The climate is changing faster than ever, which is why 'fix our climate' is one of the five goals of the Earthshot Prize. Prince William, Sir David Attenborough and Christiana Figueres highlight inspiring and often unexpected solutions to the challenge. In this film, we'll explain the scale of the problem posed by climate change and will introduce you to some amazing people already working on climate crisis. One of these three finalists will win the Earthshot Prize and get the platform and resources they need to scale their ground-breaking work. Nine more solutions for fixing our climate will receive the same support over the course of this decade.

The sparkling blue waters of the Mediterranean Sea are home to over 700 varieties of fish and almost 10 per cent of the world's marine species. Its coastline is one of the most densely populated in the world and the human pressure on this sea is magnified each summer with the influx of holiday makers. Western civilisation developed around these shores but now human activity is having a profound effect on this endangered sea.

Sagan discusses comets and asteroids as planetary impactors, giving recent examples of the Tunguska event and a lunar impact described by Canterbury monks in 1178. It moves to a description of the environment of Venus, from the previous fantastic theories of people such as Immanuel Velikovsky to the information gained by the Venera landers and its implications for Earth's greenhouse effect. The Cosmos Update highlights the connection to global warming.

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 Arctic is the harshest environment on Earth: little food grows, it's dark for months on end, and temperatures stay well below freezing for much of the year. Yet four million people manage to survive here. Human Planet tells remarkable stories of extraordinary people who make their homes in nature's deep freeze. In springtime, Amos and Karl-Frederik set out across the sea ice with their dogs to catch a real-life sea monster: a Greenland shark! Inuit mussel-gatherers venture underneath the sea ice at low tide for a perilous race against time as they gather their food. And the children of Churchill, Manitoba, set out on the most dangerous trick or treating Halloween in the world: they risk coming face-to-face with deadly polar bears on the streets of their town. Who'll get the tastiest snack?

Are the wealthy just born in the right place at the right time? Are the poor victims of a system designed to keep them down? Or do physics and biology determine who is rich and who is poor? Throughout history, distribution of wealth is governed by hidden forces: DNA, environmental stress, patterns of human migration and even the laws of thermodynamics! Nature seems to demand winners and losers in life. But does this mean greed is king, and the rich can take what they want? Or is cooperation – between microorganisms, monkeys, and humans – more essential to survival of a species?