Climate

People living in India are experiencing some of the hottest summers on the planet. Conditions are particularly harsh in Indian cities, like Kolkata, where high temperatures are combined with high humidity. Understanding how conditions in Kolkata have evolved could provide an important addition to the growing study of the problems facing megacities in the hot, humid tropics. Yet in Kolkata, this understanding is obscured by different, often incompatible, methods of assessing the intensity of heat stress. This narrative review considers the problems encountered when attempting to develop a clear understanding of past increases or even to quantify current conditions using conventional meteorological or remote sensing data. Rather than trying to arrive at a precise quantification of how much hotter it is now in Kolkata than in the past, we argue for more fine-grained, individual-level understanding of how heat is experienced. An example of this approach is provided by a study that used telemetric devices to continuously monitor the temperature and humidity to which elderly residents of slum areas in Kolkata were exposed during 24h periods as they went about their daily lives. This study indicates that individuals experience a diversity of heat conditions that are inadequately represented by outdoor temperatures. Living in dwellings where indoor temperatures are often hotter than outdoor temperatures, the daily heat stress experienced by this vulnerable group varies between conditions that are stressful but endurable to those that approach the limits of human heat tolerance. Given the likelihood of even hotter environments in the future, urban planners will need access to more comprehensive heat studies, focusing on continual monitoring of heat stress and physiological responses of individuals from different walks of life.

Cities are among the major consumers of environmental resources and contribute significantly to the degradation of many ecosystems. For this reason, the European Union is prioritising the transformation of the role of European cities to become key actors in enabling sustainable and efficient urban systems. Part of this effort is enacted through the Mission “Cities,” that guides cities in developing Climate City Contracts (CCC), which are innovative governance instruments that outline municipalities’ collaborative and systemic plans to reach climate neutrality. This article examines how 102 Mission Cities across Europe plan to reach climate neutrality by 2030, by analysing the selection of typologies of actions included in their CCCs. Results reveal distinct regional patterns in how municipalities design their portfolios of climate actions in key topics: an integrated and diversified combination of sectoral measures and governance innovations in Northern and Western Europe, a focus on upgrading core infrastructures in Central and Eastern Europe, and prioritisation of interventions in mobility and the Built Environment in Southern Europe. These findings provide insights for policy and planning strategies, and highlight countries that progress faster in specific topics and those that still face relevant barriers.

Local governments play a critical role in advancing climate change mitigation under national carbon neutrality strategies; however, practical mechanisms for policy learning and collaboration remain limited. This study analyzes the Kyoto Roundtable, a transdisciplinary dialogue platform designed to support municipalities toward decarbonization in Japan. Based on a policy-learning framework co-designed with frontrunner municipalities, we implemented five roundtable sessions involving municipal officers and researchers. Analysis of workshop discussions, action-planning sheets, and participant surveys illustrates how structured dialogue supports policy learning and coordination. The findings indicate that inter-municipal networks and sustained science–policy dialogue play a crucial role in motivating local climate policy development. Mutual learning and knowledge exchange within the roundtable enhanced participants’ engagement and capacity to adapt policies. The interaction between horizontal inter-municipal collaboration and vertical support from supramunicipal and national governments contributed to early-stage policy diffusion. These findings suggest that transdisciplinary dialogue platforms can function as critical infrastructure for scaling local decarbonization by sustaining policy learning and inter-municipal collaboration.