Code associated with a manuscript analyzing the cooling effects trees have on urban areas worldwide.
Manuscript to be submitted to Science, April 2023
Title: Cooling contributions of trees and targets for reducing urban heat in over 2,000 global cities
Authors: Christine R. Rollinson[1*], Jessica B. Turner-Skoff[2], M. Ross Alexander[3,4], Melissa Custic[5], Lindsay Darling[1,5,6], Ayo Andra J. Deas[7], Trent W. Ford[8], Renata Poulton Kamakura[9], Brendon Reidy[1], Zach Wirtz[5]
Affiliations: [1] Center for Tree Science, The Morton Arboretum; Lisle, IL 60532 USA [2] Science and Conservation, The Morton Arboretum; Lisle, IL 60532 USA [3] Consortium for Advanced Science and Engineering, University of Chicago; Chicago, IL 60637 USA [4] Decision and Infrastructure Sciences Division, Argonne National Laboratory; Lemont, IL 60439 USA [5] Chicago Region Trees Initiative, The Morton Arboretum; Lisle, IL 60532 USA [6] Forestry and Natural Resources, Purdue University; West Lafayette, IN 47907 USA [7] Earth and Environmental Sciences, The Graduate Center, City University of New York; New York, NY 10016 USA [8] Illinois State Water Survey, Prairie Research Institute, University of Illinois, Urbana-Champaign; Champaign, IL, 61820 USA [9] Nicholas School of the Environment, Duke University, Durham, NC 27710 USA *Corresponding author. Email: crollinson@mortonarb.org
Abstract: Most cities worldwide experience urban heat islands (UHI), and warmer metropolitan areas are associated with lower tree cover than the surrounding region. However, the cooling capacity of urban trees as nature-based solutions for mitigating UHIs at global scales remains unresolved. We analyzed annual surface temperature and vegetation cover in 2,047 cities between 2001 and 2020 and found that trees have a strong cooling effect in all major biomes and are five times more effective at cooling than other vegetation. However, urban tree cover would need to more than double to fully mitigate UHIs. Furthermore, UHI intensification and regional warming outpaced observed tree cover growth by 5 and 10 times respectively. Growing urban green infrastructure is critically needed to ameliorate urban heat challenges worldwide.
One-Sentence Summary: Trees are highly effective at cooling urban areas, and urban forest growth is necessary to slow warming trends.
Repository Contents All data is publicly accessible through the sources cited in the manuscript. Scripts are numbered in the order to be exectued. Note: All scripts are workflows that are designed to be worked interactively as numbers are generated within them. The final script (script 7) largely follows the order of the submitted manuscript with specific language from the manuscript to aid in transprency of how particular values were calculated.