Reuters: Six candidates are vying to become head of the U.N.'s top authority on climate change science this week, seeking to narrow down uncertainties about future warming to guide a trillion-dollar shift to greener energies. Top scientists - all men - from Austria, Belgium, Sierra Leone, South Korea, Switzerland and the United States will seek to become chair of the Intergovernmental Panel on Climate Change (IPCC) in a vote due on Tuesday at an IPCC meeting in Croatia. Governments have to pick a successor...