Guardian: Twenty Nobel prizewinners, including US energy secretary Steven Chu, Nigerian writer Wole Soyinka, and Kenyan environmentalist Wangari Maathai, have compared the threat of climate change to that posed to civilisation by nuclear weapons. Borrowing a phrase from US civil rights leader Martin Luther King, they said at the end of a three-day climate change symposium hosted by Prince Charles in London: "We must recognise the fierce urgency of now. The evidence is compelling for the range …