The heat island effect is defined by urban areas experiencing higher temperatures than surrounding areas. Heat is trapped better by buildings and roads than by trees and grass. Infrastructure coupled with rising temperatures and machinery are the main causes. There are two types of heat islands: surface and atmospheric. Surface refers to the actual materials, such as the pavement, while atmospheric refers to the hotter air. It is possible for a building’s roof to be 60 degrees warmer than the surrounding air on a 90 degree day. There can be a difference of 1-7 degrees in temperature between urban areas and their surroundings during the day. This effect is expected to increase in the future. Heat islands can be a problem because of heat-related health risks and other environmental consequences. 

This issue can be reduced through some measures. The first line of action is to increase the amount of trees and vegetation in the area. Through evapotranspiration, trees can provide cooling properties. Creating more green spaces in cities can help. Green roofs are another solution, where vegetation is planted on the roof. If green spaces cannot be placed on roofs, it is possible to create “cool roofs” instead. In this case, the roof is made of a material that will reflect sunlight away from the building. A similar strategy would be to implement “cool pavement”. A paving material that doesn’t get as hot as regular pavement is used here. The “cool pavement” material should reflect more sunlight and be more infiltrative than regular pavement. 

Although there are ways to mitigate the heat island effect, with climate change the temperatures will continue to rise. This amplifies the heat island effect in urban areas. Boston has experienced the heat island effect significantly during the hot months. They have implemented some resilience strategies, such as installing waterparks and cooling facilities around the city. However, they know that if greenhouse gas emissions are not reduced, the problem will worsen. They explain that in the last decade, there were more hot days than in the last 50 years in Boston. Additionally, if emissions continue at the rate they are today, the number of 80 degree days per year will significantly grow. Therefore, Boston has created a climate action plan to reduce emissions in addition to heat resillience strategies.

https://www.epa.gov/heatislands

https://www.epa.gov/heatislands/learn-about-heat-islands#heat-islands

https://www.epa.gov/heatislands/heat-island-cooling-strategies

https://www.boston.gov/departments/environment/preparing-heat