To stop global warming, change how we eat?

Producing and cooking food is actually a huge contributor to global carbon emissions. How to take a bite out of the problem: Reduce food waste and change farm practices and eating habits. 

A woman picks up vegetables discarded by food vendors at a garbage dump site of a wholesale market in Xi'an, Shaanxi province July 27, 2014. About 60 tonnes of vegetables are discarded every day in the market.

What we eat affects the earth.

When most of us take a bite of a sandwich during lunchtime, we’re not thinking about how our meal impacts the earth’s atmosphere and contributes to climate change. Yet scientists say the food and agriculture sector is a major emitter of planet-warming greenhouse gases. Producing and cooking food contributes around 30 percent of carbon emissions worldwide, researchers say. That’s more than the emissions from personal travel, lighting, and heating and air conditioning combined. What’s more, by 2050, emissions from food production alone, if unchecked, are on track to reach or exceed international targets for total greenhouse gas emissions.

With that in mind, experts say humanity needs to radically alter the way it produces and consumes food – especially to reach a goal of holding the rise in earth’s average temperature to below 2 degrees C.

Some important signs of change are already under way, notably movements by individuals, companies, and nonprofits to reduce the amount of food that ends up being produced for humans but never eaten.

“There is a growth of city-food movements, bringing together people who care about food,” says Tim Benton, a professor of population ecology at the University of Leeds, England. “Where people talk about food, respect it, and see food waste as a negative, then things start to happen.”

But he and others say the steps needed for serious carbon reduction are just beginning. Some environmentalists say a vital piece of the answer must be agricultural methods that are less carbon-intensive – and changing dietary habits in the same direction.

“We need to convert more crop production to organic and ecological,” says Kendra Klein, staff scientist and agro-ecology expert at Friends of the Earth, an environmental organization. “And really the most important thing is reducing meat consumption.”

Creating carbon

How is it that producing and eating food contributes so much to global warming? Several factors are prominent:

  • Fertilizer use releases large amounts of nitrous oxide, while manure from livestock releases methane, a gas that heats the planet around 80 times faster than carbon dioxide.
  • Livestock production is responsible for around half of all carbon emissions from the agriculture, forestry, and land-use sectors, researchers say. Put another way, a third of the crops grown worldwide are fed to animals to produce meat, a system experts say is highly inefficient.
  • Food waste is another major contributor to carbon emissions, particularly in the United States and Europe. The Food and Agricultural Organization of the United Nations (FAO) estimates that around a third of all food produced for human consumption is wasted. That’s around 1.3 billion tons of lost food. If less food is wasted, less will need to be grown. Research released Thursday concluded that food waste alone is responsible for around 3.3 gigatonnes of carbon emissions.
  • Emissions from agricultural machinery and the transportation of crops and livestock also play a role, as does inefficient land use and the clearing of rainforests to make space for food production.

As the world’s population continues to grow, so will demand for food. Over the past decade, food demand spurred the global expansion of farmland by around 10 million hectares a year, according to research published in the journal Nature Communications. In many places that means trees and rainforests were razed to make space for crop and livestock production, reducing the earth’s ability to absorb carbon dioxide.

The search for solutions

How can the trend lines on food-related emissions be changed?

Improved agricultural methods are succeeding in increasing crop yields without increasing land use, but they aren’t doing it fast enough. Moreover, the methods used to increase crop yields sometimes have other damaging effects on the environment, experts say.

“Often the way we’ve gone about producing those higher yields is through irrigation-intensive and high pesticide-intensive agriculture,” says Ms. Klein. “So it might look efficient, but it’s actually phenomenally environmentally inefficient.”

“Our current food production methods are, by and large, unsustainable as they create significant environmental costs via greenhouse gas emissions and other routes,” says Professor Benton. “This allows food to be cheap enough for us to over-eat and waste.”


Still, modest steps can have an effect. Professor Benton says that if most households did something differently, the aggregate impact would be huge. What’s more, momentum is building around community efforts to cut back on food waste and change consumption patterns.

At a Christian Science Monitor breakfast for reporters on Tuesday, Environmental Protection Agency administrator Gina McCarthy discussed how her agency is collaborating with faith communities on efforts to reduce food waste.

“We’re doing some really neat things, like the food recovery challenge, which is looking at how we address the overall UN [United Nations] goal that we embraced to try to reduce food waste,” McCarthy said.

“We thought it would be a nice opportunity for us to talk with faith leaders about how they can reduce greenhouse gases, in this case methane, by looking at how they work with their community and divert what would otherwise be wasted food to food pantries,” she continued.

Meanwhile, a plethora of projects, from grassroots “freegan” movements in urban areas to food recovery initiatives launched by big conglomerates like Starbucks and Whole Foods, are attempting to crack down on food waste.

Similarly, more consumers are taking seriously the idea of cutting back on meat consumption for environmental reasons.  A report released by the US National Academy of Sciences in February, looked at the potential results if this approach could be implemented to the fullest degree. Humans could reduce food-related greenhouse gas emissions by around 70 percent by switching to a plant-based diet, the report concluded.

“We know that the public conversation is really changing,” says Klein. “Last year in the US we saw that the issue of eating less meat really made it onto the national stage, and many leading figures are being vocal about being vegan or vegetarian or reducing meat consumption.”

What's more, demand for organic food is also increasing. Research shows that organic production cuts carbon emissions per acre by 50 percent or more, compared with conventional farming, Ms. Klein explains. That’s because it requires fewer pesticides and less fertilizer. Creating synthetic fertilizer is energy intensive and emits a lot of greenhouse gas. Pesticide-free soil, on the other hand, holds more carbon and thus provides more opportunities for carbon sequestration.

The increasing demand for organic food thus provides ample opportunity to cut back on carbon emissions.

Still, Klein says consumer behavior alone can’t solve the problem. She urges policies to further encourage the shift toward organic food production.

“A consumer trend can only take us so far,” says Klein. We know that organic production and consumption has been growing by double digits for over a decade, but right now organic sales are about 4 percent of total food sales, and the amount of land for organic production is less than 1 percent,” she says. “So there’s a huge opportunity.”

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