A world powered by renewable energy will prize a very different set of resources than we do today. Which countries hold the key to unlocking wind and solar energy, and how will this shake up the world order? University of Swansea's Andrew Barron discusses.
Cape Town is in the midst of a devastating water security crisis. World Resources Institute experts Betsy Otto and Leah Schleifer outline what other cities around the world can do to avoid a similar fate.