To better understand the different processes and interactions that govern the earth system and to determine whether recent human-induced changes could ultimately de-stabilise its dynamics, both natural system variability and the consequences of human activities have to be observed and quantified. In this context, the European Space Agency published in 2006 “The Changing Earth: New Scientific Challenges for ESA's living Planet Programme” as the main driver of ESA’s new EO science strategy. The document outlines 25 major scientific challenges covering all the different aspects of the Earth system, where EO technology and ESA missions may provide a key contribution. In this context, and responding to a request from ESAC (Earth Science Advisory Committee) to enhance the ESA scientific support towards the achievement of “The Challenges”, the Agency has launched the Changing Earth Science Network as an important programmatic component of the new Support To Science Element (STSE) of the Earth Observation Envelope Programme (EOEP). In this paper we summarize the objectives of this initive and provide a review of the first projects that were selected in 2009 and are now generating their first results.