As another heat wave grips Southern California, Los Angeles is confronting a problem that goes beyond how high the thermometer climbs. Not everyone experiences the heat in the same way.
In neighborhoods with mature trees, residents can find shade along sidewalks, streets and parks. In communities with little tree canopy, people can face long stretches of asphalt and concrete with few places to escape the sun.
The difference is not simply cosmetic. It can be a matter of health.
UCLA researchers have found that excess emergency department visits during heat events cluster in lower-income communities with less tree canopy, including parts of South Los Angeles, East Los Angeles and the San Fernando Valley. Formerly redlined neighborhoods are often hotter than better-rated neighborhoods elsewhere in the city.
In Los Angeles, heat is an equity issue, and shade is part of the protection.
Los Angeles does not have an equal distribution of trees.
UCLA research has documented major differences in tree canopy between neighborhoods. Some areas of Los Feliz approach 40 percent tree canopy, while nearby East Hollywood has about 13 percent. Wealthier areas such as Brentwood and Shadow Hills can have substantially more.
Researchers have also found that trees can make a significant difference in neighborhood temperatures. A UCLA study of heat-vulnerable Los Angeles communities found that tree shade could provide cooling of up to 8 degrees Celsius, or 16 degrees Fahrenheit, compared with hotter surfaces.
Another UCLA study found that for every additional 10 percent of tree cover, temperatures in the Los Angeles region were about 2 degrees Fahrenheit cooler. Researchers found that vegetation loss during drought was particularly severe in lower-income communities.
That creates a troubling cycle. The neighborhoods that often have the fewest trees can also face some of the greatest exposure to heat.
A campaign built around 28,000 trees
Against that backdrop, TreePeople has launched Rooting for LA, a campaign to plant and steward 28,000 trees by 2028 across greater Los Angeles.
The organization says the initiative is about more than increasing tree canopy. Its goals include cooling neighborhoods, restoring habitat, supporting biodiversity, creating greener schoolyards, capturing stormwater and helping recover landscapes damaged by wildfire.
TreePeople describes trees as living infrastructure, a useful way of thinking about their role in a city increasingly challenged by extreme heat, drought, wildfire and water insecurity.
But the campaign also raises a larger question.
Where will those trees go?
Planting 28,000 trees is one thing. Making sure they reach neighborhoods that need shade most, and keeping them alive, is another.
UCLA research on Los Angeles’ urban forest has found that access to trees is highly unequal. Wealthier neighborhoods have historically received more investment in trees and shade, while many under-resourced communities have been left with less canopy and more heat-absorbing pavement.
The consequences become more serious during extreme heat.
Low-income communities often have fewer trees and less access to other forms of cooling. They may also have more pavement and concrete that absorb heat during the day.
For residents who walk to work, wait for buses, take children to school or spend time outdoors, shade is not a luxury.
It can be the difference between exposure and relief.
UCLA and USC researchers are also working through ShadeLA to expand natural and built shade across Los Angeles County, with particular attention to communities that need it most.
Trees are only part of the solution. Bus shelters, shade structures, cooling centers and other infrastructure also matter.
But trees offer something those temporary solutions cannot.
They can keep providing benefits for decades.
The lesson from Los Angeles’ past
Los Angeles has attempted major tree planting campaigns before.
Ahead of the 1984 Olympics, TreePeople helped lead an ambitious effort to plant one million trees. The campaign was a major grassroots undertaking, but researchers have noted that many of those trees did not survive because some were planted in unsuitable locations or were not adequately maintained.
That history offers an important lesson for today’s campaign.
The success of a tree planting effort cannot be measured only by the number of trees put into the ground.
It must also be measured by where they are planted, how they are maintained and whether they survive long enough to create meaningful shade.
A newly planted tree may look good in a photograph.
A mature tree shading a sidewalk during a heat wave is infrastructure.
Climate change is making the challenge more urgent.
Los Angeles already experiences an urban heat island effect, with asphalt, concrete and other surfaces absorbing heat during the day and releasing it at night. Dense neighborhoods can remain hotter after sunset, limiting the body’s ability to recover from heat.
For communities that already have fewer trees, the problem can compound.
Less vegetation means less shade.
More pavement means more heat.
Higher temperatures can mean greater health risks.
And drought can make it harder for existing trees to survive.
That is why TreePeople’s 28,000-tree commitment matters beyond its headline number.
The larger opportunity is to help address a longstanding imbalance in who has access to one of the simplest forms of climate protection.
Shade.
Who gets the shade?
Los Angeles is becoming a hotter city.
But the heat is not distributed equally, and neither is protection from it.
The 28,000 tree campaign cannot solve that problem on its own. Trees cannot replace cooling centers, public health programs, resilient housing or other protections against extreme heat.
But strategically planted and properly maintained trees can become part of Los Angeles’ long term defense against rising temperatures.
They can also help address an environmental inequality that has been decades in the making.
The most important question may not be how many trees Los Angeles plants.
It may be who gets to stand beneath them when the next heat wave arrives?
UCLA research on Los Angeles’ urban forest has found that tree access is highly unequal. Nearly 20% of the city’s urban tree canopy is concentrated in just a small number of census block groups, while wealthier neighborhoods historically received more investment in trees and shade.
The consequences become more serious during extreme heat.
Low-income communities often have fewer trees and less access to other forms of cooling. They may also have more pavement and other heat-absorbing surfaces.
For residents who walk to work, wait for buses, take children to school or spend time outdoors, shade isn’t a luxury.
It can be the difference between exposure and relief.
A broader UCLA and USC effort, ShadeLA, is now working to expand both natural and built shade across Los Angeles County, with a particular focus on communities that need it most. The coalition says shade can dramatically reduce the way outdoor heat is experienced and is among the most effective low-cost ways to reduce heat risk.
That work underscores an important point: trees are only one part of the solution. Bus shelters, shade structures, reflective surfaces and other infrastructure also matter.
But trees offer something those temporary solutions cannot.
They can keep providing benefits for decades.
