Climate shift has at times been pointed to as a cause of conflict, fuelling for instance the 1789 French Revolution by wrecking harvests and driving hungry peasants to the city.
However, evidence in support of the theory has often been dismissed as patchy or anecdotal. The case though has recently received a strong boost with the first scientific study to declare an unmistakeable link between climate fluctuations and violence.
According to the study, tropical countries affected by the notorious El Nino weather event were twice as likely to be hit by internal unrest as compared to the phenomenon's cooler, wetter counterpart, La Nina.
The study's authors claim the civil war and the famine that hit the Horn of Africa were typical outcomes of a climate swing that caused drought and overstressing of an already
Known formally as the El Nino-Southern Oscillation (ENSO), the cycle occurs every two to seven years, lasting between nine months to two years, often severely damaging agriculture, forestry and fishing.
It starts with the build-up of warm water on the western side of the tropical Pacific and shifts across the ocean. In this part of the cycle, El Nino, can cause dramatic rainfall and temperature pattern changes, unleashing scorching heat or drying winds across much of Africa, South and Southeast Asia and Australia.