Essential climate variables (ECVs) critically contribute to the characterisation of Earth' s climate, providing a picture of climate change at a global scale.

Collectively, they provide the empirical evidence to support climate science and better predict future change. They can be used to guide mitigation and adaptation measures, to assess climate risks, to attribute climatic events to underlying causes, and to support climate services.

Science and policy circles have widely endorsed the ECV concept. Climate modellers use ECVs to study drivers, interactions and feedbacks due to climate change, as well as teleconnections, tipping points, and fluxes of energy, water, carbon, and to predict future change.

Systematic observation of Earth’s climate is the fundamental basis upon which the UNFCCC was founded and the Paris Agreement adopted. The Global Climate Observing System (GCOS) currently specifies 55 ECVs, of which about 60 per cent can be addressed by satellite data.

Satellite observations are unique in providing global coverage and time series of consistent observation. ESA’s Climate Change Initiative (CCI) exploits the full satellite archive to develop the scientific basis and produce data records of the 21 ECVs that cover the whole world and stretch back more than thirty years.

All CCI's ECV datasets are fully validated and have high levels of traceability and consistency, including quantitative estimates of uncertainty required by both climate science and modelling communities.