Strategies for a changing climate
Riding BMX is a lot harder than it looks. Gripping the handlebars of my borrowed bike, I roll cautiously around the banked turn, crest a small rise, and plummet down again—only to find myself stuck in the trough on the other side. Swearing under my breath, I look up to see 45-year-old Rick Wood swoop past me.
“Pedal once right before you hit the bottom!” he calls encouragingly. “It’ll get you over the hump!”
Wood, The Trust for Public Land’s Tennessee state director, is taking me on a two-wheeled tour of Stringer’s Ridge. The leafy hills of the hundred-acre park contain some of the best mountain biking within riding distance of downtown Chattanooga. Six years ago, The Trust for Public Land helped protect this land from a proposed condo development. Today, it’s the site of the city’s first green infrastructure project: the pump track we’re riding on.
The word “infrastructure” conjures up a picture of pavement and pipelines. But done right, infrastructure can also look like fun. The pump track—an all-ages bike skills area named for the pumping action of riders’ arms as they negotiate the hills and dips—has been specially designed to help manage stormwater runoff, reduce flooding, and recharge the city’s water supply.
This kind of versatility is more important than ever. As cities begin to feel the effects of climate change, planners are asking their parks to work a little harder—to help safeguard residents from storms and heat waves as well as providing a place to play. It may sound like a lot to ask of a neighborhood bike park. But with careful planning, it’s possible—no BMX skills required.
Climate change's urban frontier
With their glowing lights, gridlocked traffic, and crowded streets, you might think that cities are the worst offenders when it comes to climate change. But that’s not the case. As The Trust for Public Land’s Jad Daley points out, studies show that the suburbs produce more greenhouse gasses per capita.
For example: the average resident of New York City accounts for nearly 13,500 fewer pounds of carbon emissions than someone living in the suburbs. Why? Because people in cities can walk or take public transportation more often, and the smaller footprint of their more densely built housing is typically more energy-efficient than, say, sprawling single-family homes in Westchester.
From the standpoint of a climate scientist, this means the planet benefits when people move to the city, because they end up producing less carbon. “Making cities more attractive places to live is a climate strategy,” says Daley.
But while city-dwellers play an important role in combating climate change, they are also uniquely vulnerable to its effects. Paved-over landscapes can produce a “heat island” effect in warm weather and exacerbate flooding in storms—as evidenced by the devastating aftermath of Hurricane Katrina and Superstorm Sandy.
With climate scientists predicting an increase in the frequency of such extreme weather events, planners must decide how best to prepare communities for the challenges to come. That’s where The Trust for Public Land’s Climate-Smart Cities™ program comes in. Led by Daley, it applies the organization’s expertise in conservation planning and urban park creation to four strategies for climate-resilient cities.
FOUR STRATEGIES FOR CLIMATE-SMART CITIES
Even in Chattanooga—which has become a magnet for outdoorsy types—most residents still depend on cars to get around. Creating better networks of walking and biking routes encourages people to ditch driving, reducing carbon emissions as well as the health care costs associated with lack of exercise.
“A resident might ask, ‘So what if my city has a beautiful rail-trail—how do I get there from my house?’” Daley says. “It’s about advancing from a simple spine to a network that looks more like veins and capillaries.
In Kirkland, Washington, the Climate-Smart Cities team helped design an ambitious network of connector trails to feed into the regional Eastside Rail Corridor. Planners used transportation data to determine where access points and greenways can maximize connections between schools, residential hubs, and businesses—including Google, whose Kirkland campus is a major employer. Fully implemented, the plan would reduce the city’s carbon emissions by hundreds of thousands of pounds every year.
Materials like concrete and steel absorb and radiate heat, causing late-afternoon temperatures to soar as much as seven degrees Fahrenheit higher than surfaces covered in greenery. At night, that difference can jump to more than 20 degrees.
With some studies predicting a tenfold increase in heat-related deaths by the middle of the century, mitigating this heat island effect is an issue of equity as much as climate science: vulnerable populations—such as the elderly and lower-income households without air-conditioning— bear disproportionate risk.
But green space such as parks, tree canopies, and even small rooftop gardens can help cool the urban landscape. In Los Angeles, The Trust for Public Land is working to transform the city’s 900 miles of unused alleyways to provide some respite from the heat. The “green alleys” replace dark pavement with light-colored, permeable paving, as well as drought-tolerant plants for greenery and shade.
Like many U.S. cities, Chattanooga relies on a combined wastewater and stormwater system that allows runoff from the streets to mix with raw sewage. Treatment plants can handle only so much: during heavy rains, any overflow is sent—unprocessed—straight into the Tennessee River.
With more intense storms predicted in the years to come—and new federal regulations imposing stiff fines on pollution—urban communities need new ways to reduce the amount of rainwater going down the drains. Rather than spending billions on new treatment plants, cities are looking to the ground they walk on: every opportunity to replace asphalt with porous pavement or thirsty plants reduces the burden on the sewers.
The Trust for Public Land helps cities incorporate this green infrastructure into schoolyards, playgrounds, and parks—like the Stringer’s Ridge pump track. Specially selected vegetation in the right spots can help filter and absorb runoff before it ever reaches the aging sewers.
In coastal and river cities, climate-savvy planners must contend with the prospect of rising seas and higher storm surges. Placing parks and green space where they can act as natural buffers helps shelter vulnerable communities, while also providing a place for people to get outdoors.
Planning for this kind of flood protection can mean conserving natural landscapes, such as bluffs, sand dunes, wetlands, or even barrier islands. Or it can mean creating something new: smart city parks built to flood—so that surrounding neighborhoods don’t.
In Newark, for example, Riverfront Park was still under construction when Superstorm Sandy hit. But it emerged relatively unscathed from the ensuing floods, because its landscaping and durable boardwalk were designed with rising water in mind. Now open to the public, the park offers nearby residents the best of both worlds: a connection to the river when conditions are good, and protection from it when the weather turns ugly.
Putting climate resilience on the map
“Each of these factors in their own right presents an opportunity to create a more climate-resilient city,” says Daley. “But you want to get the most bang for your buck, you need to identify the opportunities to meet multiple goals at once.”
To do that, the Climate-Smart Cities program uses sophisticated mapping software—Geographic Information Systems, or GIS—to reveal where investment in parks and green space will yield the biggest payoff.
Working with a partner city, The Trust for Public Land assembles a local team of policymakers and researchers to supply data from their fields of expertise. In Chattanooga, for example, officials provided The Trust for Public Land with detailed information about the region’s floodplains. Satellite data on land-surface temperature helped pinpoint heat islands. Population density, income levels, the location of existing trails and bike lanes, and even social and health-related data—such as likelihood of heart disease in a given neighborhood, or the number of children or seniors—all came together in one system.
With this master map, Daley and Wood can help Chattanooga evaluate where parks and green space can do the most to help protect its most vulnerable residents from the effects of climate change—while serving the city’s long-term goals for transportation, recreation, and even housing. It’s a powerful resource for visualization and collaboration: with city agencies and their community partners all accessing the tools through one online portal, the map provides a common language for planning decisions that affect the entire community.
Planning at street level
Back in the office, Wood spreads a printout of a GIS map across a large table. Red dots mottle the downtown area like a bad case of chicken pox. “The red here is ‘high need,’” Wood says. “If you think about it, it makes sense: lots of pavement, people, and density.”
Wood traces his finger along the blue line of the Tennessee River and stops on the NorthShore district. From here, the main road climbs from the waterfront up to the Hill City neighborhood, site of Stringer’s Ridge. As it travels away from the river, Spears Avenue transitions from a row of trendy boutiques to a narrow stretch of single-family homes covered in aluminum siding. There are few trees.
“As you can see, Spears Avenue isn’t red, it’s orange,” says Wood, pointing to the map. “But believe me, it gets hot.” Last summer, Wood says, he and an engineer walked the length of Spears Avenue together and had to stop every few minutes to rest in the beating sun—hardly an encouraging sign for planners hoping to convince residents to ditch their cars.
To help transform the road into a viable bikeway, the city will plant trees (that’s the “cool” strategy) and rain gardens with thirsty plants (“absorb”). And Spears Avenue won’t be a bike path to nowhere: it will “connect” the downtown district—site of several public housing projects, large employers, and the University of Tennessee—to the trails of Stringer’s Ridge and existing bike and pedestrian corridors that extend into the suburbs.
A neighborhood on the rise
For the residents of Chattanooga’s Hill City district, the Climate-Smart Cities plan is the next level of a long-range parks plan that’s already brought welcome change.
Neighbors remember the old Stringer's Ridge as a dubious site for illegal encampments and a dumping ground for discarded junk. But The Trust for Public Land's purchase of the property for the city—and the massive, community-led cleanup and trail-building effort that followed—has made the forest a destination.
Resident Hattie Darby, 79 years old, was born and raised in Hill City. She graduated from the segregated Spears Avenue School, which once stood on the site of the Stringers Ridge pump track. When builders broke ground to start shaping the track’s jumps and berms, they found the remains of the school buried underneath—and incorporated its old stone walls into the track’s design.
When developers targeted Stringers Ridge for an extensive condo project, Darby was among their most most vocal opponents. The building plan required leveling the ridgeline, and Darby and her neighbors feared that erosion and runoff would foul the houses below.
The successful conservation of the property was a relief, its transformation into a much-loved park a bonus. "I think it looks good with all the green around us," Darby says. "When you cross the bridge coming this way and look up, it looks real nice."
Chattanooga's lush backdrop is often one of the first things visitors notice—and no wonder: it's easy to appreciate green space for its beauty, especially in a place once called the “dirtiest city in America.” By all accounts, Chattanooga has pulled off an impressive transformation, from decaying industrial river town to a regional standout for urban quality of life.
Now, Chattanooga must turn its attention to protecting the ground it’s gained, optimizing its celebrated park system as armor against rising temperatures and intensifying storms. The value of green space as infrastructure is not as easy to see as its beauty: after all, natural systems for managing water and heat often do their work in thin air or below the surface, visible only when charted on a map. But with a climate-smart strategy, forward-thinking cities can harness parks’ potential to meet the challenges of a changing climate—creating livable communities for generations to come.