Botanical Gardens Lower City Temperatures by 5 °C

Global temperatures are increasing, with 2023 being officially recognized as the hottest year on record. A recent study suggests that incorporating nature into urban areas could mitigate temperature spikes during heatwaves.

If you reside close to wooded regions, you likely appreciate that seeking shade under trees is an effective way to escape the midday heat while hiking. While living in urban areas may limit such opportunities, even a trip to a nearby park or botanical garden can offer relief from the heat.

Cooling Effects and Temperature Reductions

Indeed, a study conducted by the University of Surrey in the UK has revealed that botanical gardens have the potential to reduce inner-city air temperatures by up to 5 °C. Following closely behind are wetlands and rain gardens, which cool the air by 4.7 and 4.5 °C respectively. Additionally, trees lining streets contribute to a temperature reduction of 3.8 °C, while city parks manage to lower air temperatures by 3.2 °C.

“We’ve long understood that green spaces and water play a role in cooling urban environments,” stated Professor Prashant Kumar, founding director of the Global Center for Clean Air Research at the University of Surrey, as well as professor and chair in Air Quality and Health, and co-director at the Institute for Sustainability. “However, this study offers the most comprehensive insight to date, with explanations for such phenomena ranging from trees providing shade to evaporating water cooling the air.”

The research highlights that on July 19, 2022, the UK experienced a record-breaking air temperature of 40.3 °C (104.5 °F), with approximately 62,862 deaths attributed to summer heat across Europe in the same year. Additionally, the 2003 heatwave in Europe resulted in an economic loss of €16 billion due to drought and crop failures. The team of 29 scientists from the UK, Australia, Brazil, China, Hong Kong, and the US also emphasizes the IPCC’s acknowledgment that “green and blue urban infrastructure elements are particularly effective in reducing air temperatures in cities.”

Assessing Urban Green Infrastructure

From a vast collection of over 27,000 research papers, the researchers meticulously selected 202 for meta-analysis based on various categories of urban green-blue-grey infrastructure, including parks, engineered greening projects, wetlands, green walls, parks, and botanical gardens.

Trees and plants contribute to heat reduction by diminishing the direct sunlight reaching the ground and emitting moisture into the atmosphere. Water bodies cool their surroundings through processes like evapotranspiration, shading, the albedo effect, groundwater replenishment, and temperature moderation. Moreover, they can function as heat sinks, cooling during the daytime and providing warmth during the night. Green roofs and walls not only provide insulation for buildings but also minimize heat absorption. Additionally, vegetation can act as windbreaks, facilitating natural ventilation.

Read the original article on: New Atlas

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