The Age of Uncertainty looks at the legacy of climate change... the consequences of a "business as usual" scenario. Do we really need more proof?

We begin in ancient Peru, where the Moche civilization was destroyed by a massive El Nino event... even human sacrifice did not appease their gods. Today we're just as vulnerable to El Ninos, which may be becoming more powerful as higher temperatures destabilize our atmosphere.

The story of Isle Derniere - a once-fashionable resort off the tip of Louisiana - foretells the fate of barrier islands all along the East Coast. Like Fire Island, where Erika Freid's house had to be rebuilt 80 feet back from an ever-eroding beach. In places like tiny Badger, Newfoundland and even in inland cities like Northampton in the UK, surprise floods are wiping out property and people's lives. But the greatest effects are felt in the far North - where melting permafrost and thinner sea ice are threatening the lives of people and animals.

In Georgian Bay, cottager Eric Harding is mowing his beach for the third year in a row. The effects of climate change on the Great Lakes means lower water levels, as evaporation increases in both summer and winter months. The impact of rapid change worries biologist Karl Schiefer, who predicts massive species extinctions in our future, as rapid warming and fragmentation of habitat places birds and animals at risk. Already, off the coasts of the world, fish are disappearing at an alarming rate - victims ofover-fishing and warmer temperatures. Dr. Tim Parsons warns of the "de-evolution" of the seas - as warmer waters create excellent habitat for jellyfish, which are increasingly taking over.

Across the west, trees are dying - victims of drought and wildfires. And farmers everywhere must confront ever more uncertain growing seasons. In the Canadian west, drought and extreme weather are keeping farmers on their toes, while in Bangladesh, higher sea levels and more violent monsoons is forcing farmers like Binod Biswas to make drastic changes.

Proof is everywhere. In the marshes of the Louisiana coast, marsh guides Danny and Toby Duet have seen erosion in the hundreds of feet in their own lifetimes. And the city of New Orleans - already well below sea level and sandwiched between the Mississippi and the sea - is certain to be a victim. Tarot reader John Williamson reads the future, and it's grim.

As temperatures climb, the most severe effects are already being felt in places like France, where 15,000 people died in the heat of summer 2003, and across many other urban areas. Dr. Jean Zigby is concerned about the rise in climate related illness in his practice. And in a Harvard lab, startling results - higher CO2 levels means a 10% increase in growth rate in species like ragweed - but a 61% increase in pollen production.

But perhaps the greatest threat is to global stability. As Earth's population increases, each new arrival expects his or her ration of energy, food, water. How we achieve this will depend on how we manage our resources - will "dirty" energy be the only way?

Climate change is deceptive - it doesn't show itself in any one form. Little by little, our world is changing. But the good news is that we can reduce its impact. Around the world, millions upon millions of people do care - especially the young. And they are going to change the world.