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CONCRETE JUNGLES: THE CRITICAL ROLE OF TREE COVER IN PUBLIC HEALTH

It’s no secret global temperatures are rising and that the associated damages pose a great threat to almost all aspects of human life. However, by planting more trees across the world, we can save thousands of lives as trees mitigate the effects of climate change and associated heat, especially in urban areas. On World Cities Day, take the time to contemplate how cities can play a role in the fight against climate change.

Rising temperatures increase cases of infectious diseases and worsen asthma or other respiratory diseases. Climate change impacts the main factors that determine life expectancy. These include the availability of clean air, safe drinking water, secure shelter, and access to food.

Low income communities are most vulnerable to the effects of climate change due to limited access to these basic needs. It is expected that climate change will increase annual deaths per year by 250,000 globally ; heat stress will likely become a leading cause of death in cases related to climate change.

People living in urban areas are likely to face the worst of these threats to health. Cities are on average 10°F hotter than the surrounding suburban neighborhoods. These areas, known as frontline communities, are disproportionately inhabited by low-income and/or people of color. To expose communities unprepared and underfunded for negatively changing conditions is a disservice to all those affected.

These inequities did not come from out of nowhere. The early twentieth century and its associated rise in urbanization saw the practice of redlining, where urban planners at the Federal Housing Administration unjustly outlined African-American neighborhoods as risky for development. Spare real estate for green areas were disproportionately allocated towards wealthier whiter areas. By denying mortgages, inflating interest rates, and zoning areas nearby for industry or highways, segregationist tactics isolated communities of color physically and financially. The heat islands we see today are the lingering remnants of these unjust policies.

In the United States alone, extreme heat causes around 1,300 deaths annually. For example, cities have noted soaring rates of emergency calls during temperature extremes, mostly relating to chronic obstructive pulmonary disorder and cardiac arrest that has been aggravated by the heat.

Approximately three quarters of urban residents live in neighborhoods with less than 20% tree cover. These urban heat islands have less tree cover than the suburban neighborhoods nearby. With less green spaces providing shade, any potential cooling from latent heat transfer is removed. If you have ever felt the blanket of heat standing out in a parking lot in the middle of summer as opposed to under the shade of trees, that is what this is like. With more shade and greenery, cooling is much more conducive.

There are also other contributing factors for these higher temperatures, like the albedo effect. The albedo of a surface describes how reflective it is. For example, light colored surfaces such as snow reflect the sun’s energy back into the atmosphere, away from the ground. Darker surfaces such as concrete absorb then retain the energy and convert it into heat. The absence of trees and increased prevalence of manmade concrete surfaces creates an environment that accelerates this effect, trapping heat close to the Earth and creating uninhabitable climates.

However, there is a simple solution to the heat island problem. Studies have shown that daytime air temperatures in areas that have over 40% canopy cover are substantially lower, even on some of the hottest days. Planting trees in urban areas can significantly improve the quality of living in these areas. Not only would these trees provide much needed shade, which cools buildings and pavement, they also cool the environment through their transpiration process.

EARTHDAY.ORG’s Canopy Project makes planting trees simple – for as little as one dollar, you can help plant a tree. These donations are crucial in fighting climate change and mitigating its impacts. By donating to the Canopy Project, we can plant more trees to keep communities cool and healthy while also improving the quality and quantity of life for their inhabitants.

Written by Miriam Gilman and Connor Russell

October 31, 2022

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