Abstract
Long-term food demand scenarios are an important tool for studying global food security and for analyzing the environmental impacts of agriculture. We provide a simple and transparent method to create scenarios for future plant-based and animal-based calorie demand, using time-dependent regression models between calorie demand and income. The scenarios can be customized to a specific storyline by using different input data for gross domestic product (GDP) and population projections and by assuming different functional forms of the regressions. Our results confirm that total calorie demand increases with income, but we also found a non-income related positive time-trend. The share of animal-based calories is estimated to rise strongly with income for low-income groups. For high income groups, two ambiguous relations between income and the share of animal-based products are consistent with historical data: First, a positive relation with a strong negative time-trend and second a negative relation with a slight negative time-trend. The fits of our regressions are highly significant and our results compare well to other food demand estimates. The method is exemplarily used to construct four food demand scenarios until the year 2100 based on the storylines of the IPCC Special Report on Emissions Scenarios (SRES). We find in all scenarios a strong increase of global food demand until 2050 with an increasing share of animal-based products, especially in developing countries.
Generated Summary
This research presents a method for creating food demand scenarios for total and animal-based calories. The study uses time-dependent regression models to analyze the relationship between calorie demand and income. The scenarios are customized by using different input data for gross domestic product (GDP) and population projections and by assuming different functional forms of the regressions. The study uses historical data from the FAOSTAT database from 1961 to 2007 and the World Bank’s World Development Indicator (WDI) to analyze total calorie demand and animal-based calorie demand. The study explores how total calorie demand increases with income and also identifies a non-income related positive time-trend. It estimates that the share of animal-based calories will increase strongly with income for low-income groups, whereas, for high-income groups, two ambiguous relations between income and the share of animal-based products were found. The method is applied to create four food demand scenarios until the year 2100, based on the IPCC Special Report on Emissions Scenarios (SRES). The research focuses on regional results and the projected per-capita demand values remain in reasonable ranges, considering the income growth in the scenarios.
Key Findings & Statistics
- Total Calorie Demand and Income Elasticity: The study found a positive relationship between total calorie demand and income, with an income elasticity of demand (β) estimated at 0.1002 ± 4.37 × 10^-4 (mean ± SE). This value decreased from 0.101 in 1961 to 0.0995 in 2007. The model’s fit was highly significant, with a coefficient of determination of 0.65 and a slope of 0.66.
- Total Calorie Demand Projections: At high-income levels (I = 60,000 US$), total calorie demand was projected to increase from 3587 kcal capita^-1 d^-1 in 2000 to 4289 kcal capita^-1 d^-1 in 2100 using the ga formulation. The gB formulation predicted a change from 3661 kcal capita^-1 d^-1 in 2000 to 3805 kcal capita^-1 d^-1 in 2100.
- Animal-Based Calorie Share: The linear regression model (ha) of animal-based calorie share found that ln(I) and time (t) were significant predictors for ln(CLS), with a slope of 0.63 and an intercept of 0.04. The model predicted a decrease in animal-based calorie share at higher incomes (60,000 US$) from 0.42 in 2000 to 0.2 in 2100. The hB model showed a declining parameter p = P1 + P2 · t, and increasing λ = λ1 + λ2 · t over time.
- Regional Trends in Total Calorie Demand: Projections indicate a strong increase in total calorie demand up to 2050 across all scenarios (A1, A2, B1, and B2).
- World Population Growth: World population is projected to grow by 65% (A1 and B1 scenarios), 78% (B2 scenario), and 114% (A2 scenario) from 1990 to 2050.
- Per-Capita Demand Influence: Increase in per-capita demand has a substantial impact on total demand, increasing by 18% (A2), 21% (B2), 26% (B1), and 36% (A1) from 1990 to 2050.
- Regional Variations in Per-Capita Demand Growth: The regions with the highest growth rates in per-capita demand are Sub-Saharan Africa, South, Central, and South-East Asia.
- Comparison with Literature: The study’s global estimate for per-capita calorie demand in 2030 is within 100 kcal capita^-1 d^-1 of values from Alexandratos et al., Valin et al., and Kruse for the B2 scenario. For 2050, the B2 scenario estimate (3177 kcal capita^-1 d^-1) is between the results of Kruse and Alexandratos.
- Animal-Based Demand Projections: Animal-based calorie demand is projected to increase until the mid-21st century, with some countries reaching over 2000 kcal capita^-1 d^-1.
- Regional Animal-Based Demand: Animal-based demand increases in all scenarios, but it is strongest in Sub-Saharan Africa.
- Share of Animal-Based Calories: The increase in the share of animal-based calories is more decisive than the increase in total calorie demand per capita.
Other Important Findings
- The SRES storylines suggest that the A1 and A2 scenarios describe a society with an affluent, wasteful, and materialistic consumption pattern, even though dynamics like increased health consciousness in rich countries might also reduce the consumption of animal-based calories. In contrast, the B1 and B2 worlds have societies with high environmental awareness that translate into a de-materialization of consumption, a reduced intake of animal-based calories and lower rates of household waste.
- The increase in per-capita demand in high-income countries might be attributable to an increase in food waste at the household level.
- The animal-based share in developing countries increases faster in the environmental than in the materialistic scenarios.
Limitations Noted in the Document
- The study acknowledges that data quality for long-term projections is low, and the understanding of socio-economic dynamics is weak.
- The study uses a single global approach for estimating food demand at the country level, which might not fully capture regional peculiarities.
- The assumption of convergent diets, where national dietary patterns become more homogeneous over time, may influence the results.
- The study’s reliance on the FAOSTAT database and WDI introduces potential limitations in data accuracy and completeness.
Conclusion
The study provides a valuable tool for creating customized food-demand scenarios, which requires only GDP and population data. The ex-ante customization approach, which adapts core assumptions of functional relations, offers a more logical and consistent framework than ex-post adjustments. The results of this study align well with other research and projections. The study highlights the growing food demand and the increasing share of animal-based calories, emphasizing the need for further investigations into food security and the environmental implications of livestock production. The findings of this study also suggest that the dynamics of excessive consumption of animal-based calories may be interesting for health studies. The work contributes to our understanding of global food demand scenarios and offers a foundation for future research. Moreover, the research suggests that there are limitations with simplistic economic demand models that rely on a positive elasticity constant over time and income. In the environmentally oriented scenarios, food demand is lower than in the materialistic scenarios. The projections show that many people live in countries with an average demand of 2000-2500 kcal capita−1 d−1. The major geographical areas of concern are clustered in the tropics.