Publications

Zhan, WF; Wang, CL; Wang, SS; Li, L; Ji, YY; Du, HL; Huang, F; Jiang, SD; Liu, ZH; Fu, HY (2024). Fraction-dependent variations in cooling efficiency of urban trees across global cities. ISPRS JOURNAL OF PHOTOGRAMMETRY AND REMOTE SENSING, 216, 229-239.

Abstract
Investigating the relationship between cooling efficiency (CE) and tree cover percentage (TCP) is critical for planning of green space within cities. However, the spatiotemporal complexities of the intra-city CE-TCP relationship worldwide with distinct climates, as well as the differing impacts of consistently increasing tree cover within urban regions on cooling potential, remain unclear. Here we used satellite-derived MODIS observations to investigate the CE-TCP relationship across 440 global cities during summertime from 2018 to 2020. We further investigated the impacts of enhancing tree cover by a consistent amount in different urban locales on the reduction of population heat exposure among specific age groups. Our results demonstrate a nonlinear CE-TCP relationship globally - CE exhibits an initial sharp decline followed by a gradual reduction as TCP rises, and this nonlinearity is more pronounced in tropical and arid climates than in other climate zones. We observe that 91.4% of cities experience a greater reduction in population heat exposure when introducing the same amount of TCP in areas with fewer trees than in those with denser canopies; and heat exposure mitigation is more prominent for laborers than for vulnerable groups. These insights are critical for developing strategies to minimize urban heatrelated health risks.

DOI:
10.1016/j.isprsjprs.2024.07.026

ISSN:
0924-2716