Urban forestry: Nature's answer to hot cities

Abstract

Extreme urban heat poses escalating risks to human health, infrastructure resilience, and energy security. An expanding body of evidence demonstrates that urban forestry—the intentional conservation, expansion, and management of trees, woodlands, and allied vegetated systems—offers a potent, multifaceted response. Urban tree canopies moderate air and surface temperatures through shading, evapotranspiration, albedo modification, and wind attenuation, collectively shrinking summertime peak temperatures by 1°C-12°C in sites ranging from European city centers to South Asian megacities. They also sequester atmospheric carbon, intercept stormwater, filter pollutants, bolster biodiversity, and enhance mental and physical health, yielding documented economic returns of USD$1.37-$3.09 for every $1 spent [3, 4]. Yet benefits remain inequitably distributed, with lower-income and BIPOC communities consistently receiving the least canopy cover. This review synthesizes more than 300 recent studies and 59 primary sources to examine cooling mechanisms, ecosystem co-benefits, design guidelines, governance frameworks, and research gaps, and proposes a transdisciplinary agenda for climate-ready, equitable urban forest expansion.