More than 10,000 migrants and refugees traveled to Western Europe via Hungary over the weekend, fleeing conflict-ravaged and impoverished homelands in the hope of finding a more secure life abroad. Even as Europe wrestles over how to absorb the new arrivals, human rights activists and migration experts warn that the movement is not likely to slow anytime soon. Intractable wars, terror and poverty in the Middle East and beyond will continue to drive the surge. One additional factor, say scientists, is likely to make it even worse: climate change.

From 2006 to 2011, large swaths of Syria suffered an extreme drought that, according to climatologists, was exacerbated by climate change. The drought lead to increased poverty and relocation to urban areas, according to a recent report by the Proceedings of the National Academy of Sciences and cited by Scientific American. “That drought, in addition to its mismanagement by the Assad regime, contributed to the displacement of two million in Syria,” says Francesco Femia, of the Washington, D.C.-based Center for Climate and Security. “That internal displacement may have contributed to the social unrest that precipitated the civil war. Which generated the refugee flows into Europe.” And what happened in Syria, he says, is likely to play out elsewhere going forward.

Across the Middle East and Africa climate change, according to climatologists at the U.S. Department of Defense-funded Strauss Center project on Climate Change and African Political Stability in Texas, has already affected weather. These changes have contributed to more frequent natural disasters like flooding and drought. Agricultural land is turning to desert and heat waves are killing of crops and grazing animals. Over the long term, changing weather patterns are likely to drive farmers, fishermen and herders away from affected areas, according to Femia’s Center for Climate and Security, and into urban centers — as has already happened in Syria. Both the Pentagon, which calls climate change a “threat multiplier” and U.S. Presidential candidate Hillary Clinton have warned of “water wars,” in which rival governments or militias fight over declining resources, sending even greater waves of migrants in search of security and sustenance. On Aug. 31, Secretary of State John Kerry warned that climate change could create a new class of migrants, what he called “climate refugees” at a conference on climate change conference in Anchorage, Alaska. “You think migration is a challenge to Europe today because of extremism, wait until you see what happens when there’s an absence of water, an absence of food, or one tribe fighting against another for mere survival,” he said.

Security analysts say they are already seeing the impact, particularly in migration patterns from northern Africa and the Sahel region, which is the band of farmland just below the Sahara desert. “All the indicators seem to fairly solidly convey that climate change — desertification and lack of water, or floods, are massively contributing to human mobility,” says Michael Werz, a Senior Fellow at the Center for American Progress policy group in Washington, D.C. Syrians and Afghans may make up the largest number of refugees flooding into Europe right now, but Africans from the Sahel are not far behind. “No one is saying ‘I’d better pack my stuff and go to Europe because I expect CO2 emissions to rise,’” he says. But the knock on effects — failed crops, ailing livestock and localized conflicts over resources—are already driving residents of the Sahel northward to flee poverty. Libya’s collapse has opened the doors wide for migrants, and the smugglers who ship them across the Mediterranean to Europe.

As Europeans debate over what to do about the influx of migrants, there has been a call for an international effort to stabilize the regions from which they come. But it’s not enough to talk about ending conflict, says Femia. “A lot more attention has to be paid to putting more resources into climate adaptation and water security and food security, so migration doesn’t become the primary option.” Tackling the problem at its source doesn’t mean ending conflict, but stopping it before it starts. And that means addressing climate change as well.

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