It is widely acknowledged that a robust record of climate is at the foundation of understanding, predicting, and mitigation of climate change and the emerging agenda of adaptation to climate variability and change. The Global Climate Observing System (GCOS) is involved in both defining the observational requirements for that record and in addressing the needs for improving it. The requirements were broadly defined in the GCOS Implementation Plan (2004). A particular concern of GCOS is global coverage and an appropriate balance of in-situ and satellite observations. More recently, the GCOS community has been involved in defining more specifically the requirements for satellite-based climate products, the subject of a companion paper. In addition, one of the priority actions from the Implementation Plan has been the establishment of a reference upper air network, for which planning is well underway.

The issue of prominent global data gaps in developing nations is central for GCOS. There is also an increasing realization in the development community that climate data is essential to meeting development goals. GCOS has completed a series of Regional Workshops in developing nations to highlight regional observing system needs, and this has been a major contributor to a nascent program known as Climate for Development in Africa. Direct support for climate station renovations depends on donor countries and is the province of the GCOS System Improvement Programme. Other issues of particular interest to GCOS include advancing the in situ ocean observing system; sustained operation of research-based networks; and climate satellite mission continuity.

In 2008 nations that are Parties to the UN Framework Convention on Climate Change are due to provide national reports including information on their observing systems and observing plans. Prior to this GCOS will be involved in advising the Parties on ensuring the reporting guidelines reflect the needs expressed in the GCOS Implementation Plan. The information in these reports will be particularly timely, as will the release of the Intergovernmental Panel on Climate Change Fourth Assessment Report in 2007. Both will help highlight the strengths and weaknesses of the current observing system. These will assist GCOS providing a report to the UNFCCC in 2009 on progress with the GCOS Implementation Plan, which will take the form of a major reevaluation of adequacy and implementation of climate observing systems.