A s US troops withdrew from Somalia in the spring of 1994, a teenaged Muse Omar Jama began working as an exchange trader in Mogadishu’s Bakara market. More than three decades later, he still does the same job, but wonders for how much longer. Jama, 49, sits in a plastic chair in the one-room office he shares with other traders. The auto-rickshaws speed by outside, but inside is quiet; the noise of bargaining has faded and the traders exchange few words between themselves. Their battered metal safes, filled with millions of Somali shillings, are closed and locked. The paper fortunes inside have suddenly become worthless. “It’s like we went bankrupt overnight,” says Jama. Last month, fed up with greasy, ripped and aged banknotes, a handful of traders in Mogadishu decided they would no longer accept them. Soon businesses, shops and even bus drivers were following suit, and the decision quickly spread to regions outside the capital.…