The United Nations’ chief climate scientist recently said that planetary warming threatens “a multitude of security impacts.” For years, U.S. military officials have called climate change a “threat multiplier,” warning that rising temperatures would fuel political instability, conflict and mass migration in the decades ahead. But, until now, experts had not established a firm link between climate change, political violence and displacement.

New research has found strong evidence that climate change is spurring conflict, which is driving people to abandon their homelands and seek safety elsewhere. It should come as no surprise that rising temperatures are worsening droughts, heat waves and floods, leading to shortages of food, water and other resources, resulting in conflict in many regions of the world. In so doing, climate change is an indirect cause of migrant exodus, according to scientists.

“The effects of climate change go way beyond pure meteorological changes and have consequences for social and political processes worldwide,” said study co-author Jesus Crespo Cuaresma of the International Institute for Applied Systems Analysis (IIASA) and a professor of economics at Vienna University of Economics and Business. “Acknowledging this evidence could take us closer to finding global solutions to the problem.”

Syrian refugees strike at a railway station in Budapest, 2015. Source: Mstyslav Chernov

In recent years, climate change has been blamed for unrest and civil war in the Middle East and sub-Saharan Africa, and for the the extensive migration often that follows. This is believed to be the first study to show that climate change is responsible. “None of the existing pieces used statistical methods to assess whether this relationship was a causal one,” Crespo Cuaresma said.

The scientists cited the ongoing conflict in Syria as a major example of the climate-conflict-migration chain, adding that other struggles in Africa also have sent refugees fleeing from their homes, often to Mediterranean countries in Europe. Poorer countries enduring greater political instability are more vulnerable. “Sub-Saharan African countries are among those where climatic shocks appear to have the strongest effect on the probability of conflict,” Crespo Cuaresma said. “The case of South Sudan, for example, is particularly important.”

South Sudanese refugees line up for rations, 2016. Source: United Nations

IIASA scientists — which also included Guy Abel of Shanghai University, Raya Muttarak of the University of East Anglia, and Michael Brottrager of Johannes Kepler University Linz — studied asylum applications from 157 countries from 2006 to 2015, which were obtained from the UN High Commissioner for Human Rights. They used asylum seekers because they were more likely than other migrants to be fleeing conflict.

The team examined data on intensity and duration of droughts as well as data on conflict-related fatalities. They fed their numbers into computer models, along including data on the distance between country of origin and destination, population sizes, migrant networks, the political status of the countries, and ethnic and religious groups, among other variables. They determined that climate change played a significant role in migration, most notably by worsening droughts that were exacerbating conflict.

The relationship between climate change, conflict and migration. Source: Global Environmental Change

“We found that the increase in asylum seeking flows in the period 2010 to 2012 was driven by drought-induced conflict,” Muttarak said. “Certainly, it depends on a combination of political and economic characteristics of a country that we look at. If droughts are going to become more frequent or intense due to climate change in the future, this may lead to a higher number of asylum seekers in certain contexts.”

However, “our study shows that climate affects migration through conflict in a country with a medium level of democracy,” she added. “This implies that enhancing capacity to adapt and cope with climatic shocks, coupled with good governance, could reduce the outbreak of conflict and subsequently asylum seeking.”

Protestors march in Sana’a during the Yemeni Revolution, 2011. Source: Noor Al Hassan

The research is especially relevant as it applies to the period from 2010 to 2012, which marked the so-called Arab Spring, when political uprisings burgeoned into civil war. In Syria in particular, prolonged drought caused by climate change decimated crops, causing rural families to relocate to urban areas. This, in turn, led to overcrowding and unemployment and, ultimately, political unrest and civil war. Sub-Saharan Africa was subject to similar trends during the same time period, thought the outcome was not precisely the same. Researchers cautioned their findings were not universally applicable, because affected countries will differ in key ways.

“Climate can affect conflict in many different ways — by exacerbating the competition for resources, by causing internal migration flows that increase the probability of political tensions, etc.,” Crespo Cuaresma said. “Climate change will not cause conflict and subsequent asylum-seeking flows everywhere. But in a context of poor governance and a medium level of democracy, severe climate conditions can create conflict over scarce resources.”

A family gathers sticks and branches for firewood and protection on the outskirts of Dadaab, Kenya, where drought has driven refugees to flee, 2011. Source: Oxfam

The researchers recommended that the UN consider the relationship between climate, conflict and migration in the context of the Sustainable Development Goals, which are targets for ending poverty, improving health, protecting human rights and ensuring the ecological well-being of the planet. While the Global Compact for Migration, a UN-sponsored agreement completed late last year, does recognize climate change as a major factor in migration, Crespo Cuaresma said it does not go far enough. It isn’t binding, and key countries — the United States among them — have not agreed to it, he said.

Discussions about the Sustainable Development Goals often focus singularly on a particular goal without considering their interconnectedness, he said. Their study demonstrates that, “when thinking about these global goals, the interaction among them needs to be taken into account when assigning priorities and designing policies.”

Marlene Cimons writes for Nexus Media, a syndicated newswire covering climate, energy, policy, art and culture.