Extreme Heat Wave Blankets U.S. and Europe

Researchers warn this trend will continue amid climate change. Learn about the health consequences of excessive heat.

sun and skyscape

Medically reviewed in July 2022

Updated on July 21, 2022

A “heat dome” has descended upon Western and Central Europe, fueling record-breaking temperatures as high as 106° Fahrenheit. The extreme weather event, which occurs when the atmosphere traps sweltering air like a lid, has claimed more than 1,000 lives. In the United States, more than 110 million people are also under heat alerts in 28 states. As of July 21, cities across the country—from California to New England—are grappling with scorching temperatures well above 90° Fahrenheit.

Though still unusual, heat waves have become increasingly common and extreme in recent decades. In the U.S. alone, there were 3,066 heat-related deaths between 2018 and 2020. The worrisome trend is expected to continue as the global climate shifts.

What is happening
The burning of fossil fuels, such as coal and gas, releases carbon dioxide (CO2) into the atmosphere where it accumulates. Like a blanket, this CO2 traps heat, warming the Earth and its oceans, which is disrupting the delicate balance of connected ecosystems.

As the planet warms, weather patterns are changing. Warmer air and melting Arctic ice weakens the polar jet stream—the strong band of winds that forms at the point where balmy air from lower latitudes meets the frosty air of the Arctic. Weaker winds cause the jet stream to lose strength and become wobbly, allowing the cold air normally trapped in the Arctic to descend into North America. In recent years, this has resulted in bizarre spring-like weather in the Arctic and freezing temperatures in Europe, adding to mounting concerns about the effects of human-induced climate change.

The temperature of the world’s oceans and the Earth’s atmosphere affects wind and precipitation as well as the circulation of heat. Global warming is influencing the severity, duration, and frequency of heat waves.

How extreme heat harms
How does this affect the health of people? Extreme heat events can be dangerous—even deadly.  

Heat waves can lead to heat-related illnesses, such as heat cramps, heat exhaustion—and in the most extreme cases, heat stroke. Heat stroke occurs when the body is no longer able to regulate its temperature, causing it to rise quickly. Since the body can’t cool down effectively, heat stroke, without immediate medical attention, can cause death.

Extreme heat can also exacerbate existing chronic health issues, such as diabetes. It’s also linked to heart or respiratory conditions since high temperatures are often associated with higher levels of dangerous air pollutants.

While people can adapt to gradual changes in their environment, they are much more vulnerable to dramatic and unexpected temperature swings.

Extreme heat can affect people’s ability to think and work productively. More than one billion workers around the world are exposed to extreme heat events, according to an August 2021 review published in The Lancet. Of these people, one-third experience negative health effects as a result, the researchers cautioned.

Certain groups are more vulnerable
People who have more trouble regulating their body temperature are more vulnerable to extreme weather events, such as heat waves. Among those at greater risk: babies and young children, those who are pregnant, and older people.

People who work outdoors and athletes are also more likely to experience the negative health effects of extreme heat waves.

Underserved low-income communities where people lack air conditioning, access to cool public facilities or pools and other resources that could mitigate the health risks of heat waves are also at higher risk for heat-related illnesses. Those living in crowded cities are also more vulnerable to intense heat. Concrete and other human-made surfaces absorb more sunlight during the day and radiate this heat in the evening. The air quality where people live and their mental health also play a role in how susceptible they are to extreme heat events, according to the National Institute of Environmental Health Sciences.

Since 1999, people older than 65 and non-Hispanic Blacks have had a higher-than-average risk of death from heat-related heart disease than the general U.S. population, the Environmental Protection Agency reports.

What can be done
Climate change is coinciding with growth of the aging population. As extreme weather events happen with greater intensity and frequency, this group at high risk for health-related consequences is expanding, The Lancet review points out, noting that without strategies in place to protect against a hotter future, heat-related illness and deaths will increase.

More research is needed to better understand how climate change is affecting human health, the researchers advised. They added that early warning systems, which enable people to anticipate and prepare for extreme weather events can help protect community health.

Investment in green spaces and new technologies, such as cool roofs (which are designed to reflect more sunlight), can help cities withstand extreme heat.  Other measures which can help:

  • Greater access to air conditioning or cooling centers
  • Strategic landscape design, such as planting trees or creating urban forests to offer more shade and lower temperatures in public spaces
  • Heat alerts that prompt people to hydrate and avoid strenuous outdoor activity during peak sun hours
  • Access to public drinking fountains, swimming pools, and spray pads
  • Updated building codes to increase energy efficiency
  • Investment in green energy, reducing reliance on fossil fuels
Article sources open article sources

Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report (MMWR): QuickStats: Percentage Distribution of Heat-Related Deaths,* by Age Group — National Vital Statistics System, United States, 2018–2020; June 17, 2022 / 71(24);808.
National Ocean Service. What is a heat dome? Jul 7, 2021.
U.S. Environmental Protection Agency. Climate Change Indicators: Heat-Related Deaths. Oct 22, 2021.
National Oceanic and Atmospheric Administration. On the sudden stratospheric warming and polar vortex of early 2021. Jan 28, 2021.
Centers for Disease Control and Prevention. Extreme Heat Can Impact Our Health in Many Ways. Accessed Jul 20, 2022.
U.S. National Institute of Environmental Health Services. Temperature-related Death and Illness. Jun 6, 2022.
Ebi KL, Capon A, Berry P, Broderick C, de Dear R, Havenith G, Honda Y, Kovats RS, Ma W, Malik A, Morris NB, Nybo L, Seneviratne SI, Vanos J, Jay O. Hot weather and heat extremes: health risks. Lancet. 2021 Aug 21;398(10301):698-708.
United Nations. Climate Action: Renewable energy – powering a safer future. Accessed Jul 20, 2022.

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