Humanity is under threat - from storms that seem to get ever fiercer, earthquakes that seem ever more deadly, and killer viruses that are engulfing the globe. Some scientists think it's time for us to fight back. Can we - should we -hack the planet?

Located beneath Russia's Ural Mountains, Orda Cave is legendary among divers for its unique beauty. The cave's waters are clearest in winter, when the land above lies frozen. With temperatures approaching minus 40 degrees, NHK attempts to film the cave for the first time ever using 4K cameras. Scientists give them insight into the cave's origins, enabling the crew to uncover the miraculous story of how the cave was naturally formed 300 million years ago by climate change and a shifting landscape.

Japan's landscapes range from snowy mountains to subtropical warmth. They are full of wildlife - and animals' and people's lives often cross as they adapt to these extremes. The central island of Honshu is home to over 100 million people, and its biggest city, Tokyo, is one of the largest urban metropolises on earth. But it has a wild heart - most of Honshu is mountainous. This wilderness is home to an astonishing range of wildlife - black bears, monkeys, exquisite fireflies and even cow demons. But all across this island, from the mountains to the edge of the sea, people and nature are drawn together in the most unexpected ways.

In the far south west of Japan, there is a chain of islands stretching towards the tropics - a place where all life is influenced by the power of the sea, and where volcanoes and typhoons are forces to be reckoned with. The journey begins at an island at the top of the chain and travels south, revealing unexpected stories of isolation, unique wildlife and unsolved mysteries.

Nearly a generation after the acclaimed Blue Planet documentary was released, David Attenborough returns to narrate this groundbreaking sequel/reboot. Blue Planet II focuses more heavily on mankind's influence on the world's oceans through both global pollution and climate change. This series features a variety of revolutionary segments never before seen in a video documentary. One Ocean Footage of marine life in different environments around the north, beginning with a tropical coral reef which has medicinal properties for dolphins, and is used as a tool by tusk fish. In Japan, a shipwreck is home to the Asian sheepshead wrasse, which can change gender, while in the polar north, walruses struggle to find ice floes for their pups to rest on as climate change takes its toll on the environment.

Corals build themselves homes of limestone in the warm, clear, shallow seas of the tropics. Their reefs occupy less than one tenth of one per cent of the ocean floor, yet they are home to a quarter of all known marine species. The broad-club cuttlefish has found its place by using a hypnotic display that apparently mesmerizes its prey, causing it to let down its defences. On the Great Barrier Reef a remarkable grouper uses sign language, dubbed the headstand signal, to reach out to an entirely different creature, a reef octopus, to flush small fish out of their hiding holes and into the groupers waiting mouth.