Kidney failure, blood clots, cardiac arrest, inflammation of the pancreas, leaking intestines.
These are just a few of the potentially fatal maladies that can overwhelm a person exposed to heat waves, according to a new University of Hawaii at Manoa paper that documents at least 27 ways a hot spell can kill a human being.
The paper, published in the American Heart Association journal Circulation: Cardiovascular Quality and Outcomes, not only identifies the various physiological pathways to a death-by-heat-wave but concludes that everyone’s at risk.
The research is offered up by the same man, UH professor Camilo Mora, who was the lead author of a recent systematic review that concluded that three-quarters of the world’s inhabitants, including those living in Hawaii, will be exposed to deadly heat waves by the end of the century unless greenhouse gases are not substantially reduced.
“It’s going to feel like a terror movie if we don’t take care of this,” Mora said in an interview. “We’ve got to take this seriously.”
In his previous paper, Mora and his colleagues scoured news archives and other sources to uncover scores of heat waves and hundreds of thousands of related deaths in recent decades.
But the question of why people died was, for the most part, a mystery, he said. Most of the scientific papers on climate and newspaper accounts say only that people succumbed to the heat, while noting that most of the victims are elderly, very young or sick.
That doesn’t tell the whole story, Mora said.
“It feeds ignorance and an optimism that dying in a heat wave can only happen to someone else,” he said.
While it’s true the old, the very young, the sick, and people on medications are especially vulnerable, the new research reveals that it can happen to anyone.
“It can even happen to you,” he said. “It’s a lot closer than you think.”
This summer, for example, while 100 million Americans were warned to stay inside during heat waves on both coasts, a healthy couple perished in the punishing midday heat during a seemingly innocuous hike in a New Mexico national park.
“So many things can happen. Anything can go wrong,” said Mora, an associate professor of geography in the UH-Manoa College of Social Sciences.
In the latest paper, the researchers carried out a systematic review of medical literature into the known ways in which heat kills people, identifying five physiological mechanisms with impacts on seven vital organs.
Next, they carried out secondary searches using as keywords all possible combinations of the mechanisms and vital organs. In the end — and sparing the unpleasant details — the researchers figure they identified 27 ways in which things can go wrong during a heat wave.
In the earlier paper, published in June, Mora’s team found more than 1,900 deadly heat waves going back to 1980.
Most of the lethal heat waves were recorded in developed countries and affected cities such as New York; Washington, D.C.; Los Angeles; Chicago; Toronto; London; Beijing; Tokyo; and Sydney. But the researchers were surprised to find many more in developing countries, including a heat wave in Pakistan last year that killed more than 1,000 and another in India two years ago that killed more than 2,000.
As part of the study, the researchers identified a threshold of heat and humidity beyond which conditions defeat the body’s natural cooling system. The threshold is variable because lower temperatures can become lethal as relative humidity goes up.
The study concluded that the areas around the globe where the threshold is exceeded for 20 or more days per year have been increasing and are expected to grow even with significant cuts in greenhouse gas emissions.
Currently, about 30 percent of the world’s human population is exposed to such deadly conditions each year.
The study also found that tropical areas are the most vulnerable to the deadly conditions, as they are hot and humid year-round.
Mora said he conducted the studies because he is concerned the public doesn’t fully comprehend how serious climate change really is.
Hawaii will be increasingly vulnerable, he said, although the death toll from future heat waves may not be great because air conditioning is widespread. But not everyone has A/C, and power grids can break down under added demand, he said.
