Agriculture, bioenergy, and water implications of constrained cereal trade and climate change impacts

In high-importing regions, producers need higher domestic prices to stimulate domestic cereal production in ID (e.g., Middle East and Western Africa in Fig 5) and, with the import dependency constraint, net importers do not benefit from the comparatively low price of cereal crops in the global market. Fig 5 shows these effects on the regional corn prices in the four representative regions. The effects of the import dependency constraint on cereal prices depend on how much and in which direction the CIDR in RF deviates from 0%. USA and Bra- zil, both with RF CIDR of -14% in the base year (Fig 1), show a slight decrease in regional prices in ID compared to RF (Fig 5). Western Africa, with RF CIDR of 24%, shows a slight increase in the regional prices, while the Middle East, with RF CIDR of 59%, shows a larger increase in regional prices than Western Africa. The regional price of corn is higher for these four regions in CC than RF and in IC than ID (Fig 5). In the USA and Brazil, the increase in price due to climate change impacts on crop yields is comparable to the decrease in price due to the import dependency constraint, thus price in IC is similar to RF. In Western Africa and Middle East, with CIDR>0%, the effects on prices from the import dependency constraint are much larger than from climate change. The cereal domestic production credit is modeled as a subsidy to the producers to increase production sufficiently to meet domestic demand. So the price received by producers includes both the “market” component of the price and a subsidy from the cereal domestic production

credit (S5 Fig in S1 File). Under ID, the price received by producers in the net exporting regions, USA and Brazil, is slightly lower than RF. For the net cereal importers in RF, the total price paid to producers, including subsidy and market price, is higher than in RF; for the Mid- dle East, the price received by producers is nearly twice as large in ID than in RF. 3.3.3 Impacts on non-cereal crops and other key outcomes. We also explore the effects of global zero cereal import dependency on other key outcomes: non-cereal crop production, consumption, exports, and imports; crop producer revenue; net trade revenue; caloric con- sumption; the food expenditure share of income; irrigation water consumption; and ethanol production using corn and sugarcane. Tables 1 and 2 show the 2050 results for USA and Mid- dle East—the top net exporter and importer of cereals in RF (See S1 File for Western Africa Fig 5. Regional price paid for corn consumption over 2015–2050 in 5-year time steps in selected regions under four model scenarios. https://doi.org/10.1371/journal.pone.0291577.g005 PLOS ONE Agriculture, bioenergy, and water implications of constrained cereal trade and climate change impacts PLOS ONE | https://doi.org/10.1371/journal.pone.0291577 September 15, 2023 10 / 18