When the rains failed in 2015 and drought gripped southern Mindanao in the Philippines, Corazon Vegafria knew what she had to do: move to the city of Koronadal, about an hour away by bus, and find work as a domestic helper to support her family.

Her husband looked after the children while Vegafria sent home most of the 2,000 pesos ($38) she earned every month cooking and cleaning at her employer's home.

"We had no choice — we needed the money, and I could easily find a job in the city," she said. Six months later, she returned home "when the situation improved."