Turn Up the Trees, Turn Down the Heat: Green Belts Offer Cities a Natural AC

Source: University of Surrey

Countryside to the Rescue: Green Belts Could Cool Cities by Half a Degree

Cities are sweltering. But a new study suggests a surprising solution might lie just beyond the urban sprawl: rural areas. Researchers from the University of Surrey and Southeast University (China) found that preserving green belts around cities could bring down summer temperatures by up to 0.5°C (0.9°F).

The Urban Heat Island Effect

Cities are notorious for being hotter than surrounding areas. Buildings, asphalt, and concrete absorb and retain heat, creating an "urban heat island" effect. This can lead to a range of problems, including increased heatstroke risk, worsened air quality, and higher energy consumption for cooling.

The Cooling Power of Countryside

The study, published in Science Daily, analyzed 20 years of data from 30 Chinese cities. It revealed that the size and composition of the rural land surrounding a city significantly impact its temperature. Wider green belts, particularly those extending outwards for at least half the city's diameter, had the greatest cooling effect.

The Science Behind the Cool Down

So how exactly does the countryside cool the city? Warm air rising from urban areas creates a low-pressure zone at ground level. This "sucks in" cooler air from surrounding areas, including rural belts with more vegetation. The more extensive the green belt, the stronger this cooling effect becomes.

A Green Solution for a Hot Problem

This research suggests that protecting and expanding green belts around cities could be a cost-effective strategy for mitigating the urban heat island effect. In addition to temperature reduction, green belts offer other benefits like improved air quality, biodiversity support, and recreational opportunities.

Looking Forward: Planning for Cooler Cities

As cities continue to grow, incorporating green belts into urban planning becomes even more crucial. This study provides valuable data for city planners and policymakers looking for natural solutions to combat rising urban temperatures. By working with surrounding rural areas, cities can create a win-win situation: cooler cities and healthier ecosystems.