Project Home Page: http://www.gfg2.eu/ Introduction — The Gfgsquared (GfG2) project is an international research related project with focus on the use of Global Navigation Satellite Systems (GNSS) for Earth observation in a more general sense. Novel GNSS applications with outstanding social importance are identified. These applications can be classified into the nine Social Benefit Areas (SBAs), which include current crucial problems of mankind: agriculture, biodiversity, climate, disasters, ecosystems, energy, health, water, and weather. They are identified and described by the Group of Earth Observations (GEO, see: www.earthobservation.org). Climate — The GNSS occultation technique offers globally distributed estimates of temperature profiles covering the interesting region including the upper troposphere and the lower stratosphere. Ground-based networks provide observations of the water vapour content above each site.