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This review seeks to survey, understand, and reconcile the widely divergent estimates of long-run global crop output, land use, and price projections in the current literature. We review the history of such projections and the different models and assumptions used in these exercises. We then introduce an analytical partial equilibrium model of the global crops sector, which provides a lens through which we can evaluate this previous work. The resulting decomposition of model responses into demand, extensive supply, and intensive supply elasticities offers important insights into the diversity of model parameterizations being employed by the existing models. Along with the methodology for implementing productivity growth, this helps explain some of the divergences in results. We employ a numerical version of the analytical model, which serves as an emulator of this entire class of models, to explore how uncertainties in the common underlying drivers and economic responses contribute to uncertain projections of output, prices, and land use in 2050. We place each of the published estimates reviewed here into the resulting empirical distribution of outcomes at mid-century. In addition, we quantify the sensitivity of these projections to model inputs. Our findings suggest that the top priority for future research should be improved estimation of agricultural factor supply elasticities, a topic that has been largely neglected in recent decades.
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Download all Supplemental Material as a single PDF. Includes Supplemental Figures 1–3 (also reproduced below), Supplemental Tables 1–4, and Supplemental Appendix.
Supplemental Figure 1. Historical price trends.
Source: World Bank Pink Sheet, accessed 8-Sep-2015 (http://go.worldbank.org/4ROCCIEQ50).
Note: Trend2005 is the linear regression of the agricultural price series between 1960 and 2005. The other trend line, calculated by Excel, is the linear trend line for the whole period.
Supplemental Figure 2. The commodity composition of food crops growth: 1961–2006
Source: Calculated by authors using data from FAO (2014)
Supplemental Figure 3. Global population and GDP projections for SSP2
Source: Authors’ calculations based on SSP2 projections retrieved from SSP2 database (https://tntcat.iiasa.ac.at/SspDb/dsd?Action=htmlpage&page=about).
Notes: (1) Trends between 2005 and 2010 are derived from a mix of data extracted from the World Bank’s WDI database and extrapolation. (2) Trends reflect the latest version of the SSP database, and not the version (0.53) linked to the AgMIP exercise, though differences were slight at the global level. (3) The global GDP projection is evaluated at $2007 constant prices at market exchange rates.