Giant hole, thought to have been caused by methane release, is biggest of its kind discovered in Russia’s Yamal peninsula. It is the 17th crater of its kind to be found and documented in Yamal since 2014.

Usually polar bears feed on seals and young walruses, or scavenge the carcasses of whales. If these are in short supply they kill reindeer, muskox, geese and apparently, fox.

Weatherwatch A recent heatwave in Siberia’s frozen wastes has resulted in outbreaks of deadly anthrax and a series of violent explosions

Locals say they saw flames and smoke as a major bubble of methane blasted below the surface and created another sinkhole in the Russian Arctic peninsula.

The aim is to give warnings over seismic activity that could lead to the sudden formation of new craters, which could potentially damage key industrial infrastructure.

Scientists rush to site of latest tundra eruption - which formed a crater 50 metres deep - amid fears for homes and key industrial sites.

Changes in traditional diet and lifestyle of native ethnic groups in the Yamalo-Nenets region have brought the first cases of obesity. Change in wildlife routes and climate are among factors causing diets to change.