The Earth Is Getting Hotter. This Is How Heat Can Kill You

Weather conditions at which humans can spontaneously die are happening more often than ever before.
Derya Ozdemir

Hundreds of people died in the United States and Canada last week as a result of record-breaking temperatures caused by a "heat dome" that drove temperatures to more than 120.2°F (49°C) in regions known for their cooler weather.

While the government put up cooling centers, provided water to the homeless, and took other measures to prepare for the unprecedented heat, many individuals died in their homes, often alone without air conditioning or fans. Some were elderly, including an individual who was 97 years old.

486 fatalities were recorded over five days in British Columbia alone at the start of June, which is a 195 percent increase above the typical number over that period, per BBC. According to the British Columbia Chief Coroner Lisa Lapointe, the significant increase in deaths reported was likely due to the extreme weather.

Most recently, a group of scientists stated that the scorching heat that engulfed western Canada and the U.S. would have been "virtually impossible" without the effects of climate change, describing the deadly heatwave as a one-in-a-1,000-year occurrence, according to CBC.

The event would have been 150 times less likely if people had not impacted the climate to the level that they have, the scientists said. They also expressed concerns about global warming, saying it is causing temperatures to climb faster than models predict. As the world heats up, we can expect extreme events such as this to become more common, and heat-related deaths to become more and more regular. 

Without immediate climate action, the world will likely experience a sharp uptick in heat-related deaths by the middle of the century.

How does heat kill you?

In the case of British Columbia, many of the excess deaths are thought to be due to hyperthermia, which occurs when the body's heat regulation system is overwhelmed by the heat, causing a person's internal temperature to rise.

Our core body temperature is about 37°C, and in normal health, our bodies can typically handle variations of about 3.5°C. However, anything more than that, the body begins to show signs of distress.

Our bodies sweat to keep us cool, so the problem starts when we get dehydrated or when the external mixture of hot hair and humidity becomes too high. In this scenario, you can no longer push the sweat via your pores. As blood moves toward your skin, you flush all over in an attempt to transfer heat away from your core. As your salt reserves dwindle, your muscles cramp up and as your body kicks up an immune response, your organs start to swell. It's possible that you'll start having hallucinations as your thoughts get fuzzier and fuzzier. To conserve energy, your body starts to vomit so that it can stop wasting energy on digestion. Seizures may follow, and death can happen as a result of a heart attack or organ failure.

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The heat can kill you directly by inducing heat stroke, which affects the brain, kidneys, and other organs. It can also raise your risk of developing a heart condition, a stroke, or breathing problems.

The elderly, those with chronic illnesses, people from low-income families, outdoor laborers, and athletes who compete in extreme heat are among the most at risk. However, extreme heat can damage anyone at any age.

But how can you avoid getting too hot during an extreme weather event? It's common sense when you think about it: You need to stay cool enough so you don't sweat, avoid the sun, exercise as little as possible, sleep in cool rooms, drink cool drinks frequently, fan and mist the body to cool off and wear as light clothes as possible.

However, if the world gets even hotter, avoiding the heat can become rather impossible. According to research published in the journal Science Advances last May, there are some heat and humidity conditions at which some humans abruptly die, the so-called "wet bulb" conditions, as first reported by Motherboard.

The wet bulb temperature is the temperature at which humidity and heat have reached a threshold where sweat evaporation is no longer effective in cooling a person. Between 1979 and 2019, scientists found over 7,000 cases of these fatal wet bulb conditions, and data suggests that they've been gradually rising in frequency over time. The worst part, such conditions weren't expected until the mid 21st century, per the climate models.

According to the study, when relative humidity is above 95% and temperatures are at least 88°F (31°C), or in other words, when wet bulb conditions are attained, otherwise healthy persons can die unexpectedly.

"Even if they’re in perfect health, even if they’re sitting in the shade, even if they’re wearing clothes that make it easy in principle to sweat, even if they have an endless supply of water," study co-author and a Columbia University environmental scientist Radley Horton explained to Motherboard. "If there’s enough moisture in the air, it’s thermodynamically impossible to prevent the body from overheating."

Wet bulb conditions are on the rise across South Asia, the Middle East, Australia, and parts of the United States, according to scientists. In another example, on June 20, surface temperatures near Verkhojansk, the Arctic circle, which is known for its snow caps and sub-zero temperatures, peaked at 118°F (48°C) on June 20. With the rising temperatures and extreme weather events, a future shaped by human-fueled climate change seems scary and bleak.