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

Mega-exporters play a significant role in transmitting impacts We find that innumerable countries heavily rely on a handful of key mega-exporters, making them vulnerable to the climate impacts experienced by these mega-exporters. For the three crops aggregated, we identify nine mega-exporters: the USA, France, Germany, Russia, Austra- lia, Brazil, Argentina, Ukraine, and Canada (Fig 4, S5 and S6 Figs). These mega-exporters con- tribute 77% of global calorie exports from the three crops. The USA in particular, but also Canada and Brazil are expected to face negative climate impacts. The other six mega-exporters are expected to benefit from combined yield improvements for the three staple crops under 2˚C warming (see S6 Fig). These beneficial yield impacts are driven by wheat yield gains linked to increased carbon dioxide concentrations [24]. To comprehend the transmission of climate impacts, we compare the domestic impact of the mega-exporters with those of their importing partners (see Fig 4, S5 and S6 Figs). We find that the USA, Russia, Brazil, and Ukraine aggravate the supply impacts for more countries than they mitigate, while France, Germany, Brazil, Argentina, Australia, and Canada play a mitigating role for more countries than they aggravate. Additionally, the USA, which is Fig 4. This figure shows for which countries mega-exporters aggravate (orange) or mitigate (blue) the climate impacts. The central map shows the various mega-exporters identified through our analysis. Each panel on the four corners shows a particular mega-

exporter (panel label) and the role it plays in mediating the climate impacts for countries that source calories from it. For readability, we only show four of the nine mega-exporters and the importing partners that rely on a particular mega-exporter for at least 10% of their calorie supply from wheat, maize, and rice aggregated. The figure shows that 37 countries rely on the USA, 22 on France, 11 on Germany, and 11 on Russia for at least 10% of their total calorie supply. The maps are generated using R version 4.2.1 and shapefiles sourced from the NaturalEarth project (naturalearthdata.com). https://doi.org/10.1371/journal.pone.0314722.g004 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 10 / 16