Satellite‐based evidence highlights a considerable increase of urban tree cooling benefits from 2000 to 2015

Zhao, Jiacheng; Zhao, Xiang; Wu, Deming; Meili, Naika; Fatichi, Simone

doi:10.1111/gcb.16667

Cited by 31 publications

(6 citation statements)

References 102 publications

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“…Finally, note that we estimate statistically the change in LST and air temperature at the scale of a US census block, which includes a variety of land-use types. This makes our estimates of temperature impact per unit increase in tree cover different from (and lower in magnitude than) the estimates of tree cooling e ciency of Zhao et al 77 , who used Landsat-based estimates of tree cover and LST to quantify change in LST for those pixels with tree canopy.…”

Section: Estimating Bene Tsmentioning

confidence: 63%

Current inequality and future potential of US urban tree canopy cover for reducing heat-related mortality, morbidity and electricity consumption

McDonald

Biswas²,

Chakraborty

et al. 2023

Preprint

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Excessive heat is a major and growing risk for urban residents. Urban trees can significantly reduce summer peak temperatures, thus reducing heat-related mortality, morbidity, as well as cooling energy demand. However, urban tree canopy is inequitably distributed in US cities, which has been shown to contribute to higher summer temperatures in people-of-color (POC) neighborhoods. Here, we utilize a unique dataset of high-resolution tree canopy cover to estimate the inequality in summertime heat-related mortality, morbidity, and electricity consumption across a sample of 5,723 US municipalities and other places, housing 180 million people during the 2020 census (50.6% in majority non-Hispanic white neighborhoods, 49.4% in majority people-of-color, POC, neighborhoods). We also model the potential to increase tree cover in these municipalities in 5% increments up to a realistic maximum, the 90th percentile of tree cover observed in each municipality for each impervious surface class. On average, trees in non-Hispanic white neighborhoods cool the air by 0.19 ± 0.05⁰C more than in POC neighborhoods, leading annually to trees in white neighborhoods helping prevent 190 ± 139 more deaths, 30,131 ± 10,406 more doctors’ visits, and 1.4 ± 0.5 terawatt-hours (TWhr) more electricity consumption than in POC neighborhoods. The greatest inequality in the protective value of trees occurs in the Northeastern US. We estimate that for these 5,723 municipalities, the maximal feasible urban reforestation program in residential neighborhoods could add 1.2 billion trees, reducing population-weighted average summer temperatures by an additional 0.38 ± 0.01⁰C. Relative to the current status quo, this increase in the cooling benefits of trees would reduce annual heat-related mortality by an additional 464 ± 89 people, annual heat-related morbidity by 80,785 ± 6110 cases, and annual electricity consumption by 4.3 ± 0.2 TWhr, while increasing annual carbon sequestration in trees by 23.7 ± 1.2 MtCO2e and decreasing annual electricity-related GHG emissions by 2.1 ± 0.2 MtCO2e. The total economic value of these benefits, including the value of carbon sequestration and avoided emissions, would be USD 9.6 ± 0.5 billion, although in many neighborhoods the cost of increased tree cover exceeds these benefits. The exception is neighborhoods that currently have lower tree cover, especially those that are majority POC, as these neighborhoods have a much higher return-on-investment from tree planting.

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Section: Estimating Bene Tsmentioning

confidence: 63%

Current inequality and future potential of US urban tree canopy cover for reducing heat-related mortality, morbidity and electricity consumption

McDonald

Biswas²,

Chakraborty

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…While the results of this study can provide an indicative value for similar cities, caution should be applied when generalizing as cityspecific characteristics like climate, the amount of potential greening, and the built environment will influence estimates and a recent PWS study shows that increased tree cover in many European cities does not lead to reduced air temperatures [15]. The types of trees, such as their leaf area index, and the albedo of the built environment are also important considerations [55].…”

Section: Discussionmentioning

confidence: 90%

The potential of urban trees to reduce heat-related mortality in London

Taylor,

Simpson,

Brousse

et al. 2024

Environ. Res. Lett.

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Increasing temperatures and more frequent heatwave events pose threats to population health, particularly in urban environments due to the Urban Heat Island (UHI) effect. Greening, in particular planting trees, is widely discussed as a means of reducing heat exposure and associated mortality in cities. This study aims to use data from Personal Weather Stations (PWS) across the Greater London Authority to understand how urban temperatures vary according to tree canopy coverage and estimate the heat-health impacts of London’s urban trees. Data from Netatmo PWS from 2015 – 2022 were cleaned, combined with official Met Office temperatures, and spatially linked to tree canopy coverage and built environment data. A Generalized Additive Model was used to predict daily average urban temperatures under different tree canopy coverage scenarios for historical and projected future summers, and subsequent health impacts estimated. Results show areas of London with higher canopy coverage have lower urban temperatures, with average maximum daytime temperatures 0.8 °C and minimum temperatures 2.0 °C lower in the top decile versus bottom decile canopy coverage during the 2022 heatwaves. We estimate that London’s urban forest helped avoid 153 heat attributable deaths from 2015-2022 (including 16 excess deaths during the 2022 heatwaves), representing around 16% of Urban Heat Island-related mortality. Increasing tree coverage 10% in-line with the London Strategy would have reduced UHI-related mortality by a further 10%, while a maximal tree coverage would have reduced it 55%. By 2061-2080, under RCP8.5, we estimate that London’s current tree planting strategy can help avoid an additional 23 heat-attributable deaths a year, with maximal coverage increasing this to 131. Substantial benefits would also be seen for carbon storage and sequestration. Results of this study support increasing urban tree coverage as part of a wider public health effort to mitigate high urban temperatures.

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“…VPD affected ΔH more than CWD did. The former acted as the primary determinant of ΔH, indicating the control of atmospheric moisture conditions (Zhao et al., 2023) on transpiration pressure of plants. A high VPD early in the growing season directly acts on the activities of associated enzymes in plant leaves, inducing stomatal closure (Yuan et al., 2019), inhibiting seedlings establishment, and even leading to seedling mortality (Jalakas et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

Uppermost global tree elevations are primarily limited by low temperature or insufficient moisture

Xie,

Shen,

Wang

et al. 2024

Global Change Biology

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The impact of anthropogenic global warming has induced significant upward dispersal of trees to higher elevations at alpine treelines. Assessing vertical deviation from current uppermost tree distributions to potential treeline positions is crucial for understanding ecosystem responses to evolving global climate. However, due to data resolution constraints and research scale limitation, comprehending the global pattern of alpine treeline elevations and driving factors remains challenging. This study constructed a comprehensive quasi‐observational dataset of uppermost tree distribution across global mountains using Google Earth imagery. Validating the isotherm of mean growing‐season air temperature at 6.6 ± 0.3°C as the global indicator of thermal treeline, we found that around two‐thirds of uppermost tree distribution records significantly deviated from it. Drought conditions constitute the primary driver in 51% of cases, followed by mountain elevation effect which indicates surface heat (27%). Our analyses underscore the multifaceted determinants of global patterns of alpine treeline, explaining divergent treeline responses to climate warming. Moisture, along with temperature and disturbance, plays the most fundamental roles in understanding global variation of alpine treeline elevation and forecasting alpine treeline response to ongoing global warming.

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Satellite‐based evidence highlights a considerable increase of urban tree cooling benefits from 2000 to 2015

Cited by 31 publications

References 102 publications

Current inequality and future potential of US urban tree canopy cover for reducing heat-related mortality, morbidity and electricity consumption

Current inequality and future potential of US urban tree canopy cover for reducing heat-related mortality, morbidity and electricity consumption

The potential of urban trees to reduce heat-related mortality in London

Uppermost global tree elevations are primarily limited by low temperature or insufficient moisture

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