Drones buzz above traffic-clogged roads in Ordos, Inner Mongolia, as white-capped police officers attempt to manage lines of hundreds of trucks waiting to be loaded with cargoes of coal. Many have been there for days.

The jams disrupting the Chinese city, one of the most critical coal hubs anywhere, show the enormous task facing the world’s top energy consumer as it races to ease a power crisis that’s stifling key industries and that some economists warn risks crimping global growth.

For more than a month, energy shortages have rippled through China’s manufacturing centers for steel, aluminum and cement, and prices of coal — which the country relies on for almost two-thirds of its electricity — have made dizzying gains. As the approaching winter threatens to ratchet up demand, authorities are taking extraordinary steps to intervene.