Nature-based solutions in urban environments can provide cooling effects, decrease air pollution, and improve mental health, amongst others important ecosystem services and health-related benefits. Ambitious plans, such as the pledge to plant 3 billion trees in the EU, the European Green Deal, or the Green City Accord support this direction. Their implementation, however, requires transformative changes on the ground to overcome business as usual approaches. The Urban ReLeaf project delivers change by bringing public authorities and citizen groups together to shape green infrastructure actions in their cities. Six pilot cities co-create citizen-centric innovations for the democratisation of urban greenspace monitoring and the wider policy making process in pursuit of urban climate resilience. This poster showcases the stories of the six cities and their approaches to participatory, and data-driven decision making. Athens is undergoing a greening transformation with a new, citizen-powered tree registry providing critical data for better management of greenspaces. Cascais engages citizens in sharing perceptions and thermal comfort levels while using greenspaces to validate the effectiveness of its parks. Meanwhile in Dundee, a city facing increasing grey infrastructure in deprived areas, actions to enhance the accessibility of greenspaces are co-developed with citizens and stakeholders. Mannheim has a heat action plan to safeguard its most vulnerable residents but has identified critical data gaps. Citizen observations of trees and thermal comfort, when integrated with official data streams, will aid the delivery of climate adaptation measures. Riga engages diverse audiences to address concerns about air pollution and greenspace usage, to ensure better informed policies. Finally, in Utrecht, data on temperature, humidity and heat stress, collected by and for citizens, will help them reduce the urban heat island effect and shape effective mitigation strategies
