Single-authored

Do weapons imports increase or contain violence?
Surprisingly causal estimates remain missing, leaving this question unanswered. Except for a few studies constrained to the US. However, most of the suffering from armed violence is experienced by developing countries. Countries who most of the time lack the technology and production capacity to produce weapons, forcing them to imports weapons from developed countries. 
Using an instrumental variable and worldwide data from 1992 to 2011, I show that weapons imports increase the probability of internal conflict, the number of internal conflicts within a country, the number of battle-related deaths and the number of refugees.
A simple back of the envelope computation reveals that if Europe would stop for a year to send weapons to Africa it would reduce the number of refugees by half a million.

with Jean-Philippe Bonardi, Dimitrija Kalanoski and Rafal Lalive

Countries across the world introduced various types of lockdown measures restricting their populations’ movements in order to reduce the morbidity and mortality rates related to the COVID-19 pandemic, caused by the novel coronavirus SARS-CoV-2 that first emerged in China in 2019. We analyze whether these measures helped reduce the spread of infections and the number of deaths. We also compare their effectiveness in developed countries against developing countries. Our data covers 184 countries in the period from 31st December 2019 to 4th May 2020 and identifies when lockdowns were adopted, along with confirmed cases of infections and deaths due to COVID-19. The panel data structure, by addressing inherent endogeneity issues, enables us to make some causal claims. We find that partial lockdowns were as effective in reducing the number of infections and deaths as stricter measures. We estimate that in developed countries, they reduced about 650,000 deaths, but we do not find such significant effects in developing countries. This suggests that lockdowns work only if the opportunity costs of staying at home are not too high. We also find that countries that acted fast fared better, but that closing borders has had no appreciable effect, even after fifty days.

with Dominic Rohner

PNAS (2021)

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In an era where global trade is under pressure, it is heatedly debated whether a more integrated, globalized world is fueling or appeasing conflicts. Past studies have focused on how trade links impact interstate wars, but the effects of globalization on domestic conflict have been severely understudied. Our dataset of the strategic importance of each point of the globe allows us to shed light on this controversy. This algorithm-based measure is constructed by using exclusively natural terrain features, thereby avoiding common methodological pitfalls confounding results. We find that while strategic locations may often be the object of armed competition, periods of international trade booms increase the incentives to protect trade routes and attenuate the conflict risk at strategically important locations.

With Massimo Morelli and Dominic Rohner

Natural resources are often argued as one of the major drivers of conflict. Primary energy consumption, today, are oil (34%), coal (27%) and natural gas (24%). While coal and oil relationship on conflict have been well studied, natural gas remains to be addressed. The cheapest and less technology intense way of sending natural gas is by pipeline. Thus, we study how central positions in the pipeline network drives military interstate disputes. The Caucasus, Central Asia, the Middle-East and Eastern-Europe are often experiencing tensions caused by this natural resource. Those regions are typically the one linking large suppliers to consumers. Interestingly they are not necessarily producer of gas but sometimes only central player on the pipeline network.

with Jean-Philippe Bonardi, Dimitrija Kalanoski, Rafael Lalive, Raahil Madhok, Frederik Noack, Dominic Rohner and Tommaso Sonno

Environmental Research Letters (2021)

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In Spring 2020, COVID-19 led to an unprecedented halt in public and economic life across the globe. In an otherwise tragic time, this provides a unique natural experiment to investigate the environmental impact of such a (temporary) ``de-globalization". Here, we estimate the medium-run impact of a battery of COVID-19 related lockdown measures on air quality across 162 countries, going beyond the existing short-run estimates from a limited number of countries. In doing so, we leverage a new dataset categorizing lockdown measures and tracking their implementation and release, extending to August 31st 2020. We find that domestic and international lockdown measures overall led to a decline in PM2.5 pollution by 45 percent and 35 percent, respectively. This substantial impact persists in the medium-run, even as lockdowns are lifted. There is substantial heterogeneity across different types of lockdown measures, different countries, and different sources of pollution. We show that some country trajectories are much more appealing (with fewer COVID-19 casualties, less economic downturn and bigger pollution reductions) than others. Our results have important policy implications and highlight the potential to "build back better" a sustainable economy where pollution can be curbed in a less economically costly way than during the COVID-19 pandemic.