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About this book

This book explores the fundamental determinants of long term changes in agricultural land use and the associated implications for environmental and food security. The book is designed around the idea that each chapter focuses on one driver, or underlying determinant, of land use change at global scale. It starts with key factors which have been influential in the past, such as growth population, incomes and agricultural productivity, thereafter turning to new drivers such as biofuels, climate change and demand for environmental services. Specialized topics include food security outcomes, projections of future agricultural prices, greenhouse gas emissions, the role of globalization and market integration. The book draws heavily on the emerging body of literature on these topics, summarizes key findings and organizes these within a unifying economic framework.

Table of Contents

Frontmatter

Chapter 1. Overview of Global Land Use, Food Security and the Environment

Abstract
Feeding the world’s population while ensuring the environmental sustainability is one of the world’s ‘grand challenges’. As we look ahead to the middle of this century, will the world’s agricultural resource base be up to the task of meeting the diverse demands being placed on it by growing population, rising incomes, growing biofuel production and rising demand for land-based environmental services? In this chapter we lay out a framework for thinking about the long run sustainability of the world’s food and environmental systems. This model brings together factors from the demand side (population, income, biofuels) as well as the supply side (technological progress, climate change, competing land uses) in order to predict the equilibrium use of land in agriculture over the long run. Absent economic responses, this boils down to a food race between demand growth and improving yields. By bringing the responsiveness of demand and supply to scarcity into the picture, we find that the resource requirements due to growing demands are muted. This framework also gives us a vehicle for determining how much of the adjustment to potential scarcity will come through reduced consumption and how much from increased supplies. The former has important consequences for nutrition, while the latter can have serious environmental impacts. This basic framework, which is fully developed in Appendix B, forms the basis for the economic analysis throughout this book.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 2. Population and Income as Drivers of Global Change

Abstract
This chapter begins by reviewing the historical relationship between population and cropland expansion. It also considers the role of per capita income growth in shaping land use—particularly land devoted to non-agricultural uses, including forests, over the historical record. We then turn to the consideration of population as a determinant of future land use reviewing the basic concepts in demography, including the demographic transition, as well as a summary of the latest population projections to 2050. We also consider the interplay between population growth and current differences in consumption patterns across regions. Many of these differences are driven by per capita incomes. As population growth slows down relative to historical growth rates, it is expected that per capita incomes will play a larger role in driving overall food consumption. Therefore we next turn to the role of income as a determinant of consumption behavior. This includes discussions on dietary upgrading—the shift in consumption from starchy foods towards meats, dairy and processed foods—as well as the statistical evidence on how consumers’ responses to food prices and to additional income vary by income level. The chapter concludes with projections to 2050, based on the SIMPLE model, in which we explore the implications of population and income growth rates over this future period on global food demand and land use change.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 3. Productivity Growth and Yields in the Global Crops Sector

Abstract
Despite strong growth in population and incomes over the past century, cropland expansion has been modest and crop prices have trended downwards. This remarkable accomplishment has been largely due to technological innovation as well as intensification of crop production. This chapter explores the topic of crop productivity growth and its implications for long term land use, the environment and food security. It begins with a review of the historical evidence before moving into the debate about future productivity growth. Here, there are two distinct ‘camps’: one focusing on slowing yield growth to paint a relatively pessimistic picture, and one focusing on strong growth in total factor productivity (TFP) in order to find grounds for optimism in feeding the world in 2050. We find grounds for reconciling these two points of view when we draw a distinction between different measures of productivity growth. We also discuss one of the key determinants of future productivity growth—namely investment in research and development of new crop varieties and technologies for cultivation. To conclude the chapter, we present a series of simulations to 2050 using the SIMPLE model. These serve to highlight the fact that yields and productivity growth are not synonymous in an economic model. Rather, output per hectare depends both on TFP growth as well as the intensification of production.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 4. Economic Responses to Scarcity

Abstract
Chapters 2 and 3 have focused largely on drivers of global change which are exogenous to the economic framework developed in this book, including population, income and total factor productivity. In this chapter we focus exclusively on the endogenous responses to the scarcity which emerges when demand growth outpaces productivity growth. These include three margins of economic response: the demand margin, or consumers’ response to higher prices, the extensive margin of supply, which captures the potential responsiveness of total cropland area to higher returns in agriculture, and the intensive margin of supply, which captures producers’ scope for substituting nonland inputs for land in response to increased scarcity. Each of these margins is explored in detail, and this is followed by a series of simulations with the SIMPLE model showing how they interact with one another in order to determine total cropland conversion. This analysis demonstrates that purely biophysical analyses of global change significantly overstate the amount of cropland conversion required in the face of growing demand.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 5. Water, Food and Environmental Security

Abstract
Water scarcity has emerged as one of the key issues for food and environmental sustainability in the twenty-first century. Agriculture is far and away the largest consumer of water in the world, and irrigated agriculture accounts for 70 % of all freshwater withdrawals globally. An increasing portion of this is coming from groundwater, which is favored by farmers. However, shortages are emerging in many places and these are expected to result in curtailed supplies of irrigation water to farming. While irrigated area accounts for less than 20 % of all cropland, it accounts for about 40 % of production, and attempts to reduce this dependence will require significant expansion of rainfed area to make up for the resulting production losses. Fortunately, there is considerable scope for increasing the efficiency of water use in agriculture, through improved delivery to the plants, as well as through increased water use efficiency by the plants themselves. This chapter explores the role of water in agriculture in some detail as well as offering a series of simulation results, based on SIMPLE, to highlight the interplay between restrictions on irrigated agriculture and global land use change.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 6. Climate Change Impacts in Agriculture

Abstract
In this chapter, we begin by reviewing the evidence on climate change, its consequences for temperature and precipitation, and the resulting mechanisms through which it affects crop production. These include: the impact of temperature on crop development, how elevated CO2 levels affect plant photosynthesis and respiration, increased water stress for crops due to higher temperatures and uneven rainfall, extreme temperature damage, and additional crop damage from pests and disease. We then review the empirical evidence quantifying some of these impacts historically and use these as a basis for some global simulations of climate change impacts using the SIMPLE model. In addition to analyzing the basic impacts on land use and food prices, we also explore potential responses to climate change, including adaptation through additional investments in irrigation, as well as the development of heat and drought tolerant crop varieties via increased funding for agricultural research. We also show how successful adaptation to climate change can offer significant mitigation benefits, stemming from the fact that improved yields lessen the need for land conversion, which in turn reduces further emissions from land use change.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 7. Land-Based Environmental Services

Abstract
As the world becomes richer, competing priorities for land use are emerging. Developing countries are increasingly following the lead set by rich countries and they are setting aside reserves to preserve biodiversity as well as create opportunities for eco-tourism. Initiatives to reduce deforestation and forest degradation have also gained momentum over the past decade, with ambitious REDD+ initiatives associated with climate mitigation getting added attention. This chapter reviews the environmental demands for land, how they have evolved historically, their likely paths in the future, and the implications for global cropland availability. Particular attention will be paid to the potential for land-based carbon sequestration as a path to climate change mitigation. Recent research has shown that such initiatives could have a very significant impact on global cropland supplies and also on food prices and food security. We review this evidence and use it as the basis for SIMPLE model simulations in which the supply of land to agriculture is altered in light of projected carbon sequestration initiatives. Results highlight the impacts on food prices and food security from these competing uses of land.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 8. Biofuels as a Driver of Long Run Land Use Change

Abstract
Bioenergy has played an important role in the global economy ever since the invention of fire. However, bioenergy for transportation—commonly referred to as biofuels, is a more recent phenomenon. This chapter explores the forces driving the recent ‘biofuel boom’ and discusses the implications for food and environmental security. One of the most important aspects of this boom has been the impact on global land use change. Increased demand for feedstocks has boosted prices and this in turn has encouraged additional land conversion. Here, we examine the role of these ‘market-mediated responses’ to growing biofuels demand from both a conceptual and a quantitative perspective. The latter includes a series of special simulations with the SIMPLE model showing how, by ignoring economic responses to scarcity, early estimates of global land use change tended to overstate the impact of biofuels on prices and land conversion.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 9. Livestock and Processed Foods

Abstract
The majority of crop output is consumed not directly, in raw form, but rather indirectly, either through processed food products, or livestock products which embody crops in the form of feedstuffs. Projecting the long run demand for crop production requires understanding the behavior of demand for these value-added products. Given their importance as a source of crop demand, as well as their environmental impacts, we focus our attention on livestock products, the demand for which has been growing strongly in the developing world. As low income households experience income gains, they upgrade their diets, including a great portion of animal protein. A review of recent trends reveals remarkably rapid growth in pork, poultry and dairy consumption in some of the world’s most populous countries. In recent decades, there has been a strong shift in livestock production towards more intensive production techniques, which has, in turn boosted the demand for feed concentrates based on corn and soybeans. The rapid growth in livestock production has also had important environmental impacts. Beef has by far the greatest environmental footprint on land, water and greenhouse gas emissions, with dairy, pork and poultry having lesser impacts. We conclude the chapter with projections based on the SIMPLE model which serve to disentangle the diverse forces driving the long run livestock demand for crop output.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 10. Food Security and Nutrition

Abstract
Can we feed the nine billion people in 2050? This is perhaps the most fundamental question related to future food security. So far our projections show that average food consumption will continue to increase in the future given the trends in key drivers of the global farm and food system discussed in earlier chapters. Although this is the most common approach in the literature, looking at the average rate of consumption alone is highly unsatisfying in world vast disparities where many households are now over-consuming food, even as others remain under-nourished. This chapter begins by looking at how food security is defined and measured, discussing the potential limitations of these metrics. In particular, we focus our discussion on the issue of food accessibility and how this is incorporated into the United Nations’ framework for calculating the incidence of hunger and caloric malnutrition worldwide. This gives rise to an approach based on the distribution of food consumption in each region. We will then revisit the historical trends in hunger and malnutrition as a prelude to our projections of the future distribution of food consumption and nutrition those households facing nutrition shortfalls using a modified version of the SIMPLE model. We conclude by taking a closer look at how these nutritional outcomes are influenced by future trends in agricultural productivity, biofuels and climate change.
Thomas W. Hertel, Uris Lantz C. Baldos

Chapter 11. Global Change and the Food System in 2050

Abstract
This chapter seeks to draw together many of the diverse threads developed in the preceding chapters and reach some general conclusions about land use change, associated greenhouse gas emissions, food prices and caloric malnutrition in 2050. We begin by validating the SIMPLE model over the historical period: 1961–2006. This involves comparing model predictions with observed outcomes. We also consider how alternative restrictions on the economic responses in the model affect these predictions. This provides us with a guide to uncovering the ‘error signatures’ of many commonly used models of global agriculture which abstract from one or more key economic responses to global scarcity. With this foundation, we move on to projections for the 2006–2050 period. Here, we decompose the drivers of global change, including population, income and productivity growth, and their impact on key sustainability metrics. Based on this work, we expect continuing, although perhaps slowing, cropland conversion, along with flat to declining crop prices given anticipated trends in agricultural productivity. Meanwhile, strong income growth is expected to lead to sharp reductions in malnutrition, which will be further facilitated by greater global integration in agricultural markets.
Thomas W. Hertel, Uris Lantz C. Baldos

Backmatter

Additional information