Heatwave Mortality: Experts Offer Differing Views

The increasing frequency and intensity of heatwaves have raised concerns about their impact on human health and mortality rates.
Why it matters: Climate change is making extreme heat events more common and severe, posing significant risks to vulnerable populations and challenging societies to adapt.
The details:

• Over 100 people in India have died from extreme heat in the past three-and-a-half months, more than 60 people died during a Mexican heat dome, and Saudi Arabia experienced over 550 heat-related deaths during a pilgrimage.
• Human activity, particularly greenhouse gas emissions, is exacerbating these extreme weather conditions.
• High temperatures are particularly dangerous for the very poor, the very old, the very young, the very ill, and those who work outdoors.

Experts remain divided on whether climate change will lead to increased mortality rates overall.

What they’re saying:

• “If we don’t adapt, heat wave mortality will increase sharply,” said Michael Wehner, a senior scientist at the Lawrence Berkeley National Laboratory.
• “As temperatures push above [40º-50ºC] consistently, we expect many deaths, especially in places where air conditioning and shelter are absent,” explained Martin Siegert, a glaciology professor at the University of Exeter.
• “Heat deaths are declining over time, despite warming, because societies are becoming less sensitive to temperature faster than temperatures are rising,” argued Patrick Brown, a visiting research professor at San Jose State University.

“I don’t expect death tolls to increase but instead continue to decrease because crop yields and calories available per person have increased,” said Brown, citing decreases in death rates from malnutrition, famines, climate-influenced diseases, and natural disasters.

The other side: Some argue that fossil fuel companies should be held accountable for climate-related deaths and harms.
What’s next: While adaptation efforts and technological advancements may mitigate some risks, the full extent of climate change’s impact on human health remains uncertain.

Full story

Californias Caldor fire moved east toward Lake Tahoe as firefighters continued to battle the blaze on August 23, 2021. Climate change is making extreme weather conditions like this more common. Over 100 people in India have died from extreme heat in the past three-and-a-half months.

More than 60 people died during a Mexican heat dome. Saudi Arabia had over 550 deaths from heat during a pilgrimage. Human activities like emitting greenhouse gases are making these extreme weather conditions worse.

Greenhouse gases include carbon dioxide, methane, nitrous oxide, fluorinated gases, and water vapor. “If we don’t adapt, heat wave mortality will increase sharply,” said Michael Wehner, a senior scientist at the Lawrence Berkeley National Laboratory. He said humans can adapt, and some steps are already being taken to increase awareness of heat wave dangers.

But high temperatures are still very dangerous, especially for vulnerable groups like the very poor, old, young, ill, and outdoor workers. Martin Siegert, a glaciology professor at the University of Exeter, explained why heat waves and storms are so hazardous. “For heat, when temperatures get too hot for the human body, around 40º-50ºC, the body needs more energy to cool itself and starts to function improperly,” Siegert said.

“As temperatures push above that consistently, we expect many deaths, especially in places where air conditioning and shelter are absent.”

Patrick Brown, a visiting research professor at San Jose State University, has a different view.

Heat’s growing toll

He argues that climate change is not necessarily causing more deaths overall.

“Heat deaths are declining over time, despite warming, because societies are becoming less sensitive to temperature faster than temperatures are rising,” Brown said. He noted improvements in health care, more residential air conditioning, and changes in behavior. Some have argued that fossil fuel companies should be held responsible for climate-related deaths.

A consumer advocacy nonprofit released a memo suggesting that major fossil fuel companies could be criminally responsible for deaths from climate disasters and other climate-related harms. Despite these concerns, Brown believes that climate-related death rates will keep going down due to technological advances. “I don’t expect death tolls to increase but instead continue to decrease because crop yields and calories available per person have increased,” said Brown.

He also pointed to decreases in death rates from malnutrition, famines, climate-influenced diseases like malaria, and natural disasters. On the other hand, Siegert expects mortality rates to increase not only from heat waves and superstorms but also from flooding and other weather events. “The largest impacts from hurricanes are flood-related,” Siegert emphasized.

He urged people to follow evacuation notices to avoid these deaths. He also worried about the potential increase in infectious tropical diseases, though noted that this area is not as well understood. In summary, while climate change continues to pose major risks, experts disagree on whether mortality rates will increase.

Adaptation efforts and technological advances may reduce some risks, but the full impact of climate change on human health is still uncertain.