GC035-09
The Historical Impact of Anthropogenic Climate Change on Global Agricultural Productivity

Tuesday, 8 December 2020: 21:02
Virtual
Ariel Ortiz Bobea, Cornell University, Ithaca, NY, United States, Toby Ault, Cornell University, Department of Earth and Atmospheric Science, Ithaca, NY, United States, Carlos M. Carrillo, Cornell University, Earth and Atmospheric Sciences, Ithaca, NY, United States, Robert G. Chambers, University of Maryland College Park, Agricultural and Resource Economics, College Park, MD, United States and David B Lobell, Stanford University, Stanford, CA, United States
Recorded Presentation
Abstract:
Agricultural research has fostered productivity growth, but the historical influence of anthropogenic climate change on that growth has not been quantified. In this study we develop a robust econometric model of weather effects on global agricultural total factor productivity (TFP) and combine this model with counterfactual climate scenarios from CMIP6 to evaluate impacts of past climate trends on TFP. We obtain country-level TFP estimates from the USDA ERS international productivity dataset and historical weather conditions from Princeton’s Global Meteorological Forcing Dataset for land surface modeling. These TFP estimates encompass both crop and livestock production.

Research to date on the historical impact of anthropogenic climate change focuses overwhelmingly on yields of major cereal crops or on total Gross Domestic Product (GDP). However, recent studies in this area are of limited value for assessing overall agricultural productivity for the following reasons: (i) cereal crops represent only about 20% of agriculture’s global net production value (Fig. S1), (ii) variations in measures such as yield, could deviate from changes in overall productivity if farmers also adjust inputs in response to weather, and (iii) growth and levels of total and agricultural GDP diverge considerably in most countries, and thus climate change impacts on total GDP could deviate considerably from agricultural impacts.

Our baseline model indicates that anthropogenic climate change has reduced global agricultural TFP by about 21% since 1961, a slowdown that is equivalent to losing the last 9 years of productivity growth. The effect is substantially more severe (a reduction of ~30-33%) in warmer regions such as Africa and Latin America and the Caribbean. We also find that global agriculture has grown more vulnerable to ongoing climate change as higher temperatures are becoming increasingly damaging in the second half of the sample. Results are highly robust. We conduct extensive placebo checks on the baseline model showing the result is unlikely to arise due to chance, and we also consider 200 systematic variations of the econometric model.

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