Urban Heat Islands

lake monona landscape

A number of my friends decided to visit the beautiful island of Hawaii this month.  Daydreaming about spending time on the beach or hiking Oahu’s “Stairway to Heaven” made me think about a different kind of island: The Urban Heat Island. Urban heat islands aren’t literal islands, though. Certain cities are referred to as urban heat islands because metropolitan temperatures tend to be higher (as much as 3 degrees Celsius annually) than local rural areas. Madison, Wisconsin is no exception to this concept.

“The growing season in Madison lasts around five days longer than in surrounding rural areas, meaning the meteorological conditions that contribute to trees leafing out and gardens growing last a little longer in the city. Moreover, the heat island effect can protect a city against late spring and early fall freezes, and often keeps urban nighttime temperatures above freezing on nights when rural areas experience mild freezes” – UW-Madison Water Sustainability and Climate

Rankings of the hottest “heat islands” vary depending on who you ask. In spite of this, heat islands follow a certain formula. Cement, dark roofs, air pollution, and the absence  of vegetation all contribute to high heat in urban areas. Although tamer winters sounds like a desirable side effect of heat islands, the negative impacts include lower air quality and higher incidence of heat related illnesses such as heat stroke.

vehicle on street in between high rise buildings with stores on the bottom
Photo by Dimitris.s12 on Pexels.com

Concrete roads and dark shingles store up heat and lead to higher temperatures at nighttime. Not only this, but also dark surfaces can heat up runoff exceptionally well which ends up warming the surrounding water. Both people AND aquatic life suffer from high heat. It’s no surprise that the Environmental Protection Agency has addressed this issue and assembled solutions for the general public to cope with the problem.

aged aging background bark
Photo by Fancycrave.com on Pexels.com

Vegetation has the ability to reduce air temperature through evapotranspiration. Like a fan over water, trees and plants release water as moisture which ultimately brings down surface temperature. The fact that plants are brighter in color help as well. Green and white roofs (mentioned in a previous post) help block out heat from the sun.

An article on National Geographic also pointed to people- yes, you and me- as heat emitters. Even the most energy-efficient “sustainable cities” are going to have human heat signatures. But have no fear! Ample vegetation and thoughtful city planning are simple ways to curb the heat island issue. Of course, the complication of other factors like runoff and thermal insulation requires a more exhaustive solution.

environmental heat graph
Depiction from Bay Area Monitor.

Do you live in a populated area? Or is your town further removed? Have you ever noticed a difference in temperature between landscapes? Let me know in the comments!

11 responses to “Urban Heat Islands”

  1. Very interesting!! I live in a small town (half a million) so I haven’t ever really noticed this… Well except for when I lived in Paris, the metro stations underground were like rainforests… and packed with people.

    Liked by 1 person

    1. Oooh that’s a good comparison though! Thanks for stopping by 🙂

      Liked by 1 person

  2. Hi Jess, great post! I learned a lot from this one, such as the fact that the growing season is slightly longer in Madison when compared to nearby rural areas.

    Liked by 1 person

    1. Thanks Josh 🙂 despite the longer growing season here I haven’t really noticed any farming going on in the city? But if they were all on the rooftops…that would explain it 😂

      Liked by 1 person

      1. Haha, no urban farming going on in Madison yet?

        Liked by 1 person

      2. None from my vantage point. Perhaps i could be the urban garden pioneer of Madison and try to grow some mushrooms or something on my window ledge…to quote einstein “The person who follows the crowd will usually go no further than the crowd”

        Liked by 1 person

      3. Haha, you should definitely start the urban farming movement in Madison! It doesn’t have to be anything major: just a window planter with a few veggies or mushrooms.

        Liked by 1 person

      4. Oh no, you should grow basil if you can! Fresh herbs > dry herbs.

        Liked by 1 person

  3. I hadn’t heard of heat islands. This was a very interesting read. It definitely explains the difference between the temperature in the larger city close to where I live. I wonder how many cities consider vegetation and the impact it has to the heat islands when planning new parks or developments. Thank you for sharing – there is a great lesson to be learned here.

    Liked by 1 person

    1. Glad you enjoyed it! That’s a good question about city planning. I wonder the same thing. Vegetation helps with heat but small patches of grass like in my neighborhood just don’t seem effective in solving the problem. Cheers!

      Liked by 1 person

  4. It’s fascinating that the growing season is longer in urban areas than in the surrounding rural areas.

    Liked by 1 person

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