Polar bears are the biggest bears in the world and the only marine bear. There are estimated to be around 26,000 globally. They’re mostly found in Canada, but also in Russia, the US, Norway and Greenland. Their main prey is seal, specifically seal blubber, as they need a diet high in fat to survive the freezing Arctic conditions.

Polar bears are great swimmers but they can’t outswim seals. So they hunt them on the Arctic sea ice, waiting for them to come up for air and then pouncing. But as the amount of sea ice decreases due to global warming, the polar bear populations that live in the more southerly, warmer parts of the Arctic are in decline.

BBC Science correspondent Victoria Gill explains what it’s like to see a polar bear up close and the challenges they’re facing. Alysa McCall, a scientist at Polar Bears International, gives us her top facts about polar bears and Arctic sea ice.

And we explore whether refreezing parts of the Arctic could be a realistic solution, with Kerry Nickols, from Ocean Visions, a non-profit organisation which looks at ways to protect and restore Arctic sea ice.

Instagram: @bbcwhatintheworld Email: whatintheworld@bbc.co.uk WhatsApp: +44 330 12 33 22 6 Presenter: Hannah Gelbart Producers: Julia Ross-Roy, Benita Barden and Thuong Le Video Journalist: Baldeep Chahal Editor: Verity Wilde