Salt Lake City: A "Heat Island" with Health Consequences

Aug 20, 2014

Salt Lake City, like other cities, captures heat and holds onto it much longer than surrounding communities in rural Utah, because it is a "Heat Island."
Salt Lake City, like other cities, captures heat and holds onto it much longer than surrounding communities in rural Utah, because it is a "Heat Island."
Credit Garrett / Flickr Creative Commons

Cities are getting hotter thanks to climate change. And the heat in cities is rising faster than rural America. It’s a trend playing out in Utah.

Eric Pardyjak is a University of Utah mechanical engineering professor who studies what are called “heat islands,” which generally make summer nights hotter in cities than in rural communities.

“Typically, you’ll have some kind of increase in temperature in the urban area as a result of a number of factors,” he says. “But, basically, on a hot, sweltering night in the city, it takes a long time for things to feel quite a bit cooler. Whereas, if your aunty lies in the rural outskirts, she feels cooler very rapidly.”

Pardyjak says buildings, air conditioning, pavement and even colors play a role in creating heat islands.

A new study by the research nonprofit, Climate Central, looked at 60 cities and found that their daily high temperatures are about 17 degrees hotter on average than nearby rural areas.

The analysis does not include Salt Lake City on technical grounds. But Pardyjak says Utah’s biggest city does follow the trends. He also says the valley’s unique geography means solutions that work elsewhere might not be effective locally.

“The solutions are not obvious in Salt Lake,” he says. “So, if someone asks me what’s the right strategy in my yard, I don’t know that I know the right answer for that. We need more research and efforts towards being able to understand these very specific solutions.

Alyson Kenward, who led the Climate Central study, she says the trends are important because heat is already the number-one weather-related cause of death. Not only are the young, the old and the poor the most likely populations to be harmed, but she says the heat also boosts ozone pollution.

“So, we really do need to be worried about hot summer temperatures, particularly, moving forward in the future with more urban heat and climate change.”

National Weather Service data shows that, in four of the past five Julys in Salt Lake City, 25 days or more were over 90 degrees. Meanwhile, climate scientists say Utah is warming about twice as fast as the global average.