Hurricane Maria and Heat Wave Henrietta?
For decades, meteorologists have named hurricanes and ranked them according to severity. Naming and categorizing heat waves too could increase public awareness of the extreme weather events and their dangers, contends a newly formed group that includes public health and climate experts. Developing such a system is one of the first priorities of the international coalition, called the Extreme Heat Resilience Alliance.
Hurricanes get attention because they cause obvious physical damage, says Jennifer Marlon, a climate scientist at Yale University who is not involved in the alliance. Heat waves, however, have less visible effects, since the primary damage is to human health.
Heat waves kill more people in the United States than any other weather-related disaster (SN: 4/3/18). Data from the National Weather Service show that from 1986 to 2019, there were 4,257 deaths as a result of heat. By comparison, there were fewer deaths by floods (2,907), tornadoes (2,203) or hurricanes (1,405) over the same period.
What’s more, climate change is amplifying the dangers of heat waves by increasing the likelihood of high temperature events worldwide. Heat waves linked to climate change include the powerful event that scorched Europe during June 2019 (SN: 7/2/19) and sweltering heat in Siberia during the first half of 2020 (SN: 7/15/20).
Some populations are particularly vulnerable to health problems as a result of high heat, including people over 65 and those with chronic medical conditions, such as neurodegenerative diseases and diabetes. Historical racial discrimination also places minority communities at disproportionately higher risk, says Aaron Bernstein, a pediatrician at Boston Children’s Hospital and a member of the new alliance. Due to housing policies, communities of color are more likely to live in urban areas, heat islands which lack the green spaces that help cool down neighborhoods (SN: 3/27/09).
Part of the naming and ranking process will involve defining exactly what a heat wave is. No single definition currently exists. The National Weather Service issues an excessive heat warning when the maximum heat index — which reflects how hot it feels by taking humidity into account — is forecasted to exceed about 41° Celsius (105° Fahrenheit) for at least two days and nighttime air temperatures stay above roughly 24° C (75° F). The World Meteorological Organization and World Health Organization more broadly describe heat waves as periods of excessively hot weather that cause health problems.
Without a universally accepted definition of a heat wave, “we don’t have a common understanding of the threat we face,” Bernstein says. He has been studying the health effects of global environmental changes for nearly 20 years and is interim director of the Center for Climate, Health and the Global Environment at the Harvard T.H. Chan School of Public Health.
Defined categories for heat waves could help local officials better prepare to address potential health problems in the face of rising temperatures. And naming and categorizing heat waves could increase public awareness of the health risks posed by these silent killers.
“Naming [heat waves] will make something invisible more visible,” says climate communicator Susan Joy Hassol of Climate Communication, a project of the Aspen Global Change Institute, a nonprofit organization based in Colorado that’s not part of the new alliance. “It also makes it more real and concrete, rather than abstract.”
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The alliance is in ongoing conversations with the National Oceanic and Atmospheric Administration, the World Meteorological Organization and other institutions to develop a standard naming and ranking practice.
“People know when a hurricane’s coming,” Hassol says. “It’s been named and it’s been categorized, and they’re taking steps to prepare. And that’s what we need people to do with heat waves.”