Index and credits:
1. Drug addicts gather around fire to warm themselves, in a suburb of Tehran, Iran. (Ebrahim Noroozi / AP)
2. Nico Rosberg of Germany and Mercedes GP drives through the sirty side of the track during day four of Formula One Winter Testing at Circuit de Catalunya in Montmelo, Spain. (Dan Istitene / Getty Images Europe)
3. Flamingoes at the Memphis Zoo huddle together for warmth in Memphis, Tennessee. (Jim Weber / AP Photo)
4. Assistant harbormaster Isaac Perry uses a boat to break through a fresh layer of ice covering Marion Harbor, Massachussets. (Peter Pereira / Standard Times / AP)
5. Palestinians ride donkey carts during a sandstorm. (Mohammed Abed / Getty Images)
