A large chunk of northern Russia is tundra where the ground is hardened by the arctic conditions into permafrost. Yet even in these harsh climes humans manage to thrive - like the Nenet people, whose nomadic reindeer-herding way of life takes them across north-west Siberia.
But as climate change takes hold, the permafrost is melting, releasing large quantities of carbon dioxide and methane. It's causing problems for the Nenet, altering the availability of their reindeers' food as well as prompting other changes in the local eco-system.
