Publications

2019.

“Feeding the world, leaving the land : economics of growth, population and resource constraints”, B. Lanz, S. Dietz, T. Swanson, forthcoming Cambridge University Press.

2018

“The expansion of modern agriculture and global biodiversity decline: An integrated assessment”, B. Lanz, S. Dietz, T. Swanson, Ecological Economics 144: 260-277.

The world is banking on a major increase in food production, if the dietary needs and food preferences of an increasing, and increasingly rich, population are to be met. This requires the further expansion of modern agriculture, but modern agriculture rests on a small number of highly productive crops and its expansion has led to a significant loss of global biodiversity. Ecologists have shown that biodiversity loss results in lower plant productivity, while agricultural economists have linked biodiversity loss on farms with increasing variability of crop yields, and sometimes lower mean yields. In this paper we consider the macro-economic consequences of the continued expansion of particular forms of intensive, modern agriculture, with a focus on how the loss of biodiversity affects food production. We employ a quantitative, structurally estimated model of the global economy, which jointly determines economic growth, population and food demand, agricultural innovations and land conversion. We show that even small effects of agricultural expansion on productivity via biodiversity loss might be sufficient to warrant a moratorium on further land conversion.

2017

“Global Population Growth, Technology, and Malthusian Constraints: A Quantitative Growth Theoretic Perspective”, B. Lanz, S. Dietz, T. Swanson, International Economic Review 58(3): 973-1006.

We structurally estimate a two‐sector Schumpeterian growth model with endogenous population and finite land reserves to study the long‐run evolution of global population, technological progress, and the demand for food. The estimated model closely replicates trajectories for world population, GDP, sectoral productivity growth, and crop land area from 1960 to 2010. Projections from 2010 onward show a slowdown of technological progress, and, because it is a key determinant of fertility costs, significant population growth. By 2100, global population reaches 12.4 billion and agricultural production doubles, but the land constraint does not bind because of capital investment and technological progress.

“Global Economic Growth and Agricultural Land Conversion under Uncertain Productivity Improvements in Agriculture”, B. Lanz, S. Dietz, T. Swanson, American Journal of Agricultural Economics 100(2): 545-569.

We study how stochasticity in the evolution of agricultural productivity interacts with economic and population growth at the global level. We use a two-sector Schumpeterian model of growth, in which a manufacturing sector produces the traditional consumption good and an agricultural sector produces food to sustain contemporaneous population. Agriculture demands land as an input, itself treated as a scarce form of capital. In our model both population and sectoral technological progress are endogenously determined, and key technological parameters of the model are structurally estimated using 1960-2010 data on world GDP, population, cropland and technological progress. Introducing random shocks to the evolution of total factor productivity in agriculture, we show that uncertainty optimally requires more land to be converted into agricultural use as a hedge against production shortages, and that it significantly affects both optimal consumption and population trajectories.

2016

BRPP3 “Multi-scale simplification of agricultural land: a review and research agenda on the external costs for global food production”, D. Eaton, S. Dietz, B. Lanz, T. Swanson, J. Tewklsbury, Biodiversity Review Project Paper 3.

Processes of agricultural simplification take place at different spatial scales from the field to the globe. We propose the concept of multi-scale simplification to bring together these linked processes. Whereas it is well documented that agricultural simplification has brought about increases in production on the one hand and environmental harms outside the production system on the other hand, we ask whether multi-scale simplification also imposes external costs on agricultural production itself, due to its effects on vulnerability to pests and disease, pollination and soil fertility.

We review the evidence and propose an economic model compatible with the existence of external costs on production, which can serve as the basis for future empirical research across disciplines. The model proposes several mechanisms, by which maximizing production of the whole food system implies reducing the extent of agricultural simplification.

2014

“Running with the red queen : an integrated assessment of agricultural land expansion and global biodiversity decline”, B. Lanz, S. Dietz, T. Swanson, Biodiversity Review Project Paper 2.

Modern agriculture relies on a small number of highly productive crops and the continued expansion of agricultural land area has led to a significant loss of biodiversity. In this paper we consider the macroeconomic consequences of a continued expansion of modern agriculture from the perspective of agricultural productivity and food production: as the genetic material supporting agriculture declines, pests and pathogens become more likely to adapt to crops and proliferate, increasing crop losses due to biological hazards.

To evaluate the macroeconomic consequences of a reduction in agricultural productivity associated with the expansion of agriculture, we employ a quantitative, structurally estimated model of the global economy in which economic growth, population and food demand, agricultural innovations, and the process of land conversion are jointly determined. We show that even a small impact of global biodiversity on agricultural productivity calls for both a halt in agricultural land conversion and increased agricultural R&D in order to maintain food production associated with population and income growth.

“Global population growth, technology, and malthusian constraints : a quantitative growth theoretic perspective”, B. Lanz, S. Dietz, T. Swanson, Biodiversity Review Project Paper 1.

How much further will the global population expand, will we exhaust natural land reserves, and what is the role in this story of economic growth? We study the interactions between global population, technological progress, per-capita income, and agricultural land expansion from 1960 to 2100. We structurally estimate a two-sector Schumpeterian growth model with endogenous fertility and finite natural land reserves, in which a manufacturing sector provides a consumption good and an agricultural sector provides food to sustain contemporaneous population. The model closely replicates 1960-2010 data on world population, GDP, productivity growth and crop land area, and we employ the model to make projections from 2010 to 2100. Results suggests a slowdown of technological progress, and, because it is the main driver of a transition to a regime with low population growth, significant population growth over the whole century. Global population is slightly below 10 billion by 2050, further growing to 12 billion by 2100. As population and per capita income grow, demand for agricultural output almost doubles over the century, but the land constraint does not bind because of capital investment and technological progress. This provides a first integrative view of future population development in the context of modern growth theory, and thus a novel perspective on a key driver of future resource scarcity.