In Mongolia, nomadic herders are seen as the proud heirs of Genghis Khan and are nicknamed "the emperors of the plains". But in recent years, global warming has had dramatic consequences for their way of life. The "dzuds" in particular - harsh winters, which follow scorching summers - have done terrible damage. In the steppes, weakened by the cold and lack of food, animals die out one after the other. Nomads have seen their herds of livestock decimated - already a meagre source of income.