Snow plows are making their way down the national highway in the West African country of Mauritania. But they aren't clearing snow; they're clearing sand.

Mauritania is getting buried under sand as Saharan dunes shift 3 to 4 km (2 to 3 miles) per year. Whole houses have been consumed, and entire cities have been abandoned.

When 75-year-old Sidahmed Ould Magaya goes to sleep on windy nights, a wall of sand accumulates around his house, sealing the door shut. He has to pay $6 for workers to dig him out in the morning. He has ended up selling one goat a month to pay the diggers. In most buried towns, people have resorted to going in and out through their windows.

The encroaching sand is due to climate change and the cutting of desert plants. Climate change has resulted in less rainfall, which means there is less moisture to hold the sand together in clumps. The uprooting of desert vegetation for camel feed, firewood, and insulation means there's nothing to anchor the sand in place.

The Mauritanian government has created a 109-page action plan to stop the sand from taking over, using measures such as planting green belts around cities and staking sticks into dunes. So far, though, the plan hasn't received any funding from the budget.

Meanwhile, the dunes continue to advance .…