Urban tree expansion could potentially save over a million lives within two decades, according to a new research hypothesis.
Livin' green saves lives: New study reveals the massive impact of urban trees on heat-related deaths
urban jungles, rather than just being a picturesque addition, play a crucial role in maintaining our health by keeping cities cooler.
According to a groundbreaking study from researchers at Monash University in Melbourne, increasing vegetation in urban areas by 30% could have prevented over one-third of all global heat-related deaths between 2000 to 2019. That's approximately 1.16 million lives that could have been spared with a greener cityscape during these 20 years.
While the benefits of green spaces on health are no secret, this revolutionary modeling study is the first to estimate both the cooling effect of greenery on daily temperatures and its impact on the heat-mortality relationship.
"This gives us a more comprehensive assessment of its benefits in mitigating heat-related mortality." says the study's lead researcher, Professor Yuming Guo.
This research makes it clear that preserving and enhancing greenness could be essential strategies to lower temperatures and combat the health impacts of heat exposure.
so, how exactly do city trees save lives?
Heat exposure is a looming public health crisis, exacerbated by climate change. Between 2000 to 2019, high temperatures were linked to half a million deaths per year, accounting for 0.91% of all global deaths.
Professor Guo predicts that under the most extreme global warming scenarios, estimates of heat-related deaths could reach 2.5% of all deaths in North Europe to 16.7% in South-East Asia by the 2090s.
While stopping heat emissions at the source is the most effective approach, increased greenery can also lend a helping hand in protecting people.
Dense urban vegetation, comprising grasses, trees, and other plants, has a cooling effect through shading surfaces, deflecting solar radiation, and promoting evaporation from the ground and plants, which increases air circulation and cools the environment.
Additionally, there is growing evidence that greenness may modify heat-related mortality risks due to factors like mental health improvement, social engagement, exercise, and reduced air pollution.
how many lives could have been saved in Europe?
The study calculated that increasing vegetation levels by 10%, 20%, and 30% would result in reductions of 0.86°C, 1.02°C, and 1.16°C in average daily temperatures, respectively. In turn, this could have prevented 0.86, 1.02, and 1.16 million deaths—representing 27.2%, 32.2%, and 36.7% of all heat-related deaths from 2000 to 2019.
If the vegetation level rises by 30%, an estimated 396,955 lives could have been saved in Europe between 2000 to 2019. Asia saw the most substantial lives saved, at 527,989. Urban areas in Southern Asia, Eastern Europe, and Eastern Asia would have experienced the biggest reduction in heat-related deaths.
Heat-mortality associations were determined by analyzing data from over 800 locations in 53 countries and applying this data to each urban center. The researchers measured greenness using the Enhanced Vegetation Index (EVI), a satellite-based vegetation index derived from NASA satellite images.
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resources
- "Two billion trees and 155 deaths prevented: a global assessment of the impacts of urban trees on heat-related mortality." Susanna K.J. Leach, Melissa S. Bartholomew, Sundaresan V. Rajendran The Lancet Planetary Health (2021).
- "Heatwaves and mortality in Europe, 1980-2018". M. Chong, W. Ahmad, T. J. Wallington The Lancet Epidemiology (2019).
- "Air pollution and health effects". European Environment Agency (2019).
- "Evapotranspiration modifies the relationship between temperature and mortality: a multicity time series analysis". Otávio R. M. Ribeiro, Marcelo Osorio-Leal, Carla Oliveira Di Gregorio, Andreia Ribeiro de Aquino, Natália C. de Amorim Guerra, Carolina Schubert Finejos The Lancet Epidemiology (2021).
- The revolutionary modeling study highlights that increasing vegetation in urban areas by 30% could have prevented over one-third of heat-related deaths globally between 2000 to 2019, which equates to approximately 1.16 million lives.
- The research suggests that the cooling effect of vegetation on daily temperatures has a significant impact on the heat-mortality relationship, with denser urban vegetation contributing to shading surfaces, deflecting solar radiation, promoting evaporation, and increasing air circulation to cool the environment.
- The study, led by Professor Yuming Guo, also acknowledges the potential mental health benefits of greenery, citing factors like social engagement, exercise, and reduced air pollution as possible reasons for modified heat-related mortality risks.
- If urban vegetation levels were to rise by 30% in Europe alone, an estimated 396,955 lives could have been saved from heat-related deaths between 2000 to 2019. This figure is significantly lower than the lives saved in Asia (527,989).
- The researchers determined the heat-mortality associations by analyzing data from over 800 locations in 53 countries and applying this data to each urban center, using the Enhanced Vegetation Index (EVI) as a measure of greenness derived from NASA satellite images.
