BEIJING, CHINA—Sensors have been installed in 20 of the 183 caves that make up the Bingling Temple Grottoes in northwestern China’s Gansu Province. The sensors will measure changes in temperature, humidity, carbon dioxide density, and other conditions, so that scientists can measure the impact visitors have on the caves, which contain Buddhist statues, stupas, and murals. The temple is located along the route of the ancient Silk Road.