How Much Meat Should We Eat?

As governments drag their feet in responding to climate change, many are looking for actions they can take as individuals, and eating less meat is an obvious place to start. In terms of greenhouse gas emissions, livestock accounts for more than all the cars and trucks combined.

The situation could get worse if our appetite for meat continues to increase. The UN predicts that the world will eat 14 percent more by the year 2030. Demand for pasture and feed crops will increase. It can seem like the only option for people concerned about climate change.

Is it true? A growing body of research suggests that the world could raise a modest amount of beef, pork, chicken and other meat so that anyone who wants could eat a few times a week. It turns out that a world with some animal agriculture in it could have a smaller environmental footprint than a vegan world. If we want to hit the environmental sweet spot, we need to change the way we raise livestock and the way we eat meat.

The future that seems sustainable to me is one where we have livestock, but it's a very different scale. The livestock industry is going to have to change.

Feeding animals to feed ourselves

Meat has an outsized environmental impact because it is more efficient for people to eat plants than to feed them to animals. Chickens need 2 pounds of feed to produce each pound of weight gain, pigs need 3 to 5 pounds, and cattle need 6 to 10, and a lot of that weight gain is bones, skin and guts. 40 percent of the world's arable land is now used to grow animal feed, with all the attendant environmental costs related to factors such as pollution, water use, and pesticides.

People and livestock compete for food. Animals with multiple stomachs, like cattle, sheep and goats, can digest grass, straw, and other plant material that humans can't eat and convert it into animal feed. Many of the world's agricultural lands are too steep to be suitable for crops. A scientist at the University of California, Davis says that the land can't be used for anything other than ruminant livestock.

Natural forest or grassland vegetation could take up carbon in the atmosphere. Researchers say this regrowth could be a major contributor to global climate-mitigation strategies. Moderate levels of grazing are compatible with that. Replacing croplands with well-managed pastures in the southeastern US is thought to capture more carbon from the atmosphere.

The soy meal left over after pressing the beans for oil can be used by livestock. 20% of the US dairy herd is in California's Central Valley, where cows feed on waste from specialty crops. Most people wouldn't eat fallen fruit, food scraps and insects, which can be fed on pigs and chickens, which can't digestcellulose.

Hannah van Zanten, a sustainable food systems researcher at Wageningen University in the Netherlands, says that a world without meat would require about one third more cropland to feed everyone. We need to talk about meat raised the right way.

Other benefits that come from livestock include: Matin Qaim, an agricultural economist at the University of Bonn, says that it is more difficult for poorer people to get iron and B12 from a vegan diet than it is from a vegetarian diet. Many poor people in traditional pastoral cultures get their wealth from livestock. On small, mixed farms, animals that spend a lot of time in the field can help to concentrate nitrogen for use in the garden by depositing their waste in the farm yard.

Many of the world's natural grassland have evolved in the presence of animals. Think of the bison that vanished from the American prairies if you will, but domestic livestock can still fill the same role. The Nature Conservancy's sustainable grazing lands program head says that grassland are disturbance- dependent. Most of the systems evolved with fire. Good livestock management practices can help them. You can have good outcomes if you do it right and in the right place.

According to some experts, the world is better off with meat and dairy than it is with nothing at all. We might have done it right. What amount of meat could the world consume? It may be enough to give meat-eaters some hope, according to most studies.

Looking at the whole plate

A back-of-the-envelope calculation was published in Vaclav Smil's book, Should we eat meat? Let's assume that we stop clearing forest for new pastureland, let 25 percent of existing pastures go back to forest or other natural vegetation, and feed livestock as much as possible on leftovers. Smilimate thought that the rational meat production could yield two-thirds as much meat as the world was currently producing. Even as the population continues to grow, there is still enough meat on the world's plate to promise a significant place for it.

There are a number of surprising implications if that is the case. The amount of meat or dairy that could be produced in this way depends on a lot of other things. A world full of healthy eaters can support less livestock on its leftovers if people eat a healthy, whole-grain diet. If people get most of their cooking oil from canola, they leave less nutrition in their meal than if they get their oil from soy.

The nature of the meat surprised me. People are usually encouraged to eat less beef and more pork and chicken because they are more efficient at converting feed into animal meat. The amount of pork and chicken that can be raised is limited by the availability of food waste. When cattle are on pasture, they can eat beef, mutton and dairy products.

It would take a lot of changes to make such a world a reality. Cities would need systems for collecting household waste, sterilizing them and processing them for feed to maximize the flow of food waste to pigs and chickens. There are some Asian countries that are ahead of the game. The whole infrastructure is ready. "We don't in Europe." The abandonment of animal agriculture based on grain-fed livestock in feedlots would cause a lot of economic disruption.

People in rich countries would have to change their eating habits. The world would only be able to produce enough meat and dairy for everyone to eat if no crops were fed to animals. The average North American eats about 70 grams of animal meat a day while the average European eats 51.

It would bring benefits to the environment. The world would need about a quarter less cropland than it currently uses. The regrowth of surplus cropland could benefit both the environment and the economy.

There's more to meat'ssustainability. Methane is a potent greenhouse gas due to the gut microbes that let animals digest grasses and other food. Methane from ruminants accounts for 40% of all greenhouse gas emissions from livestock. There are ways to reduce methane produced by animals. It's still a serious problem at the moment.

The problem is worse because grass-fed cattle grow slower. It takes three to four years for grass-fed Brazilian cattle to reach slaughter weight, compared to 18 months for US cattle finished on grain. Grain-fed animals eat less roughage and produce less methane. The World Wildlife Fund-US says grass-fed beef emits more methane as a result.

Raising livestock on leftovers and marginal land that isn't suitable for crops eliminates the need to grow feed crops, with all their associated emissions, and there will be fewer livestock overall. The result is that greenhouse gas emissions may go down. Van Zanten and her colleagues compared emissions from livestock raised on leftovers and marginal lands against those raised on a grain-based diet. They calculated that livestock on leftovers would produce up to 31 percent less greenhouse gas emissions.

Methane may be less of a concern as long as the herds don't increase. Methane contributes about 80 times more warming than carbon dioxide does. The climate crisis always gets worse when CO2 is added to the atmosphere. Methane lasts a long time in the atmosphere. The rate at which old methane washes out of the atmosphere will be equal to the rate at which new methane is emitted if livestock levels remain constant over the course of decades.

There is good reason to reduce meat consumption if the world is approaching a climate tipping point. Some of the land devoted to feed crops and pastures would be allowed to return to native vegetation if livestock were completely eliminated. Matthew Hayek, an environmental scientist at New York University, and his colleagues reported in 2020 that over 25 to 30 years of regrowth, this would tie up enough atmospheric CO2 to completely offset a decade's worth of fossil fuel emissions. The gains become even more attractive due to the rapid reduction in methane emissions.

Hayek wants us to be moving in the opposite direction. Aggressive, experimental, bold policies will not try to reduce meat consumption by 20 or 50 percent.

There would be no additional methane burden on the climate if livestock levels remained constant over the course of the century. Matin Qaim is the correct person to attribute it to.

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