Like the fox, this lemming’s coat changes from brown to white at the onset of winter as light levels decrease. They forge a living under the snow in ‘subnivean tunnels’. Their claws grow longer in preparation for a winter of digging through the snow to reach vegetation to eat. Their tunnels can extend up to 15m. Lemming populations are cyclical and can be susceptible to a warming world. Rain on snow events in winter can freeze lemmings under the snow and cause a population to crash. Six long years later and this sequel proves worth the wait - not quite matching the wonder of the first but providing a magical new adventure nonetheless. The mountains of Japan are the snowiest place on Earth, providing hostile conditions for a lone male Japanese macaque cast away from his troop. His only chance of survival comes with finding another male whose embrace will provide him with life-saving warmth. But in the frozen peaks, the deadliest force is an avalanche whose full destructive power is captured for the first time using high-speed camera racer drones. Working in conjunction with bee scientists, the team used a new low-light sensitive 6K camera called the ‘Mavo’ to reveal the secret life of the Lapland bumble bee as she emerged from her underground burrow and raised her brood. This happens in total darkness so the team needed a camera which could capture enough detail without disturbing the queen. This is something we have to get right. Highly charged films about climate change have their place but I feel that if you make it too weighty and too heavy going, you could alienate your audience.

Frozen South takes us to the most hostile ice world of all – Antarctica, an entire continent covered in snow and ice full of surprises. Here hardy animals cling around its coastal fringes. They sometimes do so in surprising numbers as on the island of South Georgia where, even in winter, colonies of king penguins number in their thousands. We meet lonely albatross forming unexpected male-male pairs as there are no longer enough females to bond with, before journeying across the Southern Ocean to meet the largest animal on earth - giant Antarctic blue whales. These are seldom seen, let alone filmed. Under the sea ice we meet a mother Weddell seal who must defend her pup from the attractions of an amorous male. With this time study I really hope we can land the scale of the change that's taking place, how rapidly this change is taking place, and what the implications are for the localised, highly cold-adapted animals. And, as we learn in episode six, how these changing worlds are also impacting all of us. In essence, it will show why we are more closely connected to these highly remote regions than perhaps we first appreciated. The last film is a very powerful watch. I think that anybody who knows anything about these regions will probably say the situation is bleak in many ways. But what we've tried to set up from the beginning is that these people are striving to turn things around before it's too late. And in the final messages of this series we are trying to inject a sense of hope. We've got scientists talking about the fact that at our fingertips we do have the technology to be using renewables, to be transforming society, and that there is the will. The will is greater now than ever. What's so powerful is that it comes from the scientists themselves. These are people who literally, day by day, see the ice disappearing but they still have hope that we can do something about this. A whole fleet of light-weight fast-response drones were used to document ice calving from Store glacier in Greenland – a fast and ephemeral event.

The hooded seal can inflate a large balloon like sac from its left nostril. This is done by shutting one nostril valve and inflating a membrane which then protrudes from the other nostril. It is the only animal to perform this extraordinary behaviour. Our journey begins in the Arctic, where every summer huge quantities of ice calve from the edges of Greenland’s melting glaciers. On top of the ice cap itself, glaciologist Alun Hubbard descends into a moulin to try to understand the mechanisms that are driving this historic loss of ice. In Frozen Ocean the series dives into a world of water and ice to reveal the animals which survive on and under the Arctic sea ice. It’s a seasonal story that begins in the depths of winter. This is a time of plenty for polar bears who can afford to play in the short winter days, through to the perils of spring as the sea ice breaks up, finally to its bountiful summer where visitors are drawn to the ocean from afar to feed up and breed. World-renowned composer Hans Zimmer and Bleeding Fingers Music have previously composed the BAFTA-nominated score to Planet Earth II, and critically-acclaimed music for Blue Planet II.

For others, the frozen sea is a trap. A pod of beluga whales has been confined to an ice hole for five months, slowly starving to death as the food around them runs out. Their salvation lies in the strengthening sun that comes with spring, melting the sea ice, allowing their escape. And then finally we look at how Greenland, the world’s largest island in the Arctic Ocean, is being affected by climate change. This culminates in a big calving event, with big bits of ice falling off the front of the ice sheet. We look at how this is affecting the Arctic’s wildlife, specifically a family of polar bears, and how hunting is getting harder and harder for them.Today, due to climate change, our frozen peaks are undergoing rapid change. Using groundbreaking time-lapse photography, we reveal mountain glaciers vanishing before our very eyes and discover what a warming world may mean for our most famous mountain resident of all, the giant panda. The incredible ice-covered mountains of the Karakorum range have seldom been filmed. The Frozen Planet II team gained access to fly with the Pakistani Military and document both the ice fields and the mythical mountain, K2. Flying at over 7,000m, this was one of the highest altitude aerial filming trips ever undertaken by the BBC Natural History Unit and the pilot and crew had to be on oxygen at all times. The other thing is that I loved the original Frozen Planet series. As documentary makers we want to surprise the audience every episode and ring the changes. Whilst there’s a huge opportunity to apply new storytelling techniques and go with new filming technology to the Poles, I also felt that we could broaden out the series to really surprise the audience with the breadth and variety of all the different frozen worlds scattered across our globe. Remarkably, at any given time, a fifth of our planet is covered in snow or blanketed in ice. There is an opportunity to tell a much bigger of the frozen zone of the planet. The longest continuous time any team member spent on location was three months. The longest journey to location took three weeks, and the longest quarantine period (due to COVID) was 42days.