SOUTH HANGAY PROVINCE, Mongolia — They call it the zud, a prolonged period of heavy snows and paralyzing cold that adds to the challenges of living on a treeless expanse nearly the size of Alaska. But this year's zud followed a punishing summer drought that stunted the grass and left Munkhbat Lkhagvasuren's herds emaciated and his family in debt after borrowing money for fodder.

As the snow piled waist high this winter and temperatures plunged to 40 below zero, Lkhagvasuren crammed two dozen of the weakest goats and sheep into his yurt. The unlucky ones, more than 1,000 animals, froze to death in a great heap outside his front door. "I tried everything but could not fight against nature," he said tearfully in a recent interview, the stench of rotting flesh overpowering despite a devilish wind. "I am broken and lost."