Bag of food waste
Bagged food waste amid food waste containers.

Food waste is a big deal. A really big deal. Thirty percent of the food produced globally is wasted every year. But hold onto your leftovers. In the U.S., it’s more – 40 percent.

“Scandalous” is what JoAnne Berkenkamp, a senior advocate with the Natural Resources Defense Council’s Healthy People and Thriving Communities Program calls it.

There’s the waste of the food itself. The waste of the money associated with producing the now wasted food. The waste of labor associated with all of the above. And the social inequity between people who really need food, but can’t get it and those who have too much and just trash it. And for climate change?

It’s a huge deal.

If food waste were a country, it would be the third-largest emitter of greenhouse gases behind China and the U.S., according to the World Resources Institute. A study by Project Drawdown, a coalition of experts focused on climate change solutions, ranks reducing food waste as the No. 3 action item out of 80 – to the tune of more than 70 gigatons of carbon reduction. And that’s not including any number of other food-related solutions on the list.

And there are studies that indicate as much as 11 percent of greenhouse gas emissions could be eliminated if food waste were brought to zero. Fat chance, that.

“Food waste is a huge issue from a climate perspective, and that is a fact that often goes underrecognized,” Berkenkamp says.

Reducing waste at beginning of supply chain

Broadly, experts more or less agree that in producing way more food than is necessary, the world is using more resources – many of them with climate change implications – than it needs to. That can mean unnecessary greenhouse gas emissions for everything from fertilizer to manufacturing packaging to refrigeration to cooking to the disposal of the excess itself. Plus, there’s the additional pressure on already-stressed resources, such as water and land, that may be facing marginal conditions for agricultural production as a result of climate change impacts.

And they pretty much agree that whatever you do to decrease food waste, it’s best done at the beginning of the supply chain, before all kinds of climate-harming impacts actually occur.

“That means really working on strategies that prevent surpluses of food from occurring in the first place,” Berkenkamp says. “Not just dealing with food when we’re ready to throw it out.”

Experts largely agree also that some aspects of food waste that many folks think are among the biggest culprits in climate change are not.

For example, transportation emissions – from those “food miles” local farms and consumers say they can avoid – are often better minimized by the efficiency of big industrial deliveries. And landfills, while not the best way to deal with food waste because of the potent greenhouse gas methane they can emit, are far from the biggest offenders.

But who the biggest offenders actually are depends on whom you ask. Here are three that come up on most lists.

Emissions from the farm

Berkenkamp says she thinks that most of the emissions associated with wasted food happen when animals are raised and food is grown.

Animal production is a far bigger greenhouse-gas generator than growing crops. Excess produce is often plowed under, putting nutrients back into the soil, but it’s still a waste of otherwise edible food.

By contrast, raising animals accounts for a host of emissions, including those associated with the food grown for the animals, the energy needed to heat, cool, water, and clean them, and running equipment such as milking machines. That’s in addition to the much-ridiculed issue of methane, off-gassing, let’s say, from cows and other farm animals.

If you’re producing more food than can actually be used, then every single one of these processes is contributing unnecessarily to climate change.

“It takes so much more resources to grow beef,” says Jon Foley, executive director of Project Drawdown and a climate scientist. “In the U.S., feedlot beef takes 30 or more calories of plants to grow one calorie of boneless beef. More land, more fertilizer, more water, more subsidies, more environmental impact. So far and away, throwing away a pound of beef has a lot more impact to the planet than throwing away a pound of lettuce.”

Emissions all along the supply chain

Brian Lipinski, an associate with WRI, has a slightly different take. He says the biggest climate impact from food waste is cumulative. “You’re adding up things along the way. So you’re adding up all the greenhouse gas associated with land conversion and then with the farming practice and then with transportation to maybe a distribution center and refrigeration and retail and then at the home and methane in landfills,” he says. “There’s no one big contributor here. It’s a team effort in the wrong way.”

So to avoid that cumulative effect – the embedded emissions – it’s best to start dealing with any waste before it leaves a farm, rather than getting it all the way to a consumer’s plate, only then to have it go to waste.

“What can be a little frustrating working on this issue is that the consumer-facing articles are ‘Oh, here’s how to use your broccoli stems,’” Lipinski says. “That’s not how we solve the food waste issue.” Broccoli slaw may be delicious, he said, but “it’s not going to end the climate impact of food waste.”

He thinks if you have to deal on a consumer level – again, not his first choice – the way to go is to make it as invisible as possible. Simplify and standardize date labels so people won’t throw out things they don’t need to throw out. Improve packaging so it’s less carbon-intensive and can keep food fresh longer.

The idea, he says, is to encourage behaviors, and not just words, mindful of the climate, and to do so without consumers having to actively make a conscious choice.

“It’s how to get on people’s personal agenda,” he says, “rather than having them just say ‘Oh that’s a shame.’”

Cause and effect of emissions from the land

Land issues are part of food waste in two ways – cause and effect. Some help exacerbate climate change, but others are the result of climate change.

Conversion of land to farming, especially via deforestation, can lower its carbon storing capabilities. And then the role of that land, if it produces more food than needed, will once again add to climate change stress with more fertilizer, water, pesticide.

And climate change itself can make food production more problematic as a result of drought, floods, and other environmental changes involving, for instance, more invasive species and pests.

Project Drawdown’s Foley points to top food contributors to climate change, and they’re all land-related. They become an official food waste problem when, as usual, there’s over-production.

One is deforestation – especially for growing beef – with its own climate change impact. Also soybeans and palm oil. Another is excess methane produced in rice fields and cattle operations. Rice also has an enormous impact on water resources. And there’s also the nitrous oxide as found in fertilizers – especially when it’s over-used on key crops.

“These are big levers,” he says. “So produce less.”

Monica McBride, manager of food waste at World Wildlife Fund, agrees.

WWF, as a conservation organization focused on biodiversity, points to the food system as one of the largest drivers in the loss of biodiversity. McBride says that 70 percent of biodiversity loss is driven by agricultural expansion – some of which is likely contributing to food waste.

So it’s avoided production again that can help lower food waste and its greenhouse gas emissions.

“It’s not only the avoided emissions from actually producing the food in terms of the nitrogen that’s required, the water, all the inputs – transportation and packaging – it’s also avoiding conversion of native habitats or forests into agricultural land,” she says. “So that is the biggest play.”

Jan Ellen Spiegel is a long-time Connecticut-based journalist whose career has included radio, television, print, and digital reporting. She has won awards for her reporting on energy, environment, climate...