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  3. The past 50 years have seen massive expansion of agriculture, with food production more than doubling in order to meet demand. B

The past 50 years have seen massive expansion of agriculture, with food production more than doubling in order to meet demand. B

admin2012-04-09  52
问题     The past 50 years have seen massive expansion of agriculture, with food production more than doubling in order to meet demand. But it has left us with 60% of all ecosystem services degraded, accelerated species extinction, and huge loss in genetic diversity. Currently, four plant species—wheat, maize, rice and potato— provide more than half of the plant-based calories in the human diet, while about a dozen animal species provide 90% of animal protein consumed globally.
    As the agricultural frontier has expanded, those farmers previously dependant on a more diverse source of livelihood have converted to cash crops. As traditional varieties and breeds die out, so too do the traditional knowledge and practices of local farmers. The focus on agricultural commodities rather than on food production to meet the basic needs of people has undermined diversity and self-reliance, and left farmers vulnerable to volatile markets, political instability and environmental change.
    Increased food production in some parts of the world has been at the expense of natural and semi-natural ecosystems that provide us greater long-term security. In Britain, studies have shown that hay production is higher in meadows with a greater number of species. In Australia, crop yields are higher in regions where native biodiversity has been preserved. In the seas, too, areas with a higher number of conserved species generate more fish for humans to catch and eat. There are many other examples from land and sea to show that a healthy environment means more food and a greater capacity to survive natural disasters. The current food crisis, meanwhile, will only be exacerbated by climate change, with southern Africa and South Asia expected to be particularly badly affected.
    So what are the solutions to feeding a growing world population in the face of climate change? We have been hearing about a Green Revolution for Africa, major irrigation and fertilization programs, genetically modified seed varieties, as well as banning the use of crops for bio-fuel production. Amazingly, there is very little attention being paid to what fundamentally underpins (支持) all of our food systems—biodiversity and the services provided by ecosystems, such as soil, water and resilience to disasters. We have to change the economic rules of current food production systems. We must eliminate agricultural and fisheries subsidies that support elites in the North, and get rid of protectionist measures in OEGD (Organization for Economic Cooperation and Development) countries for agricultural products. We have to allow for value-added trade for the benefit of the South, and expand fair trade and labeling processes that create incentives and add benefits to producers in the South. We must change food production systems, moving from the existing model based on high inputs accessible through markets, to systems based on locally available and more environmentally-friendly inputs.
What has resulted in the degradation of the ecosystem for the past 50 years?
选项 A、The sustainable development of agriculture.
B、The human’s destruction to the environment.
C、The human’s demand for biological diversity.
D、The increasing demand in food production.
答案D
解析 细节辨认题。定位句指出，过去50年农业飞速扩展，粮食产量翻了一番多，但是这也造成60％的生态环境被破坏，物种灭绝的速度加快和基因多样性减少。由此可知，人们对粮食生产的不断需求造成生态环境的恶化，因此D)正确。
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