Around 30% of the land's surface is desert, the most varied of our ecosystems despite the lack of rain. Unravel the secrets of desert survival and experience the ephemeral nature of this dynamic environment. Watch Saharan sandstorms nearly a mile high and desert rivers that run for a single day. In the Gobi Desert, rare Bactrian camels get moisture from the snow. In the Atacama, guanacos survive by licking dew off cactus spines. In the USA, the brief blooming of Death Valley triggers a plague of locusts 65km wide and 160km long. A unique aerial voyage over the Namibian desert reveals elephants on a long trek for food and desert lions searching for wandering oryx.

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

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.

In 1901, a group of divers excavating an ancient Roman shipwreck near the island of Antikythera, off the southern coast of Greece, found a mysterious object - a lump of calcified stone that contained within it several gearwheels welded together after years under the sea. The 2,000-year-old object, no bigger than a modern laptop, is now regarded as the world's oldest computer, devised to predict solar eclipses and, according to recent findings, calculate the timing of the ancient Olympics. Following the efforts of an international team of scientists, the mysteries of the Antikythera Mechanism are uncovered, revealing surprising and awe-inspiring details of the object that continues to mystify

This edition features a spectacular journey along the Andes, the world's longest mountain range, stretching from the equator almost to Antarctica. In this harsh and unforgiving landscape, wildlife such as bears, pumas, condors and flamingos fight for survival in the numbing cold, ferocious winds and thin air.

This episode explores the nature of the greenhouse effect (discovered by Joseph Fourier and Svante Arrhenius), and the evidence demonstrating the existence of global warming from humanity's influence. Tyson begins by describing the long-term history of the planet Venus; based on readings from the Venera series of probes to the planet, the planet had once had an ocean and an atmosphere, but due to the release of carbon dioxide from volcanic eruptions, the runaway greenhouse effect on Venus caused the surface temperatures to increase and boiled away the oceans. Tyson then notes the delicate nature of the amount of carbon dioxide in the atmosphere can influence Earth's climate due to the greenhouse effect, and that levels of carbon dioxide have been increasing since the start of the 20th century. Evidence has shown this to be from mankind's consumption of oil, coal, and gas instead of from volcanic eruptions due to the isotopic signature of the carbon dioxide. The increase in carbon dioxide has led to an increase in temperatures, in turn leading to positive feedback loops of the melting polar ice caps and dethawing of the permafrost to increase carbon dioxide levels. Tyson then notes that humans have discovered means of harvesting solar power, such as Augustin Mouchot's solar-driven motor in the 19th century, and Frank Shuman's solar-based steam generator in the 1910's. Tyson points out that in both cases, the economics and ease of using cheap coal and oil caused these inventions to be overlooked at the time. Today, solar and wind-power systems would be able to collect enough solar energy from the sun easily. Tyson then compares the motivation for switching to these cleaner forms of energy to the efforts of the Space race and emphasizes that it is not too late for humanity to correct its course.