Current food trade helps mitigate future climate change impacts in lower-income nations

would vary substantially by income. Considering the ecological crises spurred by existing spe- cialized and concentrated food production systems, diversification strategies may be beneficial for multiple objectives [34]. Our study contributes to the large body of literature on drivers of resilience in agri-food sys- tems. While highly connected and diversified agri-food systems may be more resilient due to the pooling of risk [39–41], such systems can also be more vulnerable due to cascading or cor- related crop failures in major food baskets [13, 42, 43]. Previous work [42] has emphasized two resilience principles—maintaining diversity and redundancy, and managing connectivity [44, 45]. Diversity in systems comprise not only variety but also balance in terms of the strength of different elements and disparity across these elements [45]. Our crop-aggregated consumption impact estimate incorporates diversity as a function of both calorie source diversity (across the three crops and their derived commodities) and import partner diversity (spatial diversity), and disparity as differences in climate impacts across crops and trading partners. Further, we measure connectivity by identifying the key actors, their exposure and sensitivity to climate change, and their interactions with other countries. We find that under the current food regime, mega-exporters play a large role in mediating climate risk. The network of such mega- exporters represents overly connected systems (which threaten resilience [45]) that have a

large structure (many countries depend on them) and considerable strength (many countries relying on mega-exporters for a large share of food supply). We recommend that countries should take a systemic risk perspective [46] that considers the complex intertwined nature of the food systems. There are several caveats to our analysis that should be noted. First, our analysis is limited to three crops because of the lack of robust estimates of crop-specific climate impacts and their economic ramifications for a larger variety of food items. Second, our analysis does not iden- tify trade-offs between efficiency and resilience to supply disruptions as done by others [47] and this warrants future work. Third, our study does not allow for market or management related adaptation, either in the form of changing trade networks and demand due to rapid population growth or cropland allocation. Other economic [5, 19] and modelling [48–50] studies have shown the climate adaptation potential of these strategies. Our work could be expanded to examine the potential of shifting future trade networks on food supply risks, but incorporating future demand changes, especially in regions experiencing rapid population growth would be a necessary first step for effective future planning and policy design. Fourth, the climate impacts used in our analysis, despite being the latest efforts in the field, have large uncertainty [24]. Lastly, our global mean temperature framing of climate impact does not account for the differences in carbon dioxide concentration at these warming levels across the

climate models. These variations can be large across climate models and strongly influence yield projections [51]. Conclusion The significance of cross-border climate impacts in food systems has grown with the increas- ing complexity and concentration of our global food systems. However, assessment of cross- border impacts has received limited attention in national climate assessments. Here we devel- oped a simple analytical method to assess how climate impact on calorie supply of countries is attenuated or amplified by imports. We find that climate impacts are attenuated for a lot more low-income countries than high-income countries when food trade is incorporated in climate impact assessments. We show how mega-exporters play a disproportionately large role in mediating climate impacts. Our methodological approach is simple, adaptable, and easily reproducible to allow nations to evaluate cross-border climate impacts in food systems. PLOS ONE Current food trade helps mitigate future climate change impacts in lower-income nations PLOS ONE | https://doi.org/10.1371/journal.pone.0314722 January 3, 2025 12 / 16