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Global climate change, food supply shocks, and conflict-induced migration
Une population mondiale croissante peut-elle être nourrie si des changements climatiques ont lieu? Pour aborder cette problématique complexe, nous conduisons une analyse structurelle intégrant l'évolution de l'économie mondiale et du climat, l'utilisation des énergies fossiles, ainsi que les déterminants clés de l'offre et la demande de nourriture, comme la surface agricole disponible, les décisions de fertilité, et le progrès technique.
Dans un premier temps, nous analysons la manière avec laquelle une réduction de la productivité dans l'agriculture causée par les changements climatiques affecte l'évolution de l'économie ainsi que la croissance démographique au niveau global. Dans un deuxième temps, nous étudions les implications au niveau régional. Cela nous amènera à considérer les pressions migratoires internationales résultant de pénuries de nourriture dans les pays en voie de développement, ainsi que les liens entre politique climatique et immigration dans les pays développés.
Une approche économique pour étudier les changements climatiques offre une perspective novatrice pour la formulation de politiques publiques au niveau global et régional.
According to IPCC (2014), the climate system has unequivocally warmed, and without mitigation the range of increase in global mean temperatures relative to preindustrial levels will be 2.5 to 7.8 degrees celcius by 2100. The IPCC further projects an increased frequency of extreme weather events, with significant impacts across locations even for moderate changes in global average temperatures (Schleussner et al., 2016). This suggests that a mix of mitigation and adaption will be necessary.The objective of this research program is to inform climate policies in relation to agricultural productivity and food security impacts, induced local conflicts and forced migration. Growing empirical evidence shows that agricultural yields are very negatively affected by extreme weather shocks (e.g. Schlenker and Roberts, 2009), yet existing work assessing social cost of carbon (SCC) does not consider food-related impacts of climate change on population (Greenstone et al., 2013). Building on Nordhaus (1993, 2017) and Lanz et al. (2017), I develop a structurally-estimated climate-economy model that treats agriculture separately from other economic activities, and includes population growth and the demand for food as endogenous outcomes. This allows me to introduce realistic agricultural productivity `damages,' and assess how the SCC is affected by climate induced food supply shocks.In this setting, I consider international migration as an adjustment margin to climate change, food scarcity, local conflicts and political crisis (Hsiang et al., 2011, 2013). Empirical evidence - although still controversial - suggests that climate and environmental shocks have a direct impact on migration (Cai et al., 2016; Missirian and Schlenker, 2017). In contrast, I consider how climate change induces food scarcity, and in turn generates local riots and conflicts (Bellemare, 2015; Crost et al., 2018). This, in turn, would lead to an indirect impact of climate change on forced migration (Carleton and Hsiang, 2016; Koubi, 2017). Following Nordhaus and Yang (1996) and Burzynski et al. (2018), I extend my climate-economy model to have multiple regions, and introduce labor mobility in response to regional climate impacts (Prieur and Schumacher, 2016). This will deliver evidence on how indirect climate migration affects the SCC.Taken together, the research program offers novel perspectives on climate-change and migration as an adaptation margin, as well as implied trade-offs with mitigation.
Impacts of rainfall shocks on out-migration are moderated more by per capita income than by agricultural output in Türkiye
2023, Delacrétaz, Nathan, Lanz, Bruno, Amir H. Delju, Piguet, Etienne, Rebetez, Martine
Rural populations are particularly exposed to increasing weather variability, notably through agriculture. In this paper, we exploit longitudinal data for Turkish provinces from 2008 to 2018 together with precipitation records over more than 30 years to quantify how variability in a standardized precipitation index (SPI) affects out-migration as an adaptation mechanism. Doing so, we document the role of three potential causal channels: per capita income, agricultural output, and local conflicts. Our results show that negative SPI shocks (droughts) are associated with higher out-migration in rural provinces. A mediated-moderator approach further suggests that changes in per capita income account for more than one quarter of the direct effect of droughts on out-migration, whereas agricultural output is only relevant for provinces in the upper quartile of crop production. Finally, we find evidence that local conflict fatalities increase with drought and trigger out-migration, although this channel is distinct from the direct effect of SPI shocks on out-migration.
Growth and adaptation to climate change in the long run
2021, Lanz, Bruno
Impacts of rainfall shocks on out-migration are moderated more by per capita income than by agricultural output in Türkiye
2023, Delacrétaz, Nathan, Lanz, Bruno, Amir H. Delju, Piguet, Etienne, Rebetez, Martine
Growth and adaptation to climate change in the long run
2021, Lanz, Bruno
Growth and Adaptation to Climate Change in the Long Run
2019, Simon Dietz, Lanz, Bruno
Can a growing world be fed when the climate is changing?
2020, Simon Dietz, Lanz, Bruno
Growth and adaption to climate change in the long run
2023, Lanz, Bruno
Growth and adaptation to climate change in the long run
2022, Simon Dietz, Lanz, Bruno
Impacts of Rainfall Shocks on Out-migration in Türkiye
2023, Delacrétaz, Nathan, Lanz, Bruno, Amir Hooshang Delju, Piguet, Etienne, Rebetez, Martine