Nature

The third episode is devoted to the ways in which plants reproduce. Pollen and a stigma are the two components needed for fertilisation. Most plants carry both these within their flowers and rely on animals to transport the pollen from one to the stigma of another. To do this, they attract their couriers with colour, scent and nectar. It isn't just birds that help pollination: some mammals and reptiles also do so. However, it is mostly insects that are recruited to carry out the task. To ensure that pollen is not wasted by being delivered to the wrong flower, some species of plant have developed exclusive relationships with their visitors, and the gentian and its attendant carpenter bees is one example. Since pollen can be expensive to produce in terms of calories, some plants, such as orchids, ration it by means of pollinia and a strategically placed landing platform. Other orchids offer no reward for pollination, but instead mislead their guests by mimicking their markings and aroma, thus enticing males to 'mate' with them (Pseudocopulation). The most extreme fertilisation method is one of imprisonment, and one plant that uses it is the dead horse arum. It is often found near gull colonies, and mimics the appearance and smell of rotting flesh. Blow-flies are attracted to it, and are forced to stay the night before being allowed to depart in the morning, laden with pollen. Finally, Attenborough introduces the world's largest inflorescence: that of the titan arum.

Acclaimed National Geographic photographer James Balog was once a skeptic about climate change. But through his Extreme Ice Survey, he discovers undeniable evidence of our changing planet. In Chasing Ice, Balog deploys revolutionary time-lapse cameras to capture a multi-year record of the world's changing glaciers". His hauntingly beautiful videos compress years into seconds and capture ancient mountains of ice in motion as they disappear at a breathtaking rate. Traveling with a team of young adventurers across the brutal Arctic, Balog risks his career and his well-being in pursuit of the biggest story facing humanity. As the debate polarizes America, and the intensity of natural disasters ramps up globally, Chasing Ice depicts a heroic photojournalist on a mission to deliver fragile hope to our carbon-powered planet. Directed by Jeff Orlowski

Is God worshipped in other worlds, across the cosmos? How might alien deities differ from our own? The answer may lie buried on Earth. Animal behaviorists are testing elephants and finding them capable of having spiritual thoughts. Artificial intelligence researchers are building enlightened robots that contemplate the divine. Meanwhile, cosmologists are looking for universal equations that could replace God. Have advanced aliens discovered everything there is to know about the universe? Or are they looking to a higher power for answers?

The documentary deals with the future of conservation. It begins by looking at previous efforts. The 'Save The Whales' campaign, which started in the 1960s, is seen to have had a limited effect, as whaling continues and fish stocks also decline. In the 1990s, as head of the Kenya Wildlife Service, Richard Leakey took on the poachers by employing armed units. Although it was successful in saving elephants, the policy was detrimental to the Maasai people, who were forced from their land. The need for "fortress" areas is questioned, and the recently highlighted Raja Ampat coral reef in Indonesia is an example. The more tourism it generates, the greater the potential for damage — and inevitable coastal construction. Sustainable development is viewed as controversial, and one contributor perceives it to currently be a "contradiction in terms". Trophy hunting is also contentious. Those that support it argue that it generates wealth for local economies, while its opponents point to the reducing numbers of species such as the markhor. Ecotourism is shown to be beneficial, as it is in the interests of its providers to protect their environments. However, in some areas, such as the Borneo rainforests, the great diversity of species is being replaced by monocultures. The role of both religion and the media in conservation is argued to be extremely important. Contributors to the programme admit a degree of worry about the future, but also optimism.

Earth’s oceans help make our planet different from every other planet in the solar system. As far as we know, no other place is the right temp for liquid water, the most essential ingredient for life to exist. The oceans are Earth’s primary stabilizing force, and their immense power helps to shape the appearance and behavior of the entire planet and everything living on it. And they are also the planet's great unknown - their deepest points have been visited less than the surface of the moon.

The second episode is about how plants gain their sustenance. Sunlight is one of the essential requirements if a seed is to germinate, and Attenborough highlights the cheese plant as an example whose young shoots head for the nearest tree trunk and then climb to the top of the forest canopy, developing its leaves en route. Using sunshine, air, water and a few minerals, the leaves are, in effect, the "factories" that produce food. However, some, such as the begonia, can thrive without much light. To gain moisture, plants typically use their roots to probe underground. Trees pump water up pipes that run inside their trunks, and Attenborough observes that a sycamore can do this at the rate of 450 litres an hour — in total silence. Too much rainfall can clog up a leaf's pores, and many have specially designed 'gutters' to cope with it. However, their biggest threat is from animals, and some require extreme methods of defence, such as spines, camouflage, or poison. Some can move quickly to deter predators: the mimosa can fold its leaves instantly when touched, and the Venus flytrap eats insects by closing its leaves around its prey when triggered. Another carnivorous plant is the trumpet pitcher that snares insects when they fall into its tubular leaves. Attenborough visits Borneo to see the largest pitcher of them all, Nepenthes rajah, whose traps contain up to two litres of water and have been known to kill small rodents.