The Global Climate Observing System (GCOS) has been presented in the last report for the United Nations Framework Climate Convention(www.unfccc.int), namely the fifth national Communication. In such a report the different networks for the four components of the GCOS program are described in details. It concerns the atmospheric component with the meteorological observations (GSN for the surface measurements and GUAN for the upper air ones) but also the physico-chemical part (GAW). That also includes the RAMCES network specifically devoted to the long term monitoring of greenhouse gases. Considering the oceanographic part, the system includes (i) the measurements done by voluntary observation ships and ships of opportunity, (ii) the tide gauges network (GLOSS), (iii) the drifting and anchored meteorological buoys, (iv) the PIRATA observatory for the tropics and finally the Coriolis system which includes a complete tridimensional measurement of the ocean with the ARGO project. Then we consider the terrestrial part, which includes the observations of mountain glaciers, but also the measurements of Carbone fluxes over terrestrial ecosystems done under the european projects framework (Carbo-Europe). At last we give a quick overview of the observations done by satellite instruments devoted to the climate monitoring. During this presentation two questions arose concerning first the durability of such a system (important for climate monitoring), second the link with the GEOSS. For the first question, we can mention the difficulty met by researchers to support a network designated for research experiment in the long term, and also propose a solution with the concept of Observatory (Observatoire de Recherche en Environnement), illustrated by the Glacio-Clim observatory for the glaciers at different latitudes. For the second question we can mention the Global Monitoring Environment System (GMES), which aims to monitor the general environment in Europe and means the Europe contribution to GEOSS.