In the past century, the glaciers and ice fields of the European Alps have lost half their volume to global warming, and their continued retreat, like that of glaciers everywhere in the world, is accelerating. By 2100, many scientists predict, they will have all but disappeared. The meltdown has already disrupted the region’s sensitive mountain ecosystems and tourist resorts—some local communities have taken to laying protective white blankets over the snow and ice—but it has also opened up new avenues of scientific inquiry. As the glaciers recede, they are releasing some of the human artifacts that they have absorbed through the ages, including humans themselves. Ötzi, the five-thousand-year-old mummified mountaineer discovered in 1991, remains the most astonishing find. But hundreds of other archeological objects, preserved in remarkable delicacy, have also turned up—medieval crossbow bolts, coins of Roman vintage, a pair of twenty-six-hundred-year-old socks. In July, an employee of a Swiss ski company came across the mummified remains of a couple who had gone missing in 1942; they were found fully dressed, with their wartime identity cards, backpacks, an empty bottle, a pocket watch, and a book.

Last week, a paper in Scientific Reports described another recent find, of an object four thousand years old: a circular box, several inches wide, made of willow and pine and sewn together with twigs. It was discovered, in 2012, near the summit of Switzerland’s Lötschenpass, almost nine thousand feet up, and was dated to the Bronze Age. The recovery of a wooden artifact so old and well preserved would be remarkable under any circumstances, but this one contained something curious. “We saw that it has this amorphous glob in the middle of it,” Jessica Hendy, an archeologist at the Max Planck Institute for the Science of Human History and one of the paper’s co-authors, told me. She and her colleagues, led by André Colonese, of the University of York, analyzed the glob using a technique typically reserved for ceramics; it detects the presence of fats, revealing if a clay pot once contained, say, dairy or meat. But this time, and for the first time in the history of archeology, the analysis showed traces of grain—“some sort of wheat,” Hendy said, and barley or rye. Science outlets promptly began referring to the artifact as a lunchbox.

The Lötschenpass discovery fits in with the larger picture that archeologists are painting of ancient life in the Alps, Albert Hafner, of the University of Bern, told me. Hafner was not involved in the lunchbox paper, but from 2004 to 2012 he and a team of researchers conducted an exhaustive examination of nine hundred artifacts from a different mountain pass nearby. The items included a bow-and-arrow kit from forty-eight hundred years ago, rings made of braided twigs that held together the posts of pasture fences, and a wooden box nearly identical in age and make to the one studied by Colonese’s team. Taken as a whole, the artifacts indicate that the alpine passes, when they were open, were traversed often by herders and hunters. As far back as seven thousand years ago, people who lived in the lower valleys were bringing their goats and sheep to graze in high-elevation fields for days or weeks at a time. The wooden containers weren’t lunchboxes so much as bread boxes or dry mini-fridges—big enough to hold several days’ worth of meals, but light enough to schlep over mountains. Whatever one calls them, by four thousand years ago they enabled these early commuters to transform the alpine environment into their workplace. The grazing gradually lowered the tree line, converting forests to meadows and setting in motion wider changes that, a few millennia later, would make the impact discernible to scientists.

All of these insights are a testament to glacial storage, which can preserve organic material—wood, fabric, tissue—with unmatched fidelity. (Ötzi’s body yielded intact blood cells, and he was found to carry the bacterium responsible for Lyme disease.) But now the great coolers are vanishing, dumping out their stores in the Alps and around the world, spurring archeologists to action. In 2008, Hafner convened the first Frozen Pasts symposium, which brought together researchers from the United States, Canada, Norway, and other melting regions of the planet. (The fourth Frozen Pasts meeting was held last October.) In 2014, he co-founded the Journal of Glacial Archaeology, which shares the latest insights into Bronze Age arrows in Norway, Incan ice mummies in Argentina, and the pollen contents of caribou dung from ice patches in southwestern Yukon. Hafner is sanguine about the trade-off that climate change has presented. “What we should do as archeologists is use the situation and learn as much as possible,” he said.

But glaciers are fickle preservationists. Large ones aren’t much use, since they can slide between thirty and a hundred feet per year. “They’re moving quite fast, and all the objects inside are completely mixed and destroyed,” Hafner said. “People, when they come out after a hundred years, they come out in a hundred pieces that are found over twenty or thirty years.” The best finds—Ötzi, the artifacts from the mountain passes—have emerged from stationary ice patches of perhaps a hundred feet in length. “These are very rare events,” Hafner said. “If we find five more like Ötzi, that will be perfect.” Such ancient artifacts are becoming accessible at an unprecedented rate, but they are disintegrating just as quickly; wood items might last for a few years, but ancient leather will dry out and blow away in a week.

So glacial archeologists are in a hurry, racing to find whatever the ice disgorges before the ice is altogether gone. A report issued in April by the Austrian Alpine Association noted that, between October of 2015 and September of 2016, eighty-seven of the ninety glaciers it monitors had retreated, ten of them by more than a hundred feet and one by more than two hundred feet. When the glaciers go, their contents will go, too, and the discipline of glacial archeology, lacking anything to study, will follow soon after. Even so, Hafner is optimistic. “In the Alps, there’s still a chance to make good finds,” he said. “Not often, but when they come, they’ll be spectacular.”