Cranking your air conditioner? Taking cold showers? Avoiding being outside? You might be one of many suffering from the recent effects of extreme heat. In recent weeks, we’ve experienced almost unbearable high temperatures, ranging from a manageable 78 degrees to an intolerable 92 degrees. Temperatures are rising due to climate change, and according to the Maine Climate Council’s 2024 technical report, 2023 was the second warmest year on record for the state.

How does extreme heat affect us?

The increase in the number of extreme heat days over the past century poses major health concerns to the public. Recent studies on the physiological limits of our heat tolerance show that the temperatures we once believed humans could tolerate may be too high. Maine has a relatively cool climate and low rates of air conditioning in homes, schools, workplaces and residential facilities. As a result, Mainers are likely to be unacclimated to extreme hot weather, especially vulnerable populations, which include people experiencing housing insecurity and those more susceptible to heat-related illnesses.

Mainers all over the state have begun to install electrical heat pumps as a method of cooling (and heating during colder months) in their homes, which have proved to be the cheapest and most energy efficient way to heat and cool homes. Unlike oil furnaces, heat pumps don’t emit carbon dioxide, a fossil fuel that contributes to global warming. As we begin to see more prolonged higher temperatures, we are simultaneously confronting a new “heat island effect,” which unfortunately exacerbates the problem.

Heat island effect

“Heat islands” are urbanized areas that experience higher temperatures than outlying areas. Structures such as buildings, roads and other infrastructure absorb and re-emit the sun’s heat more than natural landscapes such as forests and water bodies. These urban areas become “islands” of higher temperatures. In fact, daytime temperatures in urban areas are about 1 to 7 degrees higher than temperatures in outlying areas and nighttime temperatures are about 2 to 5 degrees higher.

South Portland has set goals in One Climate Future to mitigate this extreme heat. The objective is to expand South Portland’s “cooling capacity,” which entails protecting and expanding green spaces, investing in public spaces where residents can cool off, and promoting building designs, retrofits and other strategies to help keep indoor spaces cool. On Jan. 1, 2024, South Portland’s Tree Protection Ordinance went into effect after being passed by the City Council in November 2023. Under the new rules, removal of multiple trees, older trees and historic or donated trees is restricted.

How to mitigate heat island effect

There are many ways to reduce urban heat island effects. By planting trees and vegetation, you can provide shade and cooling through “evapotranspiration.” Trees and vegetation can also reduce storm water runoff and protect against erosion. Native plants are a great type of vegetation to plant, as they are well acclimated to our climate, drought and erosion resistant and require less maintenance than non-natives. Also, some people have opted to plant vegetation on the roof of their home, garage, shed, greenhouse, etc., otherwise known as a “green roof” or “eco-roof.”

A “cool roof” is designed to significantly reflect sunlight and heat away from a building, more so than a conventional roof. Similarly, implementing a “cool pavement,” either reflective or permeable, remains cooler than conventional pavements by reflecting more solar energy and enhancing water evaporation. Cool pavement also reduces storm water runoff and improves nighttime visibility.

Coffee & Climate

Grab a coffee and join us virtually on Aug. 9 from 9 to 10 a.m. when the One Climate Future team will be joined by Sheba Brown, community science program manager at the Gulf of Maine Research Institute, and Tatyana Vashchenko of Portland’s Parks and Recreation Department. Together we will discuss urban heat islands research and what is being done to increase our tree canopy in a sustainable way.

Jenna d’Arcy is an AmeriCorps/GPCOG Resilience Corps Fellow serving in the Sustainability Office through September. She can be reached at jdarcy@southportland.org. Our Sustainable City is a recurring column in the Sentry intended to provide residents with news and information about sustainability initiatives in South Portland. Follow the Sustainability Office on Instagram @soposustainability.