The last chapter explains how the 2010s became another lost decade in the fight against climate change – as the move to natural gas delayed a transition to more renewable sources of energy.
Engineer Tony Ingraffea, in the 1980s, helped develop a new technique for extracting gas and oil from shale rock, which ultimately became known as 'Fracking'. It was to unleash vast new reserves of fossil fuels and was promoted as a cleaner energy source. But Ingraffea explains how he later came to regret his work when he realized that gas could be even worse for climate change than coal and oil.
Dar-Lon Chang, a former ExxonMobil engineer, speaks for the first time on camera alleging that as the company increased its natural gas operations, it was not sufficiently monitoring methane leaks that were contributing to climate change. Now, after a year of unprecedented wildfires, drought and other climate-related disasters, multiple lawsuits are being brought in US courts in efforts to hold Big Oil legally accountable for the climate crisis.

The unearthing of a gruesome grave filled with thousands of skeletons at the beach of Kamakura in Japan could be about to unlock the true extent of the merciless violence and mystery surrounding the true origins of one of the most feared and revered warriors of all time: the Samurai.
In the Middle Ages, Kamakura was the capital of Japan. The 'Shogun', a kind of aristocratic military dictator, ruled here. This shogunate ended in 1333 with the Battle of Kamakura. A drastic event in Japanese history, because this resulted in not only political, but also social, philosophical and technical innovations. The remains of the samurai warriors who fell near Kamakura now provide scientists with detailed insights into the time of the Kamakura shogunate and the bloody conflict between the shogun and the emperor.
The chilling burial ground dates back to 1333. Kamakura was one of the most heavily fortified regions of Japan. When the Emperor became angered by the growing powers of the ruling Hojo family, he sought to retake control of the region, setting the stage for a war that would change the shape of the nation. Among over 4000 sets of remains, six have a unique story to tell: the husband and wife involved in a sword fight to the death; the warrior monk; a peasant boy soldier; and members of the ruling Hojo family, captured and decapitated, with their heads displayed as trophies of victory. These remains reveal the secrets of the Samurai, their ferocious fighting skills and their merciless killing techniques.

Recent archaeological sites in England offer a whole new perspective on the life and death of the seafarers and marines who built the British Empire in the 18th and 19th centuries. The bones of sailors reveal surprising and shocking facts. Apparently not only seasoned men but also half children did their service in the Royal Navy; according to the investigations, the youngest were no older than 13 years. A forensic archaeologist studies the injuries on bones discovered at the site of an battle and suggests how these people may have died.
Three-hundred-and-fifty skeletons, exhumed from Royal Navy graveyards from the age of Nelson's Navy, are throwing an extraordinary new light on how these sailors lived, fought, outwitted their enemy, and, from the oldest to youngest, suffered for victory. These men were the beating heart of the most victorious fleet in history and never have so many of these sailors' remains been available for forensic investigation.
Six remarkable stories stand out: the child sailor, the top man, the American gunner, the freed slave, the marine and the victim of the sailor's most dreaded disease: syphilis. Broken bones, amputations, injuries from blows with a saber or cutlass, sexually transmitted diseases, but also malnutrition - the list of causes of death is long. There is definitely no tale of seafaring romance. These fighters and sailors sailed the globe as cannon fodder, conquered an empire for the crown, and were themselves forgotten. No longer just bones in a box, the men of Nelson's Navy are back from the dead.

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.

Mountains create frozen habitats on every continent on Earth, and each of these high-altitude worlds holds unique challenges for its surprising and remarkable life.
We begin our journey close to the equator - the furthest point from the poles - in East Africa. Here on the high slopes of Mount Kenya, during the day the tropical sun keeps the cold at bay, but at night the frost descends. During this cycle of freeze and thaw, a pregnant high-casqued chameleon must choose the right time to give birth if her newborns are to escape the deadly night freeze.
Away from the equator in the European Alps, long cold winters give way to short, bountiful summers. For a pair of golden eagles raising their chick, the demand to provide enough food for it drives them to tackle prey five times their size. To catch a goat-like chamois, they risk it all using one of the most daring and breathtaking hunting techniques ever witnessed.
The mountains of Japan are the snowiest place on Earth, providing hostile conditions for a lone male 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.
The roof of the world is home to an array of unexpected cold-loving creatures. In the remote Southern Alps of New Zealand, a species of parrot - the kea - uses its famed intelligence to feed on the dead. And in the Andes in South America, flamingos thrive in high-altitude volcanic lakes, but their chicks must race to escape the winter freeze or risk becoming trapped in the ice.
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.

Antarctica is the most hostile of all earth’s frozen worlds. Yet even here, amongst some of the most challenging conditions on the planet, life finds a way not just to survive, but thrive.
Our journey begins at the far edge of the continent, on its far-flung sub-Antarctic islands. Here we meet king penguins that, to feed at sea, must face the danger of ferocious leopard seals lurking in the shallows. On another island, we witness for the first time male Antipodean wandering albatross partnering up with each other as the females in their population are disappearing due to fishing activity.
Heading towards the continent of Antarctica, we traverse the roughest seas on earth - the Southern Ocean - where we find the rarely filmed Antarctic blue whale, the largest animal to have ever lived. At the edge of Antarctica, the sea is so cold that it freezes over, creating a vital ice platform for a mother Weddell seal to raise her precious pup. Still, she needs to protect him from aggressive males.
In spring, the coast of Antarctica is free of snow, drawing in thousands of breeding chinstrap penguins. Stones are at a premium to build their elevated nests and protect chicks from meltwater. But stealing is commonplace, and to make matters worse, with climate change we find chicks today shivering with hypothermia – a warming Antarctica means increased meltwater. Other residents are facing an uncertain future too, including wave-washing killer whales. We discover that their favourite prey, Weddell seals, are now harder to reach, so instead they are resorting to targeting much more feisty prey, including leopard seals, an apex predator in its own right. This dramatic encounter has never been filmed before.
Travelling into the interior of the continent - into the frozen heart of Antarctica - we find great surprises. This is one of the most volcanic regions on earth, and one of the driest. We reveal unexpected sand dunes, hidden in a rare ice-free valley. Then, on the exposed mountain tops, sticking out from the otherwise ice-covered interior, we find tiny snow petrels, which raise their chicks further south than any other bird, and defend their territory by projectile vomiting!
The greatest revelation lies deep in the interior, beneath the surface of an ice-covered lake, where we discover ancient alien-like structures - giant stromatolites - built by primitive lifeforms. If life can make it here, in the extremes of Antarctica, it raises the possibility that life can exist elsewhere, including in the frozen lakes of distant planets.