Conifers May Ameliorate Urban Heat Waves Better Than Broadleaf Trees: Evidence from Vancouver, Canada

Abstract

Anthropogenic greenhouse gas emissions are increasing the frequency of deadly heat waves. Heat waves are particularly devastating in cities, where air pollution is high and air temperatures are already inflated by the heat island effect. Determining how cities can ameliorate extreme summer temperature is thus critical to climate adaptation. Tree planting has been proposed to ameliorate urban temperatures, but its effectiveness, particularly of coniferous trees in temperate climates, has not been established. Here, we use remote sensing data (Landsat 8), high-resolution land cover data, and Bayesian models to understand how different tree and land cover classes affect summer surface temperature in Metro Vancouver, Canada. Although areas dominated by coniferous trees exhibited the lowest albedo (95% CrI 0.08–0.08), they were significantly (12.2 °C) cooler than areas dominated by buildings. Indeed, we found that for conifers, lower albedo was associated with lower surface temperatures. Planting and maintaining coniferous trees in cities may not only sequester CO2 to mitigate global climate change, but may also ameliorate higher temperatures and deadly heat waves locally.

Improving the Climate Resilience of Urban Road Networks: A Simulation of Microclimate and Air Quality Interventions in a Typology of Streets in Thessaloniki Historic Centre

“…Future research could focus on investigating and comparing the environmental effects of the complete vehicular traffic electrification scenario, as well as a shared space scenario, including the introduction of a tramway in an exclusively protected corridor, a traffic lane reserved for electric vehicles, and a protected public space for pedestrians and bicycles. There is also plenty of room for future street microclimate studies to further investigate the impact of different vegetation species since there are indications that certain species (i.e., conifers) might be more efficient in lowering ambient urban temperatures [45]. Finally, the relationship between the subjective thermal comfort sensation and air quality needs further investigation, as it has been indicated by a recent study [46].…”

Urban Heat Island Mitigation: GIS-Based Analysis for a Tropical City Singapore

“…Therefore, green spaces have a significant drop in heat emitted due to photosynthesis. Additionally, trees can block a significant amount of shortwave solar radiation, neutralize carbon dioxide and transform sensible heat into latent heat of vaporization [69]. Trees can also store heat in their trunks and roots to prevent carbon from releasing into the atmosphere again [56].…”

Ecological adaptations among spruce species along an environmental gradient in urban areas

“…Among the assortment of plants, preference is given to those with high phytoncide 1254 (2023) 012114 IOP Publishing doi:10.1088/1755-1315/1254/1/012114 2 properties [6,10,11]. In particular, such plants are conifers, which clean the air of harmful substances all year round, absorbing almost all types of chemical compounds entering the atmosphere with emissions from industry, energy, motor vehicles [12][13][14][15]. However, improving environmental conditions, coniferous plants themselves suffer from the negative effects of air pollutants, which leads to changes in their biological parameters, biochemical characteristics and, in general, to a decrease in their viability [6,11,16].…”