Assessing urban heat islands in Southeast Asia megacities: An integrated study of land use, climate change and heatwave occurrences

Abstract

Rapid urbanisation and climate change are intensifying Urban Heat Island (UHI) effects across Southeast Asian (SEA) megacities, compounding heatwave risks and threatening urban sustainability. This study, conducted under the Asia-Pacific Network for Global Change Research (APN) collaboration, presents the first integrated, multi-decadal assessment of UHI–heatwave interactions in SEA, focusing on Kuala Lumpur as a representative pilot city. Using multi-source satellite observations, Local Climate Zone (LCZ) mapping, and the Weather Research and Forecasting (WRF) model, the research analyses both historical (2000–2024) and projected (+1°C climate perturbation) thermal dynamics. Results show persistent UHI hotspots concentrated in compact built-up LCZs (LCZ 1–3), where daytime intensity reached 4–5°C above that in vegetated areas. The mean daytime UHI was 3.6°C, while the nighttime average was 0.9°C, indicating strong diurnal contrasts linked to surface morphology. Model simulations during the April 2024 heatwave demonstrated that LCZ-informed urban canopy configurations (LCZ_local) outperformed standard schemes (RMSE ~ 2.5°C), confirming the value of localised land-use parameterisation. Under a +1°C warming scenario, UHI intensity is further amplified to 4.5°C in dense LCZs, highlighting future heat stress hotspots. Long-term heatwave analysis (1980–2024) revealed that the regional mean heatwave intensity increased by ~0.1°C², duration nearly doubled (15–30 days yr⁻¹) and frequency more than doubled (2.7–5.4 events yr⁻¹), particularly over urbanised regions such as Kuala Lumpur. This study uniquely integrates multi-decadal remote sensing, LCZ-based geospatial analysis and climate modelling to link past UHI evolution with future projections, an approach rarely undertaken in tropical developing regions. The findings provide actionable evidence for embedding LCZ-based thermal planning, green infrastructure and climate adaptation measures into SEA urban policy. The framework established here offers a replicable, science-policy pathway toward heat-resilient, low-carbon cities across the Asia-Pacific region.