Yale Program on Climate Change Communication

The length of the average heat wave season in the United States has tripled since the 1960s. In the U.S., more people die from heat each year than from floods, tornadoes, hurricanes, and other hazards combined. As the climate warms, researchers expect more frequent heat waves and a dramatic increase in dangerous heat index days. 

According to the CDC, groups especially vulnerable to extreme heat events include the elderly, people with preexisting health conditions, and low-income communities. Having access to air conditioning (AC) or cooling devices at home is especially important. Ownership and use of air conditioning devices decrease the risk of heat-related health impacts (Ostro et al., 2010), and mortality from heat exposure can be avoided when “individuals perceive the risk, have access to necessary resources, and take appropriate precautionary action” (Howe et al., 2019, p 6743). Unfortunately, many people do not accurately perceive their own vulnerability to heat.

Air conditioning can protect people from extreme heat. However, air conditioners also increase energy demand and their growing use can increase the risk of dangerous power outages during heat waves. In the summer of 2020, the surging demand for electricity during the heat waves in California contributed to the state’s first rolling blackout in nearly 20 years. Yet, despite the critical importance of air conditioning during extreme heat events, there are few studies about who has access to it and who uses it across different communities (Gronlund & Berrocal, 2020). 

Using data from our Climate Change in the American Mind (CCAM) surveys and building upon existing research, we examine how different populations in California perceive the threat of extreme heat events and how their built environment influences their disaster preparedness. Specifically, we ask, how do perceptions of extreme heat events vary across different socioeconomic groups? What demographic factors are associated with air conditioning ownership? And finally, what less expensive, less carbon-polluting alternatives exist to help populations respond to issues of increasing heat?

In 2019, the Yale Program on Climate Change Communication released a web tool that depicts the geographic variations in Americans’ perceptions of the risks of extreme heat (Howe et al., 2019). We found that Americans living in warmer climates (e.g., the southern half of the country) perceive greater heat risk than Americans in cooler areas (e.g., the northern half). Additionally, some vulnerable groups have higher risk perceptions than less vulnerable groups. For example, in census tracts with a higher proportion of residents with incomes below the poverty line, the average heat-related risk perception is higher than in wealthier tracts. Researchers also found that locations with more women or with more Hispanic residents tended to have relatively high risk perceptions. Surprisingly, age was not a predictor of public risk perceptions  – locations with more residents over the age of 65 had lower heat-risk perceptions, despite their high relative vulnerability. 

Using data from our 2018 and 2019 CCAM surveys (n = 589), we examined how respondents in California answered the question “How worried are you that extreme heat might harm your local area?” as a measure of perceived risk (Figure 1). 

We found that women in California are more worried than men about the risk of extreme heat events; and non-White Hispanic residents are more worried than respondents who identified as “White” or “Other.” Even though the elderly are more vulnerable to heat, we also found that older populations are the least worried about these threats. This gap is concerning because older adults are not only more physically vulnerable to heat, but also often live in homes that are less well-equipped for extreme heat. The population aged 60 years and over is expected to grow more than three times as fast as the total population in California by 2060, and many are unaware of the risks they face from extreme heat.

Figure 1. Extreme heat risk perceptions in California differ by gender, race, & age.

The perceived risk of extreme heat also varies by political party affiliation. Fewer Republicans than Democrats are worried about extreme heat events. In fact, three times as many Democrats (27%) as Republicans (9%) are “very worried” about the local occurrence of extreme heat waves (Figure 2). Further analyses of income, demographics, and other factors could shed light on the underlying reasons for such differences.

Figure 2. Party affiliation reveals differences in extreme heat risk perception.

Understanding differences in public risk perceptions of extreme heat can inform strategies to reduce these risks, including the use of AC. Room AC is less effective at reducing indoor temperatures, but central AC is more expensive to install, although some central AC systems can be more energy efficient than room AC. We asked Californians whether they have air conditioning in their home and if so, whether it is room or central AC (n = 852 (CA)). Three quarters (75%) of Californians have air conditioning, but this is 16 percentage points lower than the average rate of AC ownership across all other states in the U.S. (91%; n = 7,324).

We found differences in AC ownership along race and ethnicity lines as well as homeowner or renter status. We found that fewer Hispanic respondents (48%) have central AC compared to White, non-Hispanic respondents (58%). Respondents who are homeowners (59%) are more likely to have central AC than renters (39%). Overall, 77% of respondents who are homeowners have AC (either room or central), while 71% of renters have AC. There was no difference in perceived heat risk between homeowners and renters. By housing type, more respondents in single family homes that are detached (77%) have AC compared to respondents in attached single family homes (67%) or apartments (73%).

Figure 3. Air conditioning ownership varies depending on race, renter status, and housing type in California.

The same populations who face the highest risks from heat are more likely to be those who lack AC in their home. The relationships between energy costs of AC ownership and use also need further investigation. Members of many of the same groups that do not own air conditioning units likely also have more trouble paying their energy bills.

Nearly one in three U.S. households reported challenges in paying energy bills, and Hispanic households report higher household energy insecurity than do non-Hispanic households. Thus, any discussion of health vulnerability to heat extremes must consider the financial barriers from the potentially high cost of installing AC and the higher energy bills incurred from running AC.

Although rates of AC ownership in the West are increasing, this does not necessarily indicate that vulnerability to extreme heat is declining overall. In fact, disparities in AC access and use are increasing, especially in the context of synergistic disasters like extreme weather and the COVID pandemic. Communities of color have been disproportionately affected by the economic impacts of COVID. For some, the costs of purchasing an air conditioning unit and paying higher energy bills may be out-of-reach. Moreover, increased ownership of AC may require additional public infrastructure because current rates of usage have stressed California’s power grid.

Individual Actions to Protect Oneself

Taking preventative steps can greatly reduce the health risks of extreme heat. Increasing education and outreach efforts can help vulnerable groups develop an awareness of their risk. Innovative efforts to raise awareness include groups like the Extreme Heat Resilience Alliance, who are leading efforts to rank-name heat waves in a similar manner to hurricanes and other extreme weather events. They hope that establishing a heat wave naming system will help communicate the urgency and health impacts of elevated temperatures. For residents without reliable access to air conditioning during California’s heat wave, this state resource lists locations of cooling centers by county. There are also public programs to help reduce heat risks: the Low Income Home Energy Assistance Program (LIHEAP) helps low-income people pay for air conditioning and the Weatherization Assistance Program assists with reducing energy needs. Increased air conditioning use, however, also raises concerns about energy insecurity and an increase in harmful emissions from power plants (Abel et al. 2018). Adaptation to extreme heat requires a holistic approach that prioritizes cleaner energy sources and supports vulnerable communities. There are also ways to stay cool without air conditioning:

1. Keep your head wet – soak it in water regularly to stay wet. We lose the most amount of heat through our heads.
2. Keep a wet towel around your neck.
3. Reduce activity, move slowly.
4. Drink fluids with electrolytes. (Constant water intake and sweating can cause you to lose too much salt, causing an electrolyte imbalance putting the body in a water purge mode.)
5. If you must walk outside, use an umbrella to shade you from the sun.
6. If sleeping is difficult, soak a bed sheet in water and drape it over you.
7. Plantings, fans, opening certain windows, and other low-cost methods can also help keep your home cool.

And of course, it is always a great idea to check on neighbors who may need assistance staying cool.

Acknowledgements:
Bianca Taylor provided some of the helpful tips on staying cool without AC.

Citations:

Abel, David W., et al. “Air-Quality-Related Health Impacts from Climate Change and from Adaptation of Cooling Demand for Buildings in the Eastern United States: An Interdisciplinary Modeling Study.” PLOS Medicine, edited by Madeleine Thomson, vol. 15, no. 7, July 2018, p. e1002599. DOI.org (Crossref), doi:10.1371/journal.pmed.1002599.

Gronlund, Carina J., and Veronica J. Berrocal. “Modeling and Comparing Central and Room Air Conditioning Ownership and Cold-Season in-Home Thermal Comfort Using the American Housing Survey.” Journal of Exposure Science & Environmental Epidemiology, vol. 30, no. 5, Sept. 2020, pp. 814–23. DOI.org (Crossref), doi:10.1038/s41370-020-0220-8.

Howe, Peter D., et al. “Public Perceptions of the Health Risks of Extreme Heat across US States, Counties, and Neighborhoods.” Proceedings of the National Academy of Sciences, vol. 116, no. 14, Apr. 2019, pp. 6743–48. DOI.org (Crossref), doi:10.1073/pnas.1813145116.

Ostro, B., et al. “The Effects of Temperature and Use of Air Conditioning on Hospitalizations.” American Journal of Epidemiology, vol. 172, no. 9, Nov. 2010, pp. 1053–61. DOI.org (Crossref), doi:10.1093/aje/kwq231.

Methodology:

Surveys were conducted using the Ipsos KnowledgePanel®, a representative online panel of U.S. adults (18+). All questionnaires were self-administered by respondents in a web-based environment.

The average margin of error for each wave of data is +/- 3 percentage points at the 95% confidence level. Percentage values are weighted to align with U.S. Census parameters. For tabulation purposes, percentage points are rounded to the nearest whole number.