Doomsday urgent

Heat lowers children’s test scores and raises the risk of miscarriage in pregnant women. Prolonged exposure increases death rates from heart and kidney disease. When people are stressed by heat, they are more impulsive and prone to conflict. Racial slurs and hate speech in social media spike. Suicides rise. Gun violence increases. There are more rapes and more violent crime. In Africa and the Middle East, studies have found a link between higher temperatures and the outbreak of civil war.

The harshest truth about life on a superheated planet is this: as temperatures rise, a lot of living things will die, and that may include people you know and love. A study in The Lancet, a prestigious medical journal, estimated that 489,000 people worldwide died from extreme heat in 2019. That’s far more than all other natural disasters combined, including hurricanes and wildfires. It is also more than the number of deaths from guns or illegal drugs. And those are only the deaths that are directly attributable to heat. There are also deaths caused by the heat-related amplification of ground-level ozone pollution (aka smog), or the smoke from wildfires in desiccated forests. The smoke can drift thousands of miles, lofting tiny particulates into the atmosphere. When you inhale them, they can trigger a variety of health problems, from asthma to heart attacks. The toll is enormous: globally, between 260,000 and 600,000 people die each year inhaling smoke from wildfires. Smoke pollution doesn’t only kill people near fires either. Wildfires in western Canada have been directly linked to spikes in hospitalizations three thousand miles away on the East Coast of the US.

Earth’s history is full of wild temperature swings, driven by volcanic eruptions, meteor strikes, and geologic mayhem. There have been palm trees in the Arctic and two thousand feet of ice over New York City. But for the last three million years or so, while humans evolved, the climate has been relatively stable. Stable enough, anyway, that our ancestors could migrate, adapt, and thrive.

But those days may be over. The last time the Earth was hotter than it is today was at least 125,000 years ago, long before anything that resembled human civilization appeared. Since 1970, the Earth’s temperature has spiked faster than in any comparable forty-year period in recorded history. The eight years between 2015 and 2022 were the hottest on record. In 2022, 850 million people lived in regions that experienced all-time high temperatures. Globally, killer heat waves are becoming longer, hotter, and more frequent. One recent study found that a heat wave like the one that cooked the Pacific Northwest is 150 times more likely today than it was before we began loading the atmosphere with CO2 at the beginning of the industrial age. The ocean, which hundreds of millions of people depend on for their food supply and which has a big influence on weather, was the hottest ever recorded in 2022. Even Antarctica, the coldest place on Earth, is not immune. In March of 2022, a heat wave invaded the ice-bound continent, pushing temperatures seventy degrees—seventy degrees!—above normal.

Extreme heat is remaking our planet into one in which large swaths may become inhospitable to human life. One recent study projected that over the next fifty years, one to three billion people will be left outside the climate conditions that gave rise to civilization over the last six thousand years. Even if we transition fairly quickly to clean energy, half of the world’s human population will be exposed to life-threatening combinations of heat and humidity by 2100. Temperatures in parts of the world could rise so high that just stepping outside for a few hours, another study warned, “will result in death even for the fittest of humans.”

Life on Earth is like a finely calibrated machine, one that has been built by evolution to work very well within its design parameters. Heat breaks that machine in a fundamental way, disrupting how cells function, how proteins unfold, how molecules move. Yes, some organisms can thrive in higher temperatures than others. Roadrunners do better than blue jays. Silver Saharan ants run across superhot desert sands that would kill other insects instantly. Microbes live in 170-degree hot springs in Yellowstone National Park. A thirty-year-old triathlete can handle a 110-degree day better than a seventy-year-old man with heart disease. And yes, we humans are remarkable creatures with a tremendous capacity to adapt and adjust to a rapidly changing world.

But extreme heat is a force beyond anything we have reckoned with before. It may be a human creation, but it is godlike in its power and prophecy. Because all living things share one simple fate: if the temperature they’re used to—what scientists sometimes call their Goldilocks Zone—rises too far, too fast, they die.

Excerpted from the book The Heat Will Kill You First by Jeff Goodell. Copyright © 2023 by Jeff Goodell. Reprinted with permission of Little, Brown and Company. All rights reserved.

This was first published in the 1-15 December, 2023 print edition of Down To Earth