The O.E.C.D. warned Wednesday that the Middle East war's disruption to energy supplies will drag global economic growth down to 2.8 percent this year from 3.4 percent in 2025. Inflation across G20 economies will average 4 percent this year and 3.1 percent next, above previous forecasts. The conflict has closed the Strait of Hormuz, choking off a critical oil shipping route.

Oil inventories have dropped by more than 100 million barrels in both April and May, hitting Asian importers like India, Vietnam, and the Philippines hardest. O.E.C.D. chief economist Stefano Scarpetta flagged supply risks beyond energy, including fertilizer for agriculture and helium for semiconductor manufacturing. Damage to regional energy infrastructure remains unknown.

U.S. growth would slow modestly to 2 percent, while the eurozone faces a near-halving to 0.8 percent. Booming artificial intelligence investment and emergency government spending are providing some support, though AI is itself energy-intensive. Households can draw on savings to sustain spending in the short term.

In a pessimistic scenario where energy prices stay elevated, global growth could plummet to 2.1 percent this year and 1.8 percent next, pushing some countries into recession. That would be half the 25-year average growth rate. "Households and firms will face a very dire situation," Scarpetta said.