A climate of conflict: How the little ice age sparked rebellions and revolutions across Europe

The Little Ice Age (LIA) – lasting from ∼1250 to ∼1860 - was a long period of cooler, drier conditions, characterized by increased climate instability. The most significant climate extremes were more closely associated with interannual temperature variations or particularly severe, isolated cold spells than with prolonged cold spells lasting many years. During this pre-industrial phase of climate instability, many rebellions broke out, one of the most famous being the French Revolution of 1789. A key question, however, relates to the precise and often intricate role of climate in precipitating these widespread uprisings and rebellions that profoundly reshaped human institutions, particularly in the European context. Using data for solar activity, temperature, precipitation, volcanic forcing and the evolution of grain prices, we compared and contrasted the occurrence of rebellions and revolutions across a wide geographical area comprising Europe-Russia-Ottoman Empire with LIA climate and hazards. We find that climate change primarily affected people's livelihoods by reducing harvests, lowering food-resource availability and sharply increasing cereal prices. Climate therefore played a major role in heightening population vulnerability by exacerbating one of the greatest scourges: malnutrition. For the populace, this fuelled social anger towards political authorities for failing to mitigate the impact of climate change. This study primarily reveals that environmental causes did not generate social crises during the LIA but rather triggered a cascade of environmental and human events that interacted, ultimately leading to highly conflictual situations. The LIA serves as a warning to modern political systems, highlighting the necessity to anticipate the consequences of current climate change to mitigate its impact on societies and prevent social unrest and conflict.