How What We Eat and How We Eat It Helps Contribute To Climate Change

In 2018, scientists at Oxford University pointed out that our estimations of the effect of methane in the atmosphere were wrong. Methane is a powerful greenhouse gas. The biggest source for which humans are responsible is the digestive systems of the cattle, sheep, and goats we keep. (Other major sources are oil and gas production, coal mines, waste dumps, paddy fields where rice is grown, and the thawing of permafrost.) While carbon dioxide accumulates in the atmosphere across many hundreds of years, methane quickly breaks down. Its impact on global temperatures is sharp and short.

The scientists explained that methane had mistakenly been treated in climate calculations as if it were an accumulating gas. This means that its long-term impacts were overstated, and continued emissions at a constant level make little contribution to rising temperatures. Livestock farmers leaped on this finding, claiming it meant that the contribution of their animals to global heating had been overestimated.

But the recalibration also means that the short-term impacts of reducing methane were underestimated. Almost as soon as you stop releasing the gas, its contribution to global heating stops. As effective action against climate breakdown has to be quick, to prevent temperatures and Earth systems from crossing crucial thresholds, this makes cutting methane not less important, but more important.

Greenhouse gases emitted by moving food are tiny by comparison to those emitted by growing it.

Another mistaken belief is that the best way to cut greenhouse gases is to eat food that is locally grown. There might be good social and cultural reasons to buy local food. Local markets might help to enhance the food system’s modularity and resilience. But there are seldom good climate reasons. This is because the greenhouse gases emitted by moving food are tiny by comparison to those emitted by growing it. For example, if you buy pasture-fed beef or lamb, the contribution of transport to its total climate costs, depending on where it comes from, is likely to be between 0.5 and 2 percent. Raising the meat accounts for roughly 95 percent of its emissions (the rest are caused by processing, packing, storing, and displaying it). You would have to ship a kilo of dried peas roughly one hundred times around the world before its greenhouse gases matched those of a kilo of local beef.

Air freight accounts for just 0.16 percent of our total food miles: planes tend to carry only the most perishable and expensive products, such as shellfish, French beans, sugar snaps, asparagus, and blueberries. All other foods are trucked or shipped. Generally, the carbon footprint of local, out-of-season fruit and vegetables is much bigger than that of fresh produce imported from other countries: keeping them in cold storage or growing them in heated greenhouses uses more fossil fuel than trucking them.

If you make a dedicated round-trip of over 6.7 kilometers to buy your vegetables directly from the farm that grows them, you counteract, on average, all the emissions you save by avoiding the carbon costs of storage, packing, transport to a regional food hub, then delivery of the vegetables to your doorstep. This is because much more fuel is used by individual car journeys than in mass transport. No change to the way we eat comes anywhere near the impact of reducing our consumption of animal products, especially beef and lamb.

So livestock, even when integrated into mixed farming systems (producing both animals and crops), are powerful drivers of ecological destruction. But in recent years a new front in the public relations war has opened, promoting a remarkable claim: if managed in a particular way, animal farming can restore the living world and reverse climate breakdown.

Such assertions had been made for three decades. But they remained obscure until, in 2013, TED published a 20-minute talk by the Zimbabwean rancher and ecologist Allan Savory. He maintained that by raising the numbers of cattle, sheep, and goats kept on drylands—in one case by 400 percent—and using “planned grazing” in a “holistic management” system, he could reverse soil erosion and the spread of deserts, restore lush vegetation, bring back wildlife, and even undo climate change. He showed before-and-after photos that appeared to provide spectacular proof of his claims. His talk has now been watched 11 million times, between the TED site and YouTube. His story was taken up by several documentaries, including the viral Netflix film Kiss the Ground, narrated by Woody Harrelson.

I like Allan. When I was diagnosed with cancer, he sent me a kind and charming email. I know he’s sincere and believes what he says. But, as soon as I watched his talk, I noticed that at least one of his claims could not possibly be correct. He stated that if we follow his prescription, “we can take enough carbon out of the atmosphere” to “take us back to pre-industrial levels.”

No change to the way we eat comes anywhere near the impact of reducing our consumption of animal products, especially beef and lamb.

Since 1750, roughly 490 billion tons of carbon have been released from fossil fuels, and around 190 billion tons by cutting forests, draining wetlands, plowing soils, and other kinds of land use. So, to return atmospheric carbon to pre-industrial levels, grassland soils would need to absorb 680 billion tons.

Since the dawn of agriculture, roughly 133 billion tons of carbon are reckoned to have been lost from the world’s soils. Of this, between 70 and 90 billion tons have been released from steppes, savannas, and grasslands, the ecosystems Allan is talking about. As the great soil scientist Rattan Lal notes, the carbon lost from the world’s living systems is roughly equivalent to the maximum amount they could, in a perfect world, absorb. This means that grassland soils could draw down from the atmosphere a maximum of 13 percent of the carbon released in the industrial era.

This would still represent a massive contribution toward preventing climate breakdown. But unfortunately what could be done in theory is not the same as what can be done in practice. A study of the global potential for sucking up carbon by changing the way we farm suggests that, at most, 64 billion tons could be absorbed this century by agricultural soils. If we assume, again being generous, that two-thirds of this absorption happens on steppes, savannas, and grasslands, this brings the potential down to 43 billion tons, or about 6 percent of Allan’s target of 680 billion.

Unfortunately, that’s not the end of the matter. For even if Allan’s system does cause carbon to be absorbed by the soil, that gain is counteracted by the greenhouse gases cattle, sheep, and goats and their manure release: methane and nitrous oxide. A global review drawing on 300 papers found that, in the very best cases, the carbon absorption on grazing lands amounted to 60 percent of the greenhouse gases the animals on the land release, through burping and defecating. In other words, livestock grazing, even if we make the most generous possible assumptions, cannot wash its own face, let alone reverse historical emissions.

To make matters worse, more recent scientific findings challenge the very notion of storing carbon in soil. The old belief that large, stable carbon molecules (collectively called humus) persist in the soil for long periods appears to have been debunked. Most of these molecules can be broken down by soil bacteria. And, as temperatures rise, increasing the speed at which bacteria process it, carbon is likely to be released from soil faster than scientists once reckoned. It now seems wrong to treat any carbon as safely removed from the atmosphere, if it’s lodged in soils in which air circulates. (The carbon in waterlogged soils, such as peat and the mud in marshes, is more stable.)

I phoned Allan to ask for evidence. I found his answers rambling and unconvincing. He was unable to direct me to any scientific papers supporting the claims in his talk. But I wanted to be sure I wasn’t missing anything. So, after Kiss the Ground was released, I set aside a month to read scientific papers about the “holistic” systems that he and other ranchers were promoting.

I discovered that there were similar problems with all his major claims. In a minority of cases, there were some improvements, by comparison to ordinary grazing, in soil quality and plant production, on ranches using his methods. But, as one paper notes, “the vast majority of experimental evidence does not support claims of enhanced ecological benefits,” even by comparison to other kinds of grazing. Even a review of the few scientific papers approved by Allan’s organization, the Savory Institute, found that his system performed no better than conventional but well-managed grazing.

A global review of the scientific evidence for Allan’s system of “holistic planned grazing” found that there is no difference, on average, in plant growth between ranches following his methods and ranches managed conventionally. Instead, there seems to be plenty of evidence that his methods can inflict severe damage on ecosystems.

By making ranching more economically viable, this money is likely to accelerate climate breakdown, as land that might otherwise be rewilded continues to be grazed.

In his TED talk, Allan described the “crust of algae” that often grows on desert soils as “the cancer of desertification.” Trampling by cattle destroys this “cancer,” and allows a dense sward to grow in its place. In reality, the crust is a rich ecosystem of bacteria, fungi, algae, mosses, and lichens, which prevents erosion and absorbs carbon and moisture.

These crusts are often extremely fragile, and are quickly destroyed by cattle, often with devastating and irreversible consequences for ecosystems, as invasive, exotic plants can then colonize the land, replacing native species. Trampling by livestock, which Allan claims improves the soil and helps it to store carbon, in most cases has the opposite effect, compacting and eroding it.

Intense grazing of the kind Allan promoted in his talk damages the vegetation on riverbanks, the crucial habitat for many species in drylands and deserts. Drylands that livestock have never entered tend to have a greater range and abundance of native plants than those used for any kind of grazing. As a general rule, the best way of ensuring that dryland ecologies recover is to remove the farm animals.

So what do the famous photos in his talk show? They purport to show bare, eroded land miraculously springing back to life when his grazing regime begins: thick grass and shrubs surge from the naked ground and erosion gullies refill with soil. But is that really what they depict? Because they are either unlabeled or mislabeled, it’s hard to tell. But at least a couple of them appear to show the opposite of what he claims: the survival or recovery of the ecosystem was caused not by introducing livestock, but by taking them away.

Sadly, scientific findings have not prevented some of the world’s biggest meat companies from using false claims about the alleged benefits of pasture-fed beef in their advertising. Worse still, a new market has developed, in which companies such as Microsoft buy carbon credits from ranches practicing holistic grazing, on the mistaken grounds that this offsets their emissions. By making ranching more economically viable, this money is likely to accelerate climate breakdown, as land that might otherwise be rewilded continues to be grazed. In other words, the companies investing in these programs ignore the opportunity costs of livestock farming. You might as well buy carbon credits from a coal mine.

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