The Conference of the Parties (COP), by its decision 5/CP.10, expressed its appreciation to the Global Climate Observing System (GCOS) for preparing the Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC (hereinafter referred to as the GCOS implementation plan). By the same decision, the COP requested the secretariat of the GCOS to provide information to the Subsidiary Body for Scientific and Technological Advice (SBSTA) on how the actions identified in the GCOS implementation plan are being implemented. At its twenty-third session, the SBSTA requested the GCOS secretariat to provide a comprehensive report at its thirtieth session on progress with the GCOS implementation plan (FCCC/SBSTA/2005/10, para. 94), in addition to the regular reporting requested by the COP in decision 5/CP.10. In response to this request, the GCOS secretariat submitted the progress report contained in this document. In accordance with the procedure for miscellaneous documents, this submission is contained in this document and reproduced in the language in which it was received and without formal editing