Increased droughts, heat-waves and floods under climate change intersect in cities with further concerns linked to the Sustainable Development Goals. In the light of these challenges, we will analyse and discuss multiple data- and model-driven approaches to provide solutions and opportunities for transformation in cities, with numerous regional examples. Starting with a model for droughts, The "Urban Drought Nexus Tool" facilitates the sustainable development of cities under increasing droughts. The tool integrates multiple types of information and still can be applied to other case studies with minimal adjustments on the parameters of land use, water consumption and energy use in the water sector. The tool needs hydrological projections under climate scenarios to evaluate climatic futures, and requires the co-creation of socio-economic future scenarios with local stakeholders. Thus, it is possible to provide specific information about droughts taking into account future water availability and future water consumption. 

Ultimately, such complex systems as those formed by the water-energy-land nexus can be reduced to single variables of interest, e.g. the number of events with no water available in the future and their length, so that the complexities are reduced and the results can be conveyed to society in an understandable way, including the communication of uncertainties (Cremades et al., 2021). Continuing with climate services, they aim to efficiently address the manifold challenges generated at the intersection between anthropogenic factors and the natural environment, especially in a changing climate. The end user's needs for climate products and services are commonly fulfilled by national and local providers based on data retrieved from various networks. 

Enhanced urban climate services can be implemented by integrating all the available data sources into products co-developed with multiple stakeholders particularly to respond to climate change-related risks, such as heatwaves or flash flood events. Both temporal and spatial resolutions are significantly increased allowing more precise monitoring and interventions. The case study focuses on Bucharest (Romania; Cheval et al, 2020). Pollution is still an important issue for European cities, so in the light of global concerns about CO2 emissions and urban air quality, European cities are aiming to reduce vehicle circulation and promote sustainable mobility. However, incorporating such schemes into broader urban planning strategies is challenging, and achieving stakeholder buy-in often means the difference between success and failure. In some countries, measures aimed to reduce traffic pollution have been rejected by parts of the political spectrum, prompting attempts to abolish them. 

This is the case of the low emissions zone in the Spanish capital, Madrid, as well as proposals in France to increase fuel tax on sustainability grounds. We will discuss an integrated participatory modelling approach evaluating the feasibility and likely impacts of different approaches to implementation of sustainable mobility, with a special focus on the case of Madrid (Spain; Roodposhti et al., 2020). Beyond low-emission zones, fully-fledged transformations are envisioned. Cities are fundamental to climate change mitigation, and computing "climate-smart urban forms" provides urban transformation examples cutting emissions related to energy consumption from urban mobility in half. They show how to reinforce fractal hierarchies and population density clusters within climate risk constraints to significantly decrease the energy consumption of urban mobility. The model that we present aims to produce new advice about how cities can combat climate change, and explore its evolution into considering further aspects beyond mobility, such as the different levels of energy consumption related to building design (Cremades & Sommer, 2019; Rosenfelder et al., 2021). Finally, thermal comfort is an increasing concern for urban planners, and preliminary results will be presented on machine learning tools producing responses that alleviate urban heatwaves by transforming urban hotspots. 

Type of session: the session is a hybrid comprising short-lecture contributions by 4 different teams as outlined in the session abstract, with a final panel discussion about the needs for further tools with input from the audience. The session is initially a closed session, still it could be adjusted to accommodate one additional abstract if indicated by the organisers. Session co-organisers and collaborators: Dr. Richard Hewitt (Complutense University of Madrid, Madrid, Spain), Dr. Sorin Cheval (Meteo Romania - National Meteorological Administration, Bucharest, Romania), Angel Lazaro MSc (Wageningen University and Research, Wageningen, The Netherlands), Markus Rosenfelder (University of Freiburg, Freiburg, Germany), Gunther Gust (University of Freiburg, Freiburg, Germany). References. Cheval, S., Popa, A. M., Șandric, I., & Iojă, I. C. (2020). Exploratory analysis of cooling effect of urban lakes on land surface temperature in Bucharest (Romania) using Landsat imagery. Urban Climate, 34, 100696. Cremades, R., Sanchez-Plaza, A., Hewitt, R. J., Mitter, H., Baggio, J. A., Olazabal, M., ... & Tudose, N. C. (2021). Guiding cities under increased droughts: The limits to sustainable urban futures. Ecological Economics, 189, 107140. Cremades, R., & Sommer, P. S. (2019). Computing climate-smart urban land use with the Integrated Urban Complexity model (IUCm 1.0). Geoscientific Model Development, 12(1), 525-539. Roodposhti, M. S., Hewitt, R. J., & Bryan, B. A. (2020). Towards automatic calibration of neighbourhood influence in cellular automata land-use models. Computers, Environment and Urban Systems, 79, 101416. Rosenfelder, M., Wussow, M., Gust, G., Cremades, R., & Neumann, D. (2021). Predicting residential electricity consumption using aerial and street view images. Applied Energy, 301, 117407.