In this video: Alarm bells toll for civilization as Brazil’s biggest city runs out of water due to deforestation linked to drought.

Brazil’s biggest city, Sao Paulo, is experiencing its worst drought in decades. Now, a leading climatologist and earth scientist has told the BBC that there is a direct link between deforestation in the Amazon and the record drought. Water levels are dangerously low and state authorities have acknowledged there may be extended power cuts and other emergency measures in 2015.