Editor's Note: Stewart Patrick is a Senior Fellow and the Director of the Program on International Institutions and Global Governance at the Council on Foreign Relations. He is the author of Weak Links: Fragile States, Global Threats, and International Security.

By Stewart Patrick

Appropriately enough, Halloween this year brings some scary news. On that date, the global population will surpass seven billion, according to the UN Population Fund. That’s quite a strain on an already crowded planet where one billion go to bed each night hungry or malnourished. And there’s no sign of a let-up. The planet should hit eight billion inhabitants by 2025 - and could hit ten billion by 2083.

The dilemma for humanity - and earth itself - is stark. In recent years, the world has been rocked by recurrent volatility in the supply and prices of staple foods. And yet economists say that global agricultural production must double in the next forty years to keep up with population growth and changing dietary preferences (including growing consumption of meat in developing countries).

However, doubling agricultural production will subject the planet to tremendous ecological damage, unless agricultural methods are drastically altered. This is the conclusion of a groundbreaking study in the journal Nature, “Solutions for a Cultivated Planet.”

Bottom line? In trying to feed ourselves, we risk killing the planet.

The scale of contemporary agriculture is mind-boggling. Farming and animal husbandry now take up nearly forty percent of the planet’s ice-free land area. Having converted huge tracts of grassland, savannah and temperate forest, farmers and ranchers are now exploiting more sensitive areas. By 2010, they had cleared 27% of the world’s tropical forests. This is an ecological tragedy, because these biomes are irreplaceable components of the global ecosystem - for example, they serve as carbon sinks, contain the majority of the world’s biodiversity, and provide vast quantities of fresh water.

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Furthermore, agriculture accounts for an astounding 30-35% percent of humanity’s greenhouse gases (thanks to deforestation, emissions from fertilized soil, rice cultivation and methane emissions from livestock). Fertilizer is also a major source of pollution, as it degrades aquatic ecosystems, damages marine fisheries, and disrupts natural processes that replenish soil nutrients. Finally, irrigation accounts for 70 percent of human demand for fresh water, which is simply unsustainable in many regions.

Fortunately, the Nature article provides five solutions to help humanity “meet the twin challenges of food security and environmental sustainability.”

1. Stop expanding agriculture: At first glance, this may sound counterintuitive. Humanity needs more food, after all. But the world needs to slow and ultimately cease expansion of agriculture, particularly into tropical forests, where food production benefits are marginal and vastly outweighed by the environmental gains of keeping these biomes intact. Critical to the success of this “solution”, of course, will be to provide economic incentives at both the global level (such as the Reducing Emissions from Deforestation and Degradation or REDD program) and at the national and local level, such as initiatives to promote ecotourism, and sustainable harvesting of rain forest products.

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2. Intensify agriculture in underperforming regions: Crop yields vary enormously by region. The average hectare of land in sub-Saharan Africa, for example, produces one sixth the caloric value of Illinois farmland. Closing yield gaps will require new techniques but need not imply massive industrialization. Reform of inefficient farming and animal husbandry practices, better soil and forestry management, a more diverse menu of crops, and openness to genetically-modified seed stock will significantly raise efficiency. These steps promise enormous productivity gains not only in Africa but also Latin America and Eastern Europe. The Nature authors suggest that “bringing yields to within 95% of their potential for sixteen important food and feed crops” could increase global food production by 58%.

3. Reduce unsustainable uses of water, nutrients, and chemicals. More efficient irrigation systems are one key to increased agricultural production, particularly where water is scarce. But productivity gains will also require a more sophisticated approach to the use of chemical fertilizers, as well as manure and leguminous crops. As the Nature authors explain, the world confronts a “Goldilocks” problem. There are too many places where farmers either overfertilize (like China and the United States) or underfertilize (as in much of the developing world), and too few where they get it “just right.” This trend will have drastic consequences, unless national governments, farmers, agronomists, and ecologists can cooperate effectively.

4. Reduce food waste: Globally, huge quantities of food are never consumed—perhaps a third of the total, according to the UN Food and Agriculture Organization. In the developing world, entire cargoes rot before reaching consumers, thanks to inefficient storage, transportation, distribution, and refrigeration systems. But massive quantities are also wasted in the developed world by countless consumers after purchase.

5. Eat less meat. It has been an iron law of development: the richer countries get, the more meat they demand. Farmers and ranchers have responded in kind. A jaw-dropping 75 percent of all agricultural land is currently devoted to raising livestock (including land for grazing, pasture, and growing animal feed). This trend is ecologically devastating and economically inefficient. “It takes 30 kilos of grain to produce one kilo of boneless beef,” as John Foley, one author of the Nature article, observes. Changing the dietary preferences of seven billion humans is no easy feat, of course. But even modest dietary adjustments - such as prioritizing pasture-fed over grain-fed beef or shifting toward chicken and pork - could pay major dividends.

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Combined, these core strategies could “increase global food availability by 100-180%, meeting projected demands while lowering greenhouse gas emissions, biodiversity losses, water use and water pollution.” Implementing any one of these five solutions would be a Herculean challenge. But the message (NPR) from the scientists is even more sobering. We don’t get to pick and choose among them: We need to do them all.

Translating these proposals into action will be among the most daunting challenges humanity has ever faced. It will require a widespread sense of urgency, sustained political will on an international, national, and local level, and the deployment of economic and regulatory incentives to shift the market preferences of billions of individual producers and consumers. As so often in human endeavors, the binding constraints on performance are more likely to be political and economic than purely technical.

The views expressed in this article are solely those of Stewart Patrick.