The Subsidiary Body for Scientific and Technological Advice (SBSTA), at its twenty-third session, welcomed the efforts by the Global Terrestrial Observing System (GTOS) secretariat to develop a framework for the preparation of guidance materials, standards and reporting guidelines for terrestrial observing systems for climate and encouraged the GTOS to continue its work. It also called on the GTOS secretariat to assess the status of the development of standards for each of the essential climate variables in the terrestrial domain. The SBSTA invited the GTOS secretariat to report on its progress by the twenty-sixth session of the SBSTA (FCCC/SBSTA/2005/10, para. 93). This document contains two progress reports by the GTOS secretariat on the above-mentioned topics. In accordance with the procedure for miscellaneous documents, these reports are reproduced in the language in which they were received and without formal editing