A study involving the UB reveals the historical impact of climate on human conflict

The effects of climate change are not just limited to rising temperatures or the proliferation of extreme weather events. Its influence can disrupt global peace and security and contribute to the outbreak of tensions and armed conflicts. This is one of the main conclusions of the study Climate, peace, and conflict-past and present: Bridging insights from historical sciences and contemporary research, recently published in the scientific journal Ambio. 

The article is the result of an international collaboration between 20 experts in history, geography, archaeology and peace and conflict studies. The study involves three researchers from the University of Barcelona, Agustí Alcoberro, Mariano Barriendos and Pau Castell, who have brought their expertise in medieval and modern history and environmental history to analyse the interactions between climate and conflict in different historical periods. 

The study presents a comparative analysis of climate impacts in past and current conflicts, and highlights how history can provide tools for understanding and managing the risks arising from contemporary climate change. 

When climate unleashes tensions: a look at history 

The study shows that extreme weather events — such as prolonged droughts, floods or sudden changes in temperature — have played a significant role in the outbreak of social tensions and armed conflicts. These phenomena have affected agricultural production, generated migration and intensified competition for natural resources. 

One of the cases analysed in the study focuses on 17th century Catalonia, a period marked by severe floods and drought episodes. These environmental adversities occurred in a context of growing social tension and coincided with a wave of persecutions for witchcraft. In this area, Agustí Alcoberro and Pau Castell have documented how, at times of climatic crisis, accusations of witchcraft were intensified, often directed against women, as a way of channelling social discontent. 

Professor Alcoberro notes that “in the second and third decade of the 17th century, two very different realities fatefully converged. On the one hand, the ‘little ice age’, which had begun around 1580, reached its peak. It was characterized by cool summers, colder winters and, above all, a combination of atmospheric havoc. Moreover, the spread of the modern concept of witchcraft, through witchcraft manuals, blames the devil and, by extension, witches for extreme weather phenomena, such as storms, hailstorms or very dense fogs that ruin harvests. All this has an impact on an impoverished population that needs to identify an enemy. In Catalonia, in the years 1614-1628, more than 1,000 women were executed, often reported by their neighbours and condemned by local courts”. 

The study also reviews other historical cases, such as the crisis of the Hittite empire more than 3,000 years ago — linked to a severe drop in agricultural production due to climatic changes — or the peasant revellions in China in the 19th century, aggravated by periods of extreme drought. 

The Mediterranean, a historically vulnerable region 

The paper highlights that the Mediterranean basin has been, and continues to be, one of the most vulnerable regions to the effects of climate change. Historically, water scarcity, pressure on natural resources and climate variability have generated tensions that, in several cases, have led to armed conflicts or episodes of social violence. 

Mariano Barriendos, a UB researcher specializing in historical climatology, has contributed to the study with a detailed reconstruction of extreme climatic episodes, such as the severe floods of 1617 in Catalonia. Using historical documentary sources, his research provides a better understanding of the effect of climatic fluctuations on society over the centuries and the role they have played in the escalation of tensions and conflicts. 

The authors of the paper warn that the Mediterranean is currently exposed to a similar combination of environmental and socio-economic pressures. Without proper management, these dynamics could be reproduced in the future. 

Learning from the past to face the future 

One of the central contributions of the research is the claim of the importance of integrating the historical perspective in the analysis of conflicts related to current climate change. The study of historical patterns can help to better understand the mechanisms that connect climate phenomena with social and political tensions. 

UB researchers have helped to show that while climate can act as a triggering factor, the severity and persistence of conflicts depend to a large extent on institutional responses, community resilience and resource management. The study also highlights that the effects of climate on security are not always immediate: they often manifest themselves indirectly, with time lags or geographical shifts. 

Commitment and action for a more resilient future 

The article concludes with a call for institutions and policy makers to incorporate the historical perspective into their climate mitigation and adaptation strategies. Learning from the past can be key to designing more effective policies that prevent the escalation of tensions and foster more equitable and resilient societies to cope with today’s climate challenges. 

The UB researchers stress that history offers valuable lessons for understanding how societies have responded to climate crises in the past and how these responses can inspire current policies. 

Reference article 

White, Sam; Collet, Dominik; Alcoberro, Agustí et al. “Climate, peace, and conflict—past and present: Bridging insights from historical sciences and contemporary research”. Ambio, February 2025. DOI: 10.1007/s13280-024-02109-1.