“If a country switches from a democracy to a dictatorship—which would cause many more asylum applications—that would have a huge effect and we don’t account for it in the model,” he said. Schlenker noted that while these would be huge increases, the number of migrants who fled the Syrian Civil War was “much larger than the predicted impact we’re seeing with climate change.”
Researchers who study the intersection of climate and politics said that the historical connection was an extremely sturdy finding, but they shared in Schlenker’s skepticism about the future projections.
“This is a very strong study showing a robust relationship between temperature and forced migration,” said Claire Adida, a political scientist at the University of California at San Diego, by email. “The authors were meticulous in their analysis.”
“They show that the relationship holds only when you look at temperature deviations over the growing season and in the crop area ... This, by the way, is consistent with a lot of other research in agricultural economics showing that climate change and conflict are likely to be related via the effect of climate change on agricultural income,” she said.
Elizabeth Chalecki, a political scientist at the University of Nebraska at Omaha, agreed that the core finding was strong, but she identified a few more variables that she said could be related. Forced migration could also depend on whether commodity crops were available to relieve a food shortage or whether there were broader non-climatic events—like a genocide—happening in the region.
“The researchers admit that their correlation is ceteris paribus, meaning all things being equal, but that never is the case in real life,” she said. “If nationalist politics are on the rise across the EU and elsewhere, then doing something about climate change might be good national-security policy, not just good environmental policy.”
Giovanni Bettini, a political theorist at Lancaster University, said it was important to be careful about discussing climate migration as fait accompli.
“The inference that correlation equates causation is very problematic,” he said, adding that the link between climate change and political mobility was a “political open question.”
And he said it was important to treat projections not as settled science but as one of many tools for thinking about the future. It was crucial, too, he said, to talk about migrants with nuance and care not to fall into racial tropes. “Climate refugees are never white, in the discourse,” he said. “The dangerous flocks of people who are set to be uprooted in the future, creating dangerous security threats for ‘us,’ are always somewhere else.”