The Russian invasion of Ukraine significantly impacted international grain and oilseed markets, raising global food security concerns. Ukraine and Russia are major exporters of these commodities, particularly to low-income countries in the Middle East and Africa. Pre-existing rising energy and fertilizer prices were exacerbated by the conflict, increasing agricultural production costs. While many studies focus on short-term or specific regional effects, this study provides a global, longer-term, economy-wide perspective using a computable general equilibrium (CGE) model. The study's novelty lies in its incorporation of circular flows of income and expenditures (crucial for food access analysis), an integrated land-food-fertilizer-energy perspective, and a comprehensive assessment of environmental consequences, including biodiversity and greenhouse gas emissions. This approach allows for a holistic evaluation of the trade-offs between food security and environmental concerns resulting from the conflict.

The authors note that many existing analyses of the conflict's impact on food markets focus on short-term effects, specific countries, individual commodities, or sectors. This study differentiates itself by offering a global, longer-term, economy-wide perspective, incorporating circular income and expenditure flows, and an integrated assessment of the land-food-fertilizer-energy nexus and its environmental implications. This contrasts with previous studies relying on expert judgments or sector-specific models. The authors mention studies by Abyo et al., Rauschenberger & Kriatovos, Benton et al., Balana et al., and Weir & Duchoslav, among others, but do not extensively discuss their findings.

The study employs the Modular Applied GeNeral Equilibrium Tool (MAGNET) model, a computable general equilibrium (CGE) model that integrates food, fertilizer, and energy markets globally. MAGNET accounts for bilateral trade flows and circular income and expenditure flows for various labor types, explicitly representing N, P, and K agricultural and energy markets and segmented labor markets (agricultural and non-agricultural). Food availability is measured in local per capita terms, incorporating purchasing power. The study assesses environmental impacts through agricultural land use and greenhouse gas (GHG) emissions. Three scenarios are developed: (1) Ukraine impacts (trade blockade with Russia and Belarus, GDP loss, reduced agricultural production, higher trade costs), (2) Ukraine and Russia impacts (adding EU and US sanctions against Russia, GDP loss, reduced Russian exports of grains and oilseeds), and (3) Ukraine, Russia, and energy price impacts (adding a global energy price increase). Each scenario builds upon the previous one, allowing for an assessment of the individual and combined effects of these shocks.

The study's key findings include: * **Economic Impacts:** Significant GDP falls in Ukraine (-33%) and Russia (-11%) during 2022-2024. Other regions experience smaller impacts, with Central Asia most affected (-0.5%). Energy price increases have the most substantial impact on GDP declines. * **Production Impacts:** Production declines in Ukraine and Russia are partly offset by increased production in other regions (1-11% increase depending on the region). Higher global prices incentivize increased production, particularly for oilseeds. Scenario 3 (including higher energy prices) shows slight increases in oilseed production, driven by non-food applications (biofuels). * **Price Impacts:** Substantial increases in world market prices for wheat (+9.2%), other cereals (+8.4%), and oilseeds (+5%). These increases are driven by reduced Ukrainian and Russian production and exports, further exacerbated by sanctions and energy price increases. Fertilizer prices, especially nitrogen, rise significantly due to higher energy costs. * **Food Availability:** Food availability decreases in many low-income countries due to reduced supply from Ukraine and Russia, with Egypt, Turkey, and the Middle East most heavily impacted. The effects are less pronounced in Europe. * **Food Access:** Food access (measured by a food purchasing power index) deteriorates in many low- and middle-income countries, particularly for those heavily reliant on cereals. The impact is less severe for those with more diverse diets. Higher food and energy prices negatively affect food affordability, especially for low-income groups, even in developed countries like the EU. * **Environmental Impacts:** Agricultural land use expansion increases globally (6.2 Mha in scenario 1, 6.6 Mha in scenario 3), primarily in Middle and South America and Rest of Africa, leading to increased GHG emissions (0.6 Gt CO2e). However, the overall GHG emissions might decrease as lower fossil fuel use (due to higher prices) outweighs the land-use-related increases (a decrease of 1.6 Gt CO2e in scenario 3), with Asia and Oceania showing the largest emissions reductions. The increase in agricultural land use poses a risk to biodiversity.

The study's findings highlight the complex and interconnected effects of the Russia-Ukraine war on global food security and the environment. While global food availability isn't threatened, affordability is severely compromised for vulnerable populations. The global response of increased production in other areas provides some offset, but increased land use poses risks to biodiversity. The counterintuitive finding of reduced overall GHG emissions reflects the dominance of reduced fossil fuel consumption over land-use-related emissions increases. The study's results are relevant for policymakers seeking to balance food security with environmental sustainability goals.

The Russia-Ukraine war negatively impacts food affordability and biodiversity. While global food production increases partially compensate for losses from Ukraine and Russia, higher food and energy prices disproportionately affect low-income populations. Counterintuitively, overall greenhouse gas emissions may decline due to reduced fossil fuel consumption, however, increased land use threatens biodiversity. Further research is needed to explore the longer-term consequences and regional variations of these effects, considering uncertainties like the war's duration and export restrictions.

The study acknowledges several limitations. The model is a comparative static analysis, assuming rational market behavior and not capturing short-term market adjustments. It also does not fully encompass all aspects of food security (utilization and stability), nor does it incorporate a detailed household-level analysis. The scenarios rely on assumptions about the war's duration and its economic and environmental effects. Regional aggregation may mask significant within-region variations. Finally, the model assumes that countries can respond normally, ignoring potential factors like droughts.