Climate Resilience Reshaping Urban Space: A New Paradigm for Joint Governance of Urban Heat Island Effect and Air Pollution

In the process of rapid urbanization, global cities are expanding at an unprecedented rate, but this expansion is not a simple increase in area; it profoundly reshapes the physical form of the urban microclimate. Especially in subtropical humid climate zones like China, the Urban Heat Island (UHI) effect and air pollution issues have evolved from isolated challenges into mutually coupled, synergistic complex crises. This coupling complexity demands that we move beyond traditional single-dimension governance thinking to build a systemic solution that considers both thermal environment and air quality.

Extreme high-temperature events driven by climate change and the exacerbation of the Urban Heat Island effect directly threaten residents' health and the stability of ecosystems. At the same time, greenhouse gases and volatile organic compounds (VOCs) emitted by cities are key drivers in the formation of secondary organic aerosols (SOA) and ozone pollution. When temperatures rise, the emissions of VOCs from both biological and anthropogenic sources within the city increase, accelerating the formation of pollutants like ozone and PM2.5, creating a vicious cycle that is difficult to break.

To address this challenge, research is shifting from traditional single-pollutant control to the integrated design of climate-resilient infrastructure. Analysis based on numerical simulations and multi-objective optimization algorithms shows that refined spatial planning design is the core breakthrough. Optimization strategies emphasize placing the focus of urban development in areas favorable for wind field guidance, while suggesting the adoption of medium-density urban forms (controlling the built-up area ratio between 0.5 and 0.8) and systematically increasing urban green space coverage (from 0.15 to 0.27). The physical mechanism of this layout is that city upwind slopes facilitate natural ventilation of airflow, effectively lowering surface temperatures; while increased vegetation cover mitigates heat stress and pollutant emissions through evapotranspiration and dry deposition mechanisms.

This is not just an engineering problem of landscape beautification; it is a strategic decision regarding climate-adaptive infrastructure investment. From an engineering capital perspective, the effectiveness of this planning means higher long-term social benefits and lower governance costs. It requires local governments and investment institutions to deeply integrate climate risk assessment into the PPP model design for urban renewal and infrastructure construction. By systematically incorporating green and blue infrastructure (GBI) into the urban fabric, achieving synergistic regulation of the thermal environment, we can not only directly improve residents' comfort and health indicators but also build inherent resilience against climate shocks for the city, providing replicable engineering experience for enhancing "livability" in the rapid urbanization process of the Global South.

Future urban planning must shift from "solving one problem" to "managing a series of interconnected risks." This requires that in investment decisions, we not only measure traditional metrics like traffic efficiency and land utilization rate but also incorporate multi-dimensional indicators such as climate risk, environmental load, and long-term social adaptability, treating climate resilience as a hard standard for measuring the health level of urban infrastructure.