Urban tree cover provides consistent mitigation of extreme heat in arid but not humid cities

Sustainable Cities and Society
By: , and 

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Abstract

Urban land cover types influence the urban microclimates. However, recent work indicates the magnitude of land cover's microclimate influence is affected by aridity. Moreover, this variation in cooling and warming potentials of urban land cover types can substantially alter the exposure of urban areas to extreme heat. Our goal is to understand both the relative influences of urban land cover on local air temperature, as well as how these influences vary during periods of extreme heat. To do so we apply predictive machine learning models to an extensive in-situ microclimate and 1 m land cover dataset across eight U.S. cities spanning a wide aridity gradient during typical and extreme heat conditions. We demonstrate how the cooling influence of tree canopy and the warming influence of buildings on microclimate linearly scales with regional aridity, while the influence of turf and impervious surfaces does not. These interactions lead tree canopy to consistently mitigate to air temperature increases during periods extreme heat in arid cities, while the influence of urban tree canopy on extreme heat in humid regions is varied, suggesting that mitigation is possible, but tree canopy can also aggravate extreme heat or have no significant effect.

    Publication type Article
    Publication Subtype Journal Article
    Title Urban tree cover provides consistent mitigation of extreme heat in arid but not humid cities
    Series title Sustainable Cities and Society
    DOI 10.1016/j.scs.2024.105677
    Volume 113
    Year Published 2024
    Language English
    Publisher Elsevier
    Contributing office(s) Geosciences and Environmental Change Science Center
    Description 105677, 13 p.
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