A recent study has found "a highly statistically significant relationship" between increasing temperatures in agricultural regions and the number of refugee applications received by the European Union. The authors point to depressed yields and increased aggression in these areas, among other factors, as driving the rise in refugee applicants.
In this study, researchers examine these numbers and assess the role of what they call "weather shocks" in pushing people to seek asylum. The authors find that the numbers increase if the temperatures in the 103 countries they looked at were too warm or too cold. Warmer temperatures, defined as being above 20C, were seen as having a bigger impact.
The researchers believe, if temperatures continue increasing, as many as 660,000 extra refugee applicants could be expected each year by 2100.
"I feel very confident that what we discovered for 2000-2014 is a causal relationship between weather and asylum applications," lead author Prof Wolfram Schlenker from Columbia University told BBC News.
"Some of these 103 countries in a given year, are shocked warmer, some are shocked colder. It's like a random assignment and it ensures that those weather shocks are uncorrelated with other factors - so we are not just capturing a correlation, we really are capturing a causal relationship, I feel pretty confident on that, given the randomness of weather."
This is not the first study to show a correlation between climate change and human behavior:
The study follows on from other research that found a connection between conflict and temperature. A 2015 study showed that climate change made drought in Syria two to three times more likely, and that this was a catalyst for the 2011 uprising. The author of that research says the new study linking asylum to temperatures is an important step.