THE global economy has stumbled from one pothole to the next in 2015. America's economy slowed to a crawl during an icy first quarter. Then fears of a Greek exit from the euro area worried markets. Now attention has turned to China, where the government is fumbling to contain a stockmarket rout and prevent a hard landing. In the background another ominous trend has been developing: world trade shrank on a quarterly basis in both the first and second quarter of this year: the worst performance since the height of the financial crisis. But how significant is a decline in trade for the global economy?
