In Mongolia , where nearly a third of the population still lives as nomadic herders, a winter so cold that livestock either freeze to death or starve as snow and ice make grazing impossible is called a dzud. These extreme seasons used to come once a decade. With climate change destabilizing the landlocked Asian countrys weather pattern, the dzud has haunted Mongolia for six of the last 10 years.

In 2018, when a dzud wiped out roughly 700,000 livestock, it was a devastating record. Last month, the death toll for this winter eclipsed 2 million , as HuffPost reported at the time. Weeks later, that figure has nearly tripled.

As of this week, at least 5.2 million animals have died since winter began, a particularly brutal event that combined the effects of two different types of dzud.

This is still just the start of the catastrophe, as the die-off is expected to reach its peak sometime in early May. The final death toll could reach 20 million, the United Nations told HuffPost on Tuesday.

Its the worst winter in at least 50 years, according to the International Foundation of Red Cross and Red Crescent Societies, which warned last week that at least 75% of herding families were affected.