How much food will we need in the future? What are current & projected agricultural demands on natural resources? How do conditions change at different scales and for different income groups?
This section of the course begins in Class 2 with a review of population, diet, and crop loss trends, which together determine how demand for food will change. We consider the global situation first but also examine regional differences and changes over time. The readings and supplementary materials (S1–S4) indicate that global food demand will grow considerably in the next few decades. However, they also project that demand will stabilize in most regions by the end of the 21st century. This has important implications, suggesting that the present century is a turning point as well as a challenge for global agriculture.
The first part of S5 provides some simple estimates of the increases in food energy (calorie) and protein demands that are implied by projected increases in population and per capita consumption. These estimates suggest that global calorie demand in 2050 may be as high as 1.5 times current levels, more in some regions. How will this affect the demand for inputs to the agricultural system? A simplified list of essential inputs includes
- Natural resources: Land, water, solar energy for photosynthesis, and nutrients
- Human inputs: Labor, capital, additional energy required to produce and distribute food, and cultivar seeds bred to have desirable properties.
The human inputs required for a 50% increase in production are probably not seriously limiting, especially on regional or global scales. But the natural resources required, especially land and water, may be limiting and are, in fact, already limiting in certain regions.
The second part of S5 considers the additional natural resources needed to meet projected increases in food demand. These resource demands depend on technological efficiencies that determine how much land (yield), water (water use efficiency), and nutrients (nutrient use efficiency) are required to produce one unit of a given crop. The concept of sustainable intensification discussed by Godfray et al (2010) in Class 1 is largely focused on improvements of these efficiencies.
In Classes 3 and 4 we review the water, land, and nutrient resources available for producing food. The readings and Supporting Information (S8) indicate that the areas where soil, terrain, and climate are suitable for successful crop production are scattered and often not located where food demand is greatest. Most of the best land and readily accessible water is already used for some form of agriculture. These findings suggest that there may not be enough unused land and water to meet projected food demand with current technology and management practices. Consequently, the analysis in S5 concludes that there will likely need to be improvements in both technology and management to meet the food security challenges of this century. This topic is considered further in Section 3.
Section 2 Class Topics
Section 2 Supporting information (SI)
S1. UN Global and Regional Population Projections
S2. FAO Food Loss Charts
S3. FAOSTAT Food Balance Sheets
S4. Background Data on Food Security
S5. Food and Natural Resource Demands
S6. The Water Cycle
S7. Recent Cropland Expansion from Deforestation
S8. Global Variability in Climate and Crop Suitability