About GCOS

The Global Climate Observing System (GCOS) is an internationally coordinated network of observing systems and a programme of activities that support and improve the network. It is designed to meet evolving national and international requirements for climate observations.

Ensuring the Availability of Global Observations for Climate

  • internationally coordinated network of observing systems, activities for network improvement.
  • 50 GCOS Essential Climate Variables
  • meet evolving national and international requirements for climate observations.
  • definition of Climate Monitoring Principles & Target Product Requirements

The GCOS Mission

GCOS is a joint undertaking of the World Meteorological Organization (WMO), the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational Scientific and Cultural Organization (UNESCO), the United Nations Environment Programme (UNEP) and the International Council for Science (ICSU). GCOS website

Its goal is to provide comprehensive information on the total climate system, involving a multidisciplinary range of physical, chemical and biological properties, and atmospheric, oceanic, hydrological, cryospheric and terrestrial processes.

GCOS goals

GCOS is intended to be a long-term, user-driven operational system capable of providing the comprehensive observations required for:

  • Monitoring the climate system
  • Detecting and attributing climate change
  • Assessing impacts of, and supporting adaptation to, climate variability and change
  • Application to national economic development
  • Research to improve understanding, modelling and prediction of the climate system

GCOS addresses the total climate system including physical, chemical and biological properties, and atmospheric, oceanic, terrestrial, hydrologic, and cryospheric components. Download the GCOS Brochure (PDF ).

Climate observations

Climate observations are vital to climate research. They provide the initial data for climate models that predict seasonal and decadal phenomena, and they are used to evaluate and improve the models used for long-term climate projections for different emission scenarios.

Observations are also used to develop application models supporting societal needs. The outputs of these models are then used to determine and assess socio-economic impacts and to inform decision-makers on climate adaptation measures.

Climate observation and analysis, coupled with research, modelling and prediction, provide the basis for decision- and policy-making in many climate-sensitive socio-economic sectors.

50 GCOS Essential Climate Variables

50 GCOS Essential Climate Variables (ECV's) are required to support the work of the UNFCCC and the IPCC. All ECV's are technically and economically feasible for systematic observation.

It is these variables for which international exchange is required for both current and historical observations.

Systematic Observation Requirements for Satellite-based Products

For satellite data to contribute fully and effectively to the determination of long-term records, they must be implemented and operated in an appropriate manner to ensure adequate stability, accuracy and homogeneity. To assist the space agencies, the GCOS Climate Monitoring Principles (GCMPs) have been extended, in consultation with CGMS, specifically for satellite observations, addressing the following satellite-specific key operational issues:

  • Continuity, homogeneity and overlap of satellite observations;
  • Enhanced orbit control;
  • Calibration and instrument characterisation;
  • Sampling strategy;
  • Sustained generation of products, data analysis, and archiving.

GCOS Target Product Requirements

Organisation & Structure

An All-Domain Climate Observing System GCOS is sponsored by the World Meteorological Organization (WMO), the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO), the United Nations Environment Programme (UNEP) and the International Council for Science (ICSU).

The contributing systems include the climate-observing components of the IOC-led Global Ocean Observation System (GOOS), the Global Terrestrial Observing System (GTOS) led by the United Nations Food and Agriculture Organization (FAO), and the WMO Global Observing System (GOS) and Global Atmosphere Watch (GAW).

Supporting International Scientific Community

GCOS is both supported by and supports the international scientific community, and the World Climate Research Programme (WCRP) co-sponsors the expert panels set up by GCOS for the atmospheric, oceanic and terrestrial domains.