2010年-世界发展银行全球_Competition_for_Land_between_Food_Bioenergy_and_Conservation_8页_332kb

Summary of the World Development Report 2010: "Development and Climate Change"

Core Content

This document is a background note for the World Development Report 2010, focusing on the competition for land between food, bioenergy, and conservation. It uses a global bio-economic model called MAgPIE to analyze the trade-offs and synergies between these competing uses of land and water resources under different future scenarios.

Main Objectives

• To assess the required rate of productivity increase in agriculture to meet future global demands for food and bioenergy.
• To evaluate how land and water constraints, bioenergy demand, trade policies, and climate change affect these productivity requirements.
• To determine the minimum technological change needed to satisfy these demands while considering the environmental and economic implications.

Key Model and Methodology

• MAgPIE is a global bio-economic model that incorporates spatially explicit land and water constraints, technological change, and international trade.
• The model operates in a recursive dynamic mode with a 10-year time step, projecting changes up to 2055.
• LPJmL is used to simulate potential crop yields based on climate, soil conditions, water availability, and plant growth.
• The model calculates shadow prices to quantify the scarcity of land and water resources.
• It simulates bioenergy production as a mix of three types: vegetable-oil-based, starch/sugar-based, and cellulose-based.

Scenarios Analyzed

The study evaluates several scenarios to understand the cumulative pressures on land and water use:

1. Business as usual (baseline):

   • Global population increases to 9 billion by 2055.
   • Calorie consumption and animal calorie share increase with economic growth.
   • Agricultural trade share doubles over 50 years.
   • Cropland expansion continues at historical rates (0.8% per year).
   • No climate impacts on yields are assumed.

2. Reduced trade:

   • Agricultural trade share remains constant at 7% (1995 levels).

3. Bioenergy 100 EJ:

   • Global bioenergy demand rises to 100 EJ by 2055.
   • Bioenergy is region-specific and fulfilled within each region.

4. Avoided deforestation:

   • Cropland expansion is restricted by excluding intact and frontier forests.
   • This increases the need for productivity growth in specific regions.

5. Climate change impacts on yields:

   • Two sub-scenarios are considered:
     • CC with full CO₂ effect: CO₂ fertilization is included, which may enhance crop yields.
     • CC with constant CO₂ effect: CO₂ fertilization is not considered, leading to higher productivity requirements.

Key Findings

• Required productivity increase in the business-as-usual scenario is about 1% per year, which is slightly lower than the historical average (1.4% per year between 1961 and 2005).
• With increased bioenergy demand (100 EJ in 2055), the required rate of technological change (TC) rises to 1.5% per year.
• Avoided deforestation further increases the required TC rate to 1.6% per year.
• Climate change without CO₂ fertilization leads to the highest required TC rate of 1.8% per year.
• With CO₂ fertilization, the required TC rate is reduced to about 1.4% per year, which is sufficient to meet global food and bioenergy demands.
• Regions most affected:
  • AFR (Sub-Saharan Africa) and MEA (Middle East/North Africa) are most impacted in the business-as-usual scenario.
  • FSU (Former Soviet Union) is most affected by increased bioenergy demand.
  • AFR and LAM (Latin America) see the largest increases in TC rates due to avoided deforestation.
  • PAS (Pacific Asia) and SAS (South Asia) face the strongest climate change impacts.

Productivity Trends

• The productivity index (2005 = 100) is used to illustrate the cumulative effects of different scenarios.
• Under business-as-usual and avoided deforestation, the average productivity on cropland would need to more than double by 2055.
• At constant CO₂ levels, the required productivity level would reach 250% of current levels to meet all food and energy demands.

Conclusion

The study highlights the increasing pressure on land and water resources due to population growth, economic development, and bioenergy demand. It emphasizes the need for stronger technological advancements in agriculture to meet these demands sustainably. The role of CO₂ fertilization in mitigating the effects of climate change is significant, and avoided deforestation policies also play a crucial part in reducing the required productivity increases. The findings underscore the importance of regional strategies and international cooperation in managing land and water use efficiently under climate change and growing demands.