In recent years, a refugee crisis has gripped the European Union, as unrest in Syria and elsewhere has sent hundreds of thousands of migrants to Europe’s shores, seeking safe harbor.
Now, a new study says that if all else were to remain equal—a necessary but major if—the stresses of climate change could drive more migrants into the European Union in future years.
As warming worsens, these influxes would accelerate. Under one scenario where warming stabilizes by 2100, asylum applications could increase by some 28 percent. But in a scenario with “business-as-usual” warming, applications could nearly triple, to more than a million asylum seekers per year.
That said, these forecasts assume that applicants’ home countries do not adapt to a changing climate.
“This is an incredibly important study,” Solomon Hsiang, a researcher at the University of California, Berkeley, who models climate change’s social impacts, said by email. He wasn’t involved with the study. “This work layers on top [of existing research] new evidence that populations try to escape these deteriorating conditions by applying for asylum in safer countries.”
The findings, published in Science on Thursday, are the latest to show how Earth’s changing climate could exacerbate global conflict.
A growing body of research suggests that climate change can sow chaos within individual countries. One 2015 study found that human activity increased the odds of the extreme drought that gripped Syria and Jordan from 2007 to 2010. Some argue that this drought helped displace Syria’s farmers, contributing to the instability that triggered Syria’s civil war.
Fewer studies, however, have zoomed out to see whether Earth’s changing climate might shape relationships among many countries.
“Even though the consequences of climate change may not be felt or seen in a given country, the interconnections between that country and all the countries of the world will be felt at home,” says study coauthor Anouch Missirian, a Ph.D. candidate at Columbia University’s School of International and Public Affairs.
Trouble on the Farm
To tease out this interconnectedness, Missirian and Columbia University economist Wolfram Schlenker looked at 103 countries that had sent asylum applications to the EU each year from 2000 to 2014. The researchers then compared these application counts against the countries’ weather data.
After crunching the numbers, Missirian and Schlenker found a U-shaped relationship between the number of asylum seekers from a given country and average annual temperatures. Overall, applications reached their lowest when temperatures swung near 20 degrees Celsius (68 degrees Fahrenheit), a temperature associated with high crop yields. But when countries saw hotter or colder swings, asylum applications increased.
Political scientist Jan Selby of the University of Sussex, who has criticized the claims that climate change was connected to Syria’s civil war, dismisses this relationship as coincidental.
“It’s not really surprising that the paper finds a statistical relationship… since, as is well known, the period since 2000 has seen both increased civil conflict and refugee flows and, independently, significant temperature increases and weather shocks,” he said by email. “The key question is whether this correlation tells us anything about causation. I would venture that it doesn’t.”
Missirian and Schlenker disagree. For one, they note that their study accounts for how weather affects a given country’s agricultural land—and finds that asylum applications vary with changes in weather over these areas in particular. Their analysis also accounted for shocks that all countries shared, such as the 2008 global financial crisis.
And since short-term fluctuations in weather are random, Schlenker says, their effects on migration wouldn’t correlate with other factors, such as whether a country was a democracy. Similarly, randomized trials let drug companies tell whether medicines outperform placebos, even though many factors determine someone’s health.
“I’m pretty much willing to go to bat that the relationship between weather shocks and asylum applications we observed from 2000 to 2014 is causal,” says Schlenker.
An Evolving Landscape
To tease out climate change’s contribution, the study assumes that the 2000-2014 relationship between temperature and migration will hold through the end of the century. But Schlenker and Missirian readily acknowledge that this might not be the case.
“You have to be very careful when you make these kinds of extrapolations, because you can expect that there will be adaptation to climate change—maybe better-suited crops, or just a reallocation of populations within a country,” says Missirian.
“It could go either way,” she adds. “The effect of temperature could be felt much more vividly, or [depending on] our capacity to adapt, much milder.”
“Sound policies, at the subnational, national, and international level, designed to increase the resilience of populations to climate-related risks, are key for minimizing an increase in forced migration,” she said by email.
Nevertheless, outside experts see the study as a wake-up call.
“It is still possible to slow the flow of refugees by slowing global climate change,” said Hsiang. “Compared to managing and resettling an unending flow of refugees, and coping with the resulting political chaos, it seems likely that reducing greenhouse gas emissions today is a bargain.”