FOUR years after the worst of the financial crisis and the world appears to be faltering again. According to The Economist's calculations, world GDP grew by just 2.1% during the first quarter of 2013 compared with a year earlier. Just 12 months ago, output was growing at a reasonable clip of 3.1%. The European Union, the world's second-largest economy, which welcomes its 28th member on July 1st, is back in recession. Meanwhile there are concerns about stumbling blocks as China seeks to rebalance toward a more consumption-oriented economy and more moderate growth rates. Long the mainstay of the world's fortunes, China alone has been responsible for nearly half of all world economic growth since the end of 2009 when the world began growing again. Other big emerging markets, Turkey, Brazil and India, are struggling to quell social unrest over frustration with governments' inability to deliver growth and make appropriate reforms.