Bond yields in the U.S., Japan and Europe have risen together, reviving concern that debt accumulated during the near-zero-rate era could become a larger risk for the global economy. Japan’s 10-year government bond yield breached 3% in September, its highest level since 1996, while the U.S. 10-year Treasury yield recently moved above 5%, a 19-year high dating to 2007. Germany and the U.K. also reached their highest 10-year yields since 2009. Inflation concerns linked to higher international oil prices after the Middle East war, heavy artificial-intelligence investment and wider fiscal deficits have pushed rates higher. The Federal Reserve (U.S. central bank) raised its benchmark rate by 0.25 percentage points on the 16th, but ING’s Padraic Garvey expects the U.S. 10-year yield to reach 5.25%. As low-rate government bonds mature, refinancing them at higher rates will increase interest costs; about one-third of OECD member countries’ fixed-rate government bonds mature between 2026 and 2028. The U.S. Congressional Budget Office projects around $1 trillion in net interest outlays against $5.6 trillion in federal revenue this year, while France expects interest costs to rise 25% to 65 billion euros. Global public debt was near 94% of GDP last year and is projected by the IMF to reach 100% by 2029, making economic growth relative to borrowing costs the central question.