Every year grizzly bear families in North America depend for their survival on a spectacular natural event: the return of hundreds of millions of salmon from the Pacific Ocean to the mountain streams where they were born. The salmon travel thousands of miles to spawn and then die. The great run not only provides food for bears, but for killer whales, wolves, bald eagles, and even the forest itself. The question is: will the salmon return in time to keep hungry bears alive?
A mother grizzly and her cubs emerge from their den high in snowy Alaskan mountains. Filming from the air the team capture a TV first, following the bears as they negotiate a near vertical slope on their journey to the coast where they await the return of the salmon. Meanwhile, the salmon are making their way to the to river mouths where they must swim upstream and against the current. The programme reveals how they tackle the torrents and leap over waterfalls, a feat equivalent to a human jumping over a house. Dozens of hungry bears eagerly await the salmon that make it up river. In another TV first, underwater cameras record the ingenuity and fancy footwork they use to collect dead salmon from the bottom of deep pools.

A decade after An Inconvenient Truth brought climate change into the heart of popular culture comes the riveting and rousing follow-up that shows just how close we are to a real energy revolution. Vice President Al Gore continues his tireless fight, traveling around the world training an army of climate champions and influencing international climate policy. Cameras follow him behind the scenes-in moments private and public, funny and poignant-as he pursues the empowering notion that while the stakes have never been higher, the perils of climate change can be overcome with human ingenuity and passion.
Renowned filmmakers Bonni Cohen and Jon Shenk have taken the baton from 2006 Academy Award-winner Davis Guggenheim. What started then as a profound slide show lecture has become a gorgeously cinematic excursion. Our extraordinary former vice president invites us along on an inspirational journey across the globe that delivers the tools to heal our planet. The question is: Will we choose to take the baton?

Morgan Freeman narrates Island of Lemurs: Madagascar, the incredible true story of nature's greatest explorers - lemurs. Scientist Patricia Wright has a passion for preserving the life of one particular creature: the lemur. These lively animals found in Madagascar face all sorts of threats, just like so many other animals in a world in which they are increasingly crowded out by humans. Her passion for the subject is compelling and plainly evident, but it's the silent testimony of the animals themselves that really makes the case. Countless hours of footage are trimmed down to create this tapestry depicting the lives of these creatures of remarkable intelligence and ingenuity. Their daily routines and extraordinary adventures are awesome to behold, as is the way that the community functions. A full immersion into the world of the lemurs means great insights on these unusual animals.

What might happen if the first manned mission to Mars crashes hundreds of miles from the rocket that would take them back home? Could they survive the crash, and travel across the brutal Martian surface to their home ship? We'll show what the astronauts would have to do to survive dust storms and space radiation, while extracting vital resources like water from the Martian soil itself. It's a dramatic vision of the very near future, where survival can depend on pre-industrial technology and human ingenuity.

The dome that crowns Florence's great cathedral of Santa Maria del Fiore, the Duomo, is a masterpiece of Renaissance ingenuity and an enduring source of mystery. Still the largest masonry dome on earth, it is taller than the Statue of Liberty and weighs as much as an average cruise ship. Historians and engineers have long debated how its architect, Filippo Brunelleschi, kept the dome perfectly aligned and symmetrical as the sides rose and converged toward the center." More than four million bricks could collapse at any moment -- and we still don't understand how Brunelleschi prevented it. To test the latest theories, a team of U.S. bricklayers will help build an experimental "mini-Duomo" using period tools and techniques.

Andrew Marr sets off on an epic journey through 70,000 years of human history. Using dramatic reconstructions, documentary filming around the world and cutting-edge computer graphics, he reveals the decisive moments that shaped the world we live in today, telling stories we thought we knew and others we were never told." Starting with our earliest beginnings in Africa, Marr traces the story of our nomadic ancestors as they spread out around the world and settled down to become the first farmers and townspeople. He uncovers extraordinary hand-prints left in European caves nearly 30,000 years ago and shows how human ingenuity led to inventions which are still with us today. He also discovers how the first civilisations were driven to extremes to try to overcome the forces of nature, adapting and surviving against the odds, and reveals how everyday life in ancient Egypt had more in common with today's soap operas than might be imagined.