When Shade is Healthcare: Summer Heat and Tree Coverage
Last month Tacoma (and the entire PNW) felt first-hand how climate change is already affecting us and changing the seasons as we know them. Summers have been getting drier, hotter, and more uncomfortable—and will continue to do so. But if your house was shaded by mature trees, you were probably a little less hot than most of us.
Trees shouldn’t be considered a luxury, especially with all the public health benefits and ecosystem services they provide. Yet in many neighborhoods, they are. The most valuable trees—those of a mature height that can provide much-needed shade during summer heat waves—are islanded in traditionally whiter, wealthier neighborhoods. That means that the energy savings and cooling effects that trees provide are unevenly distributed to the populations that have a lower energy burden (household expenditures on heating and cooling are a lower proportion of the total monthly budget) and more money.
Meanwhile, those who don’t have access to cooling tools or who have limited resources suffer negative consequences. Every summer, heatwaves cause hospitalizations and fatalities. In the most recently revised count from the Pierce County Medical Examiner’s Office, 23 people in Pierce County died of extreme heat. Statewide, King and Pierce County suffered the largest share of heat deaths. Of those experiencing heat distress, a large majority are either elderly or unhoused. In other words, extreme heat is an issue of both public health and environmental justice.
While the entire PNW experienced extreme heat, urban areas felt the heat even more strongly. Cities are often several degrees hotter than the surrounding land as a result of the urban heat island effect. In urban areas, the combined effect of high concentrations of built surfaces that absorb heat and low rates of tree coverage mean that residents are feeling higher heat levels than their rural neighbors.
Within cities, there are also disparities in temperature. Neighborhoods with a lower tree canopy cover are hotter and less comfortable, and residents have to spend more money to achieve the same level of cooling as compared to those who live in neighborhoods with more trees. The neighborhoods lacking trees are essentially the same neighborhoods that were redlined by the Federal Housing Authority in the 20th century. Those neighborhoods, such as parts of Tacoma’s Hilltop and Eastside, still bear the scars of those discriminatory practices, and the effects linger on people too; the consequences of that discrimination can be seen today in the inequitable way community members experience extreme heat.
To mitigate the impacts of climate change and improve the livability of our cities, we need to be planting more trees. All of our planting efforts, though, need to be intentional about equity and environmental justice, to make sure that those most vulnerable in our communities are receiving help first. Tacoma Tree Foundation is committed to doing this work, but only in a way that is just. We invite you all to support this work and help hold us accountable!