In the next future, the number of GNSS will drastically increase. Not only more signals and frequencies will be available, but also the new generation of navigation satellites (GALILEO), will greatly enhance the performance of GNSS based applications, both scientific and mass-market. Current and next generation GNSS can improve and sustain GEEO applications, as well as be the enablers of novel applications. With the scope to support the GEOSS 10-year implementation plan (2005-2015) the 2010 Environment FP7 work program is launching various topics under sub-activity 6.4.1 Earth and ocean observation systems and monitoring methods for the environment and sustainable development. In line with the objectives of sub-activity 6.4.1, a coordination action promoting discipline connection, identity building and integration while defining future research, technology and policy directions is needed. GNSS for GEEO and GEOSS (Gfg2) responds to these needs addressed by work program topic: ENV.2010.4.1.3-1 Exploring GNSS applications for GEEO and GEOSS. The goals of this three-year long initiative are: 1) to consolidate a community of experts with interest to exploit GNSS for GEEO and GEOSS; 2) to explore novel applications derived from GNSS for GEEO and GEOSS while enhancing research-industry collaboration to implement these applications; 3) to identify the research and technological challenges and define the strategic vision, roadmap and policy for GNSS for GEEO and GEOSS available or under development (EU and non-EU); 4) to assess the value (in this context) of the European GNSS independent constellation (EGNOS-GALILEO); 5) to promote the public understanding of GNSS for GEEO and GEOSS research and use within the GEO community, providing support to GEO tasks. Gfg2 will achieve its objectives especially by using a working methodology based on active community interaction and events (2 summer schools, 4 workshops and a socioeconomic impact workshop).