But understanding how far those disruptions reached, who suffered and who gained has been difficult. Researchers at Michigan State University's Center for Systems Integration and Sustainability (CSIS) lead a unique effort, relying on satellite images to quantify loss of cropland and employing a holistic method called the metacoupling framework and network analysis to analyze connections within a region, between neighboring areas, and across distant ones.

"The most striking aspect of our research is its ability to connect a regional conflict to its far-reaching impacts on global food accessibility," said Nan Jia, a PhD student and lead author.

The stakes are high. The United Nations Food and Agriculture Organization models suggest that 13 million more people would be undernourished in 2022 due to the Russia-Ukraine war. . Ukraine's lost production of three winter cereals in 2021 could have met the caloric needs of 76 million adults for a year.

The study revealed that regarding wheat, barley, and oats, the war has had a much greater impact on distant countries than on countries next to the Ukraine and disproportionately harms poor countries.

"It's remarkable how interconnected our world is - an event in one part of the globe can lead to food insecurity thousands of kilometers away," said Jianguo "Jack" Liu, Rachel Carson Chair in Sustainability and senior author. "By using the metacoupling framework to trace these connections, we were able to reveal the unequal impact of the war, highlighting how distant and low-income nations are often left more vulnerable in times of crisis."

Countries far from Ukraine were disproportionately affected, facing higher costs and fewer options to secure food supplies. Among these, lower-income nations in Africa, such as Sierra Leone, the Democratic Republic of Congo and Somalia - and Montenegro, Albania and Belarus in Europe, bore the brunt of the crisis, as they lacked the resources to adapt to soaring prices or find alternative suppliers.

However, amidst this challenge, the study also revealed hope: over time, major exporting countries like the United States, Canada, and Australia stepped up, partially filling the gaps left by Ukraine. But these changes can compromise biodiversity in these exporting countries, as shown in another paper "Telecoupled impacts of the Russia-Ukraine war on global cropland expansion and biodiversity " published in Nature Sustainability earlier this year by Liu and collaborators. (see news release "War a biodiversity enemy - even in peaceful locales")

"By revealing the hidden vulnerabilities in global food systems, our study emphasizes the need for international cooperation to ensure food security," Jia said. "Policymakers and global organizations can use these insights to build more resilient food networks, invest in local production in vulnerable countries, and create strategies to mitigate the impacts of future crises."

In addition to Jia and Liu, "The Russia-Ukraine war reduced food production and exports with a disparate geographical impact worldwide" was written by Zilong Xia, Yinshuai Li, Xiang Yu, Xutong Wu, Yingjie Li, Rongfei Su, Mengting Wang, Ruishan Chen. The work was financially supported by the USDA-NIFA, the National Science Foundation and Michigan AgBioResearch.