Global Systemic Climate Shocks and Their Impacts on the International Food System: A Case Study of Tambora-Scale Eruptions on Global Agricultural Yields and Prices

Diplôme Thèse Global Systemic Climate Shocks and Their Impacts on the International Food System: A Case Study of Tambora-Scale Eruptions on Global Agricultural Yields and Prices eng 2025-06-24 2025-06-24 author Lynam Gary Bernard 930906 director Stoffel Markus 131626 Forel Communs (FOREL) director Di Falco Salvatore 788423 Recherche et enseignement GSEM (RESEM) 147 10.13097/archive-ouverte/unige:189266 urn:nbn:ch:unige-1892661 Sc. 5948 <p>The April 1815 eruption of Mount Tambora, the largest in 500 years, released vast quantities of sulfuric gases into the stratosphere, forming aerosols that disrupted Earth's radiative balance. This triggered global cooling, with profound consequences: 1816's <i>"Year Without a Summer"</i> brought poor harvests, soaring grain prices, and the last major subsistence crisis in the Western world. Such historic events underscore the vulnerability of today’s highly interconnected food systems, which are susceptible to simultaneous systemic shocks. While no Tambora-scale eruption has occurred in the modern era, understanding its potential impacts is crucial to prepare for similar high-magnitude volcanic disruptions in the future. This thesis investigates the potential impacts of a modern Tambora-scale eruption on global food production and trade. Using climate simulations and statistical yield models, we map yield anomalies for maize, rice, wheat, and soybeans, identifying the most vulnerable food-producing regions. The study further explores how production shocks influence global wheat and maize prices through the Trade WIth STorage (TWIST) model, examining market resilience under various storage scenarios. We find that maize and rice suffer the most severe losses in the case of an eruption, with yield declines reaching 80% and 60% of historic lows, respectively, while soybeans and wheat demonstrate greater resilience. Regional impacts differ starkly: North America and Europe show modest yield increases for maize, wheat, and soybeans, particularly in a “sweet spot” latitude band (30–40°N), whereas tropical regions, particularly rice-producing regions, experience persistent negative shocks. Eastern Asia, a critical maize and rice producer, faces severe disruptions, with potential export restrictions exacerbating food insecurity in regions like Africa, which rely heavily on imports. Wheat exhibits mixed responses, with Europe benefiting and Southern Asia seeing minor declines. These findings underscore the vulnerability of tropical regions, the resilience of temperate zones, and the importance of understanding regional dynamics to mitigate global food insecurity. Our analysis of global price responses reveals three key insights. First, storage levels are critical for market resilience, with low-storage scenarios causing maize price swings up to five times greater than under high-storage conditions. Second, price impacts evolve over multiple years, with initial surges followed by declines, and maize exhibiting greater volatility than wheat due to its concentrated production and diverse uses. Third, wheat and maize markets show similar response patterns (ρ = 0.82), highlighting shared vulnerabilities. These findings underscore the importance of sufficient storage, coordinated policies, and long-term adaptation strategies to enhance food system resilience.</p> Dewey 550 41 Département F.-A. Forel des sciences de l'environnement et de l'eau 153 false 1394 C-CIA Climate Change Impacts and Risks in the Anthropocene 022ccb90-8b90-4301-824e-dba88b37aee3 Thesis Restricted Thesis_manucript_LYNAM_Gary_2025_fi.pdf 22285189 application/pdf Private 2027-06-24 7ed7fac56bfb682fe68f88b9309e3ac8d101e535e248db8ce28a1b43a38b3624 319662f3-4b2c-4a9e-bb5f-a84dea302258 Summary Public Summary_-_Global_Systemic_Climate_S.docx 15758 application/vnd.openxmlformats-officedocument.wordprocessingml.document 360ddd21ed0e1550d1128384cb4ccc302277db5238619cb97892fde3a0f538af d56a1a08-5a86-456a-b3f3-2499ba6f4a34 Imprimatur Public Imprimator.pdf 613424 application/pdf 598ddda8ae8d622bc6b94fe556b5cdf662f0bb0881e7f99f84c07e85e969897d openAccess Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département F.-A. Forel des sciences de l'environnement et de l'eau

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Global Systemic Climate Shocks and Their Impacts on the International Food System: A Case Study of Tambora-Scale Eruptions on Global Agricultural Yields and Prices		2025	98	0
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Lynam, Gary Bernard

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