Heat Waves Can Kill You in 27 Different Ways

People crowd the beach at Coney Island, New York, on June 30, 2012. As the planet warmed over the past decade, there has been a 2,300 percent increase in fatalities from heat waves. Reuters

Heat waves—largely known to be deadly—can kill you in a lot more ways than previously understood, according to a study published on Thursday.

Already in the past decade, there has been a 2,300 percent increase in fatalities from heat waves as the planet has experienced a warming of less than 1 degree Celsius. The United Nations recently announced the world is on track to warm by 3 degrees Celsius, and 2017 is destined to be at least the third hottest year in recorded history.

The study, published in Circulation: Cardiovascular Quality and Outcomes, adds to the evidence of looming health crises and risk to human life as the planet continues to warm.

And all the worse—there are 27 different ways to die from heat waves alone.

Deadly Heat Pathways Fig1
These are among the 27 ways a heat wave can kill you. Camilo Mora/University of Hawaii at Manoa

"Dying during a heat wave is like a terror movie with 27 bad endings to choose from," said Camilo Mora, lead author of the study from University of Hawaii at Manoa. "It is remarkable that humanity overall is taking such a complacency on the threats that ongoing climate change is posing."

In Europe, alone, during the 2003 heat wave, 70,000 people died. In the 2010 Russian heat wave, 10,000 people died. Over 2,000 died during the 2015 heat wave in India.

"We know of many case examples when people have died as a result of heat waves," said Mora. "However, why people died is a question whose answer is scattered."

Local residents crowd to collect free drinking water supplied by a municipal corporation water tanker at a slum on a hot summer day in New Delhi, on June 16, 2014. India has long suffered deadly heat waves. Periods of extreme temperatures have led to thousands of deaths since the 1990s, largely in rural areas where basic infrastructure is poor. Reuters

The paper revealed that there are five physiological mechanisms with impact on seven vital organs. Of the 35 possible combinations of death, there are 27 with medical evidence for relation to heat exposure.

The five key mechanisms the study cites are ischemia, heat cytotoxicity, inflammatory response, disseminated intravascular coagulation, and rhabdomyolysis. A number of those can harm some, if not all, organs, including the brain, heart, intestines, kidneys, liver, lungs, and pancreas.

Those mechanisms and their effects on body organs can play out in a number of ways.

Two young men play football on the dried up ground on West Common in Gerrard’s Cross, in southern England, during a heat wave, on July 26, 2006. Reuters

Gut content can leak into your bloodstream, which triggers an inflammation that allows for white blood cells to fight the infection. But that inflammation can also cause further leakage of the guts and other organs, which exacerbates the problem.

Proteins that control blood clotting can become overactive, which could cut off blood supply to the brain, kidneys, liver and lungs.

One mechanism occurs when ischemia and heat cytotoxicity are mixed with an activity like hiking, exercising, working outdoors or farming. Skeletal muscle cells break down, and as a result, leakages of myoglobin can harm the kidneys, liver and lungs.

The paper noted that everyone is at risk for these deadly outcomes, but people with physical disabilities or those who cannot afford air conditioning are at a higher risk.