世界経済・社会統計 = World development indicators

Continuing population and consumption growth will mean that the global demand for food will increase for at least another 40 years. Growing competition for land, water, and energy, in addition to the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement to reduce the impact of the food system on the environment. The effects of climate change are a further threat. But the world can produce more food and can ensure that it is used more efficiently and equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food security, different components of which are explored here.

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Food Security: The Challenge of Feeding 9 Billion People

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.

https://escholarship.org/content/qt6xw5g085/qt6xw5g085.pdf?t=ovfwpc

Solutions for a cultivated planet

Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products.

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Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change

Increasing energy use, climate change, and carbon dioxide (CO2) emissions from fossil fuels make switching to lowcarbon fuels a high priority. Biofuels are a potential lowcarbon energy source, but whether biofuels offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food-based biofuels in Brazil, Southeast Asia, and the United States creates a ‘biofuel carbon debt’ by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions these biofuels provide by displacing fossil fuels. In contrast, biofuels made from waste biomass or from biomass grown on abandoned agricultural lands planted with perennials incur little or no carbon debt and offer immediate and sustained GHG advantages. Demand for alternatives to petroleum is increasing the production of biofuels from food crops such as corn, sugarcane, soybeans and palms. As a result, land in

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Land Clearing and the Biofuel Carbon Debt

Presentation de l'editeur : This report aims to assess the full impact of the livestock sector on environmental problems, along with potential technical and policy approaches to mitigation. The assessment takes into account direct impacts, along with the impacts of feed crop agriculture required for livestock production. The livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global. The findings of this report suggest that it should be a major policy focus when dealing with problems of land degradation, climate change and air pollution, water shortage and water pollution, and loss of biodiversity. Livestock's contribution to environmental problems is on a massive scale and its potential contribution to their solution is equally large. The impact is so significant that it needs to be addressed with urgency. Major reductions in impact could be achieved at reasonable cost

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Livestock's long shadow: environmental issues and options.

Livestock's Long Shadow

In tropical Latin America, pasture land for extensive grazing continues to expand, mostly at the expense of forest cover. Until now, scientists and policy makers tackling this issue had no geographically exhaustive information at the continental level about the spatial dynamics of this process. On the basis of a land use change-modeling framework we made a projection of potential land use changes for the year 2010. The chosen modeling framework incorporates a number of essential aspects of the complexity of land use change, such as the interrelation of spatial and temporal dynamics, land use history and scale dependence. The model was provided with up-to-date, continent wide, detailed information on present land use and its location factors, selected on the basis of literature. Model inputs were established in collaboration with experts from the region. Significant statistical relations were obtained that describe land use patterns in sub-regions, giving insights into the deforestation process and its location factors. Combined with decision rules and quantitative estimates of land use change, “hot spots” of forest to pasture and crop land conversion were projected. The results envisage a predominant replacement of forest by pasture. Substantially different trends among countries are predicted, both concerning the spatial patterns of deforestation and the substitution trends between land uses. The hot spot maps also show sensitive biological areas that may be at risk. The resulting continent wide map of projected change shall help to target policy attention and measures. It also provides a context to the numerous undergoing deforestation case studies. Finally, it is proposed that the study's results be considered in the priority setting of future research on the causes of deforestation.

Projecting land use changes in the Neotropics: the geography of pasture expansion into forest

This paper describes the contract mechanism developed for the Regional Integrated Silvopastoral Ecosystem Management Project, which is being implemented with financing from the Global Environment Facility (GEF). The project is testing the use of the payment-for-service mechanism to encourage the adoption of silvopastoral practices in three countries of Central and South America: Colombia, Costa Rica, and Nicaragua. The project has created a mechanism that pays land users for the global environmental services they are generating, so that the additional income stream makes the proposed practices privately profitable.

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Paying for biodiversity conservation services in agricultural landscapes

One of the most important reasons for the degradation of biodiversity, in mountain areas and elsewhere, is that the people who make land use decisions often receive few or no benefits from biodiversity conservation. Understandably, therefore, they generally ignore potential biodiversity benefits when choosing land use practices. The end result is that biodiversity is often lost, as are many other off-site benefits such as the regulation of hydrological flows. Efforts to enhance biodiversity conservation need to take account of the constraints faced by individual land users, who decide what practices to adopt on their land. Over the years, a variety of efforts have been made to boost the profitability of biodiversity-friendly practices for land users, with mixed results. A further approach, which has received increasing attention in recent years, is to provide direct payments for the provision of environmental services such as biodiversity conservation. The simple logic of Payments for Environmental Services (PES) is that compensating land users for the environmental services a given land use provides, makes them more likely to choose that land use rather than another. The Regional Integrated Silvopastoral Ecosystem Management Project, which is being implemented by the World Bank with financing from the Global Environment Facility (GEF), is piloting the use of PES as a means of generating biodiversity conservation and carbon sequestration services in watersheds at three sites in Colombia, Costa Rica, and Nicaragua.

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Mauricio Rosales

Papers

Livestock's long shadow: environmental issues and options.

Livestock's Long Shadow

Projecting land use changes in the Neotropics: the geography of pasture expansion into forest

Paying for biodiversity conservation services in agricultural landscapes

Paying for Biodiversity Conservation Services