The autopsy should have been a piece of cake. My patient had a history of widely metastatic cancer, which was pretty straightforward as far as causes of death go. Entering the various body cavities, my colleague and I found what we anticipated: Nearly every organ was riddled with tumors. But after we had completed the work, I realized that I knew why the patient had died, but not why he’d died that day. We found no evidence of a heart attack or blood clot or ruptured bowel. Nothing to explain his sudden demise. Yes, he had advanced cancer—but he’d been living with that cancer the day before he died, and over many weeks and months preceding. I asked my colleague what he thought. Perhaps there had been some subtle change in the patient’s blood chemistry, or in his heart’s electrical signaling, that we simply couldn’t see? “I guess the patient just up and died,” he said.
I’m a hospital pathologist; my profession is one of many trying to explain the end of life. In that role, I have learned time and again that even the most thorough medical exams leave behind uncertainty. Take the current spate of heat-related fatalities brought on by a summer of record-breaking temperatures. Residents of Phoenix endured a month of consecutive 110-degree days. People have been literally sizzling on sidewalks. And news organizations are taking note of what is said to be a growing body count: 39 heat deaths in Maricopa County, Arizona; 10 in Laredo, Texas. But the precision of these figures is illusory. Cause of death cannot be measured as exactly as the temperature, and what qualifies as “heat-related” will always be a judgment call: Some people die from heat; others just up and die when it happens to be hot.
Mortality is contested ground, a place where different types of knowledge are in conflict. In Clark County, Nevada, for example, coroners spend weeks investigating possible heat-related deaths. Families are interviewed, death scenes are inspected, and medical tests are performed. The coroner must factor in all of these sources of information because no single autopsy finding can definitively diagnose a heat fatality. A victim may be found to have suffered from hyperthermia—an abnormally high body temperature—or they may be tossed into the more subjective bucket of those who died from “environmental heat stress.”
Very few deaths undergo such an extensive forensic examination in the first place. Most of the time, the circumstances appear straightforward—a 75-year-old has a stroke; a smoker succumbs to an exacerbation of his chronic lung disease—and the patient’s primary-care doctor or hospital physician completes the death certificate on their own. But heat silently worsens many preexisting conditions; oppressive temperatures can cause an already dysfunctional organ to fail. A recent study out of China estimated that mortality from heart attacks can rise as much as 74 percent during a severe, several-day heat wave. Another study from the U.S. found that even routine temperature fluctuations can subtly alter kidney function, cholesterol levels, and blood counts. Physicians can’t easily tease out these influences. If an elderly man on a park bench suddenly slouches over from a heart attack in 90-degree weather, it’s hard to say for sure whether the heat was what did him in. Epidemiologists must come to the rescue, using statistics to uncover those hidden causes at the population level. This bird’s-eye view shows a simple fact: Bad weather means more death. But it still doesn’t tell us what to think about the man on the bench.
Research (and common sense) tells us that some individuals are going to be especially vulnerable to climate risks. Poverty, physical labor, substandard housing, advanced age, and medical comorbidities all put one in greater danger of experiencing heat-related illness. The weather has a way of kicking you while you’re down, and the wealthy and able-bodied are better able to dodge the blows. A financial struggle as small as an unpaid $51 portion of an electricity bill can prove deadly in the summer. In the autopsies I’ve performed, a patient’s family, medical record, and living situation often told a story of long-term social neglect. But there was no place on the death certificate for me to describe these tragic circumstances. There was certainly no checkbox to indicate that climate change contributed to a fatality. Such matters were out of my jurisdiction.
The public-health approach to assessing deaths has its own problems. Mostly it’s confusing. Reams of scientific studies have reported on hundreds of different risk factors for mortality. Sultry weather appears to be dangerous, but so do skipping breakfast, taking naps, and receiving care from a male doctor. Researchers have declared just about everything a major killer. A few months ago, the surgeon general announced that feeling disconnected is as deadly as smoking up to 15 cigarettes a day. The FDA commissioner has said that misinformation is the nation’s leading cause of premature death. And is poverty or medical error the fourth-leading cause? I can’t keep track.
With so many mortality statistics at our disposal, which ones get emphasized can be more a matter of politics than science. Liberals see the current heat wave—and its wave of heat-related deaths—as an urgent call to action to combat climate change, while conservatives dismiss this concern as a mental disorder. A recent Wall Street Journal op-ed concluded that worrying about climate change is irrational, because “if heat waves were as deadly as the press proclaims, Homo sapiens couldn’t have survived thousands of years without air conditioning.” (Humans survived thousands of years without penicillin, but syphilis was still a net negative.) Similarly, when COVID became the third-leading cause of death in the U.S., pandemic skeptics said it was a fiction: Victims were dying “with COVID,” not “from COVID.” Because many people who died of SARS-CoV-2 had underlying risk factors, some politicians and doctors brushed off the official numbers as hopelessly confounded. Who could say whether the virus had killed anyone at all?
The dismissal of COVID’s carnage was mostly cynical and unscientific. But it’s true that death certificates paint one picture of the pandemic, and excess-death calculations paint another. Scientists will be debating COVID’s exact body count for decades. Fatalities from heat are subject to similar ambiguities, even as their determination comes with real-world consequences. In June, for example, officials from Multnomah County, Oregon—where Portland is located—sued oil and gas producers over the effects of a 2021 heat wave that resulted in 69 heat-related deaths, as officially recorded. This statistic will likely be subjected to intense cross-examination. The pandemic showed us that casting doubt on the deceased is a convenient strategy.
No matter how we count the bodies, extreme weather leads to suffering—especially among the most vulnerable members of society. A lot of people have already perished during this summer’s heat wave. Their passing is more than a coincidence—not all of them just up and died.