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 documentary series reveals the extraordinary riches and wonders of the Polar Regions that have kept people visiting them for thousands of years. Today, their survival relies on a combination of ancient wisdom and cutting-edge science. Most Arctic people live in Siberia, either in cities like Norilsk - the coldest city on earth - or out on the tundra, where tribes like the Dogan survive by herding reindeer, using them to drag their homes behind them. On the coast, traditional people still hunt walrus from open boats - it is dangerous work, but one big walrus will feed a family for weeks. Settlers are drawn to the Arctic by its abundant minerals; the Danish Armed Forces maintain their claim to Greenland's mineral wealth with an epic dog sled patrol, covering 2,000 miles through the winter. Above, the spectacular northern lights can disrupt power supplies so scientists monitor it constantly, firing rockets into it to release a cloud of glowing smoke 100 kilometres high. In contrast, Antarctica is so remote and cold that it was only a century ago that the first people explored the continent. Captain Scott's hut still stands as a memorial to these men. Science is now the only significant human activity allowed; robot submarines are sent deep beneath the ice in search of new life-forms, which may also be found in a labyrinth of ice caves high up on an active volcano. Above, colossal balloons are launched into the purest air on earth to detect cosmic rays. At the South Pole there is a research base designed to withstand the world's most extreme winters. Cut off from the outside world for six months, the base is totally self-sufficient, even boasting a greenhouse.

Playing with Nuclear Fire' - In March 2011, the Tohoku earthquake in Japan created a tsunami that killed some 16,000 people and crippled the Fukushima Daiichi nuclear power plant. In the aftermath, the government and TEPCO, the plant's operator, withheld information about the extent of the damage. Three years later, citizens and the international community are left wondering if Japan really does have the situation under control, as the government is insisting, or if the danger is far greater than anyone is willing to admit. 'No Man Left Behind' - It's estimated that over a quarter million vets from recent wars have sought treatment for PTSD. Despite these statistics, veterans often face an uphill battle to get treatment, receiving inadequate attention and, most dangerously, overprescribed narcotics and other pharmaceuticals. Ryan Duffy meets veterans struggling with mental illness and addiction.

Above all, 'In Search of Beethoven' addresses the central myth of Beethoven's life and work -- that of the heroic, tormented figure battling to overcome the tragic fate of being struck down by deafness in his prime; a man who searched for his elusive, eternal 'immortal beloved,' yet was never to attain lasting happiness.

In February 2009, Michael Moore issued an appeal to people who worked for Wall Street or in the financial industry to share first hand information, requesting, 'Be a hero and help me expose the biggest swindle in American history'. He uncovers the social costs of corporate interests pursuing profits at the expense of the public good.

The health film that health organizations don't want you to see! The documentary is the groundbreaking follow-up film from the creators of the award-winning documentary Cowspiracy. The film exposes the collusion and corruption in government and big business that is costing us trillions of healthcare dollars, and keeping us sick. What The Health is a surprising, and at times hilarious, investigative documentary that will be an eye-opener for everyone concerned about our nation’s health and how big business influences it.