Having explained the science behind global warming, and addressed the arguments of the climate change sceptics earlier in the series, Dr Iain Stewart concludes the series by looking at the biggest challenge now facing climate scientists - Just how can they predict exactly what changes global warming will bring?
It's a journey that takes him from early attempts to model the climate system with dishpans, to supercomputers, and to the frontline of climate research today: Greenland. Most worryingly he discovers that scientists are becoming increasingly concerned that their models are actually underestimating the speed of changes already underway.

Legendary oceanographer and TED prize winner Dr. Sylvia Earle is on a mission to save our oceans. Mission Blue is part action-adventure, part expose of an Eco-disaster. More than 100 scientists, philanthropists and activists gather in the Galapagos Islands to help fulfill Dr. Earle's lifelong wish: build a global network of marine protected areas, like underwater national parks, to protect the natural systems that keep humans alive.
As the expedition ends, the Deep water Horizon oil well explodes. With oil gushing into the Gulf of Mexico, Sylvia and an environmental dream team race around the world trying to defend her 'Hope Spots'.