Warriors of the sand dunes

Creeping deserts pose a severe threat worldwide, and in North China everyone is pitching in to stop them in their tracks

It was the longest day of the year, and the sun would finally disappear below the horizon only after 9.30 pm. As tour buses slowly rolled into Crescent Spring scenic area in Dunhuang, Gansu province, excited passengers held their cameras and mobile phones aloft, eager to get shots, on both sides of the road, of the sand dunes at the foot of Singing Sands Mountain.

To eyes looking on from afar in fading light these gigantic dunes could easily have been dinosaurs - albeit ones with silky smooth skin - resting quietly on their bellies and about to settle in for the night.