• Carol Jin

Heat Island Effect - It Turns Cities Into Islands



2020 has seen some pretty hot summer days. But if you live in a large city, you might have been sitting through slightly hotter days than people who reside in less urbanized areas. This is due to the heat island effect (yes, urban city-dwellers, you are living on a sort of “island”).

What is the Heat Island Effect?

The Environmental Protection Agency (EPA) defines the heat island effect as a phenomenon where “urbanized areas experience higher temperatures than outlying areas” [1].

This is because city structures such as streets or buildings absorb and re-emit heat more intensely than natural settings do. Just think about how it would feel to lay your hand on a slab of concrete that’s been exposed to full sunlight at 2:00 in the afternoon, versus putting your hand on a local tree or lake’s surface at that same time (don’t put your hand in a lake, hopefully you still get the picture that man-made structures tend to heat up more).

How strong is this heat island effect, exactly? How much warmer can urban areas become? Well, a city that accommodates 1 million people can be 1.8-5.4℉ (1.0-3.0℃) warmer than its surroundings [2]. For reference, New York City has over 8.5 million residents and Los Angeles is home to over 4 million people [3]! If you stopped to do the math, I’ll assure you that this does not mean that cities as large as NYC or LA are 50℉ hotter than their surroundings, but the average temperatures of these metropolitan areas will definitely be higher than those of their neighboring areas.

How Turning Up The Heat Turns Down Environmental Sustainability

  • Increased Energy Demand: Cities that are trapped in self-sustaining heat bubbles have very little choice but to crank up their air conditioners. This takes up a lot of electrical energy that must be provided by fossil fuel-emitting power plants.

  • Warmed Water Can Stress Natural Ecosystems: As rain encounters heat-island surfaces such as rooftops or streets, this water naturally heats up through its direct contact with hot cement or brick and then consequently flows into rivers, lakes, and streams at temperatures way warmer than natural. Raising the temperatures of whole aquatic ecosystems can put potentially-fatal stress on the organisms living in them.

Some Cool Examples of Urban Planning

At this point, humanity can’t tear all of its urban buildings down to pop the bubbles of heat surrounding major cities. However, we have seen breakthroughs in designing modern buildings with sustainability in mind. Here are some really cool efforts to reduce the heat island effect through implementing green architecture [5]!

  • Pixel Building (Melbourne, Australia): This is Australia’s first carbon-neutral building that generates all of its own energy and water on-site rather than relying on power plants or external water treatment plants.

Photo: Abraham Clark

  • Bosco Verticale (Milan, Italy): These twin residential buildings are more obvious when it comes to displaying its “green” agenda—every floor is shrouded in greenery that improves surrounding air quality! In spring, Bosco Verticale flaunts a beautiful pink color scheme.



  • Torre Reforma (Mexico City, Mexico): You don’t need to have plants all over a building to call it green architecture. Green architecture is just a branch of design that takes environmental sustainability into account, and the Torre Reforma fits into this category because its slimness optimizes the amount of natural light that shines into it, thus reducing the need for energy-consuming artificial lights.

[Schindler Worldwide]

Thank you for reading! With our help, the world can make a U-Turn for the better.

Note: Bracketed numbers next to certain texts (e.g. [1], [2], etc.) indicate that the aforementioned information in the article is derived from the corresponding source in the References below.


[1] Heat Island Effect. (2020, August 24).

[2] urban heat island. National Geographic Society. (2012, October 9).

[3] The 200 Largest Cities in the United States by Population 2020.

[4] Heat Island Impacts. (2020, July 29).

[5] Cable News Network. (2020, April 22). Green buildings: 18 examples of sustainable architecture around the world. CNN.


©2020 by U-Turn The Earth