What did increased domestic violence in India and Australia, a spike in assaults and murders in the US, ethnic violence in Europe and land invasions in Brazil have in common?

According to new research, published last month, climate variations played a role in each of these incidences of violence. A look at 60 previous studies from around the world with data spanning hundreds of years, led researchers from Princeton, Berkeley and Cambridge to the conclusion that past climatic events have had a significant influence on human conflict.

They do not propose that climate was the only, or even the main driving force of conflict, but that climate variations do have a substantial effect on the occurrence of violence, both at the domestic, inter and intra state level.

Based on the behavior of human societies in the past, and assuming that future populations would respond similarly to past populations, the researchers concluded that climate change had the potential to substantially increase conflict around the world.

Drought Hit Reservoir in China

This is not the first research looking at the link between climate change and conflict, but this research used statistical methods to look at past cases and examine the causal relationship. The researchers also tried to enable future projections; finding that one standard deviation towards hotter conditions causes the likelihood of personal violence to rise by 4% and intergroup conflict by 14%.

The researchers found that the relationship between climate change to increased violence is a strong one, but they also suggest that further research is needed to determine how these changes manifest themselves into violence.

A 'threat multiplier'

This research follows previous statements by the UN in 2009 that climate change was a "threat multiplier" that exacerbates existing threats, such as persistent poverty, weak institutions, mistrust between communities and other fault lines.

UN Secretary-General Ban Ki-moon also said in 2011 that climate change "not only exacerbates threats to international peace and security, it is a threat to international peace and security".

This issue of climate change (as a cause) and conflict (as an effect) has attracted a lot of attention and critique in recent years, but I believe it is still impossible to determine what exact role (if any) climate change plays in conflicts. Research into this topic is still controversial.

Conflicts are the result of a complex interaction between political, social and economic factors and though environmental factors may play a role in this interaction, generally they are not considered to be a direct or primary driver of conflict.

Nevertheless, by increasing the likelihood of extreme weather events, affecting sea levels and water availability – it seems obvious to me that climate change can exacerbate existing vulnerabilities, and that that trend will increase in coming years.

Consider the conflict in Darfur, Sudan. In 2007, the UN General Secretary famously argued that the conflict started as "an ecological crisis, arising at least in part from climate change". Prolonged drought in Sub-Saharan Africa has lead to water and food scarcity, increasing tensions and fueling conflict over resources.

Wheat Field Irrigation in Maharashtra

Complex interaction of factors

More recently, the ‘Arab Spring’, although described as unpredictable, can be directly linked to discontent with brutal and oppressive regimes.

Closer examination, however, also indicates that environmental factors could have played a role, albeit a background role, in sparking the unrest together with "a complex interaction of other political, social, and economic factors".

In Egypt, for example, food prices had increased due to a slump in imports sparked by crop failures in exporting countries. These droughts, attributed by some researchers to climate change among other factors, put market pressure on international wheat prices impacting countries such as Egypt, the world’s largest wheat importer.

Across in Syria, a decade of droughts also lead to a dramatic decrease in crops and damaged the livelihoods of millions of people, prompting hundreds of thousands of villagers to abandon rural areas and move to the cities.

This resulted in additional stresses to already strained urban communities and when protest broke out in Syria in March 2011, disaffected rural communities took central role in the opposition movement. What followed was a brutal crackdown by the Syrian regime and a resulting civil war, but some analysts also suggest the drought initially played a huge role in fueling the initial uprising.

It is impossible, usually, to link one extreme weather event such as a drought to climate change. Nevertheless, scientists agree that climate change will usher in an increased likelihood of extreme weather events, including droughts, floods and super storms. The potential for a food crisis has also increasingly sparked headlines around the world.

Research into the potential role climate change may play in conflict will no doubt continue, but even while this research remains controversial it is wise to – out of precaution – act on the possibility that climate change will indeed acerbate conflict and violence in a significant way.

Concern for peace, therefore, is one more reason for decisive action to save our climate, for advancing an energy revolution, for saving the Amazon and fighting to #SavetheArctic.

Jen Maman is Greenpeace International´s Peace Advisor and is based in Istanbul.