Having explained the science behind global warming, and addressed the arguments of the climate change sceptics earlier in the series, Dr Iain Stewart concludes the series by looking at the biggest challenge now facing climate scientists - Just how can they predict exactly what changes global warming will bring?
It's a journey that takes him from early attempts to model the climate system with dishpans, to supercomputers, and to the frontline of climate research today: Greenland. Most worryingly he discovers that scientists are becoming increasingly concerned that their models are actually underestimating the speed of changes already underway.

At the top of our planet lies a magical realm, the Arctic Ocean. After four months of winter darkness, the sun returns to reveal a frozen ocean covered in ice. Mother polar bears emerge from their hillside dens and lead their cubs down to the sea ice to hunt, while a young male and female bear forge a surprising friendship out on the ice.
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.
Off the east coast of Greenland, the floating pack ice in spring is a nursery ground for harp seals. Mothers and pups have just a few weeks together for the pup to learn to swim before she leaves him to fend for himself. But in today’s warming climate, storms can tip helpless youngsters into the sea before they are strong enough to fend for themselves.
Summer is a time of plenty in the Arctic Ocean as plankton blooms feed millions of tiny mouths, such as bizarre skeleton shrimps, as well as the biggest: bowhead whales. These ancient and long-lived whales arrive en masse every year at secret locations known as whale spas. But today, with the loss of summer sea ice, their peace is shattered by orcas from the south. These daring predators are bold enough to take on the much larger bowheads, targeting their vulnerable calves.
The 24-hour daylight of the Arctic summer attracts visitors from afar, including huge flocks of seabirds like crested auklets. A male must use both his song and a secret tangerine perfume if he is to attract a mate. For the resident walrus, the summer heat can be unbearable. After hauling himself to the beach to moult, an old male uses an ingenious technique to get himself back to the cool of the water - a roly-poly!
Summers in the Arctic today bring record-breaking heat. With climate change, it is warming faster than anywhere else on Earth. It is predicted that the Arctic Ocean could become ice-free each summer by 2035, raising new challenges for polar bears. Without sea ice, more and more bears are becoming stranded on remote Arctic islands. It's a dangerous place to be for a mother bear with cubs, surrounded by larger, predatory males.

Journeying from pole to pole, The series 'Frozen Planet II' reveals surprising worlds that exist across the planet and the remarkable animals that make them their home. In a fragile world of beauty and hostility, nature finds a way to survive and thrive. David Attenborough explores a planet on the brink of major change.
In the first episode, we begin our journey in the far south, in the most hostile place on earth, the frozen continent of Antarctica. After being raised on the ice in winter, emperor penguin chicks find themselves abandoned by their parents in spring. To survive, they must find their own way across the treacherous sea ice to the rich waters of the Southern Ocean.
The waters surrounding Antarctica may be the richest of all, but they are also home to an exceptionally sophisticated predator, the killer whale. To reach their favored prey, Weddell seals, a family of killer whales have learnt to generate their own waves, washing the seals off their ice floes. It’s a technique that has been passed down over generations and is coordinated by the family matriarch, who can be over 100 years old.
Leaving Antarctica and travelling north, we discover frozen habitats that are created by altitude. The greatest of these is the Himalaya, the tallest mountain range on earth, which contains so much ice and snow it is known as the third pole. In the shadow of the Himalaya lies a vast frozen grassy plain that is home to the fluffiest cat in the world, Pallas’s cat. It may have extremely dense fur, but if it’s to survive the Mongolian winter, it needs to catch lots of gerbils and voles. Easier said than done when you only have short legs and paws that are sensitive to the cold.
North of the Great Steppe lies the boreal forest, which encircles the continents of North America, Europe and Asia, and remains frozen for six months of the year. Prowling these forests in the far east of Russia is the Siberian tiger, the largest cat in the world. In winter, it is on the lookout for black bears hibernating in caves, a high-risk strategy that only a cat of this size would attempt.
Above the boreal forest, we cross into the Arctic Circle, where conditions become so extreme that trees can no longer grow. This is the tundra. Living here are relics of the last ice age, musk ox. In spring, their calves face a far greater danger than the cold, grizzly bears. Encounters can be brutal, but if just a few calves survive the gauntlet, the herd’s future is secure.
To the north of the tundra is the Arctic Ocean, the only ocean that can completely freeze over. Living here is one of the most peculiar animals on earth, the hooded seal. Males have extraordinary inflatable noses, producing a bright red balloon out of their left nostrils. One male hopes this will make him irresistible.
All of the frozen habitats share one thing in common: the threat posed by today’s climate change. Travelling to the island of Greenland, home to the largest body of ice in the northern hemisphere, we witness how global warming is melting its ice cap at faster rates than ever before, with profound consequences for global sea levels. Lastly, we visit the Arctic’s most iconic resident, the polar bear, as a mother bear struggles to provide for her cubs in a world of shrinking sea ice.

Sir David Attenborough journeys to both Polar Regions to investigate what rising temperatures will mean for the people and wildlife that live there and for the rest of the planet. David starts out at the North Pole, standing on sea ice several metres thick, but which scientists predict could be Open Ocean within the next few decades. The Arctic has been warming at twice the global average, so David heads out with a Norwegian team to see what this means for polar bears. He comes face-to-face with a tranquilised female, and discovers that mothers and cubs are going hungry as the sea ice on which they hunt disappears. In Canada, Inuit hunters have seen with their own eyes what scientists have seen from space; the Arctic Ocean has lost 30% of its summer ice cover over the last 30 years. For some, the melting sea ice will allow access to trillions of dollars worth of oil, gas and minerals. For the rest of us, it means the planet will get warmer, as sea ice is important to reflect back the sun's energy. Next David travels to see what's happening to the ice on land: in Greenland, we follow intrepid ice scientists as they study giant waterfalls of meltwater, which are accelerating iceberg calving events, and ultimately leading to a rise in global sea level. Temperatures have also risen in the Antarctic - David returns to glaciers photographed by the Shackleton expedition and reveals a dramatic retreat over the past century. It's not just the ice that is changing - ice-loving adelie penguins are disappearing, and more temperate gentoo penguins are moving in. Finally, we see the first ever images of the largest recent natural event on our planet - the break up of the Wilkins Ice Shelf, an ice sheet the size of Jamaica, which shattered into hundreds of icebergs in 2009.

The documentary series reveals the extraordinary riches and wonders of the Polar Regions that have kept people visiting them for thousands of years. Today, their survival relies on a combination of ancient wisdom and cutting-edge science. Most Arctic people live in Siberia, either in cities like Norilsk - the coldest city on earth - or out on the tundra, where tribes like the Dogan survive by herding reindeer, using them to drag their homes behind them. On the coast, traditional people still hunt walrus from open boats - it is dangerous work, but one big walrus will feed a family for weeks. Settlers are drawn to the Arctic by its abundant minerals; the Danish Armed Forces maintain their claim to Greenland's mineral wealth with an epic dog sled patrol, covering 2,000 miles through the winter. Above, the spectacular northern lights can disrupt power supplies so scientists monitor it constantly, firing rockets into it to release a cloud of glowing smoke 100 kilometres high. In contrast, Antarctica is so remote and cold that it was only a century ago that the first people explored the continent. Captain Scott's hut still stands as a memorial to these men. Science is now the only significant human activity allowed; robot submarines are sent deep beneath the ice in search of new life-forms, which may also be found in a labyrinth of ice caves high up on an active volcano. Above, colossal balloons are launched into the purest air on earth to detect cosmic rays. At the South Pole there is a research base designed to withstand the world's most extreme winters. Cut off from the outside world for six months, the base is totally self-sufficient, even boasting a greenhouse.

Our journey begins with David Attenborough at the North Pole, as the sun returns after six months of darkness. We follow a pair of courting polar bears, which reveal a surprisingly tender side. Next stop is the giant Greenland ice cap, where waterfalls plunge into the heart of the ice and a colossal iceberg carves into the sea. Humpback whales join the largest gathering of seabirds on earth to feast in rich Alaskan waters. Further south, the tree line marks the start of the Taiga forest, containing one third of all trees on earth. Here, 25 of the world's largest wolves take on formidable bison prey. At the other end of our planet, the Antarctic begins in the Southern Ocean where surfing penguins struggle to escape a hungry sea-lion and teams of orcas create giant waves to wash seals from ice floes -a filming first. Diving below the ice, we discover prehistoric giants, including terrifying sea spiders and woodlice the size of dinner plates. Above ground, crystal caverns ring the summit of Erebus, the most southerly volcano on earth. From here we retrace the routes of early explorers across the formidable Antarctic ice-cap - the largest expanse of ice on our planet. Finally, we rejoin David at the South Pole, exactly one hundred years after Amundsen then Scott were the first humans to stand there