Physical location on a map; faraway place in our imagination: both those aspects of the North Pole feature in The Top of the World, a BBC World Service programme first broadcast yesterday morning. Joining Bridget Kendall are Felicity Aston, the explorer, author and former climate scientist; Klaus Dodds, professor of geopolitics at Royal Holloway, University of London, and co-author of the forthcoming book The Arctic: What Everyone Needs to Know (Oxford University Press); and Michael Bravo (see earlier post).