New study predicts potential crises for herds after examining 81,000 animal losses after Yamal was carpeted with winter-long impenetrable ice.
Currently there are 730,000 animals but numbers are 'unsustainable', risking disease spreading and chronic overgrazing.
As a debate is underway on culling as many as 250,000 reindeer due to overgrazing, Research Professor Bruce C Forbes warns against some proposed solutions.
Average temperatures in the north of the Kara and Barents seas were 4C to 5C higher than previous years.
Local photographer captures pillars of smoke rising above the underground peat fire.