Global agriculture and carbon trade-offs

Abstract

Feeding a growing and increasingly affluent world will require expanded agricultural production, which may require converting grasslands and forests into cropland. Such conversions can reduce carbon storage, habitat provision, and other ecosystem services, presenting difficult societal trade-offs. In this paper, we use spatially explicit data on agricultural productivity and carbon storage in a global analysis to find where agricultural extensification should occur to meet growing demand while minimizing carbon emissions from land use change. Selective extensification saves ∼ 6 billion metric tons of carbon compared with a business-as-usual approach, with a value of approximately $1 trillion (2012 US dollars) using recent estimates of the social cost of carbon. This type of spatially explicit geospatial analysis can be expanded to include other ecosystem services and other industries to analyze how to minimize conflicts between economic development and environmental sustainability.

Keywords: cropland expansion; food security.

Fig. 1.

Crop advantage (CA). Ratio of aggregate calories produced divided by carbon storage on each 5 × 5-min grid cell. Red values indicate areas where crop cultivation is comparatively advantaged over carbon storage.

Fig. 2.

Comparison of selective extensification versus BAU. Both the selective and the BAU simulation produce 100% more calories and assume 25% of the calories come from extensification. The blue and green shading indicate areas where less extensification would occur under the selective solution compared with BAU. The red and yellow shading indicates areas where more extensification would occur under the selective solution compared with BAU.

Fig. 3.

Crop advantage and extensification in selective and BAU simulations for the US Corn Belt (Left) and Southeast Asia (Right). (A and B) Crop advantage. (C and D) Difference in extensification in BAU simulation versus selective solution.

Fig. 4.

Net carbon storage change. Tons carbon storage preserved per grid cell under selective solution versus under BAU. Blue and green indicate areas where larger amounts of carbon storage occur under the selective solution versus BAU, whereas yellow indicates that less carbon is stored under the selective solution (areas of greater extensification).