WASHINGTON: Global warming may not only spell doom for many species, it could also trigger more interpersonal tension and violence worldwide, a new study has claimed.

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 of climate change.

The researchers analysed 60 studies from a number of disciplines - including archaeology, criminology, economics and psychology - that have explored the connection between weather and violence in various parts of the world from about 10,000 BC to the present day.

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 per cent.

There is a 4 per cent chance of a similarly sized upward creep in heat or rain sparking person-on-person violence such as rape, murder and assault.

The researchers report that climate-change models predict an average of 2 to 4 standard-deviation shifts in global climate conditions by 2050.

Establishing a correlation between violence and climate change now allows policymakers and researchers to examine what causes it and how to intervene, said lead author Solomon Hsiang, who conducted the work.

"We think that by collecting all the research together now, we're pretty clearly establishing that there is a causal relationship between the climate and human conflict," Hsiang said.

"People have been sceptical up to now of an individual study here or there. But considering the body of work together, we can now show that these patterns are extremely general. It's more of the rule than the exception.

"Whether there is a relationship between climate and conflict is not the question anymore. We now want to understand what's causing it," Hsiang said.