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Arguments - Prediction Error
Arable Land
When predicting the area of arable land available for cultivation in China, we have to consider three types of errors.
WB00860_.gif (262 bytes) There is uncertainty about the effectiveness of measures undertaken by the Chinese authorities to stop or slow arable land loss due to construction activities. It is likely that China's current cropland area will decline further due to construction activities and urbanization. However, the extent of this decline largely depends on the effectiveness of economic, administrative, and legislative measures, which we simply cannot predict. For instance, it is not clear to what extent Chinese authorities will be willing and able to stop urban and industrial sprawl or projects requiring large areas of land, such as the Three Gorges Dam project.
WB00860_.gif (262 bytes) The productivity of potential land reserves is unknown. According to research by Fischer (IIASA), China has a potential arable land reserve for rain-fed cultivation of between 15 and 30 million ha. The reserve is mainly located in Northern and Northeastern China. Much of it, however, is marginal land that would need considerable investments to improve productivity. These measures also depend on the availability and cost of certain agricultural technologies (such as drought-resistant crops, highly efficient irrigation systems, etc.), which are unknown today. The yields in these areas would likely be much lower than in China's core crop regions due to unfavorable climate conditions. Moreover, infrastructure would have to be built to access these regions. Instead of new land reclamation, it would probably be more effective to prevent further loss of high-quality cropland due to water or wind erosion and salinization.
WB00860_.gif (262 bytes) The effectiveness of erosion-control and soil-management measures is also uncertain. China has been quite successful in combating wind erosion and desertification, and large-scale programs are in place to fight water erosion. However, it is impossible to predict how effective large-scale soil conservation and reforestation programs will be in the future. The rapid process of privatization and economic development in China will certainly change the economic and social environment for state-organized conservation campaigns in ways we cannot predict.
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Related Arguments

Arable Land:   Trends     Impact    Data Quality    Prediction Error    Intervention Possibilities    Intervention Costs

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Revision 2.0 (First revision published in 1999)  - Copyright 2011 by Gerhard K. Heilig. All rights reserved. (First revision: Copyright 1999 by IIASA.)