Andy - would you care to expand (when you get back from Greenbelt!) on you comment about the only 'liveable' continents?

I realise that is possible to live on Antarctica, but it is not really simple.  I have visited or lived in Europe, Asia, N. America, Australasia/Oceania.  I have never visited Africa or S. America (I treat N. and S. America as separate continents, though not everyone does).