The increasing concern over global warming has heightened interest in climate change's impact on human societies. While many researchers agree that climate anomalies have shaped past societies, the authors argue that the scholarly discourse is too narrow. Existing research often prioritizes proxy-based studies with limitations in geographic distribution and dating accuracy, or focuses on institutional structures over climatic factors. This paper addresses two fundamental questions: What climatic anomalies destabilize societies, and what duration and intensity are necessary to instigate structural change? The authors propose that gradual, seemingly 'usual' events like prolonged droughts have more profound and 'extraordinary' impacts than short-term events.

The paper reviews existing literature that examines the impact of climate change on societies. It criticizes the reliance on proxy-based studies of past climates, citing limitations in geographic coverage, dating precision, and the wide margin of error in reconstructing human-social processes. The study also notes that contemporary climate studies often downplay the climatic factor, emphasizing institutional structures and human management capabilities. The authors acknowledge the existing research that uses proxy-based studies to connect volcanic eruptions and other extreme events to social transformations, but points out that these studies often focus on short-term events.

The authors employ a qualitative historical methodology to analyze past climates and social transformations. They examine three case studies: the climate crises in 11th-12th century Western Asia and Northern China, and the 2010s crisis in Mali. These case studies focus on geographically and culturally diverse societies in the 'Fragility Zone', areas with annual precipitation of 400-600 ml, which were previously considered politically and administratively successful. The authors use a combination of historical documents, climatic data (including temperature, drought indices, precipitation), and surveys to explore the impact of climate anomalies on food security, social stability, and political events. For the historical case studies, they utilize detailed historical records such as dynastic histories and yearly records of Nile's rise to understand the climatic conditions. For the Mali case study, they utilize high-resolution, quantitative data, including temperature, drought indices, precipitation, and qualitative data such as government reports and surveys. The researchers aim to analyze the duration and intensity of climatic events and their impact on societies, particularly their impact on food availability. The study uses the concept of resilience to understand societal responses to climate shocks, examining how extended climate events impact food availability and potentially push societies beyond their resilience thresholds. The research considers both the physical aspects of the climate event and the response of the affected societies, a combined methodology that considers both the driver and the response to understand the extent of the impact.

The analysis of the three case studies supports the authors' hypothesis that prolonged climate anomalies affecting food availability are crucial factors in societal transformations. In 11th and 12th century Northern China, a series of droughts and cold spells (dzud) weakened the Liao dynasty, ultimately contributing to its collapse. The severe and prolonged cold anomalies severely affected the Jurchen tribes, pushing them to unite and conquer the Liao. The analysis of the Liao Dynasty's history shows a period of relative climatic stability followed by a period of increasingly frequent and severe anomalies culminating in the dynasty's collapse. The study uses detailed historical sources to show that prolonged periods of food scarcity weakened the dynasty and the increased vulnerability played a crucial role in the Jurchen's success. In 11th century Western Asia, consecutive years of drought in both the Eastern Mediterranean and East Africa (affecting Nile River levels) severely impacted the Fatimid dynasty in Egypt, despite their efficient governance and management capabilities. Even with interventionist policies by the Fatimids, consecutive years of drought led to famine, social unrest, and ultimately weakened the state. The study provides detailed information from precisely dated historical documents showing how consecutive droughts severely impacted food production and distribution, causing social unrest and ultimately contributed to a weakened state. The Mali case study from the 2010s reveals a strong correlation between droughts in 2009-2010, high temperatures in 2011, and the escalating violence in 2012. Food insecurity, particularly amongst nomadic populations, fueled the conflict. The high resolution data available for this case demonstrates that the effects of climate change in impacting the availability of food were evident in a short period (2-3 years), escalating social unrest that ultimately led to a full-blown war. The study emphasizes how the combination of multiple factors, including climate, social inequality, and political instability, contributed to the outbreak and escalation of the conflict. The authors demonstrate a relationship between a period of food insecurity related to climate anomalies and the ensuing conflict.

The findings challenge the conventional dichotomy of short-term versus long-term climatic events. The authors argue that the duration of a climatic anomaly's impact on society is crucial, rather than simply its duration in calendar years. The three case studies reveal how a series of seemingly ordinary events, each individually manageable, can accumulate to create an extreme climatic event with profound societal consequences. The focus on food availability as a key variable highlights a significant aspect often overlooked in climate-society studies. The research demonstrates that gradual declines in food security, caused by prolonged climate anomalies, can have a more significant impact than acute, short-term disasters. The findings underscore the need for a more nuanced approach to studying the climate-society nexus, moving beyond simplistic categorizations and considering the cumulative impacts of seemingly ordinary events.

This study proposes a new methodological approach to assessing the impact of climatic events on societies, emphasizing the cumulative effect of prolonged anomalies and the crucial role of food security. The case studies demonstrate that extended climate anomalies impacting food availability can push societies beyond their resilience thresholds, leading to significant and lasting social changes. Future research should further investigate the interplay between climatic events, food systems, and social resilience in various contexts. The study emphasizes the need for a more nuanced understanding of how gradual, prolonged climate anomalies can affect societies and contribute to broader socio-political change.

The qualitative nature of the historical case studies may limit the generalizability of the findings. The reliance on historical documents and climate reconstructions can also lead to challenges in establishing precise cause-and-effect relationships. Further quantitative research is needed to strengthen the findings. The focus on specific geographical regions limits applicability to regions with different climate systems or societal structures. While the Mali case provides high-resolution data, the complex interplay of socio-political factors beyond climate makes isolating climate's specific contribution difficult.