On 26 April 1986, reactor number four at the Chernobyl Nuclear Power Plant blew up. Forty-eight hours later the entire area was evacuated. Over the following months there were stories of mass graves and dire warnings of thousands of deaths from radiation exposure.
For centuries we have dreamt of reaching the centre of the Earth. Now scientists are uncovering a bizarre and alien world that lies 4,000 miles beneath our feet, unlike anything we know on the surface. It is a planet buried within the planet we know, where storms rage within a sea of white-hot metal and a giant forest of crystals make up a metal core the size of the Moon.
In February 2013, a hole opened up beneath a home in Florida, and swallowed a man. Jeff Bush was asleep when a sinkhole opened up beneath his bedroom. Despite the efforts of his brother to rescue him, Jeff was never seen again and his body was never recovered. Professor Iain Stewart travels to Florida to try and understand what killed Jeff, and why the geology of this state makes it the sinkhole capital of the world.
The last episode deals with the future of conservation. It begins by looking at previous efforts. The 'Save The Whales' campaign, which started in the 1960s, is seen to have had a limited effect, as whaling continues and fish stocks also decline.
From the Norwegian fjords to the coast of Jura in the English Channel and up to the peak of the Matterhorn; go from the volcanoes of the Massif Central in southern France to the Elbe Sandstone Mountains, or the “Grand Canyon of Europe”.
No season brings more surprises than an Alaskan summer. It lures hummingbirds up from the tropics, exposes deserts in the Arctic and relies on parachuting firefighters to tackle forest fires in its vast wilderness. Summer is a narrow window of plenty, when the land is bathed in 24-hour sunlight - but in this land of extremes, you can have too much of a good thing.