In Agadez, a city in the heart of Niger that is the gateway to the Sahara Desert, Amma Attouboul has been appointed to take care of a 500-year-old mosque. The mud-brick structure could pave the way for coping with climate change.

The mosque consists of an 89-foot-tall minaret surrounded by several prayer chambers. Every two years or so, the entire structure is caked with a fresh layer of banco: a muddy mixture of water, soil, and straw that dries in open air. "These walls are exceptionally heavy," Mr. Attouboul says as his wrinkled hands gently tap the thickset walls. "Because of this, sunlight struggles to penetrate. And inside the mosque, the chambers stay cool and comfortable."

In the Sahel region, a semiarid belt of land stretching from the Atlantic Ocean to the Red Sea, temperatures are expected to rise 1 1/2 times faster than the global average, according to the United Nations Intergovernmental Panel on Climate Change. Cool nights are becoming increasingly rare, and blazing-hot days are lasting longer.

"I think we should keep building our houses like this, for our culture and for the climate," says resident Abdourahman Ibrahim.