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What Are Heat Islands? Here's Everything You Need to Know

Heat islands are an infrastructure-born effect that causes harm to humans and wildlife alike. Here's what you should know.

heat islands
Written by
Calin Van Paris
We're all getting uncomfortably used to extreme weather. The dramatic atmospheric events that come with
climate change
show up differently around the world, manifesting (thus far) as
cyclonic storms
, rampant
, and
aggressive heat
. And while some are at least partially equipped to deal with the subsequent effects, certain areas become unbearable and unlivable under these conditions, with flooding, wildfires, and more exposing the weaknesses of our infrastructure.
An urban example of this fallout? Heat islands, portions of city neighborhoods that are ultimately designed to ratchet up the temperatures rather than combat them. For climate scientist
Dr. Jeremy Hoffman
of the
Science Museum of Virginia
, the community-based research and analysis of the heat island effect in Richmond, Virginia, has led to a national initiative—one that can potentially help us rethink the way we build our cities.

What Are Heat Islands?

heat islands
"Urban heat islands are small areas where the air temperature is elevated relative to the outlying rural or more natural landscapes outside of a city," says Dr. Hoffman in an episode of
Good Together
. The elevation comes courtesy of buildings, roads, and other materials that absorb and reemit the sun's heat in a more intense way than natural landscapes might.
Surface heat islands form due to surfaces like roadways and rooftops and their tendency to emit heat, while atmospheric heat islands are caused by the generally warmer air in cities due to human activity.
"What's really interesting about our research is we've been looking at just how much temperatures can vary within a city," says Dr. Hoffman, whose research is now used by NOAA’s climate program office in over 60 cities nationwide. "We know that, on average, urban areas can be 7-10 degrees warmer than in outlying rural areas. But what we've been investigating is just how much the temperatures can be different within the same city on the same day during a heatwave that's fascinating." This variance involves factors like tree canopy, green spaces, and human infrastructure.
"There are so many different little combinations of those two extremes of natural and human landscapes," says Hoffman. "That that's really what sets the thermostat of a particular neighborhood during a heatwave."

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What Are the Impacts of Heat Islands?

Far from just being uncomfortable, heat islands have major impacts on infrastructure, ecosystems, emission output, and human well-being. To survive intense temperatures, those fortunate enough to weather the weather indoors rely on air conditioning, the uptick in usage resulting in an increase in the emissions that caused the unlivable heat in the first place.
Heat islands can cause roads to buckle and fail, overheat our sewer systems and waterways to the detriment of surrounding aquatic wildlife, and even shift the egg-laying and nesting times of urban-based birds. For humans, heat islands bring about a natural rise in heat-related illness, particularly for those who are unhoused or who make their living working outside. The heat island effect disproportionately impacts the elderly and communities of color, who are more likely—due to socioeconomic status and historically prejudiced city planning—to have limited access to green spaces, poor housing conditions, and a lack of resources to escape or deal with the heat.
"When we think about the urban heat island effect, it's really a great way to open the door into discussing all of these other societal issues that we care about and want to want to be a part of the solution for," says Dr. Hoffman.

What Can You Do to Help?

heat islands
"This is probably my favorite part of the discussion, because, really, we have an entire buffet of options," says Dr. Hoffman. The myriad solutions can be broken down into two buckets: how to cool down our cities, and how to respond to the acute shock of a
heat wave
. Both have to do with societal and governmental shifts, and both need to happen simultaneously.
In the first bucket, Dr. Hoffman notes things like planting trees, lightening the colors of surfaces, increasing variation in building height (taller buildings = more shade), restricting road width, depaving in favor of parks, adding shade structures at public transit stops, and more. To help, he suggests planting native trees in your backyard, contributing to a campaign at your HOA or in your neighborhood, and finding a nonprofit that's already doing green space improvement projects and volunteering.
And as for our collective response to heat waves? That's down to our elected officials. Solutions like community cooling centers, thoughtful emergency response, educational resources, and more can be implemented to help humans that make their homes in heat islands stay healthy and resilient.
"By doing both, the kind of mitigation or turning down the temperature and managing our societal response, we can really be improving the outlook as climate change continues to increase the frequency, intensity, and duration of these heat events that are amplified by the urban heat island effect," says Dr. Hoffman.