July 7, 2013

Commentary: 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.

By MARK HERTSGAARD

WASHINGTON - 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.”

 

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