Americans Are Underestimating the Dangers of Extreme Heat

Heat-related deaths in the U.S have surged more than 50% since 2000 as the climate warms and temperatures rise to record-breaking levels. This July alone, more than half of Americans were exposed to extreme temperatures as a heat dome descended across the country and the United Nations warned that a Super El Niño, which raises water temperatures in the Pacific, also will intensify temperatures. Yet, most Americans underestimate the dangers of extreme heat.

Across the U.S., only about 35% of Americans say they are moderately or very worried about extreme heat, according to a recent study by the Yale Program on Climate Change Communication. YSE News spoke with Jennifer Marlon, senior research scientist at the Yale School of the Environment, who co-led the study with YPCCC data scientist Nicolas Begotka ’22 that revealed a disconnect between heat risks and public concern.

Q. How much are rising temperatures and extreme heat playing a role in our lives now and how has that changed?

Rising temperatures and extreme heat are already playing a growing role in daily life, affecting people’s health, sleep, work, energy demand, infrastructure, agriculture, wildfire risk, and more. Extremes like we’re seeing today have been made much more likely due to climate change. One especially dangerous trend is the increase in very warm nights, because the body has less opportunity to cool down and recover during a heat wave.

Temperatures are rising because carbon dioxide concentrations in the air are rising, and those molecules trap heat near the Earth’s surface, like a blanket traps heat around your body. The rate at which we are releasing CO₂ is faster than at any point in at least 50,000 years (and almost certainly faster than any point in 50 million years). It is hard to convey how much and how quickly we have changed the composition of our atmosphere, and how consequential this is for our health and livelihoods.

Q. What factors were used in your study to assess heat risks?

We wanted to compare how people perceive extreme heat with the expertly assessed risks from extreme heat to people’s health. We used the Centers for Disease Control and Prevention Heat and Health Index as a measure of expertly assessed heat risk. The measure’s components include a wide range of factors that have clear associations to heat-related illness and death. Preexisting health conditions and some medications, such as diuretics and antihistamines, can increase health risks from heat by affecting the body’s ability to sweat and cool itself on hot days. Living in urban environments also exposes people to higher temperatures because of the lack of vegetation, soils, and water bodies that naturally cool the environment in more rural areas.

Q. What accounts for the discrepancy between heat risk perceptions and low concern about the dangers?

It is rare to find a place that has a high level of worry about heat in general. Most places, however, have at least some populations that are especially at-risk, such as elderly or low-income populations. The general lack of awareness and worry about the growing risks of extreme heat mean that many people and communities are being caught off guard when extremely high temperatures arrive and then persist longer than they used to.

The gap is not just about knowledge though. People use their own experience and local cues to judge risk, but those cues can lag behind rapidly changing conditions. People in hot places may have more experience and more air conditioning and cooling infrastructure, but that doesn’t eliminate risk. Experience can be protective, but it can also create a false sense of security. Las Vegas and Reno are two of the fastest-warming cities in the U.S., for example, so thinking each summer will bring the same heat as it did a decade or two ago is not true. The heat people grew up with in these areas was milder than what they are experiencing today or will experience in the coming decades.

Even when people are worried, other factors like poverty, housing quality, health status, transportation, social isolation, or lack of cooling access can limit their ability to respond.

Q. What can be done to align risks with awareness?

Aligning risk and awareness requires more than public education. Communities need locally specific heat-risk communication, trusted messengers, early-warning systems, cooling access, tree canopy and shade, worker protections, healthcare outreach, and resources targeted to places where high assessed risk is not matched by public concern.