Copyright: Sarah-Jane Walsh/ Silverback Films Arctic fox with pups, Karrak Lake, Canada. Life on our planet is powered by a solar force – the Sun. Every patch on Earth gets 4,380 hours of sunlight a year but in different doses depending on where you are: a variation that shapes much of the natural world.      

Seasonal variations in light are due to the fact that the Earth spins on a tilt  - 23.5 degrees – which means different parts of the planet are angled towards the sun at different times of the year. Through close-up, stories of beguiling animal characters, this episode reveals how the planet’s living things have come up with brilliant adaptations to survive uneven amounts of sunlight.  

The exception is on the equator where the duration of day and night remain the same throughout the year. Here, we discover how this guaranteed sunlight drives the great diversity of life we call the tropical jungles. Jumping into the canopy with acrobatic, fruit-eating gibbons, we enter the strange macro world of the fig wasp, revealing their spellbinding relationship with the jungle’s most important tree.

At the extreme ends of the Earth – the Poles - the loss of solar power lasts not for half a day but for nearly half a year. With no sunlight energy for months, the atmosphere chills, temperatures plummet and water freezes. This seems almost unliveable, unless you are an Arctic wolf or muskox – supreme polar specialists in surviving long periods without sunlight.

Animals have come up with ingenious solutions to deal with the differences in the Sun’s energy across the globe. In the Sahara, silver ants have evolved adaptations that make them masters in coping with too much sunlight. During winter’s chill, wood frogs have found a way to save energy by allowing themselves to freeze solid. In this suspended animation their hearts stop beating completely.

The seasonal shift in the the Sun’s power across the Earth means that in some places residents must cram a full life into short periods of time. For Canada’s most northerly reptile, the garter snake, the warming temperatures of late Spring trigger the largest emergence of snakes on earth, taking part in a mass mating ritual. For Arctic foxes these are also times of feverish activity, cramming feeding, hunting and breeding for the entire year into a few summer months. In Autumn, the golden snub-nosed monkeys of China’s seasonal forests, life or death is determined by a narrow window where they must stockpile enough energy resources to survive winter’s power cut.

When the cold starts to bite in the Southern Hemisphere, thousands of sooty shearwaters set off from Snares’ Island in New Zealand and head north -  chasing the sun on an epic 10,000-mile migration to arrive in Alaska’s Aleutian Islands for summer. Here, the shearwaters are joined by hundreds of humpback whales in one of the most dynamic and thrilling feeding spectacles on Earth.

Copyright: Toby Nowlan/Silverback Films A herd of puku look down over the steep riverbank at a colony of carmine bee eaters in Zambia's Luangwa Valley. Water is vital for the existence of all life. We live in a world that has it in abundance, yet most of this water is inaccessible to us. 97% is sea water, too salty for terrestrial life to use. Just 3% exists as freshwater, and almost all of this is locked up as ice, or hidden underground. Only a tiny fraction can be accessed by life on land – and only then through the action of our planet’s weather. For weather is the force that ditributes this freshwater around the world.

Every year the sun evaporates 434 million billion liters of water from our oceans – 20 times the volume of all the Great Lakes of North America and Canada combined. This water rises into the sky where it forms clouds, before falling as rain, sometimes thousands of miles away. Without the sun making rain, there would be no freshwater on Earth – and terrestrial life could not exist.

But where water is concerned, our planet is not created equal. Some regions experience extreme amounts of rain year round, some just a few millimeters, whilst others must deal with extreme shifts between wet and dry seasons. This distribution of freshwater around the globe has shaped the lives of animals all across the planet – and in doing so it has given rise to an incredible diversity of species and habitats, from the driest desert to the lushest tropical rainforest.

Copyright: Ed Charles / Silverback Films Marine iguanas getting ready to brave the chilly waters off Fernandina Island in the Galapagos. Oceans are the largest ecosystem on Earth, covering 2/3rds of the surface of our world and providing half the oxygen in our atmosphere. It’s thought that they’re home to as much as 80% of all life on Earth, and nearly 3 billion people rely on them for their primary source of food. But if it was not for one simple factor, our planet’s oceans would be little more than stagnant wastelands, and life on Earth – not just in the oceans – would cease to exist. So what is it about our Perfect Planet’s oceans that brings about so much life?

The answer is that all the world’s oceans are connected – dip your toe in the sea off Cornwall, and you are connected to every ocean and sea on our planet. There are not five, separate oceans, but one, linked by a network of powerful currents that are forever on the move. Every drop of seawater on Earth rides these currents, taking a thousand years to complete a single circuit.

All marine life depends on this continuous movement of water – from vast super-pods of dolphins and the flocks of gannets that follow them as they scour the oceans searching for a meal, to the tiny yet dazzling flamboyant cuttlefish that’s looking for a mate. All rely on currents to carry vital nutrients across the ocean – but currents are just part of the story.

Other forces bring nutrients to our planet’s coastal regions, the most productive parts of our seas. Winds blowing across the open ocean create rolling swells that travel thousands of miles towards the coast. When these swells hit the shallows, massive waves are spawned that crash against the shore, stirring up nutrients to be exploited by countless species. For some, like blacktip sharks and trevally, waves create rich hunting grounds – but for others like rockhopper penguins, the massive swells that crash into their island home make returning back to their colony a potentially deadly commute.

Our oceans are also driven by another force – the gravitational pull of the moon which causes the ocean to bulge at two points. Twice a day – every day – tides mix up the waters of our shallow seas creating new opportunities for huge amounts of life on both land and sea: the fast-flowing tides of Norway provide the perfect condition for filter feeding mussels, which are the favourite food of eider ducks, whilst more gentle tides like those seen in the Bahamas create the ideal opportunity for lemon sharks to give birth in the relative safety of flooded mangrove forests.

Without this mixing from currents, tides and waves, our oceans would stop supporting life – a healthy ocean is vital to a healthy planet.

Copyright: Silverback Films / Moonraker A visualization of Carbon Dioxide in Earth's atmosphere using data from NASA's Goddard Space Flight Centre. Our home, a blue glowing beacon of life, hangs alone in the cosmos. The only living world we know of. But a new force, one so powerful that it is upsetting the balance of life on earth, threatens our perfect planet – that force is us.

Humans are changing our planet so rapidly, it’s affecting earth’s life support systems: our weather, our oceans and the living world. To understand what is going wrong, we must look to the past.

Earth has been through at least five mass extinction events, most of which have been caused by cataclysmic volcanic eruptions. It’s not the lava or ash that wiped out life but an invisible gas released by volcanoes, Carbon Dioxide or CO₂.

Through compelling animal-led stories and expert interviews, we discover how the invisible gas is destabilising Earth. We meet rescued orphaned elephants in Kenya, victims of ever worsening droughts, and join ocean patrols off the coast of Gabon fighting to save endangered sharks. In the Amazon, we witness wildlife teams saving animals in the shrinking forests and in San Diego we enter a cryogenic zoo preserving the DNA of endangered species before they go extinct.

Almost every part of modern life depends on energy created by burning fossil fuels; this produces CO₂ in huge amounts. Humans are now acting like a super-volcano releasing carbon dioxide at an even greater rate than the prehistoric mega-eruptions that extinguished life in the past. Globally, we now release one hundred times more carbon dioxide into the atmosphere than all of Earth's volcanoes combined.

The greatest change we must make is how we create our energy, and Earth is brimming with natural power to do just that – wind, solar, wave and geothermal It’s these forces of nature, that have shaped life, which hold the key to our future.