City Spotlight: Philadelphia’s Urban Heat Crisis and Sustainable Solutions

As climate change accelerates, cities across the United States are facing record-breaking heatwaves. In the summer of 2021, several regions experienced extreme temperatures that scientists agree would have been nearly impossible without human-driven climate change. One of the cities at the forefront of this crisis is Philadelphia, where urban conditions intensify the effects of heat — especially for low-income communities.

What Is the Urban Heat Island Effect?

The urban heat island (UHI) effect occurs when cities become significantly warmer than surrounding rural areas. This is due to the abundance of heat-absorbing surfaces like asphalt, concrete, rooftops, and buildings. Add in car emissions, industrial activity, and air conditioning units, and the result is dangerously high temperatures, particularly during the summer months.

Philadelphia serves as a striking example. Since 1970, the city’s average summer temperature has risen by 3°F (1.7°C). In just the last 14 years, nearly 150 heat-related deaths have been recorded. The city has even had to declare Heat Health Emergencies, which trigger support services such as a heatline and prohibit residential utility shutoffs when temperatures exceed 101°F (38°C) for two consecutive days.

Unequal Heat: Who Is Most at Risk?

The heat crisis in Philadelphia is not felt equally. Low-income neighborhoods and communities of color bear the brunt of rising temperatures. A clear example is Hunting Park, one of the city’s most under-resourced neighborhoods. Studies show that over 75% of its land is covered by buildings and pavement, while only 9% is shaded by trees.

Due to this landscape, Hunting Park can be up to 22°F (12°C) warmer than other areas of the city. These conditions are not accidental — they are rooted in decades of redlining, a discriminatory practice that excluded communities of color from housing and financial services. As a result, formerly redlined neighborhoods across the U.S. are now some of the hottest urban areas, often up to 7°C (13°F) hotter than non-redlined areas.

Effective and Scalable Solutions

Thankfully, there are actionable solutions that can be implemented at the city level:
• Cool Roofing Solutions: Replacing black roofs with white or reflective roofing can have a significant impact. White roofs reflect up to 80% of sunlight, keeping buildings cooler and reducing energy use.
• Expanding Urban Tree Canopy: Trees naturally reduce temperatures by blocking sunlight and promoting evapotranspiration. They also enhance air quality, reduce flooding, and boost property values.

These interventions not only cool neighborhoods but also offer long-term social, environmental, and economic benefits.

A Call for Climate Justice and Resilience

As climate migration increases and more people settle in cities, urban planning must prioritize climate resilience and equity. Investing in underserved communities, increasing green spaces, and adapting infrastructure for extreme heat are no longer optional — they are essential steps toward a more sustainable, just, and livable future.