A tree sits in the middle of a big empty lot in South Sacramento. It is huge and leafy, its arms open wide, an arc of green swooping across a hot summer sky. Fenced off in this abandoned car lot, the tree is a bold sign of life in an otherwise barren expanse of dirt and busted concrete. It’s a wonder that it’s still here.
This old lot looms large for Victoria Vasquez. Her dad used to live a half mile from this spot.
“I feel so bad that at the end of his life, this is what he had to see every day,” she said. “The people here deserve better.”
Vasquez is taking me on a driving tour of the city’s tree canopy. We started in Land Park, where people push baby strollers and jog around lakes on a tree-lined path. The tree canopy here covers more than 40 percent of the land.
A few blocks later, we entered South Sacramento. The landscape shifted dramatically from brick bungalows, lush lawns and shady lanes to hardscape, weeds and chain-link fences. Tree canopy here is only 12 percent. This is the neighborhood Vasquez serves as a Sacramento Tree Foundation organizer, a program funded by Cal Fire and 91Porn Climate Investment.
“We know we have issues with the urban heat island,” Vasquez said, sitting outside the empty car lot. “This is a disgrace.”
Urban heat islands and climate justice
Urban heat islands are areas with very few trees, very little shade and a built environment that soaks up heat and releases it into the air. Trees can help make cities more livable as temperatures rise under climate change. Their presence can cool a neighborhood by as much as 10 degrees.
In Sacramento as in many other metro areas, urban heat islands often coincide with the most impoverished neighborhoods. An Arizona State University study found that for every $10,000 increase in a neighborhood’s average household income, the local temperature drops half a degree.
UC Davis urban ecologist Mary Cadenasso saw this with about Baltimore, Maryland, where she studied how temperatures and heat islands vary with social factors such as poverty.
“There are still huge temperature differences by people in the city based on where they live,” said Cadenasso, a professor in the Department of Plant Sciences. “How are pavement, vegetation and buildings distributed? Who lives in areas with greater tree canopy versus little tree canopy? That has a big impact on human comfort.”
Trees can also impact the pocketbook: A well-sited tree shading a home can reduce cooling costs by as much as 40 percent.
Cadenasso said it’s also critical to recognize that nighttime air temperatures have been increasing in Sacramento over time, and cooling Delta breezes have been declining.
“This particular change will have a dramatic effect on human health and really expose inequities in our populations that can’t avoid that heat through air conditioning and whose neighborhoods may not feel safe enough to leave windows open,” said Cadenasso.
Neighborhoods in urban heat islands also tend to have compared to communities with more trees. These include higher rates of asthma, obesity, diabetes and among the lowest life expectancy rates, making trees a social and climate justice issue.
“We have to stop thinking of trees as ‘beautification’ and more as a public health solution,” Vasquez said.