Water scarcity already affects more than 40 per cent of the world’s population and is expected to rise due to global warming. Drought-stricken Cape Town could run out of water as soon as April, but South Africa is not alone in its struggle as ever more world cities battle acute water shortages. Water scarcity already affects more than 40 per cent of the world’s population and is expected to rise due to global warming, with one in four people projected to face chronic or recurring shortages by 2050, according to the United Nations. Already hosting more than half the world’s people, cities are at the forefront of the problem, as population growth increases pressure on reserves, which are already stretched by too little rain and too much waste. Following are some of the crisis cities: MELBOURNE The Australian city suffered the so-called ‘Millennium drought’ between 1997 and 2009. It was one of the worst dry…