Researchers from Princeton University and the University of California-Berkeley report in the journal Science that even slight spikes in temperature and precipitation have greatly increased the risk of personal violence and social upheaval throughout human history.
Projected onto an Earth that is expected to warm by 2 degrees Celsius by 2050, the authors suggest that more human conflict is a likely outcome, reports Science Daily.
The researchers analysed 60 studies from a number of disciplines – including archaeology, criminology, economics and psychology – that explored the connection between weather and violence in various parts of the world from about 10,000 BCE to the present day.
During an 18-month period, the Princeton-Berkeley researchers reviewed those studies’ data — and often re-crunched raw numbers — to calculate the risk that violence would rise under hotter, wetter conditions.
They found that while climate is not the sole or primary cause of violence, it undeniably exacerbates existing social and interpersonal tension in all societies, regardless of wealth or stability.
They found that one standard-deviation shift – the amount of change from the local norm — in heat or rainfall boosts the risk of a riot, civil war or ethnic conflict by an average of 14 percent.