The space-based component of the World Meteorological Organization (WMO) Global Observing System (GOS) is an outgrowth of an evolutionary process, spanning 50 years or more, that has been driven by a combination of identifying and articulating user requirements, international agreements, and technical coordination mechanisms dealing with contingency planning, inter-calibration of observations and data exchange. Building on this predominantly weather-monitoring architecture, a broader strategy (and architecture) must be pursued for climate monitoring. While atmospheric measurements of thermodynamic processes will continue to be essential, increased attention needs to be given to other components of the climate system, including the terrestrial and oceanic domains, as well as atmospheric chemistry.
Key components are certainly in place. The Group on Earth Observations (GEO) has identified climate as one of nine Societal Benefit Areas (SBAs), the Global Climate Observing System (GCOS) has expressed observational requirements for climate through its articulation of Essential Climate Variables (ECVs), the United Nations Framework Convention on Climate Change (UNFCCC) asked Parties that support space agencies to respond to the needs expressed by GCOS, the Committee on Earth Observation Satellites (CEOS) responded with a statement of the adequacy of past, present and future satellite measurements, and has initiated several virtual constellations for targeted ECVs, the Coordination Group for Meteorological Satellites (CGMS) as the international mechanism for technical coordination among operational agencies has strengthened its climate focus, and lastly, WMO has agreed to a Vision for the GOS in 2025 that incorporates climate monitoring in its objectives in an integrated fashion, has developed a Global Satellite Inter-calibration System (GSICS), and has undertaken a targeted effort for the Sustained and Co-Ordinated Processing of Environmental satellite data for Climate Monitoring (SCOPE-CM). Each of these efforts is an essential component, but not sufficient, in and of, themselves.
There must be a call for an international space-based architecture for climate monitoring, where both operational and research and development agencies (and their coordination mechanisms) leverage their respective roles and responsibilities so that climate observations from space are coordinated, shared and sustained into the future. It is time that the rigor which has comprised global weather observations, research, modeling and forecasts through international agreements and a supporting space-based architecture (the GOS) be brought to climate monitoring from space.