Provision of food is a prerequisite for the functioning of human society. Cropland where food and feed are grown is the central, limiting resource for food production. The amount of cropland needed depends on population numbers, average food consumption patterns, and output per unit of land. Around the globe, these factors show large differences. We use data from the Food and Agriculture Organization to consistently assess subcontinental dynamics of how much land was needed to supply the prevailing diets during a span of 46 y, from 1961 to 2007. We find that, in most regions, diets became richer while the land needed to feed one person decreased. A decomposition approach is used to quantify the contributions of the main drivers of cropland requirements for food: changes in population, agricultural technology, and diet. We compare the impact of these drivers for different subcontinents and find that potential land savings through yield increases were offset by a combination of population growth and dietary change. The dynamics of the three factors were the largest in developing regions and emerging economies. The results indicate an inverse relationship between the two main drivers behind increased land requirements for food: with socioeconomic development, population growth decreases and, at the same time, diets become richer. In many regions, dietary change may override population growth as major driver behind land requirements for food in the near future.global analysis | land use | historical trends | decomposition analysis T hroughout the world, agriculture provides human society with food. Since the emergence of large-scale agriculture, this crucial activity has been responsible for the largest environmental impacts of humans on natural systems: presently, the largest shares of human land and freshwater use (1, 2), biomass appropriation (3), and the alteration of the global nitrogen and phosphorus cycles (4, 5), and a significant contribution to energy use and greenhouse gas emissions (6), are associated with the provision of food. Within agriculture, croplands take a central and often limiting role. These lands are usually of high quality and, by generating food and feed crops, they provide the lion's share of the global food supply: in 2005, more than 90% of all food calories and approximately 80% of all food protein and fats available in the world were derived from croplands [Food and Agriculture Organization (FAO) of the United Nations, http://faostat.fao.org/].The amount of cropland needed to supply a society with food depends on population numbers, the type of diet, and the food output per unit of land. Population, diets, and production techniques change over time and show large spatial variation. With socioeconomic development, population growth rates decrease (7) and diets change: typically, consumption of animal protein, vegetable oils, fruits and vegetables increases, while starchy staples become less important (8). These changes from staples toward richer diets imply that cropland demand of avera...

Uno de los mayores desafíos de la humanidad es alcanzar la seguridad alimentaria global reduciendo los impactos ambientales y alcanzado dietas sanas para todas las personas. En este artículo, hacemos una reflexión sobre la complejidad de diseñar soluciones para la seguridad alimentaria. Nos enfocamos en México por su heterogeneidad en relación a factores socioeconómicos, culturales y ecológicos. Primero, discutimos la necesidad de analizar la seguridad alimentaria integrando la sustentabilidad de la producción y consume de alimento. Luego, describimos la situación de México al analizar cinco sistemas de producción-consumo de alimento que ilustran la diversidad de sistemas agrícolas y patrones alimenticios de México. Con este análisis demostramos que el camino para alcanzar la seguridad alimentaria debe incluir tanto un sistema productivo sustentable como una dieta sustentable. La solución debe ser sitio-específica considerando la situación socioeconómica, cultural y ecológica.; por lo que se necesita una perspectiva integral geográfica con un enfoque “bottom-up”. De esta manera, no se comprometerá la seguridad alimentaria de futuras generaciones. Para esto, se necesitas políticas transversales entre las instancias/agencias gubernamentales agrícolas, salud y ambientales federales.

Abstract:Work is one of the main inputs in agriculture. It can be performed by humans, animals, or machinery. Studies have shown strong differences throughout the world in labour required to produce a kilogram of food. We complement this line of research by linking these data to food consumption patterns, which are also strongly different throughout the world. We calculate the hours of farm labour required to produce a person's annual food consumption for four scenarios. These scenarios are comprised of two extreme cases for production systems and diets, respectively, that illustrate prevailing global differences. Our results show that the farm labour requirements differ by a factor of about 200 among production systems, and by a factor of about two among consumption patterns. The gain in farm labour efficiency with mechanization is enormous: only 2-5 hours of farm labour are needed to produce the food consumed by a person in a year. This value is much lower than the time an average person spends on buying food, cooking, or eating.

Non-technical abstract A large share of our food comes from international supply food chains that are difficult to trace. Therefore, consumers are not aware of their environmental and social effects. We analysed the tomato supply system for Germany. Tomatoes consumed in Germany are produced either in The Netherlands by Polish workers and using large amounts of energy, or in Spain by West African workers and depleting the aquifer. The analysis shows the long-distance effects of food consumption that should be considered when designing strategies for a sustainable global food system. Comparable results can be expected for other food products traded around the world.

Land and water are essential local resources for food production but are limited. The main drivers of increasing food demand are population growth and dietary changes, which depend on the socioeconomic situation of the population. These two factors affect the availability of local resources: population growth reduces the land and water per person; and adoption of affluent diets increases the demand for land and water per person. This study shows potentials of global food supply by linking food demand drivers with national land and water availability. Whether the available land and water is enough to meet national food demand was calculated for 187 countries. The calculations were performed for the past situation (1960 and 2010) and to assess four future scenarios (2050) to discuss different paths of diets, population numbers and agricultural expansion. Inclusion of the demand perspective in the analysis has shown stronger challenges for future global food supply than have other studies. The results show that with the "business as usual" scenario, 40% of the global population in 2050 will live in countries with not enough land nor water to meet the demands of their population. Restriction to basic diets will be the most effective in lowering both land and water constraints. Our results identify both food production and food demand factors, and the regions that may experience the strongest challenges in 2050.