The Global Climate Observing System (GCOS) provides vital and continuous support to the United Nations Framework Convention on Climate Change (UNFCCC) in the definition and specification of requirements for observations relevant to climate change.

In 1998, and again in 2001, GCOS prepared reports on the adequacy of global observing systems for climate in providing the systematic climate observations required by the UNFCCC. The goals of the Second Adequacy Report were: to determine what progress has been made in implementing climate observing networks and systems since the first report; to determine the degree to which these networks meet with scientific requirements and conform with associated observing principles; and to assess how well these current systems, together with new and emerging methods of observation, will meet the needs of the UNFCCC (and IPCC).

These GCOS reports made considerable progress in defining what information was required in support of climate studies, how well current and planned systems met these needs, and what further actions were required by countries to better meet some of those needs.

In 2004, in response to the request from UNFCCC, GCOS prepared an Implementation Plan for the global observing system for climate. From the outset, the UNFCCC requested GCOS and GEO to coordinate their respective implementation plans. The GCOS Implementation Plan represents a commonly-agreed basis for GEO actions in the Climate area. The GCOS Plan, if fully implemented by the Parties to the UNFCCC, both individually and collectively, will provide those global observations of the Essential Climate Variables and their associated products, to assist the Parties in meeting their responsibilities under the UNFCCC.

In addition, it will provide many of the essential observations required by the World Climate Research Programme (WCRP) and IPCC.

The proposed system would provide information to:

— characterise the state of the global climate system and its variability;

— monitor the forcing of the climate system, including both natural and anthropogenic contributions;

— support the attribution of the causes of climate change;

— support the prediction of global climate change;

— enable projection of global climate change information down to regional and local scales;

— enable characterisation of extreme events important in impact assessment and adaptation, as well as the assessment of risk and vulnerability.

The GCOS Implementation Plan (GCOS IP) remains the consensus document of the international community regarding the global observing system for climate.