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. Discuss the evidence for climate change. Show how old paintings can be used to show evidence for climate change. Explain why glaciers advance and retreat. Explain the importance of meltwater.