Rising temperatures due to climate change allow mosquitoes carrying deadly malaria and dengue fever to live in new parts of the world that were previously uninhabitable, placing over half the world’s population at risk.Creating artificial roosts for bats to “farm” their guano can improve soil quality, providing a natural fertilizer while reducing insect numbers, and possibly disease burdens. Meet Heng Kim Seng, Cambodia’s bat man. In a few years, he went from rice to riches all because of bats. Under the Khmer Rouge, he hauled human waste to make the rice grow, and now he sells bat feces or “guano” as a natural fertilizer, a thriving business that could even save lives. It all started one night, back in his home village in eastern Pursat province, where he returned after the regime fell. At dusk, Seng watched bats by the thousands streaming out of palm trees and struck upon an idea. “I thought, bats are good animals … their feces make good fertilizer for all types of plants,” the grandfather recalled. “So, I came up with the idea to build artificial roosts by putting palm leaves at the top of the palm trees,” he explained. Seng started “farming” bats for their guano in 1982, and he’s never looked back. Now he can sweep up 15 kilograms (33 pounds) of guano from beneath his trees every day, which nets him around $10. Buyers know where Seng lives; he owns a bat signal, a large illuminated bat sign on the front of his house. Farmers come from as far as 500 kilometers (310 miles) away to buy up guano by the sack to fertilize their crops, including the green-skinned oranges that are famously from Pursat province. The profits allowed him to put all seven of his children through school, and some through university, a rarity in rural Cambodia. At the same time, the guano he’s farming is helping the planet, allowing farmers to combat the effects of drought, extreme rainfall and other climate change-related impacts. The guano, or “black gold,” as it’s sometimes known, may even have saved lives, by possibly reducing the impacts of climate change on human health. “This year, the rainfall is not stable like before,” says Sophea Chinn, head of the Ministry of Environment’s Biodiversity & Ecosystem Assessment Office. “Some areas have a lot of rain, which causes a lot of flooding.” In other areas, crippling drought took hold. “There is almost no water at all,” making cultivation all but impossible. These unexpected extremes can spell disaster for agriculture and livelihoods, says Sothearen Thi from Cambodia’s Forestry Administration’s Wildlife and Biodiversity Department. “If there’s too much rain, there will be soil erosion,” washing away farmers’ hard work and food.