Shifts in climate are strongly linked to increases in violence around the world, a study suggests.
The team says with the current projected levels of climate change, the world is likely to become a more violent place. The study is published in Science.
Marshall Burke, from the University of California, Berkeley, said: "This is a relationship we observe across time and across all major continents around the world. The relationship we find between these climate variables and conflict outcomes are often very large."
The researchers looked at 60 studies from around the world, with data spanning hundreds of years. They report a "substantial" correlation between climate and conflict.
The report also suggests rising temperatures correlated with larger conflicts, including ethnic clashes in Europe and civil wars in Africa.
Mr Burke said: "We want to be careful, you don't want to attribute any single event to climate in particular, but there are some really interesting results."