Rising global temperatures are threatening our health—but there are reasons to be hopeful

Gaurab Basu speaking at panel on heat stress.
Gaurab Basu speaks at a Harvard Climate Symposium panel. Others on the panel, from left, included Lisa Robinson, Francesca Dominici, and Kari Nadeau.

May 17, 2023 – The first time Gaurab Basu realized that extreme heat driven by climate change posed an immediate threat to human health was in 2018.

Basu, a primary care physician at Cambridge Health Alliance and healthy equity fellow at the Center for Climate, Health, and the Global Environment at Harvard T.H. Chan School of Public Health (Harvard Chan C-CHANGE), was taking care of a 25-year-old farmer from El Salvador who had reported persistent symptoms of an upper respiratory tract infection and shortness of breath.

Blood tests and further evaluations revealed he had Chronic Kidney Disease of Unknown etiology (CKDu), an illness that is not yet fully understood but tends to affect rural communities in Central America and South Asia. “He was exposed to severe chronic heat day in and day out for about 15 years,” said Basu. “He’s on the transplant list now and is getting dialysis. It upended his life.”

Basu spoke on a panel titled “Heat Stress: Science and Solutions” during the Harvard Climate Symposium hosted by the Salata Institute for Climate and Sustainability on May 9, as part of the University’s inaugural Climate Week. The conversation was moderated by Kari Nadeau, John Rock Professor of Climate and Population Studies and chair of the Department of Environmental Health at Harvard Chan School.

Nadeau reminded the audience that global temperatures are expected to rise by 2.8 degrees Celsius (approximately 5 degrees Fahrenheit) by the end of the century, which would expose more people—especially marginalized communities—to extreme temperatures.

Francesca Dominici, the Clarence James Gamble Professor of Biostatistics, Population, and Data Science at Harvard Chan School and co-director of the Harvard Data Science Initiative, said extreme heat is a serious threat to population health. “By 2100, heat stroke could kill more people than all infectious diseases combined,” she said.

She added that policies and solutions must be grounded in facts and that recent advancements in data science, including artificial intelligence and machine learning, mean that scientists can now accurately predict heat waves, wildfires, and other extreme weather events as well as their intensity. Perhaps more importantly, she said, it’s now possible to identify which factors put certain individuals more at risk (for example, it’s known that people taking certain antipsychotic medications are more at risk for heat stroke) and evaluate “almost in real time” the impact of different policies and interventions.

Cost-benefit analysis can also help find the best solutions for dealing with extreme heat, added Lisa Robinson, deputy director of the Center for Health Decision Science at Harvard Chan School.

Robinson explained that cost-benefit analysis helps predict what would happen if a certain policy was implemented and if it was not implemented. “Having that framework leads you to ask questions and collect data you wouldn’t collect otherwise,” she said. “My experience is that we all get excited about the new sexy-sounding solutions and it’s only when we start poking at them that we realize that there are some limitations.”

For example, a cost-benefit analysis could help officials decide where cooling centers should be located and what additional services would be needed, such as transportation and information campaigns. “We can build [cooling centers], but if people don’t come, they are not going to do any good,” she said.

Cost-benefit analysis can also help assess whether climate policies are equitable. “People think policies are going to help disadvantaged people, but don’t even ask the question about whether disadvantaged people are going to bear the cost,” she said, citing tax increases, price spikes, or lower wages as ways that could happen. “That’s an important piece we need to pay attention to.”

One promising solution for mitigating heat-related health harms would be to plant more trees, Basu said. He cited a study that found that increasing tree canopies up to 30% in cities can help lower temperatures and prevent a third of heat-related deaths.

Clinics and hospitals have an important role to play as well. Harvard Chan C-CHANGE, for example, is working with Americares to develop heat alert systems and toolkits to help health care providers and patients plan for and manage upcoming heat waves and other climate shocks.

“Solutions are happening,” said Basu. “We need to feel the wind at our back because profound progress is happening.”

Giulia Cambieri

Photo: Sarah Bastille