An examination of the photographic and artistic evidence for colder winters in the past, and a look at the changing balance of glacial advance and retreat. Visual evidence in the form of artwork depicting frost fairs on the Thames and photographs of retreating glaciers introduce this topic. The mechanisms for changes in the balance between glacial advance and retreat, namely accumulation and ablation, are demonstrated using clear animations showing the recent retreat of Alpine valley glaciers.

First broadcast:
18 October 2007

Can be used to discuss long-term and short term climate change. Examine the evidence for climate change. How can old paintings illustrate climate change? How can glaciers be used to show climate change? Explain why glaciers advance and retreat. How do glaciers vary seasonally? What is the role of meltwater? How have mountain glaciers been changing over the last 60 years or so?