Global Warming/Climate ChangeLivestockSoil BiologySoil CompositionSoil Rehabilitation

Healing the Planet Through Photosynthesis and Carbon Sequestration

If we implement wise geoengineering, even eating meat could help tackle the backlog of carbon dioxide in Earth’s atmosphere.

Carbon depleted soil, at left, compared to a carbon rich soil, at right.

Eating meat is bad for the planet, right? That hamburger you’re contemplating for lunch comes from a cow that, most likely, was raised within the industrial agriculture system. Which means it was fed huge amounts of corn that was grown with the help of petroleum, the carbon-based substance that has helped drive Earth’s climate to the breaking point. In industrial agriculture, petroleum is not only burned to power tractors and other machinery used to plant, harvest, and process corn — it’s also a key ingredient in the fertilizer employed to maximize yields.

Eating beef is particularly environmentally damaging: Cows are less efficient than chickens or pigs at converting corn (or other feed) into body weight, so they consume more of it than other livestock do. As a result, the industrial agriculture system employs 55 calories of fossil fuel energy to produce 1 calorie of beef. Meanwhile, livestock production is responsible for much of the carbon footprint of global agriculture, which accounts for at least 25 percent of humanity’s annual greenhouse gas emissions, according to the U.N. Food and Agriculture Organization.

Despite its large carbon footprint, the agricultural sector is invariably overlooked in climate policy discussions. The latest example: In his 50-minute speech on climate change last week, President Obama mentioned agriculture only once, in a half-sentence reference to how farmers will have to adapt to more extreme weather.

Perhaps no one has been more influential in popularizing the environmental critique of industrial agriculture than Michael Pollan. His 2006 best-seller, "The Omnivore’s Dilemma," revealed how corporate profits, misguided government policies and an emphasis on convenience have given Americans food that is cheap but alarmingly unhealthy for those who eat it, not to mention the soil, air and water used to produce it.

These days, however, Pollan is delivering a deeper yet more upbeat message. (Disclosure: Pollan and I have been friendly colleagues since we met at Harper’s in the early 1990s, when he was executive editor.) Now, instead of just exposing the faults of the industrial agricultural system, Pollan is suggesting radical new ways to make agriculture work for both people and the planet.

Technology is central to Pollan’s vision, but, he says, "We have to think about what technology means. Does it only mean hardware and intellectual property? If we limit it to those two definitions, we’re going to leave out a lot of the most interesting technologies out there, such as methods for managing the soil and growing food that vastly increase (agricultural) productivity and sequester carbon but don’t offer something you can put into a box." And why call even seemingly old-school methods "technology"? Because, he says, "technology has so much glamour in our culture, and people only want to pay for technology."

With the right kind of technology, Pollan believes that eating meat can actually be good for the planet. That’s right: Raising livestock, if done properly, can reduce global warming. That’s just one element of a paradigm shift that Pollan and other experts, including Dennis Garrity, the former director general of the World Agroforestry Center in Nairobi, Kenya, and Hans Herren of the Millennium Institute in Washington, D.C., are promoting. They believe that new agricultural methods wouldn’t just reduce the volume of heat-trapping gases emitted by our civilization — they would also, and more importantly, draw down the total amount of those gases that are already in the atmosphere.

"Depending on how you farm, your farm is either sequestering or releasing carbon," says Pollan. Currently, the vast majority of farms, in the United States and around the world, are releasing carbon — mainly through fertilizer and fossil fuel applications but also by plowing before planting. "As soon as you plow, you’re releasing carbon," Pollan says, because exposing soil allows the carbon stored there to escape into the atmosphere.

One method of avoiding carbon release is no-till farming: Instead of plowing, a tractor inserts seeds into the ground with a small drill, leaving the earth basically undisturbed. But in addition to minimizing the release of carbon, a reformed agriculture system could also sequester carbon, extracting it from the atmosphere and storing it — especially in soil but also in plants — so it can’t contribute to global warming.

Sequestering carbon is a form of geoengineering, a term that covers a range of human interventions in the climate system aimed at limiting global warming. Last month, the amount of carbon dioxide in the atmosphere passed 400 parts per million, its highest level since the Pliocene Epoch 2.6 million years ago. Meanwhile, human activities, from driving gas-guzzlers to burning coal, are increasing this 400 ppm by roughly 2 ppm a year.

The case for geoengineering begins with the recognition that the most widely discussed "solutions" to global warming — such as riding a bike rather than driving a car and making electricity from wind rather than natural gas — address only the 2 ppm part of the problem while leaving the 400 ppm part untouched. And that’s not enough: At 400 ppm, global warming is already contributing to a mounting litany of record-breaking weather. The only way to possibly reduce impacts in the years ahead is to address what is fundamentally driving them: the 400 ppm of CO2 currently in the atmosphere.

According to Pollan, photosynthesis is "the best geoengineering method we have." It’s also a markedly different method than most of the geoengineering schemes thus far under discussion — like erecting giant mirrors in space or spraying vast amounts of aerosols into the stratosphere to block the sun’s energy from reaching Earth. Whether any of these sci-fi ideas would actually work is, to put it mildly, uncertain.

By contrast, we are sure that photosynthesis works. Plants inhale CO2 and turn it into food for us, even as they exhale the oxygen we need to breathe.

What does all this have to do with eating meat? Here’s where Pollan gets positively excited. "Most of the sequestering takes place underground," he begins.

"When you have a grassland, the plants living there convert the sun’s energy into leaf and root in roughly equal amounts. When the ruminant (e.g., a cow) … grazes that grassland, it trims the height of the grass from, say, 3 feet tall to 3 inches tall. The plant responds to this change by seeking a new equilibrium: it kills off an amount of root mass equal to the amount of leaf and stem lost to grazing. The (discarded) root mass is then set upon by the nematodes, earthworms and other underground organisms, and they turn the carbon in the roots into soil. This is how all of the soil on earth has been created: from the bottom up, not the top down."

The upshot, both for global climate policy and individual dietary choices, is that meat eating carries a big carbon footprint only when the meat comes from industrial agriculture. "If you’re eating grassland meat," Pollan says, "your carbon footprint is light and possibly even negative."


Mark Hertsgaard has written about climate change for outlets including The New Yorker, Vanity Fair, Time and The Nation. A fellow of the New America Foundation, he is the author of six books, including “HOT: Living Through the Next Fifty Years on Earth.”


  1. While this idea of sequestering carbon through improved or varied agricultural practices is gaining popularity we need to be clear that there are many caveats, which don’t mean we can simply continue eating cattle or consuming dairy in a care free manner. Much of the evidence to support soil carbon sequestration indicates that soils reach a natural saturation point and beyond this maintain equilibrium where carbon is cycled between the soil and the atmosphere. So if you’re starting with quite well managed pasture, and close to this equilibrium point the act of raising more cattle on this land will become a net source of methane, a potent greenhouse gas. A further caveat is that these activities must occur simultaneously with efforts to reduce our reliance on fossil fuel and not be used to promote a false sense of security that we can simply continue our current fossil fueled ways of life.

  2. This article is basicly OK. But there are few important pitfalls:

    First: cattle (and all the other ruminants too) don’t just cause climate change by using much energy and producing greenhouse gasses that way. They also produce large quantities of methane in their digestive traits. Methane is, when compared on short time scale, one hundred times more potent as a greenhouse gas than carbon dioxide. This is very important to take into account, since the time scale in which the climate crisis must be tackled is rather short.

    Also, manure that falls on pasture will release part of it’s nitrogen in to atmosphere in the form of N2O, which 300 times more potent as greenhouse gas than carbon dioxide.

    Of course industriaaly produced beef produces more GHGs than, say, one produced carbon sequestering permaculture way. And it might be possible to produce carbon neutral or carbon negative beef. But if the direct methane emissions from digestive tratis of ruminants and the N2O formed from manure droppings is not taken into account the calculations are not on solid foundation.

    regards, Aapo

  3. If you’d like a more in-depth look into options for repairing the planet check out Judith Schwartz’s fine book, “Cows Save the Planet.” Judith tells the stories of people all around the world who are doing, not just talking about doing.

  4. To Nick and Aapo:

    Carbon saturation of soils refers only to soils of geological origin, not soils of biological origin, which are built annually by ruminant impact and grow deeper by the year.

    Ruminant methane emissions are not an issue on healthy open rangelands (that is, areas where biocides such as pesticides and synthetic fertilizers aren’t used), as there are bacteria which break down methane for energy (methanotrophs). Furthermore, manure itself is food for many diverse soil organisms and is a part of the carbon stored deeply in soils for hundreds or thousands of years.

    Nature has been balancing these factors for millennia, we have upset that balance but also know how to restore it.

    For more information, go to

  5. Thanks Adam, my comment regarding carbon saturation was in relation to those of biological origin and importantly it should be noted that there is considerable variability in relation to the capacity of different soil types to hold carbon. Most would agree that for severely degraded soils there will be a process over many years in which the biological depth of soils will increase each year with appropriate management steps (or simply ceasing the damaging actions) until returning to a point of equilibrium. For comparison some of the most dense biological carbon reserves occur in cool temperate forests but we cannot be dogmatic and say that the solution is to plant trees in a way that mimics cool temperate forests because there are an incredible number of factors which limit where such ecosystems could be reproduced. Several trials seeking to emulate the work of Allan Savory have failed to achieve the restoration and carbon sequestering effects that are promoted and similar to the example of forests, this suggests we cannot make sweeping claims that such method can be reproduced anywhere at anytime. This shouldn’t stop someone from having trialling the methods, though application of observation and interaction needs to be a guide as to the applicability in the local context.

    Our local agricultural institute is involved in a global research effort exploring methane production from cattle. What they can already tell us is that the methanotrophs you refer to do not draw down the majority of methane produced by cattle. The research into genetically modifying the bacteria within ruminant digestive tracts to produce less methane will be some decades away from producing results (assuming consumers are willing to be part of the experiment). Aapo’s cautions around the production of other potent greenhouse gasses are still the subject of ongoing research.

    Knowing the mentality of many in our local farming community I could see many of them degrading the carbon storage of their soils in the short term in order to gain financial credit for building them up again. I feel we would need to find ways to prevent the perverse outcome where those who have effectively managed their properties stand to gain little, should financial credit be introduced.

    And yes to your last point, nature has been balancing the carbon cycle for millennia, and I would say that re-balancing the terrestrial carbon cycle needs to be part of a much broader strategy, which includes reducing reliance on fossil fuels, for restoring climate stability.

  6. This is a wonderful article, great work, what many of us fail to realize is that when the settlers first came to North America and other continents such as Africa the number of ruminants was in the millions. Growing up, in Canada, we learned that the Bison(Buffalo) were so numerous the settlers compared the Bison to thunder rolling over the landscape. Similar to Africa with their mega herds, also numbering in the millions.

    Why do we assume that our miniscule amount of domestic ruminants would out produce the amount of methane that was being produced over a century ago, and yet the Earth some how managed very well with the methane produced. Is our take on methane a bit askewed?

    Also any ruminant animal that is fed a diet of grains will gain more weight than grass fed ruminants, there is an imbalance of omega 6 and 3. An imbalance with high amounts of omega 6 when fed a diet of only grains leads to bloating and heart disease as well as other health issues in animals. These are then passed to the consumers (us).

    Why not try another system that has a goal of reparation rather than production, a system of health rather than ignorance, it sure seems miles ahead of the current system when dealing with carbon and other greenhouse gasses. We also cannot draw a full conclusion on the effects of this ‘geoengineering’ unless we’ve tried and tested it on a scale similar to current agriculture. I’m just saying give it a try.

    Again, great article.

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