State-by-state emergency plans aimed at minimizing the impacts of natural disasters overwhelmingly understate extreme heat as a hazard to human health, according to a Duke University analysis.
The recently released policy brief, “Defining Extreme Heat as a Hazard: A Review of Current State Hazard Mitigation Plans,” highlights the need for states to better evaluate the growing threat of extreme heat as the climate changes, identify populations of people most vulnerable to high temperatures, and implement plans to educate and assist those populations.
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Ashley Ward, a senior policy associate with Duke’s Nicholas Institute for Energy, Environment and Sustainability and co-author of the brief, said the report is not a critique, but rather a guide to help states’ emergency management departments better incorporate extreme heat in their hazard mitigation plans.
“We want to give them some easy-to-pick-up roadmaps about how they can do so,” Ward said in a telephone interview. “Our hope is to make their job easier and to supplement what’s already happening at FEMA. We want to be of assistance. That’s what we’re trying to do here.”
The Federal Emergency Management Agency recently announced states must incorporate climate change into their hazard mitigation plans, a move Ward called a “really big deal” in part because it prioritizes extreme heat as a hazard.
Extreme heat is when daytime temperatures rise above 95 degrees and nighttime temperatures do not dip below 75 degrees.
Unlike natural disasters such as hurricanes or tornadoes, extreme heat is not a Stafford Act hazard.
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The 1988 Robert T. Stafford Disaster Relief and Emergency Act, which amended the Disaster Relief Act of 1974, authorizes the president to declare disasters and provide financial assistance to state and local governments.
The law mandates states update their hazard mitigation plans every five years. Many states are in the process of renewing their plans, Ward said.
So, the report focuses on current states’ plans, half of which lack a dedicated section to extreme heat, the analysis found.
Ward and co-author Jordan Clark, a postdoctoral associate for the institute’s Water Policy Program, used a scoring system created by the National Resources Defense Council, or NRDC, to assess each states’ plan.
The NRDC used the scoring system to look at the incorporation of extreme heat in southeastern states’ hazard mitigation plans.
“As we know, this is certainly a pressing problem in the southeast, but we know the southeast isn’t the only region in which heat is a problem,” Ward said.
Heat, she said, is one of the most misunderstood weather events.
Ten years ago, researchers in her field focused on something called the urban heat island effect, which is created when natural landscapes are replaced with pavement, buildings and other surfaces that absorb and retain heat.
This effect is very important and very real, Ward said, but its sole focus is on urban areas, leaving out whole populations impacted by extreme heat.
“In North Carolina, heat illness rates are about seven to 10 times higher in rural areas than they are in urban areas,” she said. “And, in fact, what we’re seeing in the small amount of research that’s coming out of the southern part of the United States is that’s not a North Carolina phenomenon. A recent study came out of Florida that showed the same thing. There’s a lot of reasons this is the case, but that just gives you one example of how broadly heat has been misunderstood.”
North Carolina has an enhanced hazard mitigation plan, also referred to as the 322 Plan, which includes natural hazards as well as man-made, technological and human-caused hazards.
The plan addresses different populations identified by the North Carolina Department of Health and Human Services, which narrows down the largest group of people who suffer heat injuries as men between the ages of 18-34 either involved in athletics or outdoor work such as farming and construction.
The plan was updated last year and approved by FEMA in February. The current plan expires February 12, 2028, according to Chris Crew, North Carolina Emergency Management mitigation plans manager.
Crew explained in an email responding to questions that the plan’s definition of extreme heat is taken from the U.S. Centers for Disease Control and National Weather Service, which identify extreme heat as hotter and/or more humid than average summertime temperatures and unusually hot and humid weather lasting at least two days.
The first recommendation offered in the report is for states to establish their own, specific standard definition of extreme heat.
“That is because extreme heat in North Carolina is not the same as extreme heat in Oregon and it’s important that people think about their geography with respect to how we define extreme heat,” Ward said.
That and other recommendations are intended to provide education and awareness about the complexities of heat, she said, how things like how extreme heat correlates to effects on human health.
Take temperature metrics. Heat index, a metric that combines air temperature and humidity, is a common metric decision makers use to define extreme heat, but it is less robust in determining potential adverse health outcomes than a metric known as wet bulb globe temperature.
Wet bulb globe temperature, or WBGT, measures heat stress in direct sunlight and includes temperature, humidity, wind speed, sun angle and cloud cover. This standard metric is used by the military and high school athletic associations, Ward said.
“And that’s important because if you’re sweating outside and it’s very humid there’s a lot of moisture in the air so your body is not evaporating that sweat off of your skin,” she said. “However, if it’s windy outside then the wind is drying the sweat off your skin and that mimics that evaporative cooling process and actually provides a protective factor for you.”
Therefore, in coastal counties especially, it’s important to think about wind speed, Ward said.
North Carolina’s Sandhills region has the highest rate of heat-related illnesses in the state. Roughly 75% of those who go to emergency departments for treatment are men between the ages of 15 to 45, Ward said.
Counties within that region, including Bladen, Hoke, Robeson, Sampson and Scotland counties, are included in a heat-health alert system through the N.C. Building Resilience Against Climate Effects program.
This CDC-funded program is tailored to vulnerable populations, including low-income and elderly communities, farmworkers, and youth in sports, according to the state’s plan.
“The State’s position is ‘Extreme’ heat is more of an individual and regional value than a specific value for everyone across North Carolina,” Crew said in an email. “Setting a statewide definition of extreme (heat) would limit the State into responding to a single type of weather scenario statewide when the State health agencies need the flexibility to respond to different weather conditions in different regions to the State.”
Ward praised North Carolina’s emergency management department, calling it a “gold star in the nation.”
While the state does include an assessment for heat hazard, it could better incorporate socially or medically vulnerable populations and teach residents how to protect themselves from extreme heat, she said.
Some ways to cool off after being exposed to extreme heat include taking a cool shower then sitting in front of a fan or placing your feet in cool water.
North Carolina’s plan notes the North Carolina Climate Science Report, which projects that much of the Piedmont and coastal plain will experience a jump in very hot days by 10 to 20 days per year between 2021 and 2040 as compared to the 1996-2015 average.
The number of warm nights in those regions is projected to increase anywhere from three to 15 nights a year. Some areas within those regions could see an increase by 18 or more nights a year.
