They wait, motionless, on the edge of a frozen world. Photographed in Churchill, Canada, this polar bear rests along the shores of Hudson Bay, where bears gather each year for the return of the sea ice that allows them hunt seals again—their main source of food. For over a decade, Polar Bears International, a non-profit organisation, has streamed live footage of their movements, offering a rare gimpse into life balanced on the edge of a warming world.

A thick layer of fat and dense undercoat keeps the cold from reaching their skin, while water-repellent hair sheds moisture after every swim. But as the bay freezes later each year, the fast grows longer—sometimes lasting more than four months. To endure it, the bears slow their pace, rest and wait for the sea to harden again beneath them. Scientists track their paths across the tundra to study how a changing climate alters migration and survival—an early warning from the top of the planet that all balance is temporary.