기후변화 이후 세계를 어떻게 먹여살리는가

유전자조작 종자는 충분치 않다. 우린 농업체계 전체를 바꿔야 한다.

here are limits to how technology can help post-climate change agriculture.

Photograph courtesy San Luis Obispo County, Calif., Department of Agriculture

On Thursday, April 12, Future Tense, a partnership of Slate, the New America Foundation, and Arizona State, will host a live event in Washington, D.C., on the future of food. “Feeding the World While the Earth Cooks” will examine post-climate-change agriculture, the rising demand for meat, and more. Click here for a full agenda and to RSVP.

When my daughter turned 7 last week, we celebrated with a homemade chocolate cake. I wonder whether she’ll be able to do that with her own child someday. Scientists are already warning that chocolate and wheat (the raw material for flour) will become harder to grow as temperature and rainfall patterns are disrupted. 

Over the next 50 years, climate change will transform the world in ways we have only begun to imagine. Humans have changed the weather on this planet, and that will change everything, especially how we grow food.

Consider corn. The major crop (by volume) grown in the United States, corn does not reproduce at temperatures higher than 95 degrees. During the 20^th century, Iowa experienced three straight days of 95 only once a decade. But by 2040, if greenhouse gas emissions remain on their current high trajectory, Iowa will experience three straight days of 95-degree heat in three summers out of four, professors Katharine Hayhoe of Texas Tech University and Donald Wuebbles of the University of Illinois have calculated. 

Meanwhile, global demand for food will be increasing. Human population is projected to swell to 9.3 billion by 2050. And as incomes rise in emerging economies, consumers will demand diets that require more resources—particularly meat.

John Beddington, the chief science adviser to the British government, has warned that by 2030 the interlocking trends of climate change, population growth, and resource scarcity may result in “major destabilization,” including street riots and mass migrations as people flee shortages of food and water. 

But that nightmare scenario need not come to pass. We already know what works—and what doesn’t—to feed a post-climate-change world. In fact, many of the practices and technologies we need are already in use, in the United States and abroad.

What’s needed is to bring these isolated success stories to scale, to make them the rule rather than the exception. But that’s not an easy task when the agricultural approaches that actually improve people’s lives can be overshadowed by inferior alternatives propped up by large PR budgets or government support. 

Take the argument that more heat- and drought-resistant seeds are what’s needed to cope with climate change. The good people at Monsanto have spent lots of advertising money to spread this message.  And joined by two other high-profile backers of genetically modified organisms—the Bill and Melinda Gates Foundation and the Warren Buffet Foundation—Monsanto has claimed to have already increased corn yields in Africa by 25 percent to 35 percent. There’s a catch, though: The only documentation for those results was found on Monsanto’s own website and was later removed.

Most peer-reviewed research has found little reason for optimism that GMO seeds will revolutionize yields in the face of climate change. The most authoritative analysis is found in Agriculture at a Crossroads, the landmark report issued by the International Assessment of Agricultural Knowledge, Science and Technology for Development in 2009. Testifying before Congress, Robert Watson, the scientist who directed the assessment, explained in the gentlest possible terms that GMO crops are an unproven technology whose benefits remain highly uncertain: “[I]t is likely to be several years at least before these [GMO] traits might reach possible commercial application [my emphasis].” 

So better seeds alone won’t save us. Instead, feeding the world under climate change will require a broader strategy, grounded in two imperatives. on the one hand, we must rapidly reduce the amount of greenhouse gases in the atmosphere, to avoid facing unmanageable amounts of future climate change. on the other, we must prepare our agricultural sectors for the climate impacts already “in the pipeline,” which will be severe enough.

The currently dominant system of industrial agriculture is a loser on both fronts. It emits enormous amounts of greenhouse gases, partly because it consumes huge quantities of oil—to power farm equipment, manufacture fertilizer, and ship food through global networks. Meanwhile, its preference for monoculture rather than diversity makes it extremely vulnerable to hot and volatile weather, as well as to the uptick in pests and diseases such weather will bring. 

“We absolutely have to develop seeds for improved and climate-adapted varieties, but we also need to increase the diversity of seeds,” says Sara Scherr, the president of Ecoagriculture Partners, an NGO in Washington, D.C. (Scherr will also be speaking at the upcoming Future Tense event “Feeding the World While the Earth Cooks.’) “A lot of the focus is on, ‘Let’s get a few seeds that are drought-resistant that can be used on millions of hectares.’ The current business model in agriculture is based on maximizing volume, which militates against diversity.”

More and more agricultural experts are saying we need a shift to ecological agriculture, sometimes known as agro-ecology. Ecological agriculture eschews applying chemical fertilizers to soil; rather, it favors compost and manure, which increase the soil’s fertility and ability to retain water—key advantages against hot, dry weather. And rather than monocultures, agro-ecology fosters a diverse agricultural landscape where nature’s processes are utilized not only to grow food but to maintain the health of the soil, water, and biodiversity that make agriculture possible in the first place. 

In western Africa, for example, thousands of the poorest farmers on earth are capturing scarce rainfall and rejuvenating soil fertility by growing trees amid their fields of millet and sorghum. Despite enduring some of the hottest, driest weather on earth, these farmers have returned greenery to 12.5 million acres of land—enough to see from outer space, courtesy of satellite imagery from the U.S. Geological Survey. More important, underground water tables have been replenished, and crop yields have doubled and tripled.

Mixing forests and farmland is also being explored in China, where Lin Erda, a senior government scientist, has joined with Greenpeace to endorse ecological agriculture as the best way to cope with climate change. Raising ducks and fish in rice paddies, for example, reduces both greenhouse gas emissions and the need for chemical fertilizers; the fish decrease the methane that the paddies would otherwise emit, while the ducks control pests. 

But how does ecological agriculture compare against industrial agriculture’s greatest strength—its ability to produce prodigious amounts of food? That’s a vital question on a planet where, even today, one in seven people goes hungry.

In Africa, extensive field studies show ecological agriculture matching the yields of conventional agriculture, while also boosting water supply and soil fertility. But Africa is a special case. Bypassed by the Green Revolution of the 1970s, it never got used to the inflated yields that industrial agriculture made possib-le. 

In the United States and Europe, switching from industrial to ecological agriculture has invariably caused an initial decline in yields. However, after a brief transition period of three to five years, ecological agriculture’s yields rebound to equal those of industrial agriculture, according to a 30-year study conducted by the Rodale Institute.

And ecological agriculture’s advantages promise to be even greater under climate change.  In drought years, Rodale found, its yields were 31 percent higher than conventional yields. Ecological agriculture also built rather than depleted soil fertility while recharging groundwater supplies. Finally, it produced 40 percent fewer greenhouse gases than industrial agriculture. 

My daughter was born into what I call Generation Hot—the 2 billion young people worldwide who will spend the rest of their lifetimes coping with the hottest, most volatile climate human civilization has ever known. Agriculture, it turns out, is one of the few tricks humanity still has up its sleeve to avoid the unmanageable and manage the unavoidable of climate change. Let’s not squander it.