Caribou migration routes are under threat. Each year, caribou make migrations in their hundreds of thousands across the Arctic. But as the climate warms, their ancient pathways are changing - and so is the frozen ground itself. #OurFrozenPlanet tells stories that land the urgency of climate change whilst inspiring hope that change is possible for us and the health of our planet. Discover more ➡️ https://www.bbcearth.com/our-frozen-planet | BBC Earth