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.

As tides rise and fall twice a day, vast amounts of water swirl around the earth. This is a huge energy source that's currently largely untapped. An estimated 3000 gigawatts are available to be harvested globally, enough to power a third of the earth's homes. Yet compared to wind and solar, the technology needed to harness tidal power is still in its infancy. The power of the ocean’s tides is the last great untapped energy source on Earth. From sub-sea kites to floating platforms, teams of engineers are racing to perfect the technology to harness the vast flows of water.

Experience up-close encounters with some of the most remarkable marine life ever captured on film while examining the impact of global climate change on the ocean wilderness as award-winning director/cinematographer Howard Hall travels from South Australia to the Indo-Pacific to teach viewers the importance of keeping our oceans clean for future generations.
Just how great of an effect does global warming have on marine wildlife, and what can be done to ensure the future well-being of our planet? As the filmmakers reveal the delicacy of our fragile ecosystem, viewers are allowed the unique opportunity to see what we risk losing should we fail to address the issue of global climate change sooner rather than later.

Widespread dietary changes are needed if we’re to combat the range of health problems associated with obesity and the environmental damage caused by industrial farming. Switching to a vegan diet is a potential solution, but selling the idea to the meat-eaters around the world is a tricky proposition.

Imagine a tornado so powerful, it can form a planet, or winds sweeping across a planet but blowing at 6,000 miles per hour! How about rain....made of iron? Sounds like science fiction, but this type of weather is occurring daily in our solar system. Scientists are just beginning to unlock the secrets of these planets and their atmospheres. Can this research help scientists solve long unanswered questions that we have about Earth? As our own planet churns with the effects of global warming, it's natural to look into the heavens and wonder about the rest of the real estate.

The film centers on our ongoing mission to explore and come to terms with the Arctic, and the compelling stories of our many forays into this captivating place will be interwoven to create a unifying message about the state of the Arctic today. Underlying all these tales is the crucial role that ice plays in the northern environment and the changes that are quickly overtaking the people and animals who have adapted to this land of ice and snow.