Since human beings have existed on the planet, nothing has done more to shape the world than ice. It may be nothing more than frozen water, but it holds extraordinary power – carving the landscape and unleashing terrible catastrophes. Ice has not only changed the course of human evolution, it may now threaten our future.

Dr Iain Stewart continues his epic story of planet Earth tonight as he comes face to face with ice on a precarious climb 150 metres up a frozen waterfall. He visits a unique ice lab in Arctic Norway, which has been dug out underneath a glacier. Viewing the glacier in action from below, he is able to learn how it is able to cause so much destruction.

Ice has such phenomenal power it can cut through solid rock. One of the world’s top climbers describes how Yosemite’s towering granite peaks of El Capitan and Half Dome have become Meccas for climbers, because of the smoothness and steepness of the rock that has been worn by glacial ice.

In order to see how the planet’s ice is changing, Iain joins an expedition up the massive Jacobshavn glacier in Greenland to see how, and why, it has retreated more than 10 kilometres in the last few years.

There is now no doubt that across most of the planet, ice is melting. It’s believed it will cause the biggest change in the appearance of the planet since the dawn of human civilisation.

Tuesday 4 December
9.00-10.00pm BBC TWO