In Fort Collins, how hot your sidewalk gets depends on where you live. Here's why.

As climate change continues to raise temperatures and records fall around the world , heat waves in Colorado are expected to become more frequent and more intense .

In the U.S., extreme heat is now one of the deadliest weather-related disasters . And the concrete jungles we’ve built can exacerbate this risk through something known as the urban heat island effect.

The Environmental Protection Agency defines the urban heat island effect as "a measurable increase in ambient urban air temperatures resulting primarily from the replacement of vegetation with buildings, roads, and other heat-absorbing infrastructure."

And that impact is not evenly distributed across our cities, as shown by a recent analysis by Climate Central examining how different areas within cities experience it.

In Fort Collins, the highest urban heat island index — defined by Climate Central as “an estimate of the additional heat that local land use factors contribute to urban areas” — was found around downtown and Highlander Heights, a neighborhood with UCHealth Poudre Valley Hospital on its west end and railroad tracks on its east.

Coloradoan photojournalist Logan Newell and I walked around Highlander Heights, including across a massive but empty parking lot, in the afternoon on July 10. On a shadeless stretch of the sidewalk, we measured the surface temperature to be 128 degrees Fahrenheit.

Less than 4 miles away at City Park, which has a body of water and numerous large trees, you can walk in almost complete shade in the sidewalk by the houses adjacent to the park. Here, the surface temperature was 72 degrees that afternoon.

Parts of the City Park neighborhood can still be just as hot, or even hotter than our readings at Highlander Heights— the parking lot where food trucks park, for example, was about 147 degrees — but the trees shading the houses provide a valuable refuge from the heat.

More temperature readings taken at the start of the heat wave on July 12 showed a similar pattern: 138 degrees for the Highlander Heights location and 82 degrees for the first City Park location. Those readings were taken slightly earlier in the day than those on July 10.

Fort Collins' plan to grow more trees

Between public and private property, Fort Collins has roughly half a million trees, excluding the Poudre River corridor and Spring Creek, said Ralph Zentz, the assistant city forester.

And the city is currently working on its Urban Forest Strategic Plan , which is its vision of how our forest could look in the next couple of decades.

“If I was to summarize it really fast, it would be to find ways to increase our canopy cover taking into consideration water use and climate change; and strategically plant new trees in places where they're going to do the most good for people,” Zentz said. This can be based on economical or environmental factors, like heat islands.

But keeping trees alive is not as easy as just planting them.

“There's a threat from invasive insects; there's a threat from climate change because as that gets worse, trees are more stressed out and the species palette, the trees that work here, is already limited and it gets more limited,” said Micaela Truslove, a horticulture specialist at CSU’s Weld County Extension Office.

Truslove is also a Ph.D. student in environmental sociology at CSU, is on the board of the Colorado Tree Coalition and spent a year as the state emerald ash borer program coordinator for the Colorado Department of Agriculture. In short, Truslove loves trees.

In the city, those half a million trees provide around 13% to 14% of canopy cover. A third of that comes from ash trees, which means that if those trees aren't treated, we can lose some of that to the emerald ash borer, Zentz said.

More: From the mountain pine beetle to emerald ash borer, Colorado forest pests spread in 2023

There are different tools to cool down houses, like white roofs that can reflect more sunlight instead of absorbing it, but trees are some of the most effective .

“A lot of carbon is stored there, so the greenhouse gasses are locked up in wood instead of causing trouble with our climate,” Zentz said. “There’s a lot of studies out there, too, that show human health benefits from nice canopy cover just because it reduces stress in people's lives.”

Environmental equity

As we mentioned before, heat and where we plant our trees are not distributed evenly in cities.

“Social conditions often have a really big impact on where we see urban canopy cover now,” Truslove said. “Areas that are lower-income areas that historically are under-resourced or where folks have been disenfranchised in the past, and still are, are those areas that we often see lower tree cover.”

In the 1930s the Home Owners’ Loan Corporation’s practice of “redlining” impacted access to home loans and shaped neighborhoods for decades to come.

“HOLC maps distinguished neighborhoods that were considered 'best' and 'hazardous' for real estate investments (largely based on racial makeup),” a 2020 study published on MDPI's Climate journal says . “... Though redlining was banned in the US as part of the Fair Housing Act of 1968, a majority of those areas deemed 'hazardous' … remain dominantly low-to-moderate income and communities of color, while those deemed 'desirable' remain predominantly white with above-average incomes.”

In Denver, the neighborhoods with the worst HOLC grade had an average temperature that was around 10 degrees warmer than the ones with the best grade, according to an analysis from Columbia University . Fort Collins was not included in this analysis.

But different levels of governments are taking steps to tackle this in Colorado.

The federal government invested $1.5 billion into urban and community forestry grant programs, which is unprecedented, Truslove said.

"The funding supports local communities and the organizations that serve them as they work to increase tree cover in disadvantaged spaces and boost equitable access to nature," a news release from the U.S. Department of Agriculture and the Forest Service says.

More: Read how land use legislation is key to tackle the energy transition in Colorado

At a city level, Fort Collins is considering economical and environmental factors to tackle these disparities and decide where to allocate its resources for the Urban Forest Strategic Plan.

To help increase the number of trees in yards, the city has a program that makes purchasing trees more affordable for Fort Collins residents.

“In the fall, we'll make available 1,000 trees that people can go online and buy for cheap, like for $25, and then the city takes on the rest of the cost,” Zentz said.

In addition to planting more trees, homeowners can also support the urban canopy by maintaining their trees. Truslove said your local county extension office, the state forest service and the Colorado Tree Coalition can help you learn how.

A '15-minute city’

Beyond planting more trees, Fort Collins has a vision to become a “15-minute city.”

This is a place where “people are able to walk, ride a bike, take the bus, using these alternative transportation methods to get to essential services like schools, hospitals, grocery stores,” Senior Environmental Planner Kirk Longstein said.

Designing a city this way can tackle many urban challenges at once. For example, reducing cars on the road means you need less parking space, which puts off a lot of heat, but that's just one of the benefits.

“Cars are a large contributor to greenhouse gasses. Having less cars on the road, we hope, is going to mitigate the climate effects of additional emissions, having those air quality days … and the tertiary benefits to public health that come from that,” Longstein said.

He mentioned a piece of legislation Colorado passed this year — Minimum Parking Requirements (HB24-1304) — that will help reduce the amount of space taken up for parking by prohibiting municipalities in some metro areas to enforce minimum parking requirements if a frequent bus service is available.

And in an ideal neighborhood for Truslove?

“We would have everyone have a big shade tree on the southwest side of their house,” Truslove said. “Or at least a park that has plentiful shade where people can go on hot days.”

This article originally appeared on Fort Collins Coloradoan: In Fort Collins, how hot your sidewalk gets depends on where you live. Here's why.