This article is part of Earth Shelter’s Spotlight Series on Philadelphia
In the summer of 2021, cities across the United States (“USA”) saw record temperatures without human-made climate change, and scientists say what scientists say is “nearly impossible” to reach. Cities are particularly susceptible to this extreme heat, as specific characteristics can cause urban areas (especially low-income residents) to bear inappropriate burdens in the impact of climate change.
What is the urban heat island effect?
For various reasons, heat islands are urban areas with higher temperatures than those in the surrounding areas. First, cities contain more man-made buildings, such as buildings, roads and dark roofs, which absorb and re-emitting the heat of the sun more than natural lands. In addition, more vehicles, more air conditioning units and more industrial facilities will lead to the heat island effect of cities around the world.
Philadelphia is a paradigm of heat island. Since 1970, average summer temperatures in Philadelphia have risen by three degrees Fahrenheit (-16°C), resulting in more extreme heat events. In the past fourteen years alone, heat-related incidents have killed nearly 150 people in Philadelphia. The size of this tragedy is only expected to grow. Just last summer, Philadelphia declared a thermal health emergency until May to June, with temperatures expected to reach 101°F (38°C) or higher for two consecutive days, or 98°F (37°C) or higher (37°C) or higher for three consecutive days or higher. The name makes services such as the city’s hotline effective and prohibits any residential utilities from closing.
Disproportionate influence
Philadelphia is a typical heat island, not only because of the overall overall warming of the city, but because in cities (like many other cities), low-income and colored communities face disproportionate effects of increasing temperatures.
The hunting park community in Philadelphia is one of the poorest areas in the city, and is illustrative. More than 75% of land cover in hunting parks consists of buildings, roads and paved surfaces, a new report from the Philadelphia City Planning Commission shows. By contrast, the canopy (which helps reduce heat) covers only 9% of the neighborhood. As a result, the community tends to be much higher than the average urban temperature: Average surface temperature data suggest that hunting parks may be as warm as 22°F (-6°C) than other communities.
The landscape differences between hunting parks and other areas of the city are largely the result of the red line, a systematic rejection of residents of specific areas that are usually based on race. The red line has largely influenced the historical housing policy in the United States, which has led to the residential quarantine that still exists today. Research shows that the surface temperatures of the former red line blocks in urban areas across the country tend to be as high as 36°F (2°C) compared to non-downline zones. Although these trends are most pronounced in the Southeast and Western cities of the United States, the Philadelphia thermal vulnerability index also indicates that they are consistent in Philadelphia as well.
Effective solution
Fortunately, action can still be taken to combat the impact of urban heat islands at a more regional level. The two most straightforward solutions are to increase the number of white roofs and increase tree covers. Data from the Clean Air Policy Center show that white or light-colored roofs can reflect up to 80% of sun rays compared to 70% of black roofs absorbing heat, thus keeping the house at a lower temperature.
Adding more canopies will also go a long way. In summer, trees tend to absorb 70% to 90% of the sun and 20% to 90% of the sun in winter, causing a significant reduction in temperatures in hunting parks and other rapidly warming communities.
Although both solutions require significant investment, the benefits outweigh the costs. In fact, the data suggests that more trees provide rainwater advantages and increase property value. More importantly, investments in reducing the impact of urban heat islands and climate change often represent a small part of efforts by underserved communities. As climate migration continues to drive people to seek asylum in cities, it becomes increasingly important to ensure cities are ready to provide these types of resources for current and future residents.