Human-Centered Urban Heat Island Intensity in Global Megacities: Nonlinear Response Patterns and Region-Specific Thresholds

As the global urban heat island (UHI) effect intensifies, understanding how UHI intensity responds to its influencing factors changes is critical for designing effective mitigation strategies. We focused on global megacities, shifted the UHI intensity assessment from physical indicators to human-related parameters, and then evaluated how human-centered UHI intensity responded to influencing factor change. We verified a significant discrepancy between traditional UHI intensity and human-centered UHI intensity worldwide, an average absolute difference of 1.27 °C with the relative difference of 77%. This highlighted the necessity of incorporating a human-centered perspective in UHI intensity assessment. We identified three key elements that shape the response of human-centered UHI intensity to influencing factor change: dominant influencing factor, response patterns (Type-I (monotonic increasing), Type-D (monotonic decreasing), and Type-P (downward parabola)), and nonlinear thresholds signifying a shift from mitigating to amplifying UHI intensity. Notably, these elements exhibited distinct clustering patterns in eastern North America, East Asia, and Europe. Consequently, mitigation strategies should be customized according to the key element identified for each city. These findings underscore that a human-centered UHI intensity assessment and region-specific mitigation strategies can help to shape resilient and sustainable urban environments.