Climate smart agriculture and global food-crop production

in S1 File) show that the production gains obtained from CSA practices can offset the negative impacts of climate change on maize and rice production and slow down consequent increases in prices. CSA practices are also successful in reducing the price of wheat which, despite an increase in production, is projected to increase in the BAU scenario. It is however difficult to draw broader conclusions about resilience, as this would require a more specific analysis of the differential effects across multiple social contexts, at different geographical scales, and for dif- ferent social groups [71,72]. 3.5 Effects of adoption rates and production costs Results for the third scenario, which uses lower adoption rates, and the fourth, which includes AWD production costs, are reported in Fig 4 along with the results from Rules 1 and 2. To pro- vide a comprehensive review of all the simulated scenarios, we consider the cumulative fresh weight harvest for the three crops. The results in Fig 4 focus on production and emissions. Similar results for harvested area are presented in Supplementary Table S15 in S1 File. As expected, social and cost barriers—heuristically included in the simulations by reducing the rate of adoption of CSA practices as in Rosegrant et al [9]—significantly affect the results with an overall reduction in benefits. Compared to BAU, yearly production for the three crops increases on average by 60 Mt (22–122 M tons) and GHG yearly emissions are reduced on average by 13 Mt CO2e (-2–31 Mt CO2e, where the negative number indicates an increase in

emissions). Therefore, the reduced adoption lowers the crop production gains observed using Rule 1 by about 40% and reduces the effects on emissions by two thirds or more. When the reduction in production costs for AWD is accounted for, AWD is adopted on some additional 0.8 million hectares leading to the highest achieved emission reduction. Yearly production is essentially unaffected but yearly abatement reaches on average 105 Mt CO2 e yr- 1 (90–134 Mt CO2e yr-1). 4 Discussion The largest positive impacts on production and food security as well as the highest levels in GHG emissions abatement, should be interpreted as aspirational targets and viewed as an upper bound of the possible effects of adopting the CSA practices considered across maize, wheat and rice. These results are predicated on high levels of uptake by farmers and their capacity to tailor the implementation of CSA practices to local conditions. The scenario that simulates lower and more realistic adoption rates and the scenarios that represent a lower pro- ficiency at using the practices, show rapidly diminishing benefits. This stresses the importance of major new investments to overcome long-standing problems such as underperforming extension services, farmers’ lack of credit, risk management and timely information about markets. These barriers are known to prevent the adoption of more productive, more resilient and sustainable agricultural systems. Even though the focus of CSA is not on mitigation benefits, the pressure on the agriculture

sector to reduce GHG emissions is likely to increase as other sectors reduce their share of global emissions. The performance of agricultural practices in terms of their abatement poten- tial is therefore important. According to our assessment, the total maximum abatement obtainable (134 Mt CO2e yr-1) is about 17% of what is considered the economically achievable mitigation from managing cropland, which is 0.77 Gt CO2e yr-1 [73]. Also, after the indirect effects of cattle emissions are accounted for (approximately 4 Mt CO2e yr-1), the maximum abatement obtainable is 13% of the 1 Gt CO2e yr-1 abatement goal for the agriculture sector to remain below the 2˚C global warming [74]. If one considers that the GHG emissions from the three crops analyzed is in the range of 1.28–1.92 CO2e yr-1 [25], our results point to a 7–10% PLOS ONE Climate smart agriculture and global food-crop production PLOS ONE | https://doi.org/10.1371/journal.pone.0231764 April 29, 2020 11 / 19