Variables (EGVs) are a defined set of key geometric and physical variables that characterize the Earth’s shape, gravity field, rotation, and mass redistribution in a globally consistent and sustainable framework.”

Tectonic crustal deformation, gravity reference frames, polar motion, sea-surface height.

ECV Chart

Essential Climate Variables as defined by the Global Climate Observing System; there are 55 focused on the atmosphere, cryosphere, ocean, anthroposphere, biosphere, and the hydrosphere.
Source: GCOS Essential Climate Variables

EOV Chart

GOOS. Graphical abstract of the publication “GOOS Essential Ocean Variables: the backbone of a sustained and evolving global ocean observing system” in Frontiers in Marine Science (Martín Miguez & Heslop et al. 2026).
Source: GOOS Essential Ocean Variables

By collecting, processing and distributing in-situ data, Environmental Research Infrastructures provide ground-truth variables contributing to the assessment of the Essential Variables (ECVs, EOVs, EBVs, EGVs).

Together with satellite data and model outputs, they contribute to take the pulse of the Earth and predict future climate scenarios.

ENVRI-Hub harmonises access to ENVRIs across different Earth domains, including Atmosphere, Ecosystem & Biodiversity, Marine and Solid Earth, through a federated and seamless access to data, services and assets, under the prism of Essential Variables.

Harmonised vocabulary: exposing and mapping the Essential Variables

One of the hardest parts of making data reusable is semantics. If one infrastructure labels a data column “temp_sea_surf” and another labels it “SST”, a computer cannot easily combine them.

The adopted solution was to:

  • web-expose a vocabulary for the Essential Variables. The NERC Vocabulary Server, managed by the British Oceanographic Data Centre, now includes an “EXV” table, where X stands for either « C », « O », « B » or « G » to reflect ECVs, EOVs, EBVs or EGVs.
  • perform mapping of ENVRIs internal vocabularies to this EXV vocabulary, using what is called the I-Adopt framework. More details regarding I-Adopt here.

Searching and Filtering ENVRI assets

To look for all the research infrastructures' services that provides data contributing to a given Essential Variable, the ENVRI-Hub proposes special filtering features in its Catalogue of Services:

  • additional Essential Variable filtering xfield in the Catalogue of Services (updating its dcat metadata schema)
  • new functionality to the Catalogue of Services to define a preset selection of ENVRIs services granting access to variables contributing to a particular ECV: the “ECV use case” functionality