June 29, 2021

Relief from the urban heat this summer, find some shade — thank a tree

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Relief from the urban heat this summer, find some shade — thank a tree Image Source: metlink.org

As the globe heats up, cities across America are moving to increase their tree canopy to mitigate urban heat island effect. "Urban Heat Islands" occur when cities have dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat from the sun. We have seen this not only in Utah but across the nation, this climate change will lead to more frequent, more severe, and longer heatwaves during summer months and making a healthy tree canopy all the more important.

Have you noticed yourself on a hot summer day choosing to walk on the shaded side of the path or sidewalk? If you have ever crossed the street to walk on the tree-shaded side you are already familiar with urban heat island and what it feels like, usually up to 30 degrees cooler! Planting shade trees on the south and west faces of your house can reduce winter heating bills by up to 15% and summer cooling bills by up to 50%. Studies have shown that well-treed businesses project a warm, welcoming and inviting atmosphere for shoppers who tend to linger and spend more time shopping, resulting in some cases in a business increase of up to 11%.

For instance, the National Weather Service data shows that, in four of the past five Julys in Salt Lake City, 25 days or more were over 90 degrees. Meanwhile, climate scientists say Utah is warming about twice as fast as the global average.

One of the easiest ways trees in urban areas can help diminish heat is shade. Trees keep urban neighborhoods cooler, reduce air conditioning bills and, most importantly, protect the most vulnerable populations during heat waves. Elderly people, young children and lower-income or on the streets population are especially at risk. Trees also remove heat-trapping carbon dioxide from the air, they absorb harmful pollutants like nitrogen oxide, nitrogen dioxide, and sulfur dioxide, also releasing oxygen. The Environmental Protection Agency (EPA) reports that shaded areas can be up to 20-45 degrees cooler than areas that lack shade. This means trees are particularly valuable along the Wasatch Front and other areas in Utah that struggle with ozone and particulate matter pollution.

That lack of tree cover can make a neighborhood hotter, and a joint investigation by NPR and the University of Maryland's Howard Center for Investigative Journalism found just that: Low-income areas in dozens of major U.S. cities are more likely to be hotter than their wealthier counterparts, and those areas are disproportionately communities of color. People who live in poorer, historically "minority" communities, where many residents rent and have less ability to landscape or plant trees, are more at risk of heat-related illnesses than the people in more well-off communities. 

Besides tackling urban heat, planting more native trees in cities comes with lots of bonuses, like food resources for wildlife, better water quality in our urban waterways, green corridors that will store carbon, and spaces that people will want to spend time in and enjoy as a community. 

There are some simple and effective nature-based solutions for cooling our cities. Planting trees in our state's urban areas is an invaluable investment for cities, people, and our precious environment.