Migrants applying for asylum in the European Union will nearly triple over the average of the last 15 years by 2100, if carbon emissions continue on their current path, according to a study.
The study, published in the journal Science, suggests that cutting emissions could partially stem the tide, but even under an optimistic scenario, Europe could see asylum applications rise by at least a quarter.
"Europe is already conflicted about how many refugees to admit," said Wolfram Schlenker, an economist at Columbia University in the US.
"Though poorer countries in hotter regions are most vulnerable to climate change, our findings highlight the extent to which countries are interlinked, and Europe will see increasing numbers of desperate people fleeing their home countries," said Schlenker.
Researchers compared asylum applications to the EU filed from 103 countries between 2000 and 2014, with temperature variations in the applicants' home countries.
They found that the more temperatures over each country's agricultural region deviated from 20 degrees Celsius during its growing season, the more likely people were to seek refuge abroad.
Crops grow best at an average temperature of 20 degrees Celsius, and hotter than normal temperatures increased asylum applications in hotter places, such as Iraq and Pakistan, and lowered them in colder places such as Serbia and Peru, researchers said.
Combining the asylum-application data with projections of future warming, they found that an increase of average global temperatures of 1.8 degrees Celsius - an optimistic scenario in which carbon emissions flatten globally in the next few decades and then decline - would increase applications by 28 per cent by 2100, translating into 98,000 extra applications to the EU each year.
If carbon emissions continue on their current trajectory, with global temperatures rising by 2.6 to 4.8 degrees Celsius by 2100, applications could increase by 188 per cent, leading to an extra 660,000 applications filed each year.
The research adds to a growing body of evidence that weather shocks can destabilise societies, stoke conflict and force people to flee their home countries.
In a widely-cited 2011 study in the journal Nature, researchers linked modern El Nino drought cycles to increased violence and war globally.
More recently, researchers have highlighted the connection between the drying of the Middle East and ongoing conflict there.
In a 2015 study in the journal PNAS, researchers made the case that climate change made Syria's 2006-2010 drought two to three times more likely, and that the drought was a catalyst for Syria's 2011 uprising.
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