ANALYSIS doi:10.1038/nature10452 Solutions for a cultivated planet Jonathan A. Foley1, Navin Ramankutty2, Kate A. Brauman1, Emily S. Cassidy1, James S. Gerber1, Matt Johnston1, Nathaniel D. Mueller1, Christine O���Connell1, Deepak K. Ray1, Paul C. West1, Christian Balzer3, Elena M. Bennett4, Stephen R. Carpenter5, Jason Hill1,6, Chad Monfreda7, Stephen Polasky1,8, Johan Rockstrom9, �� John Sheehan1, Stefan Siebert10, David Tilman1,11 & David P. M. Zaks12 Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world���s future food security and sustainability needs, food production must grow substantially while, at the same time, agriculture���s environmental footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress could be made by halting agricultural expansion, closing ���yield gaps��� on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly reducing the environmental impacts of agriculture. C ontemporary agriculture faces enormous challenges1���3. Even with recent productivity gains, roughly one in seven people lack access to food or are chronically malnourished, stemming from continued poverty and mounting food prices4,5. Unfortunately, the situ- ation may worsen as food prices experience shocks from market specu- lation, bioenergy crop expansion and climatic disturbances6,7. Even if we solve these food access challenges, much more crop production will probably be needed to guarantee future food security. Recent studies suggest that production would need to roughly double to keep pace with projected demands from population growth, dietary changes (especially meat consumption), and increasing bioenergy use1���4,8,9, unless there are dramatic changes in agricultural consumption patterns. Compounding this challenge, agriculture must also address tremend- ous environmental concerns. Agriculture is now a dominant force behind many environmental threats, including climate change, biodi- versity loss and degradation of land and freshwater10���12. In fact, agricul- ture is a major force driving the environment beyond the ������planetary boundaries������ of ref. 13. Looking forward, we face one of the greatest challenges of the twenty- first century: meeting society���s growing food needs while simultaneously reducing agriculture���s environmental harm. Here we consider several promising solutions to this grand challenge. Using new geospatial data and models, we evaluate how new approaches to agriculture could bene- fit both food production and environmental sustainability. Our analysis focuses on the agronomic and environmental aspects of these chal- lenges, and leaves a richer discussion of associated social, economic and cultural issues to future work. The state of global agriculture Until recently, the scientific community could not measure, monitor and analyse the agriculture���food���environment system���s complex linkages at the global scale. Today, however, we have new data that characterize worldwide patterns and trends in agriculture and the environment14���17. Agricultural extent According to the Food and Agriculture Organization (FAO) of the United Nations, croplands cover 1.53 billion hectares (about 12% of Earth���s ice-free land), while pastures cover another 3.38 billion hectares (about 26% of Earth���s ice-free land) (Supplementary Fig. 1). Altogether, agriculture occupies about 38% of Earth���s terrestrial surface���the largest use of land on the planet14,18. These areas comprise the land best suited for farming19: much of the rest is covered by deserts, mountains, tundra, cities, ecological reserves and other lands unsuitable for agriculture20. Between 1985 and 2005 the world���s croplands and pastures expanded by 154 million hectares (about 3%). But this slow net increase includes significantexpansioninsome areas(thetropics),aswellaslittle changeor a decrease in others (the temperate zone18 Supplementary Table 1). The result is a net redistribution of agricultural land towards the tropics, with implications for food production, food security and the environment. Crop yields Global crop production has increased substantially in recent decades. Studies of common crop groups (including cereals, oilseeds, fruits and vegetables) suggest that crop production increased by 47% between 1985 and 2005 (ref. 18). However, considering all 174 crops tracked by the UN FAO and ref. 15, we find global crop production increased by only 28% during that time18. This 28% gain in production occurred as cropland area increased by only 2.4%, suggesting a 25% increase in yield. However, cropland area that was harvested increased by about 7% between 1985 and 2005���nearly three times the change in cropland area, owing to increased multiple cropping, fewer crop failures, and less land left fallow. Accounting for the increase in harvested land, average global crop yields increased by only 20% between 1985 and 2005, substantially less than the often-cited 47% production increase for selected crop groups. (Using the same methods as for the 20% result, we note that yields increased by 56% between 1965 and 1985, indicating that yields are now rising less quickly than before.) 1Institute on the Environment (IonE), University of Minnesota, 1954 Buford Avenue, Saint Paul, Minnesota 55108, USA. 2Department of Geography and Global Environmental and Climate Change Centre, McGill University, 805 Sherbrooke Street, West Montreal, Quebec H3A 2K6, Canada. 3 Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California 93106, USA. 4School of Environment and Department of Natural Resource Sciences, McGill University, 111 Lakeshore Road, Ste Anne de Bellevue, Quebec H9X 3V9, Canada. 5Center for Limnology, University of Wisconsin, 680 North Park Street, Madison, Wisconsin 53706, USA. 6 Department of Bioproducts and Biosystems Engineering, University of Minnesota, 2004 Folwell Avenue, Minnesota 55108, USA. 7Consortium for Science, Policy and Outcomes (CSPO), Arizona State University, 1120 S Cady Mall, Tempe, Arizona 85287, USA. 8Department of Applied Economics, University of Minnesota, 1994 Buford Avenue, Minnesota 55108, USA. 9 Stockholm Resilience Centre, Stockholm University, SE-106 91, Stockholm, Sweden. 10 Institute of Crop Science and Resource Conservation, University of Bonn, Katzenburgweg 5, D53115, Bonn, Germany. 11 Department of Ecology, Evolution & Behavior, University of Minnesota, 1987 Upper Buford Circle, Minnesota 55108, USA. 12 Center for Sustainability and the Global Environment (SAGE), University of Wisconsin, 1710 University Avenue, Madison, Wisconsin 53726, USA. 2 0 O C T O B E R 2 0 1 1 | V O L 4 7 8 | N A T U R E | 3 3 7 Macmillan Publishers Limited. 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Aggregate measures of production can mask trends in individual crops or crop groups (Supplementary Fig. 2a). For example, cereal crops decreased in harvested area by 3.6% between 1985 and 2005, yet their total production increased by 29%, reflecting a 34% increase in yields per hectare. Oil crops, on the other hand, showed large increases in both harvested area (43%) and yield (57%), resulting in a 125% increase in total production18. While most crops increased production between 1985 and 2005, fodder crops did not: on average, they saw an 18% production drop as a 26% loss in harvested area overrode an 11% increase in yields. Using geospatial data15, we can examine how yield patterns have changed for key commodities (for example, maize in Supplementary Fig. 2b). These geographic patterns show us where productivity gains have been successful, where they have not, and where further oppor- tunities for improvement lie. Crop use and allocation The allocation of crops to nonfood uses, including animal feed, seed, bioenergy and other industrial products, affects the amount of food available to the world. Globally, only 62% of crop production (on a mass basis) is allocated to human food, versus 35% to animal feed (which produces human food indirectly, and much less efficiently, as meat and dairy products)and 3% for bioenergy, seed andother industrial products. A striking disparity exists between regions that primarily grow crops for direct human consumption and those that produce crops for other uses (Fig. 1). North America and Europe devote only about 40% of their croplands to direct food production, whereas Africa and Asia allocate typically over 80% of their cropland to food crops. Extremes range from the Upper Midwestern USA (less than 25%) to South Asia (over 90%). As we face the twin challenges of feeding a growing world while charting a more environmentally sustainable path, the amount of land (and other resources) devoted to animal-based agriculture merits critical evaluation. For example, adding croplands devoted to animal feed (about 350 million hectares) to pasture and grazing lands (3.38 billion hectares), we find the land devoted to raising animals totals 3.73 billion hectares���an astonishing ,75% of the world���s agricultural land. We further note that meat and dairy production can either add to or subtract from the world���s food supply. Grazing systems, especially on pastures unsuitable for other food production, and mixed crop���livestock systems can add calories and protein to the world and improve economic con- ditions and food security in many regions. However, using highly pro- ductive croplands to produce animal feed, no matter how efficiently, represents a net drain on the world���s potential food supply. Global environmental impacts of agriculture The environmental impacts of agriculture include those caused by expansion (when croplands and pastures extend into new areas, repla- cing natural ecosystems) and those caused by intensification (when existing lands are managed to be more productive, often through the use of irrigation, fertilizers, biocides and mechanization). Below, we use new data and models17,21,22 to examine both. Agricultural expansion has had tremendous impacts on habitats, bio- diversity, carbon storage and soil conditions10,11,23,24. In fact, worldwide agriculture has already cleared or converted 70% of the grassland, 50% of the savanna, 45% of the temperate deciduous forest, and 27% of the tropical forest biome14,25. Today, agriculture is mainly expanding in the tropics, where it is estimated that about 80% of new croplands are replacing forests26. This expansion is worrisome, given that tropical forests are rich reservoirs of biodiversity and key ecosystem services27. Clearing tropical forests is also a major source of greenhouse gas emissions and is estimated to release around 1.1 3 1015 grams of carbon peryear, orabout 12%of totalanthro- pogenic CO2 emissions28. Slowing or halting expansion of agriculture in the tropics���which accounts for 98% of total CO2 emissions from land clearing29���will reduce carbon emissions as well as losses of biodiversity and ecosystem services27. Agriculturalintensificationhasdramaticallyincreasedinrecentdecades, outstripping rates of agricultural expansion, and has been responsible for most of the yield increases of the past few decades. In the past 50 years, the world���sirrigatedcroplandarearoughlydoubled18,30,31,whileglobalfertilizer use increased by 500% (over 800% for nitrogen alone)18,32,33. Intensification has also caused water degradation, increased energy use, and widespread pollution32,34,35. Of particular concern is that some 70% of global freshwater with- drawals (80���90% of consumptive uses) are devoted to irrigation36,37. Furthermore, rain-fed agriculture is the world���s largest user of water13,38. In addition, fertilizer use, manure application, and leguminous crops (which fix nitrogen in the soil) have dramatically disrupted global nitro- gen and phosphorus cycles39���41, with associated impacts on water quality, aquatic ecosystems and marine fisheries35,42. Both agricultural expansion and intensification are also major con- tributors to climate change. Agriculture is responsible for 30���35% of global greenhouse gas emissions, largely from tropical deforestation, methane emissions from livestock and rice cultivation, and nitrous oxide emissions from fertilized soils29,43���46. We can draw important conclusions from these trends. First, the expansion of agriculture in the tropics is reducing biodiversity, increas- ing greenhouse gas emissions, and depleting critical ecosystem services. Yet this expansion has done relatively little to add to global food sup- plies most production gains have been achieved through intensification. Second, the costs and benefits of agricultural intensification vary greatly, often depending on geographic conditions and agronomic practices. This suggests that some forms (and locations) of intensification are better than others at balancing food production and environmental protection11,47. Enhancing food production and sustainability Until recently, most agricultural paradigms have focused on improving production, often to the detriment of the environment10,11,47. Likewise, many environmental conservation strategies have not sought to improve food production. However, to achieve global food security and environmental sustainability, agricultural systems must be trans- formed to address both challenges (Fig. 2). Food production area as fraction of total cropland 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Figure 1 | Allocation of cropland area to different uses in 2000. Here we show the fraction of the world���s total cropland that is dedicated to growing food crops (crops that are directly consumed by people) versus all other crop uses, including animal feed, fibre, bioenergy crops and other products. Averaged across the globe, 62% of total crop production (on a mass basis) is allocated to human food, 35% for animal feed (which produces human food indirectly, and less efficiently, as meat and dairy products) and 3% for bioenergy crops, seed, and other industrial products. There are striking disparities between regions that primarily grow crops for human consumption (such as Africa, South Asia, East Asia), and those that mainly produce crops for other uses (such as North America, Europe, Australia). Food production and allocation data were obtained from FAOSTAT18, and were then applied to the spatial cropland maps of refs 14 and 15. All data are for a seven-year period centred on 2000. RESEARCH ANALYSIS 3 3 8 | N A T U R E | V O L 4 7 8 | 2 0 O C T O B E R 2 0 1 1 Macmillan Publishers Limited. All rights reserved ��2011