By SLCgreen Interns Frances Benfell, Emma Johnson, and staff Jude Westwood
When my friend Tia made plans to spend the weekend in Salt Lake City, she didn’t know what she was in for. A few days before her visit, I texted her and asked, “How do you feel about waking up at 5:30 am to go heat mapping with me on Saturday?” She responded, “I don’t know what that is, but as long as you buy me coffee!”
As we drove to pick up our heat sensor on a Friday afternoon in mid-July, I explained the project to Tia. We were volunteering to drive one of ten routes across Salt Lake City with a sensor attached to our car that would measure temperature, humidity, and location along the way. Our role (along with over 40 other volunteers) was to gather data for a citizen science research project funded by the National Oceanic and Atmospheric Administration (NOAA). Salt Lake City was one of 18 communities chosen to participate in this year’s mapping project. Over 60 communities have participated since the program started in 2017.
Mayor Erin Mendenhall planting a tree in 2021 as part of her 1,000 Trees Initiative.
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After the intense heat experienced by many of us this summer you probably wouldn’t be surprised to learn that this past July was Salt Lake City’s warmest one yet and the heat wave is continuing with us as September begins.
But did you know that Salt Lake County’s summer days are abnormally hotter than those in nearby rural areas? Our culprit is referred to as the urban heat island.
What is the Urban Heat Island?
Urban heat islands occur as the built environment of a city attracts heat and prevents it from being released by covering up naturally absorbing sources. For example, grass absorbs heat but covering it with concrete for a sidewalk that attracts warmth will make the city hotter. Researchers have found that the cumulative effect of all these heat-attracting sources results in cities being up to 17 degrees hotter than surrounding areas! Research conducted by the University of Utah used temperature monitors throughout the valley to measure our urban heat index. This research discovered that our parks with grass and shade are two degrees cooler than nearby residential neighborhoods.
The benefits that shady parks and park strips provide in reducing the urban heat island are just one of the reasons that Salt Lake City places an emphasis on maintaining them. The important role tree cover plays in reducing heat is evident when looking at the images of Salt Lake City below. The map on the left shows the Urban Heat Island Effect by noting how much hotter it can be in that area. The darker the red the hotter it is. The map on the right shows the percentage of tree cover canopy in the entire neighborhood. The darker the green, the more canopy cover in the neighborhood. When comparing the two images it becomes evident that when there are more trees, the urban heat index is lower.
Heat mapTree cover map
Additionally, the image below provides another useful visual to understand what the Urban Heat Island Effect looks like in Salt Lake City. The image, taken from satellite by NASA, shows 300 West to the Wasatch Foothills. The image, taken on a hot summer day, demonstrates the Urban Heat Island Effect in action. Orange, red, and yellow indicate hot areas and blue and green illustrate the cool areas. With this in mind, it becomes clear that areas with less vegetation are the hottest. For example, Liberty Park, which is near the bottom left-hand corner, is very blue on the map indicating that it’s cool.
How can you reduce heat and contribution to the urban heat island?
by SLCgreen outreach coordinator Stephan Sveshnikov
With much of the West seeing record temperatures this summer and 98% of Utah in an extreme drought, it’s a good time to remind ourselves of what we can do to keep our city a little bit cooler and ourselves safe.
While you’ve heard a lot of discussion about saving water during this drought, today we also want to talk about reducing the urban heat island effect— which helps save water, reduce ambient temperatures, and support a healthier ecosystem.
What is an Urban Heat Island?
Cities are always hotter than the average surrounding temperature because of what’s called the “Urban Heat Island” effect. Because the concrete, black asphalt, and black roof shingle material absorbs extra heat and releases it, city temperatures can rise by as much as 18 degrees Fahrenheit compared to the surrounding area on a cloudless day! This, in turn, raises the energy consumption of the city, because our air conditioners have to work harder to keep us cool.
How can I reduce my home energy consumption during the summer?
What can you do to reduce the Urban Heat Island effect at your home or business?
First start with your own building. Saving energy means you’ll be more comfortable, save money, and reduce the ambient heat going into the neighborhood.
Cover your windows! When it’s hot, about 76 percent of sunlight on windows enters in the form of heat, according to the Department of Energy. Keeping blinds closed on the sunny side of the house or installing solar screens will keep your house from heating up as much.
Set the AC ten degrees higher if you’ll be gone from home all day, and set it at 78 degrees F or warmer if you are home. Cool off with cold drinks, a trip to the mountains, or turn on a fan to circulate air in the room you’ll be in.
Avoid using your stove and oven during the hottest parts of the day.
Energy efficient evaporative coolers (also called “swamp” coolers) are perfectly-suited to Utah’s arid desert climate and can cut cooling costs by 75% compared to a central AC!
Plant shade trees around your home. The more shade around your house, the less it will absorb direct heat from the sun, and the less your AC or swamp cooler has to work.
Insulate! Make sure you have the appropriate level of insulation in your home. Insulation helps keep your house warm in the winter, but it also helps keep it cool in the summer, because the fewer leaks you have, the less that cold air you’ve worked so hard for can escape.
Learn more about energy efficiency year-round from Empower SLC.
Planting water-wise plants and trees that provide shade can help your house stay cool even when it’s hot outside. Learn more about water-wise gardening on SLC’s Public Utilities page.
Salt Lake City’s urban forest suffered notable damage in the September 8 wind storm. The carefully maintained forest consists of nearly 85,000 public trees.
Sadly, the City lost approximately 1,500 public trees from city parks, the cemetery, park strips, and medians. We estimate that another 3,000 public trees were damaged and are in need of repair– on top of the private trees from yards that were lost or damaged.
This is certainly a sad occurrence for our environment and community– especially if you lost a beloved tree.
However, as Urban Forester Tony Gliot describes in the video below, storms are a natural part of our ecosystem and we have the opportunity to come together and re-plant many of these trees that were lost.
Salt Lake City’s Urban Forestry Division works hard to care for our existing trees and to help plant more. Even before the storm, tree planting was a priority for our city. Not only do city trees help make our streets beautiful, they help make Salt Lake City more resilient.
Urban forests are critical parts of green infrastructure, providing natural air and water filtration, mitigating the Urban Heat Island effect, and helping with carbon drawdown. As a result, trees can help make Salt Lake City a pleasant and climate resilient community.
Want to learn more about Salt Lake City’s urban forest and how you can help support our trees? Read on!
Trees vs. Climate Change
The green infrastructure provided by trees provides something we all love in the summer: shade. According to the EPA, the maximum temperatures of shaded surfaces can be between 20–45°F cooler than unshaded areas. This is especially important in cities where buildings, roads, and city infrastructure absorb the daytime heat. The absorbed heat effectively warms the entire city, making cities warmer than surrounding areas resulting in what is called an Urban Heat Island.
By making cities a little cooler in the summer, trees and vegetation help us cut down on the energy we use to cool buildings – and the associated carbon use and pollution. Trees are also able to help filter the air pollutants and sequester the carbon dioxide that we do produce. The EPA also notes that trees absorb rainwater, which is an important part of protecting our stormwater.
Recognizing these benefits is one reason why Salt Lake City has a long-term Urban Forest Action Plan. Check out the video from last year’s Summer Planning Series, which discussed the benefits of trees and how the City is working to increase our canopy to serve our entire community.
Watch the video from the 2019 Summer Planning Series walking tour on our SLC Urban Forest.
Home damage from the hurricane-force wind storm Salt Lake City experienced on Sept. 8, 2020.
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So far 2020 has been a record year for climate-related natural disasters. Alongside the global coronavirus pandemic, severe weather like what we experienced with last week’s wind storm, record breaking temperatures in August, and fires burning throughout the Western United States, have shown us first-hand the effects of climate change in our backyards.
That’s why it’s more important than ever to call attention to climate change– and the urgency of taking action at all levels.
We’re in luck because the Fourth Annual Utah Climate Week is coming up from September 21 – September 27 and offers everyone the platform not only to learn and engage, but also to call attention to climate change during what has seemed like a year of jumping from one immediate crisis to another.
So many people are struggling and so many are exhausted with all 2020 is bringing to bear on our communities. We hear that and we feel it too.
And that’s exactly why we must continue looking at the big picture, and to draw the connections between immediate events and the larger harm we’re doing to our planet.
This year’s Climate Week will be a little different– there won’t be in-person events, but there are a suite of interesting and engaging events taking place online and we hope to see you at one or more of them.
Then join us on social media to highlight why you care about climate change. Use the tags #UtahClimateWeek and #ActOnClimate to call attention to this issue!
If you’re not a big social media user, take the opportunity to do some learning, then perhaps have a conversation with your friends, family, or other networks. Whatever you do: Learn. Activate. Engage. Let’s go!
Utah Climate Week is an annual event– now in it’s fourth year– and is coordinated by the Utah Climate Action Network, Utah Clean Energy, and many partners. The week provides a chance to learn, share resources, and re-commit to the necessary work to #ActOnClimate.
We’ve been involved in planning and coordinating one event in particular and we’d like to invite you to attend.
The Utah Sustainable Business Coalition and the Salt Lake City e2 Business Program are hosting a panel discussion on how local businesses of all sizes are working to improve sustainability at their companies.
The event will be held on Tuesday, September 22 from 10:00-11:00 a.m. on Zoom.Click here to register!
As we have noted in previous blogposts, sustainability and resiliency intersect with environmental, social, economic, and equity work.
Communities of color are disproportionately affected by climate change. In Utah, the health threats of air pollution are the most obvious example. On a global scale, climate change and pollution are affecting us all, especially coupled with COVID-19, starting with communities who are already experiencing systemic racism and inequity.
Because these areas of life are directly connected, it is important to take action on every level. Individuals; businesses; and local, state, and national governments have an important role to play in addressing inequity and supporting sustainability.