The way these rooms are disinfected between patients, Lorin said, goes “beyond any terminal clean we’ve ever done in the history of the hospital.” He and his colleagues have published their protocol, for other hospitals to follow. “Gloves, toilet paper, paper towels—everything goes in the garbage,” Ulanda Wills, one of the hospital’s cleaners, told me. “Then we sanitize the room: bleach top to bottom, the ceiling and the walls in a clockwise direction.” Sometimes it takes two or three passes before the infection-prevention team gives the all-clear.
We shuffled out of the room so that the head of the cleaning team could roll in an ultraviolet-light machine, called Space-1. Its four expandable arms emit enough UV radiation to break down microbial DNA; in two minutes, it can kill ninety-nine per cent of microorganisms. A window in the door began to glow neon blue. When the door opened again, I caught a whiff of what smelled like bleach and melted wax.
Mount Sinai Brooklyn hasn’t had a C. auris outbreak since 2018. Yet no one who works there expects to eradicate the fungus. “Once you have the C. auris colonization, you’re always colonized,” George told me. Humans are a step behind: when microbes change, all we can do is react.
One way to imagine the future of microbes is to look at their past. In March, I visited one of the world’s largest collections of ice cores, at the Ohio State University’s Byrd Polar and Climate Research Center. Scientists have long drilled cylinders of ice out of glaciers and ice sheets in search of details about Earth’s prehistory, such as ancient bubbles of air and particulates from the atmosphere. Only in the past few years did they realize that microbes were also preserved in ice cores.
After zipping into a bright-orange parka, I stepped into a vast walk-in freezer that was thirty degrees below zero. My lungs tightened and my knees tensed. Long metal tubes filled with ice, some of it from glaciers that no longer exist, were stacked on rows of shelves. “These cores come from Kilimanjaro, in Africa,” Lonnie Thompson, an O.S.U. paleoclimatologist, said, pointing to some tubes. “That’s the only collection in the world.”
Thompson has been collecting glacial ice for fifty years with his wife, Ellen, who is also a paleoclimatologist. He led me to a room where researchers examine samples—it was a mere twenty-four degrees—and slid out an ice core from Huascarán, the highest tropical mountain on Earth. “You can’t go any higher, can’t get any colder,” he said. The deepest part of the core was more than thirty thousand years old; to get it off the mountain, he’d hired forty-five skilled climbers and mountaineers, as well as a helicopter. Next, he slid out a core from the world’s oldest non-polar glacier: the Guliya ice cap, on the Tibetan Plateau. It contains ice that is at least seven hundred thousand years old. I could see tiny dust particles frozen inside.
Cartoon by Andy Friedman
Virginia Rich, a microbial ecologist at O.S.U., has studied the Guliya ice with her colleague ZhiPing Zhong, focussing on samples from cold and warm periods in the past hundred and fifty thousand years. “We see a coördinated shift in microbiota,” Rich told me outside the freezer, after we had removed our parkas. They have observed changes in the over-all diversity of microorganisms, and in which species were dominant. They can’t say what consequences these changes had—only that, when the climate shifted, microbe populations did, too. Another of Rich’s colleagues, Matthew Sullivan, found that viral communities also fluctuated with a changing climate. For Rich’s next project, she’ll study a period of rapid warming in the nineteenth century—the end of the Little Ice Age. “One of the big unknowns is how quickly the microbes today are going to be adapting,” she said. “We will be able to say, for individual microbial species, How did they respond under warm versus cold conditions within the past two hundred years?”