The Intergovernmental Panel on Climate Change (IPCC) has announced a Special Report on Climate Change and Cities, which is set for release in early 2027. The substantial effort behind this report highlights the critical role that cities and city actors play as both drivers of climate change and incubators of solutions. In this talk, we identify several areas where further scientific research and synthesis is needed for building foundational insight and for supporting informed climate action in cities. Some of the themes we identify include:

• Two-Way Feedback Between Cities and Larger-scale Climates: Cities play a significant role in shaping their local and regional climates, leading to a dynamic and thermodynamic interaction that influences climate extremes and high-impact weather events.

• Compounding and Cascading Climate Hazards: Urban areas face a multitude of weather-related hazards (such as cold and heat waves, storm-related surface, riverine and coastal flooding, and extreme wind events) across various scales. The frequency, intensity, duration, and impacts of these events are amplified by climate change and compounded/cascade in complex urban systems.

• Transparency of Model Outputs in Future Climate Scenarios: Communicating the uncertainties in global future climate projections, and their propagation to the regional and local scale analyses in cities, is essential for informed decision-making and effective adaptation strategies.

• Actionability of Science for Cities: Enhancing the usability of scientific findings for urban decision-making requires collaborative efforts, such as co-production or engagement initiatives, to elicit populations’ and decisionmakers’ experiences and tailor scientific advancements to their priorities. This includes addressing issues such as representing extremes and vulnerabilities, uncertainty characterization, building resilience, and coordination among practitioners and scientists.

• Tailoring solutions to specific urban typologies: A pressing need exists to identify relevant solutions for both mitigation and adaptation within cities, tailored to specific typologies of urban form, mitigation potential, background climate, risk profile, among other characteristics. A comprehensive and dynamic typology that synthesizes urban climate change assessments and solutions is still lacking. To make the science actionable, a typology would facilitate the identification of urban solutions for implementation, yet one that bridges both mitigation and adaptation does not exist.