Mapping Urban Heat

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If there’s one consistent thread that binds humanity together, it might just be complaining about the weather. Unfortunately, there does seem to be a lot to complain about, and instances of extreme weather are increasing in number and intensity in many parts of the world. Whether it is extreme heat waves, densely packed tropical storm systems, or other climate-related changes, our weather is growing increasingly difficult to predict and live with.

Across the world, heat is the number one weather-related cause of death for mankind. As cities slowly pivot to face climate change, heat related deaths in some places are still expected to increase in the coming decades. Researchers are turning to the power of citizen science to map urban heat and use this data to promote cities’ resilience to climate driven heat waves, too.

Volunteers Mapping Urban Heat

Vivek Shandas is a professor of Urban Studies and Planning at Portland State University. With a grant from the National Science Foundation and funding from NOAA, he began a multi-city urban heat mapping venture in 2015 that spanned urban areas around the world. Starting in Portland, Oregon, Shandas developed a network of citizen volunteers and local organizations to map urban heat islands in more detail than ever before.

A mobile sensor collects temperature information in Elk Grove, California for a urban heat mapping project.  Photo: Vivek Shandas.
A mobile sensor collects temperature information in Elk Grove, California for a urban heat mapping project. Photo: Vivek Shandas.

Citizen volunteers were outfitted with a small instrument that mounted to their vehicle that recorded temperature close to the ground. They drive a pre-selected route through their city three times a day, mapping the temperature at a leisurely 30mph. This allowed for the collection of data that is hyper-specific to each city; researchers no longer have to rely solely on satellite data in order to map urban heat. Additional benefits come from the volunteers themselves, who are residents of each mapped location and have a vested interest in the future of their neighborhoods.

Preliminary Results

The study continues to show a correlation between low-income neighborhoods and industrial areas of cities and above average temperatures. Lower income neighborhoods are more likely to have an abundance of paved surfaces, fewer trees, and less green spaces that all increase temperatures in that area. A lack of air conditioning can also influence the number of heat-related deaths or health issues that a neighborhood faces during heat waves. 

The data pointed to six factors that can affect urban heat islands:

  • volume of the tree canopy
  • the height of the tree canopy
  • ground level vegetation
  • volume of buildings
  • difference in building height
  • color of the buildings

City planners have found that a mixture of tall and short buildings, trees, and ground vegetation all help to circulate air and provide shade. Rather than have all buildings or all greenery, we are learning that an intentional mixture of vegetation and human infrastructure is not only possible, but highly beneficial. Planners also found that the use of reflective roofing material was instrumental alongside tree cover for decreasing the temperature of a neighborhood. 


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Urban heat map from data captured during the summer of 2018 in Richmond, VA.  Source: NOAA.
Urban heat map from data captured during the summer of 2018 in Richmond, VA. Source: NOAA.

Promoting Climate Resiliency in Urban Areas

In 2019, Shandas and local volunteers sought to map Boston and Worchester, Massachusetts, West Palm Beach, Fort Lauderdale, and Miami, Florida, Yonkers, New York, Seattle, Washington, and Honolulu, Hawaii. Even more cities signed on for 2020, although the coronavirus may slow or halt some mapping efforts. 

People often don’t think about heat being an issue in cities that are known for being colder or wet, like Portland and Seattle. However, these locations and others will start to see more days of above average heat, and city planners want residents to get ready. Local governments are investing in studies like this so that they can design and plan their cities effectively, with an eye towards cooling down neighborhoods and promoting health and wellness across all urban spaces.

Local organizations, including those working to support cities’ climate adaptation plans and climate resiliency, are also using this data to inform their actions.

References

Morrison, Jim. Can We Turn Down the Temperature on Urban Heat Islands? 12 September 2019. Retrieved from https://e360.yale.edu/features/can-we-turn-down-the-temperature-on-urban-heat-islands

Beaudoin, Fletcher, Shandas, Vivek. Climate collaborative maps Portland heat islands: Informing infrastructure approaches to extreme heat. 29 November 2016. Retrieved from https://www.pdx.edu/sustainability/solutions-blog/climate-collaborative-maps-portland-heat-islands-informing-infrastructure-approaches

Portland State University. Portland State study shows ways to reduce extreme heat in city neighborhoods. 8 July 2019. Retrieved from https://www.eurekalert.org/pub_releases/2019-07/psu-pss070819.php

WeatherNation. Eight Cities for Urban Heat Mapping this Summer. 26 June 2019. Retrieved from https://www.weathernationtv.com/news/eight-cities-for-urban-heat-island-mapping-this-summer/

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