Syrian refugee workers lay an irrigation pipe at a pistachio plantation in Karkamis, Turkey. | Bloomberg

Even after the start of Syria’s civil war in 2011, beekeeper Muhammad Salih regularly traveled along the country’s northern border with Turkey in search of the best spots to produce the honey that sustained his family. It wasn’t until four years later, when Islamic State militants took control of his hometown and killed his brother-in-law, along with his seven children, that Salih decided it was time to move for good.

“We buried them and crossed into Turkey,” said the 46-year-old, who now lives in Karkamis, a small Turkish town near the Syrian border. “I had to sell all 250 of my beehives for a third of what they would have been worth if I hadn’t been in such a rush.”

But while Salih has left sectarian violence behind, he hasn’t been able to escape extreme weather. Drought has cut his honey production in half over the past five years.…