Financial markets have been unsettled this week by a familiar cast of forces, though the balance among them has shifted. Renewed tension in the Middle East has nudged oil prices higher without seriously disturbing the wider tone, while in Japan the yen’s slide to multi-decade lows kept the authorities on intervention watch and the Bank of Japan under pressure to act. But the development that has dominated is the continued climb in long-term interest rates, which across the major economies now stand close to their highest in two decades — a move driven far more by real yields than by any meanin...