Trash is new. During the nineteenth century, New York was dirty but much of its garbage consisted of leftovers and scraps and other items to reuse. Sunday’s roast became Monday’s hash; Monday’s bread became Wednesday’s bread pudding. Pigs roamed the streets, eating old lettuce and radish tops. “Swill children” went from house to house, collecting food scraps that they sold to farmers as fertilizer and animal feed. Bones became glue. Old grease was turned into tallow candles, or mixed with ashes to make soap. Disposable packaging was almost nonexistent.

In nearly every decade of the nineteenth century, the city’s population doubled. New York began to dump its excess into the Atlantic Ocean. In 1895, George Waring, a former military officer, became sanitation commissioner. “Colonel Waring’s broom . . . saved more lives than a squad of doctors,” the social reformer and journalist Jacob Riis wrote, of the man who put sanitation workers in white suits. Waring made New York households and businesses separate out food waste and ashes; he diverted horse manure for use as fertilizer. Food waste was turned into soap, grease, or compost, or carted to pig farms in New Jersey. Some of the ash became cinder blocks. Some went for expanding the footprint of Rikers Island. Three years after his appointment, Waring died, of yellow fever. His sorting program continued until the First World War, when it was abandoned because of labor and material shortages. By 1918, the city was again dumping waste into the ocean. Or depositing it in landfills.

The story of New York’s garbage hasn’t changed as much in the past century as you might imagine, given that we now have the technology to 3-D-print a baby Yoda, or to run a car on old vegetable oil. Paper and plastic are separated, but recycling of organics—food waste, yard waste, pretty much anything that rots—remains voluntary, even though such material makes up about a third of New York’s trash. All but five per cent of the city’s organic waste goes to landfills.

Organic waste doesn’t just stink when it’s sent to landfills; it becomes a climate poison. Yes, we’ve been schooled again and again in the importance of recycling—by friends, by pious enemies, even by “Wall-E.” But the recycling of organics is arguably more important than that of plastics, metal, or paper. Composting transforms raw organic waste into a humus-like substance that enriches soil and enhances carbon capture. In landfills, starved of oxygen, decomposing organics release methane, a greenhouse gas whose warming effects, in the long run, are fifty-six times those of CO 2 . The United States has greater landfill emissions than any other country, the equivalent of thirty-seven million cars on the road each year.

Last April, the New York State legislature enacted laws requiring large businesses and institutions to recycle their food waste, but New York City is exempt from the new rules. In 2013, when Michael Bloomberg was in his final year as mayor of New York, he instituted an organics-recycling program, which officials said could become mandatory in a few years. Bill de Blasio, who was the public advocate at the time, supported that vision, but as mayor he has failed to fund it.

I live not far from Times Square, near a food-cart-storage facility, a family-run butcher shop, and a La Quinta hotel; one of the lower floors of my building houses a catering business. Since the sides of the street are reserved exclusively for cars, there’s no room for dumpsters. Instead, each night a low wall of piled garbage bags appears, as if left by malign elves. Sometimes there are bags of kaiser rolls and tired fruit. A caramel-colored goo oozes onto the sidewalk. Walking by the trash embankment the other evening, I startled one of our neighborhood rats, which sped across the curb and down a sewer drain.

All of which I find, to be honest, totally normal.

I landed in Seoul, South Korea, on a hazy morning in early October, the day before Typhoon Mitag was expected to hit the southern coast of the Korean Peninsula. Today, South Korea recycles ninety-five per cent of its food waste, but twenty-five years ago almost nothing was recycled. In the nineteen-nineties, following the country’s rapid industrialization and the movement of its people from rural areas to the cities, the trash dumps at the cities’ edges overflowed. Poor families lived near the dumps; many of them picked through the garbage for plastics and metals to sell. Food scraps, an incidental petri dish for disease, made the dumps foul, sickening the garbage pickers.

“We had people lying down in the road in front of the garbage trucks to prevent more being brought to the landfills,” Kim Mi-Hwa, the head of the Korea Zero Waste Movement Network, told me. “The government saw that it had to do something.”

The K.Z.W.M.N.’s office is about the size of a California closet. It’s on the twelfth floor of a modern office tower, the Gwanghwamun Platinum Building, down the street from shops that offer hourly rentals of hanbok, the bright-colored traditional garment worn for ceremonies. I arrived with Lucia Lee, my interpreter. We set our shoes among a small crowd of slippers near the door. Kim, a youthful fifty-seven-year-old woman dressed in a blue-and-white striped button-up, pulled folding wooden chairs out from under a small central table. A young woman brought the three of us ceramic mugs of buckwheat tea. The office had the efficiency of a ship’s cabin.

Kim’s activism dates back to the nineteen-eighties, when she studied nutrition and food culture at university. She became involved in the pro-democracy student movements, and was a leader campaigning for equal rights for women. K.Z.W.M.N. was formed, in 1997, from a network of thirty-one grassroots organizations. “Our primary work is to advocate for change in government policies, for laws,” Kim said. “We also have a lot of programs aimed at educating the public.” K.Z.W.M.N. was instrumental in advancing Seoul’s ban on plastic bags, which went into effect at the end of 2018.

During Kim’s childhood, the city that is now a landscape of high-rises and skyscrapers was largely farmland. “After the Korean War, food waste was not a problem—people were starving,” she said. “We took our food scraps outside and fed them to the cows and pigs.”

In 1995, South Korea replaced its flat tax for waste disposal with a new system. Recycling materials were picked up free of charge, but for all other trash the city imposed a fee, which was calculated by measuring the size and number of bags. By 2006, it was illegal to send food waste to landfills and dumps; citizens were required to separate it out. The new waste policies were supported with grants to the then nascent recycling industry. These measures have led to a decrease in food waste, per person, of about three-quarters of a pound a day—the weight of a Big Mac and fries, or a couple of grapefruits. The country estimates the economic benefit of these policies to be, over the years, in the billions of dollars.

Residents of Seoul can buy designated biodegradable bags for their food scraps, which are disposed of in automated bins, usually situated in an apartment building’s parking area. The bins weigh and charge per kilogram of organic waste. At the Energy Zero House, a model apartment complex in Seoul, a slim woman wearing dark clothes demonstrated how the “smart” composting bin worked. The bin resembled an industrial washer-dryer with a cheerful teal top, and had instructions for use in both Korean and English. She waved a small card, which looked like my grocery-store points card, in front of a scanner. The lid opened in a slow, smooth, and slightly uncanny fashion. In went the waste. A weight registered in red L.E.D. Then the lid lowered, with similar robotic indifference. Nearby was a separate cannister for used cooking oil. A tidy latticed structure covered the area, like a bus stop. For a Seoul family, the cost of food-scrap recycling averages around six dollars a month.