Heat Waves: Reaching Record Highs in Tucson, Arizona MSA
According to a Brookings Institute article, and backed by reports from the Intergovernmental Panel on Climate Change (IPCC), heat waves are increasingly frequent and severe throughout the nation, primarily as a result of climate change.
By integrating information from the U.S. Centers For Disease Control and Prevention (CDC), Department of Energy, and U.S. Census Bureau Data, the Brookings Institute article examines the disproportionate impact that extreme heat and elevated energy expenses have on specific demographics, notably younger and older individuals from lower-income households and communities of color. It also emphasizes the considerable risks and expenses associated with heat in urban areas across the nation.
Analyzing four heat wave characteristics, i.e., frequency, duration, seasonality, and intensity, across nine western Metropolitan Statistical Areas (MSAs) from 1961 to 2023, the Salt Lake City MSA exhibited the most pronounced changes in duration and intensity, while the Las Vegas MSA experienced the longest seasonal length. On the other hand, the San Diego MSA exhibited the least variation in frequency, duration, and seasonality. Additionally, the San Antonio MSA recorded the smallest change in intensity. Heat wave characteristics shown in Figure 1 are classified using the number of heat waves per year (frequency); the average length of heat waves in days (duration); the number of days between the first and last heat wave of the year (season length); and how hot the heat waves were, compared with the local temperature threshold for defining a heat wave (intensity).
Figure 1: Heat Wave Characteristics in Nine Western MSAs, 1961–2023
Key Findings of the Brookings Institute Article
Intensity and duration — Heat waves are reaching record highs, worsened by climate change. The occurrence of more severe and prolonged heat waves—characterized as extended intervals of unusually high temperatures—is becoming more frequent. During the 2020s, the average heat wave has been 2.5°F above the local threshold. The CDC reports that 60 million U.S. metro area residents face over 76 days of temperatures over 90 degrees annually, primarily in the Sun Belt. The Tucson MSA is one of these metros.
What are the main risk factors — Temperature, energy costs, and the age and income of residents, are the main three factors contributing to increased vulnerability to extreme weather. Any of these factors by itself can put an individual at risk, but the places most at risk are those where two or all three factors occur simultaneously.
How many people are affected — Approximately 23 million Americans living in communities subjected to extreme heat are encountering elevated energy costs and house vulnerable groups who are the least prepared to deal with these issues.
Who are most at risk — Younger and older residents, especially in lower-income households and communities of color, are experiencing the most direct impacts of extreme weather. Rising temperatures are causing economic hardships for economically vulnerable households (younger and older residents), with a 15.5% increase in electricity prices worsening the situation. Individuals under 5 or older than 60 are at higher risk of heat exposure.
In conclusion, each of the three risk factors—temperature, energy costs, and the age and income of residents—has the potential to jeopardize individuals' safety and impose economic and environmental pressures on metropolitan regions. Nevertheless, the areas that face the greatest risk, and consequently require the most assistance, are those where all three risk factors converge. As an example, Pima County, Arizona is one of the places identified by the Brookings Institute article as being in the top 20% of places where all three risk factors coincide.
Key Policy Recommendations
Key policy recommendations from the Brookings article include:
- Increase availability of the Low Income Home Energy Assistant Program (LIHEAP). Phoenix is implementing measures to mitigate heat-related issues by offering tax incentives for green roofs, high-albedo sidewalks, and planting 1,800 trees along "cool corridors."
- Improve buildings within at-risk neighborhoods by investing in their physical condition and modernizing regulatory codes.
- Rethink how we plan and build communities in neighborhoods facing the most extreme heat.
With the number of extreme weather days predicted to worsen, this analysis is a sobering reminder of the urgency to adapt to new climate realities. Policymakers cannot rely on previous strategies to safeguard against the current climate challenges. The United States needs to adapt, as our prolonged and increasingly warm summers become a permanent reality.
