Sir David Attenborough on global warming
26 October 2011 Last updated at 16:34 BST
Sir David Attenborough's new series Frozen Planet looks at life at the North and South Poles.
Sir David says he is back on screen in the seven-part series to express his "personal view" on the effects of global warming.
Frozen Planet starts on 26 October at 21:00 BST on BBC One
Richard Bacon broadcasts Monday to Thursday 14:00 to 1600 on BBC Radio 5 live.
To hear more Radio 5 live highlights, please visit the best bits (www.bbc.co.uk/5live/bestbits) page.