Urban Agglomerations Environmental Heterogeneity and Heatwave Risks: Spatiotemporal Insights from Remote Sensing and Public Sentiment Analysis

Climate change is exacerbating urban heatwave, posing critical public health risks that are amplified by accelerating urbanization trends. The multilevel spatiotemporal interactions among environmental factors, heatwave characteristics, and public sentiment re-main unclear, especially in urban agglomerations. This study introduces an innovative analytical framework combining Geographical Convergent Cross Mapping (GCCM) for bidirectional causal inference with Bayesian Generalized Linear Mixed Models (GLMMs) for multilevel effect quantification. By systematically integrating a decade (2014-2023) of multi-source remote sensing data, environmental indicators, and 3.2 million heat-perception social media posts across five major Chinese urban agglomerations, this study explore dynamic spatiotemporal relationships between environment, heatwaves, and emotions. Results reveal pronounced asymmetric causality, with environmental im-pacts on heatwaves significantly exceeding heatwave feedback to environments. Intensity indicators (HWA, HWM) show strongest responses to environmental factors, frequency indicators (HWF, HWday) demonstrate moderate-to-strong responses, while duration indicators (HWD) exhibit slightly lower causality. Standardized effect sizes rank environ-mental factors as: Albedo (0.87), FVC (0.79), NDTI (0.75), water bodies (0.57), NTL (0.62) and Elevation (0.35), confirming the dominant influence of surface properties over hydro-logical and topographic factors. Heatwaves and public emotional responses show significant nonlinear relationships with regional variations. As heatwave intensity in-creases, all five emotional dimensions rise with distinct patterns: heat perception responds most directly, health concerns accelerate during moderate-to-high intensity events, outdoor activity preferences decrease significantly during moderate events, and energy consumption concerns peak during high-intensity heatwaves. Each urban agglomeration exhibits unique emotional response patterns due to spatial and geographical differences. These findings provide critical insights into urban thermal environment mechanisms and their societal impacts, highlighting the necessity of region-specific strategies for urban planning and climate adaptation.