Climate sciences: Driving heat out of the city

Replacing conventional vehicles with electric vehicles has the potential to reduce temperatures in cities, a study in Scientific Reports this week suggests. The switch may have added benefits, as lower heat emissions are expected to reduce energy consumption by air conditioners locally, leading to lower levels of carbon dioxide (CO2) emissions.

Whether electronic vehicles can address climate change at local and global scales is a matter of debate; despite producing lower emissions locally, the manufacturing process causes more pollution than that for conventional vehicles. Canbing Li and colleagues uncover an additional advantage of replacing conventional vehicles with electric vehicles that may support the accelerated implementation of this switch. Mile-for-mile, electronic vehicles emit much less heat than conventional vehicles, which could alleviate the urban heat island effect (a phenomenon that causes many cities to be warmer than rural surroundings due to human activities) in the summer in metropolitan areas. Using Beijing, China, as an example, the authors estimate that replacing conventional vehicles with electric vehicles could reduce the heat island intensity by nearly 1 degree C; they calculate that the subsequent reduction in air-conditioning energy consumption would result in a drop in daily CO2 emissions of 10,686 tonnes.

However, the authors note that several factors can influence the urban heat island effect, not all of which were addressed in this study. For example, there are conflicting reports regarding the impact of reduced aerosol pollution on heat island intensity. These factors may need to be considered when weighing up the benefits and disadvantages of replacing conventional vehicles with electric vehicles.

doi: 10.1038/srep09213

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