The world of Earth Science (as well as Earth Data) is rapidly changing driven by exponential advances in sensor and digital technologies. Recent decades have seen the development of extraordinary new ways of collecting, storing, manipulating, and transmitting data that are radically transforming the way we do and organise Earth sciences. This convergence of technologies creates new challenges for scientists, data and software providers to fully exploit large amount of data from diverse sources. In particular, rapid advances in digital technologies, such as the Internet and mobile devices, are now massively empowering Citizens to play an increasing important role in collecting, analysing and generating data. Although the involvement of volunteers – so-called citizen scientists - in research solutions has a long history (e.g. longitude prize challenge issued by the British Government in 1714 to solve the problem of positioning at sea), there is now an explosion of Citizen Science initiatives, ranging from building up collaborative knowledge (e.g. Open Street Map), volunteer computing (e.g. SETI@home, climateprediction.net), pattern classification (e.g. Galaxy Zoo), up to the community collection of observations (e.g. iSpex). These technologies have now moved citizens from a simple “consumer” to a “producer” of content. This session will examine the new challenges and opportunities related to the use of passion and cognitive surplus of millions of Citizens to support Earth Science for Society and in Society. These include the quality assessment, visualisation, interpretation and translation of crowdsourced data into scientific knowledge and actionable information for decision makers.