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.

The Ebola virus is one of the most virulent infections known to science. This special episode of Horizon meets the scientists and doctors from all around the world looking for the cure and hears first-hand accounts of what it is actually like to catch and survive the disease

Travelling from the unique Muslim contribution in the medieval south, Andrew Graham-Dixon immerses himself in true Spanish culture and meets the people who live and work with this artistic legacy. He looks at Muslim political and cultural influence as he travels from Cordoba to Granada, seeing classic buildings such as the Great Mosque in Cordoba, the Alcazar in Seville and the Alhambra in Granada. He also shows how the Moors introduced new foods – including citrus fruits, coffee and spices

Dr Jago Cooper reveals the history of some of South America's ancient civilisations. He begins with an epic journey into the remote Peruvian Andes in search of the mysterious Chachapoya people. Once numbering half a million, they were known as the 'People of the Clouds'. Dr Cooper reveals how they developed sophisticated methods of recording stories, traded in exotic goods found hundreds of miles from their territory, and had funeral traditions that challenge assumptions about ancient human behaviour. His search for evidence takes him to astonishing cliff tombs untouched for 500 years and one of the most spectacular fortresses in South America, where the fate of the Chachapoya is revealed.

Painting became an important means of communication for David since his face was slashed during a sword fight and his speech became impeded by a benign tumour that developed from the wound, leading him to stammer. He was interested in painting in a new classical style that departed from the frivolity of the Rococo period and reflected the moral and austere climate before the French Revolution. David became closely aligned with the republican government and his work was increasingly used as propaganda with the Death of Marat proving his most controversial work.

Human Planet is a majestic portrait of humankind and the power of nature in extraordinary symbiosis, struggle and strife. For the first time, the camera has turned on ourselves. In doing so, we see how amazing human beings can be and how we adapt to any habitat, anywhere. Human Planet is epic in ambition, extreme in content, intimate in effect. It explores how we have devised ways of surviving in every corner of Earth – from the remotest deserts to the busiest urban metropolis. Each episode focuses on an iconic environment and reveals how we have adapted to the challenges of the landscape and the endless diversity of animals and plants we live with. Discover how our remarkable intelligence, tool use, and close-knit social lives have enabled us to cope with just about anything nature can throw at us". As an air-breathing animal, the human is not built to survive in water. But people have found ways to live an almost aquatic life so they can exploit the sea's riches. From a 'shark-whisperer' in the Pacific to Brazilian fishermen collaborating with dolphins to catch mullet, this journey into the blue reveals astonishing tales of ingenuity and bravery. Daredevil Galician barnacle-collectors defy death on the rocks for a catch worth 200 pounds per kilo. In Indonesia an epic whale-hunt, using traditional hand-made boats and harpoons, brings in a sperm whale. The Bajau 'sea gypsies' of the Sulu Sea spend so much time on water they get 'land sick' when they set foot on the land! We dive 40 metres down to the dangerous world of the Pa-aling fishermen, where dozens of young men, breathing air through a tangled web of pipes attached to a diesel engine, capture thousands of fish in a vast net. We see how surfing has its origins in the ancient beliefs of the ocean-loving Polynesians, and we join a Borneo free-diving spear-fisherman on a breath-taking journey 20 metres down in search of supper.