Climate change-induced extreme heat isn’t a looming public health threat—it’s one that’s already arrived. At a July 14 Harvard T.H. Chan School of Public Health Studio event, a panel of environmental health researchers discussed this new global reality: how soaring temperatures are endangering communities, straining health systems, and demanding effective policy solutions.
Nori-Sarma shared what data tells us about our warming world: that we’re not exaggerating when we complain about the heat. “It’s not in our imaginations,” she said. “In the last decade, we’ve experienced all of the hottest years on record since [scientists] started recording global temperatures.” These years have consisted of higher baseline temperatures as well as more frequent spikes of extreme heat.
“When we think about climate change, we tend to think a lot about these really extreme disaster events—storms or flooding or wildfires,” she said. “But more people die because of extreme heat in the United States than the next few leading causes of extreme weather events combined.”
Dresser, an emergency physician, added, “I work in a couple of different emergency departments in the greater Boston area, which is not known for being a really hot part of the world. And I have seen more heat stroke and heat exhaustion and heat-related illness than I ever expected to when I was training,” he said. “Some of these cases are pretty scary.”
Who’s at risk? Everyone.
Extreme heat jeopardizes everyone’s health, though to different degrees. Those most at risk of heat-related illness include seniors; people who are unhoused, unstably housed, or living without access to climate control tools like air conditioning; and people who spend a majority of their time outdoors, such as those who do construction or agricultural work, Nori-Sarma said. Dresser added that people living with chronic health conditions are also at higher risk of both heat-related illnesses and a host of other possible medical challenges provoked by heat waves.
“A huge number of people who are using the emergency department during hot weather are there with something other than heat stroke or heat exhaustion,” he said. “It may be that the hot weather and a bit of dehydration and inflammation have led to worsening of one of their cardiovascular conditions or respiratory conditions. … It may be that their blood sugar is out of control. If you’re diabetic and the weather is hot, it’s hard to control your blood pressure and your blood sugar.”
Where you live also makes a critical difference. Cities are often two or three degrees warmer than suburbs or rural areas, Nori-Sarma explained, because urban features such as tall buildings and paved surfaces trap warm air. Her research has also found regional differences in health risks from heat. The northern U.S. has the highest rates of emergency department utilization and hospitalization during extreme heat, likely because places like the Northern Great Plains, New England, and the Pacific Northwest haven’t caught up to southern states in adapting heat mitigation strategies.
With so many groups at acute risk of heat-induced health problems, emergency rooms can get busy amid extreme heat, which impacts other patients, Dresser said.
“If you happen to have an unrelated medical event [on an extremely hot day], the health care system you rely on may be under a lot more strain,” he explained. “So, while heat finds the vulnerabilities in our society in a really devastating way for some people, it also puts all of us at risk.”
Promising solutions
Although extreme heat may be a formidable opponent, a wide variety of solutions exist to protect people against it, many of which are being tested by Harvard Chan School researchers. Dresser discussed his research into how to effectively prescribe air conditioners to medically frail seniors who’d been living without them. And Nori-Sarma shared her research into people’s use of public cooling centers—what factors draw them in and what keeps them away. Both projects rely heavily on not just quantitative data, but also qualitative interviews to hear directly from, for example, the senior who bought a new air conditioning unit but can’t install it on her own, or the parents who struggle to entertain their kids while sitting in a cooling center. “There are all of these human dimensions … that are really hard to predict purely from behind a computer screen,” Dresser said. “And so getting out into the field and talking to people and hearing about their lived experience of what does heat look like in their life has been hugely informative. And I think we need more of that as we think about how to roll out policies that will actually work for people.”
Robinson spoke about her work evaluating heat mitigation interventions, such as providing air conditioner prescriptions to low-income families, establishing local heat warning systems, requiring water breaks for outdoor workers, establishing more green spaces, and installing cool roofs and other reflective surfaces that will repel, rather than absorb, heat in cities. She uses a cost-benefit analysis approach—studying the costs of implementation versus the positive impacts likely to be generated—to help policymakers determine which interventions will be the most effective use of government resources.
Robinson said she and her Harvard Chan colleagues are contributing to a rapidly growing number of cost-benefit analyses examining climate-related solutions.
“It’s really exciting to see this literature grow because I think as it increases, we get a better understanding of how we can best spend our money in order to prevent [heat-related illness and mortality],” she said.
‘Check on your neighbors’
Nori-Sarma, Robinson, and Dresser all agreed that Dresser’s advice—to “know your risk and check on your neighbors”—is key during periods of extreme heat.
Noted Robinson, “All of us, not just the medical professionals, need to be better educated about how to identify the signs of heat stress.”
Added Nori-Sarma, “Some of the best protection that we have against the ill effects of extreme heat is just knowing who in your life might be at risk and checking in on them and making sure that they’re okay.”
