One result of the tariffs is that inflation looks to be rising faster than previously thought, the O.E.C.D. said, explaining why it revised its previous estimate, published in December. Both business confidence and consumer confidence have also ebbed.

The outlook for the 20 countries that use the euro is limp. This year, growth is expected to increase 1 percent; next year, it should rise to 1.2 percent. The grimmest forecast is for Mexico, where growth is expected to decline to negative 1.3 percent this year and negative 0.6 percent in 2026.

India, by contrast, is on track to record the strongest growth, according to the O.E.C.D. report, which estimates that gross domestic product, which rose last year to 6.3 percent, will increase to 6.4 percent in 2025 and 6.6 percent in 2026. China’s economy, too, looks to be in better health, with 4.8 percent growth expected in 2025 and 4.4 percent in 2026. If trade restrictions escalate, inflation could rise and economic growth could decline even more than anticipated, the organization warned.

The one potential bright spot is artificial intelligence, said Álvaro Santos Pereira, the group’s chief economist. A.I. is expected “to significantly boost labor productivity growth over the next decade,” he said, with even greater gains if combined with advances in robotics.