The Russian Arctic is one of the world’s most extreme habitats, yet it is a haven for polar bears, lemmings, arctic foxes and walruses. In late August, massive muskoxen bulls gather together to compete for mating dominance. Each bull can weigh 400 kilogram’s and charge at a speed of 40 kilometres an hour; a head-to-head impact can be heard more than a kilometre away

The first episode looks at how birds first took to the skies in the wake of the insects. It begins in Mexico, where Sir Attenborough observes bats being outmanoeuvred by a red-tailed hawk. Pterosaurs were the birds' forerunners, some 150 million years after dragonflies developed the means of flight, but eventually went extinct together with the dinosaurs. Birds had by then already evolved from early forms like archaeopteryx, the first creature to possess feathers. Its ancestry can be traced through reptiles, and some current species, such as the flying lizard, possibly show paths this evolution may have taken." One of the biggest birds to have ever existed was the terror bird, which proliferated after dinosaurs vanished and stood up to 2.5 metres tall. By comparison, the ostrich, while not closely related, is the largest and heaviest living bird. It was probably the evasion of predators that drove most birds into the air, so their flightless cousins evolved because they had few enemies. Accordingly, such species are more likely to be found on islands, and Sir Attenborough visits New Zealand to observe its great variety, most especially the kiwi. Also depicted is the moa, another huge creature that is now gone. The takahē is extremely rare, and high in the mountains of New Zealand, Sir Attenborough discovers one from a population of only 40 pairs. Finally, another example on the brink of extinction is the kakapo, which at one point numbered only 61 individuals. A male is heard calling — an immensely amplified deep note that can be heard at great distances from its nest.

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.

A journey through the cosmos in search of alien life. We seek out planets around distand stars and dive into the oceans of other worlds - seeking an answer to the question: is there anybody out there?

Sir David Attenborough reveals plants as they have never been seen before - on the move and dangerously devious. About the major problems of life - growing, finding food, reproduction - and the varied ways plants have evolved to solve it. Filmed from the plant's point of view, using computer animations, fibre-optics and unique time-lapse photography. The first episode looks at how plants are able to move". The bramble is an aggressive example: it advances forcefully from side to side and, once settled on its course, there is little that can stand in its way. An altogether faster species is the birdcage plant, which inhabits Californian sand dunes. When its location becomes exposed, it shifts at great speed to another one with the assistance of wind — and it is this that allows many forms of vegetation to distribute their seeds. While not strictly a plant, the spores of fungi are also spread in a similar fashion. One of the most successful (and intricate) flowers to use the wind is the dandelion, whose seeds travel with the aid of 'parachutes'. They are needed to travel miles away from their parents, who are too densely packed to allow any new arrivals. Trees have the advantage of height to send their seeds further, and the cottonwood is shown as a specialist in this regard. The humidity of the tropical rainforest creates transportation problems, and the liana-species Alsomitra macrocarpa is one plant whose seeds are aerodynamic 'gliders'. Some, such as those of the sycamore, take the form of 'helicopters', while others, such as the squirting cucumber release their seeds by 'exploding'. Water is also a widely used method of propulsion. The tropical sea bean Entada gigas has one of the biggest fruits of all plants and is dispersed by water streams. However, most plants use living couriers, whether they be dogs, humans and other primates, ants or birds, etc., and to that end, they use colour and smell to signify when they are ripe for picking.

It's a voyage of exploration like no other - to Titan, Saturn's largest moon and thought to resemble our own early Earth. For a small team of British scientists this would be the culmination of a lifetime's endeavour - the flight alone, some 2 billion miles, would take a full seven years. This is the story of the space probe they built, the sacrifices they made and their hopes for the landing. Would their ambitions survive the descent into the unknown on Titan's surface?