Forests play a key role in the Earth climate system as they cover about 30% of the land area. In the last decade they absorbed more than 7 Gt of CO2 contributing to reduce global warming and to buffer and mitigate increasing climate variability. The summers of 2018 and 2019 included some of the hottest and driest periods ever recorded globally, however the extent and severity of their impact is unknown due to lack of a comprehensive monitoring network, which generally does not include hard-to-reach areas characterised by strong logistic limitations. Therefore, novel technological solutions are urgently needed to monitor forest responses to climate change and related extreme events also in remote areas. Recent advances in Internet Of Things technology (IoT), satellite IoT connectivity and energy harvesting systems are opening unprecedented opportunities for the use of IoT devices in standalone experimental setups. In this context, the aim of the RemoTrees project is to design and build an innovative, autonomous in-situ monitoring system designed for remote forest areas and providing data via satellite communication to a dedicated RemoTrees platform. In this framework, RemoTrees will integrate existing and novel Earth Observation (EO) data with in-situ observations of Essential Climate Variables (ECVs: fraction of absorbed photosynthetically active radiation, leaf area index, soil moisture, biomass change) and other key variables including e.g. stem growth, stem moisture, sap flow, canopy transmittance, besides air humidity and temperature. RemoTrees will include study cases on interoperability with GEOSS (Global Earth Observation System of Systems), and on how in-situ data can support an improved understanding of the climate variability impact on forests. The reinforced in-situ component will be beneficial for Copernicus products validation and will enhance the assessment of climate change long-term mitigation and adaptation potential of forests, towards novel insights for climate-smart forest management.