A new analysis in Nature finds that climate change has likely played a relatively small role in driving armed conflict so far. But if temperatures reach more than 2 °C above preindustrial levels, it may substantially increase violence around the globe.

The methods: The paper published on Wednesday synthesized the judgments from a group of 11 highly cited climate and conflict experts at Stanford, the University of Exeter, the Peace Research Institute Oslo, and elsewhere.

The findings: Shifting climate conditions have “substantially increased” the likelihood of armed conflict breaking out in only about 5% of instances when it has in the past century, according to the mean estimate among the experts. Other factors were far more influential in raising conflict risks, including greater levels of poverty, inequality between groups, and a recent history of violent conflict.

But if temperatures rise by 2 °C, there is a 13% chance of substantial increase in the risk of armed conflict, the analysis found. That rises to a 26% chance if temperatures reach 4 °C. Global surface temperatures have already risen nearly 1 °C, and current energy and emissions trajectories suggest it’s almost certain they’ll reach 2 °C.

The mechanisms: Climate impacts such as higher temperatures, droughts, and floods can all create economic shocks by, among other things, reducing agricultural yields and driving up food prices. These shocks can, in turn, exacerbate other drivers of violence by deepening poverty or increasing inequality and tension between groups.

Addressing rising risks: The experts agreed that climate-related conflict risks can be reduced with investment in measures like crop insurance, training, improved food storage, conflict mediation, peacekeeping operations, and post-conflict reconstruction. But the odds of reducing those risks fall as temperature levels rise, the researchers found.

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