Imagine a smoldering hot day in downtown Boston: temperatures have reached over 90 degrees Fahrenheit, and the sidewalks and streets are absorbing the strong heat from the sun and radiating it back into the air. Days like this are becoming hotter and more frequent. This “silent storm” causes more deaths in the US than all other weather hazards combined. Heat impacts human health, infrastructure, and the environment.
The Urban Heat Island (UHI) Effect
Urban areas trap heat inside of them, experiencing hotter temperatures than in surrounding suburban areas. Cities are built of concrete, asphalt, and dark surfaces that absorb the heat during the day and re-emit it back out at night. This means that urban areas are much hotter than suburban areas during the day and don’t cool back down at night.
This phenomenon is known as the urban heat island (UHI) effect. So how do city-dwellers escape the heat? What can we do to cool off our cities?
Bostonians can cool down by going to certain spots like “the common,” Boston’s historic park, or the revitalized Seaport District, right on the harbor. Parks and areas around the water tend to be much cooler because water can absorb a lot of heat energy without changing its temperature very much, thus slowing the warming of the surrounding area. Trees provide shade and are especially cool due to evapotranspiration (when water is transferred from the trees into the atmosphere, dispelling heat), creating a cooler environment around them.
