Your local park has a hidden talent: helping fight climate change

People setting off fireworks in a park
Most people in the United States live in cities. And most people who live in urban areas primarily get outside by going to city parks. Climate change is putting pressure on people and parks alike. On a warm night in Washington, D.C. neighbors gather to put on their own July fireworks display. (Photo by Ryan Kellman/NPR)

Consider the unremarkable city park. A postage stamp of green amid the concrete. Trees, swings, grass, a basketball hoop.

Maybe your park has a public pool. Maybe it has a walking path or a barbecue grill or a leafy spot that’s good for watching birds. Yosemite it is not. Your park is not a vacation destination. Instead, it’s something much more valuable: a little piece of nature, right where you live.

People walking through a park at night
Urban parks get their power from their proximity to people. About three-quarters of residents in the 100 largest cities in the U.S. live within a 10-minute walk of a park. (Photo by Ryan Kellman/NPR)

City parks are crucial precisely because they are mundane. Their accessibility is what gives them their power. There are about 2 million acres of public parkland in the 100 largest cities in the United States, according to the Trust for Public Land.

Children play in a reflecting pool
Climate change is making heat waves in the U.S. more common, from an average of two heat waves per year during the 1960s to six per year during the 2010s. And those heat waves are 3 to 5 degrees hotter than they used to be, because of climate change. Local parks need to adapt. Dozens of cities are installing more water fountains, splash pads and pools to help people cool off. (Photo by Ryan Kellman/NPR)

All that parkland helps protect millions of Americans from the effects of global warming. Pools and splash pads offer a place to cool off on dangerously hot days. Trees provide shade, pull carbon dioxide out of the air and even lower the temperature in nearby neighborhoods. Marshes, ponds and meadows soak up water when it rains to help keep roads and homes dry.

A GIF of a woman walking down a wooded path
Well-maintained parks make people healthier. Forests reduce air pollution and heat. Walking and biking trails, skate parks and ballfields help people exercise safely and comfortably. And studies show that being outdoors helps reduce levels of stress hormones, which can help ease chronic illness. But escalating heat and other extreme weather threaten parks across the U.S. (Credit: Ryan Kellman/NPR)

But climate change is threatening the very spaces that help us cope with it. As the Earth heats up, the effects of global warming are on display in urban parks across the country.

Global warming means more-severe floods and hurricanes, which damage park buildings, courts, playgrounds, walking paths and other infrastructure. Heat waves put stress on animals and plants and threaten native species. In the most extreme cases, the effects of global climate change temporarily make some parks in the U.S. downright dangerous for humans.

Fireflies in a park at night
Being outside in green spaces can help alleviate feelings of sadness, stress and isolation. That has been on full display during the pandemic. The number of people using parks in Phoenix, Philadelphia, Dallas and Minneapolis skyrocketed in 2020. (Credit: Ryan Kellman/NPR)

“[Parks] are part of the solution, but they themselves are vulnerable to some of the same threats,” says Michelle Mueller Gamez, the manager of climate change research at the Central Park Conservancy in New York City.

But, like all urban environments, parks can adapt to a changing climate, at least to an extent. Scientists and local governments are working together to study how climate change is unfolding in urban green spaces and to figure out how to make parks more resilient.

Dog walkers holding several dogs on leash (left) and a squirrel on a concrete ledge (right)
(Photos by Ryan Kellman/NPR)

Parks departments are on the front lines

Managing a city’s worth of parks is a lot of work. There are ballfields to mow, trails to maintain, playground equipment to repair and swimming pools to staff. And there is rarely enough money to go around. Funding for parks has been stagnant or falling in most cities in the last decade.

At the same time, climate change demands ever more attention from parks departments, and dozens of cities have added new positions to meet those demands.

Two people next to a lone cactus on a rocky ridge
City parks can be wild and remote, even if they’re in the backyard. Here, early morning hikers rest before walking down Piestewa Peak, one of many mountainous city parks in Phoenix. “There’s, like, a 5 million-person city right there. And then you turn out here, and you could be in the high desert,” says Claire Miller, a longtime park supervisor in Phoenix. (Photo by Ryan Kellman/NPR)
Three people install a heat sensor on a tree (left) and a close-up of the sensor (right)
Climate-driven heat waves, heavy rain, intense drought and more-powerful hurricanes are putting stress on plants and animals in urban parks. In New York City’s Central Park, park caretakers are reacting by turning to science. The Central Park Climate Lab launched this year and will gather weather and climate data from across the park. Here, lab and park employees install heat sensors in the park. (Photos by Ryan Kellman/NPR)

That includes resilience officers and risk managers, who are explicitly focused on global warming, as well as a small army of arborists, botanists, hydrologists, restoration ecologists and conservation biologists who think more broadly about how humans interact with nature.

The challenges they face are not always obvious. Take wildfires, for example. Climate change is exacerbating drought across the country, not just in the Western U.S. where the megadrought makes daily headlines. A hotter planet also means more wildfire risk in places like the Southeastern U.S., New England and the Midwest.

People on a lit basketball court in a park at night
Basketball players take advantage of the relative cool of the evening in Philadelphia’s Lemon Hill Park. (Photo by Ryan Kellman/NPR)

One of the best ways to reduce wildfire risk is to do controlled burns, where fire experts burn a section of grass or trees on purpose to keep the ecosystem healthy and reduce the amount of fuel available for a future, unplanned fire.

Cities in the Western U.S. have been doing controlled burns in city parks for decades. Now, parks departments in Austin, Detroit, Charlotte, Des Moines, Jacksonville, Houston and New York City are doing the same: setting fire to portions of parks on purpose to stave off more destructive blazes.

An orange river boat glides by an adult and child fishing from the bank
Urban parks are part of nature. “Our mistake has been thinking that nature is something ‘out there,’ far away. We watch it on TV. We read about it in glossy magazines. We imagine a place, somewhere distant, wild and free. … This dream of a pristine wilderness haunts us. It blinds us,” writes environmental author Emma Marris in her book Rambunctious Garden. “Nature is almost everywhere.” (Credit: Ryan Kellman/NPR)

Matt McCaw manages such fires for the city of Austin. He says setting up a successful controlled burn requires a lot of expertise: You need to choose where and when to set it, and you need to understand exactly how it will behave so it doesn’t get out of control. He brings two decades of fire experience to his job managing land for the Austin Parks and Recreation department.

In many cases, climate change requires cities to rethink what parks look like. After major floods damaged city parks in Des Moines, Iowa; Atlanta, Ga.; and Houston, Texas, local leaders in all three places redesigned parks so they would be able to withstand future floods.

Two photos of the same area in a park by the Potomac: in one photo, the area is flooded
Heavy rain in Washington, D.C., in October 2021 flooded parkland along the Potomac River (left). Less than a year later, it’s back to normal (right). (Photos by Ryan Kellman/NPR)

Things that could be damaged by water, such as playgrounds and restrooms, are located on higher ground, and bike paths and grassy areas are relegated to the places most likely to be underwater after a storm. The parks are also designed to absorb and control water, in order to reduce flooding in nearby neighborhoods. Resilience and protection, all rolled into one park renovation.

“It’s harder than it sounds. It’s a science.”

It takes a lot of work to keep plants and animals healthy in city parks, especially as the weather gets hotter. Heat waves put stress on trees that already have to live with soot in the air, polluted water and lesser indignities like humans carving initials into their trunks.

But keeping trees healthy is a huge part of protecting parks and people from climate change. Stands of diverse and native trees absorb and trap more carbon dioxide than other types of greenery. The carbon stored in the forests of New York City is equal to the carbon released by more than 400,000 cars driving for a year, according to a 2020 study.

Children and a dog by a pond (left) and people skating in a roller rink (right)
Clemente and Maya Perez with their mother Sara Momii Roberts and dog Santino in leafy Prospect Park in Brooklyn, N.Y. (left). The enormous park in the heart of the city includes forests, lakes and meadows as well as a zoo, concert pavilion and roller skating rink (right). (Photos by Ryan Kellman/NPR)

Studies like that one are few and far between, however. We really do not know much about exactly how parks are reacting to, and helping to address, climate change. Enter the Central Park Climate Lab, which was launched this spring. The idea is for scientists, park employees and conservation groups to pool their money and labor and gather data about how climate change is affecting Central Park in Manhattan.

They’re starting relatively small, by installing temperature sensors and mapping tree cover in the park. “We’re learning a lot about challenges in measuring air temperature. It’s harder than it sounds. It’s a science,” says Gamez, who helps lead research in the park.

A humming bird in a bush
The trees and plants in urban parks are part of an ecosystem that must withstand air pollution, stormwater runoff and various degrees of human meddling. Climate change adds another stressor. (Ryan Kellman/NPR)
A purple flowering bush (left) and a tall deciduous tree (right)
Supporting native plants can help parks be more resilient. “Not only are they more able to respond to the changing climate, in a large extreme event for example, but they’re also part of the cultural history,” says ecologist Alex Hodges, formerly of the Central Park Conservancy in New York City. (Photos by )Ryan Kellman/NPR

But it’s crucial information. In general, large green parks cool off the neighborhoods around them, but how much? And what happens if you replace native trees with other trees, or bushes, or a grassy soccer field? The answers could help cities make important climate-related decisions.

Families playing at a swingset
Families gather in a playground with a splash pad and swings in Philadelphia’s Fairmount Park. Philadelphia has multiple projects underway to make this and other large parks in the city more resilient to heat and other effects of climate change. (Photo by Ryan Kellman/NPR)

“We know houses adjacent to parks might need less air conditioning if they have green space that’s keeping it cooler,” explains Gamez. “As we’re trying to reduce our carbon emissions, that’s great.”

The goal is to use Central Park, the grandfather of American city parks, as a testing ground that eventually helps inform park management across the country.

People on a river walk at night with the city skyline across the water behind them
Trees and other plants help keep cities cooler. In New York City, scientists are working to understand how to maximize the benefits of urban green spaces. Here, residents gather in Brooklyn Bridge Park on a hot summer night. (Photo by Ryan Kellman/NPR)

Protecting parks and people facing a hotter future

In some places, climate change is already making some city parks dangerous for humans.

Phoenix is known for its extensive and mountainous city parks.

But in the summer, many of those parks are not safe. It’s simply too hot, and even seasoned hikers have collapsed from heat exhaustion. Minor injuries, like a sprained ankle or twisted knee, often become life-threatening emergencies when people are stranded in the sun.

A desert landscape with a parking lot below
After several people were rescued while hiking during the heat of the day, the city of Phoenix closed the most popular trails on the hottest days. Instead, some trails open before sunrise and stay open until 9 p.m. to encourage people to hike in the early morning and evening. (Photo by Ryan Kellman/NPR)

Rescuing people from city parks does not fall to parks employees, but to the fire department. Special mountain rescue squads are made up of firefighters who train all year round so they can carry stretchers and first aid equipment up steep and rocky trails, and carry injured people down.

But it’s become clear that no amount of training is sufficient on the hottest days. Last year, two city firefighters from an elite mountain rescue squad ended up in the hospital after doing back-to-back rescues from city park trails on a day when temperatures lingered near 115 degrees.

A woman in a floppy hat stands in the desert (left) and flowers in a green park (right)
Claire Miller was part of the first park ranger class for the city of Phoenix more than 30 years ago, and she is still in love with the city’s parks. “To have these kinds of outdoor recreation opportunities in such a large urban city is monumental,” she says. “I always call it the nearby faraway place,” Miller adds, a sideways reference to one of her favorite Beach Boys songs. (Photos by Ryan Kellman/NPR)

After that, the fire department asked the parks department for help. Some of the hiking trails should close on the hottest days, they argued. It was just too dangerous for residents and firefighters alike.

It was a sobering moment for firefighters, who like to think they’re prepared for anything. “This is what I was made to do,” says Tommy Reeve, a member of one of the mountain rescue squads. “I was made for being on the mountains and running in the heat.”

But the weather is changing. “Sometimes when we’re on the mountain when it’s hot, it does worry me a little bit because I know we’re in danger as well, of being overheated,” he says.

Ultimately, the city decided to limit access to some of the most popular and exposed city park trails on the hottest days.

A man sits on a hill at night with a city below him
South Mountain Park and Preserve is the largest municipal park in the country. Matthias Kawski frequently walks in the park at night. On this evening in July it was a relatively cool 97 degrees. “It’s a total reset, compared to the noise down there,” Kawski says, looking over his shoulder toward the twinkling lights of apartment buildings and homes below. (Photo by Ryan Kellman/NPR)

At the same time, the parks department is trying to encourage Phoenix residents to get outside safely. City park rangers are posted near popular trailheads in the summer, asking people if they have water and cellphones. And some city parks stay open late into the evening to encourage people to hike when temperatures are in the 90s instead of 110 degrees or more.

On a warm summer night, people flock to South Mountain Park, a sprawling and wild line of hills and valleys near the Phoenix airport. The parking lot is open until 9 p.m. in the summer — a particularly important adaptation in a city of cars — but many people also show up on foot, wandering up from cul-de-sacs that abut the park’s trails.

People with flashlights on a desert trail at night
After several people were rescued while hiking during the heat of the day, the city of Phoenix closed the most popular trails on the hottest days. Instead, some trails open before sunrise and stay open until 9 p.m. to encourage people to hike in the early morning and evening. (Photo by Ryan Kellman/NPR)

It’s peaceful, but not quiet. Planes and cars rumble in the distance. Crickets hum. A coyote calls out.

Matthias Kawski sits at the top of a hill, drinking a beer and looking at the stars and the bobbing headlights of mountain bikers deep in the park. Kawski loves the outdoors. He’s drawn to epic landscapes. He says he has hiked large portions of the Grand Canyon.

But this little hill, behind his house, is the place he comes to most often. He’s here every night. And it feels grand, in its own way. “I own this place,” he says, gesturing broadly at the park laid out below him. “That’s all for me.” His little piece of nature, in the city.

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