At the recent global climate summit in Paris, the big headline was passage of an agreement that, for the first time, commits nearly every nation in the world to lowering planet-warming greenhouse gas emissions. Less noticed, but also important, was officials' effort to get nations to tackle another, lesser-known driver of climate change that also helps perpetuate hunger: the massive amount of food across the planet that goes to waste.
According to the UN's Food and Agriculture Organization, an astonishing 1.3 billion tons of food -- about a third of the global supply of nutrition -- goes uneaten each year. That's enough to feed 870 million people, on a planet where many still struggle to find enough to eat for themselves and their families.
Worse yet, that waste also puts the equivalent of 3.3 gigatons of carbon dioxide into the atmosphere each year, due to the amount of energy that it takes to grow, process and transport wasted food, as well as the effects of the methane -- a potent greenhouse gas --that's given off when it rots.
"When food is thrown away, it means that the water, the energy, the land used to produce it is also thrown away," Barbara Ekwall, a Washington-based senior liaison officer for FAO, explained in an email. "If food loss and waste were a country, it would be the biggest user of irrigation water, the second largest country on the globe, and the third largest emitter of greenhouse gases."
A lot of that waste is happening in affluent nations such as the United States, where we squander as much as 40 percent of the food that's produced for our use each year, according to a 2013 NRDC report. We end up discarding 52 percent of our fruit and vegetable supply, 50 percent of our seafood, 38 percent of grain products, and 22 percent of our meat.
NRDC staff scientist Dana Gunders says that a lot of the U.S. supply is tossed out because distributors and supermarkets reject edible fruit and vegetables with slight flaws for cosmetic reasons, or because fluctuations in wholesale prices make crops harder to sell.
But once food gets to consumers, it often goes bad in their refrigerators, in part because of bargain-loving Americans' liking for buying their groceries in bulk from sprawling big-box stores. And restaurants feel compelled to serve gigantic portions, much of which end up in the trash.
Affluent European countries waste slightly less food than Americans. "They tend to they serve smaller portions, and historically go shopping more often and have smaller refrigerators in their homes," Gunders explains. But even so, they also discard a lot of food because it doesn't meet their aesthetic standards.
In poorer, less-developed parts of the world, only about a tenth as much food per person is wasted as in the United States and Europe. But even so, vast quantities go to waste. In Africa, for example, the amount of food that goes uneaten each year could fill the needs of 300 million people, according to FAO.
Food that goes to waste in those countries, however, is more likely to be lost in the supply chain on the way to market. "You can picture a truck of tomatoes or grain in India, trying to make it down a bumpy road," Gunders said.
"Maybe the truck gets a flat tire, or else food spoils because the truck isn't refrigerated. In the U.S., we're very good at getting products to market, but once we get it, we waste it in a variety of ways. In developing countries, they may not have the technology or the infrastructure to get the product to the people who want it."
Additionally, populations that are shifting toward fast-growing mega-cities in developing countries may exacerbate the problem.
"Urbanization and population mobility -- and the mobility of food products -- change the way markets operate," Ekwall explained in an email. "The food value chain tends to be longer and involve a greater number of actors. Urbanization and a growing middle class also implies changed eating habits, (such as consuming) more rich in protein, more imported food. Urbanization can lead to more food loss and waste because of all these factors."
To confront the dilemma, international officials are aiming to cut their food wastefulness in half by 2030. As part of that effort, FAO and other organizations have developed a system to help countries track how much food they are squandering, and trade information on how to prevent losses.
In the United States and Europe, educating consumers about the harm caused by food waste could make a significant dent in the problem, experts say. In developing countries, though, it may require investing in better technology for handling food and upgrading the transportation systems that get it to the public.
Besides the need to control climate change, it's crucial to cut down food waste because population growth is going to put increasing pressure upon food production, according to Roni Neff, director of the Food System Sustainability and Public Health Program at Johns Hopkins University's Center for a Livable Future.
"We're currently in a situation where we're producing enough food on the planet to feed everyone, but 800 million people are hungry because of problems in the way the supply is distributed," she said. "But by 2050, the UN is estimating that we're going to need 60 percent more food to keep up with population growth. That doesn't give us anything to spare."