Using high-frequency data to quantify how urban nature affects air temperature and energy consumption

Globally, cities account for 78% of energy consumption and 70~75% of greenhouse gas emissions. Using spatially explicit data on urban vegetation, water bodies, and buildings, combined with extensive daily observations of air temperature and electricity consumption for the subtropical megacity of Shenzhen, China, this study shows that urban nature contributes to urban cooling, reducing energy consumption and associated greenhouse gas emissions. We found that green and blue spaces in the city's built-up area had a pronounced influence on air temperature, ranging from a cooling effect of 1.27 °C to a warming effect of 0.29 °C, with the cooling effect being dominant over the course of a year. The cooling effect was greatest at moderate temperatures (~20 °C) and was lower on hotter days. We identified a temperature threshold of 16 to 18 °C above which urban nature produces measurable reductions in cooling energy demand. We found that residential electricity consumption was more temperature-sensitive than nonresidential electricity consumption. For the study year of 2021, the net electricity savings from urban nature was 1.5 billion kWh. This reduction in energy consumption translated to almost one million tons of avoided CO₂ emissions, which was 4.65-times the sequestration capacity of the city's terrestrial vegetation and equivalent to the annual emissions of over 223 thousand people using global average annual per capita carbon emissions.