America’s tariffs jolted the global economy. Its AI spending is helping save it.

Now some of those economists are revising their global growth predictions upward.

One big reason: What the U.S. government took away with its tariffs, the U.S. tech industry gave back with its artificial-intelligence spending spree.

In October, the World Trade Organization estimated that global merchandise trade volume would grow 2.4% this year, up from its August prediction of 0.9%. Also in October, the International Monetary Fund raised its 2025 world growth forecast to 3.2%, up from 2.8% after Trump’s tariff announcement.

The upward revisions, both groups said, were partly the result of the fortune that tech companies are investing in AI this year. Amazon, Google, Meta and Microsoft alone are putting nearly $400 billion this year into capital expenditures, largely for AI.

But these metrics don’t tell the whole story. While AI is propping up global trade and growth, it is doing so unevenly and the pain from tariffs is likely to grow.

AI helps a fortunate few

The U.S. represents a quarter of the global economy. AI investments—in equipment, data centers, and research and development, for example—accounted for as much as half of U.S. gross-domestic-product growth in the first half of 2025.

Beyond the major AI powers of the U.S. and China, the spending on tech infrastructure mainly benefits a few regions already inside the specialized AI supply chain.

Consider Taiwan, the global manufacturing hub for the most advanced AI chips. American hunger for these semiconductors prompted IMA Asia, which runs executive forums, to raise Taiwan’s GDP growth forecast to 7% this year, up from its 4.4% estimate a quarter earlier.

It is a unique case, the group said, as Taiwan’s capital expenditures on plants and equipment are expected to rise 30% this year, up from a 13% increase last year. But even as AI spending powers the island’s economic numbers, consumer demand remains low and other industries struggle.

The AI boom has also pulled up South Korea, which dominates the corner of the AI supply chain that makes memory chips, and the Netherlands, home of chip-making equipment leader ASML.

Asia accounted for nearly two-thirds of global AI-related trade growth in the first half of 2025, said Oriano Lizza, a trader at CMC Markets. “The benefits are overwhelmingly concentrated in advanced manufacturing economies," he said.

The tariff cliff

Tariff pains haven’t been canceled. They have just been deferred.

Companies that paid attention to what Trump said on the campaign trail and early in his second term had ample warning before the April tariff proclamation. Importers and exporters front-ran tariffs, rushing to ship goods to the U.S. before a series of deadlines. That has boosted trade this year.

“It’s too early to say that the tariffs have had less impact than feared," said Mansoor Mohi-uddin, chief economist at the Bank of Singapore. “What’s happening is that the impact has just been delayed."

Now that the tariffs have kicked in and front-loaded inventory is dwindling, economists expect companies to pass on tariff costs to consumers and export less to the U.S.

The WTO’s outlook reflects this: At the same time it upgraded its 2025 forecast, it reduced its 2026 forecast for world merchandise trade volume growth to 0.5%, down from its August estimate of 1.8%.

A government backstop

The tariff cliff might not be a foregone conclusion. Policies from several of the world’s biggest governments are building a safety net.

Economists expect the Trump-championed One Big Beautiful Bill Act to boost the U.S. economy in the short run by extending tax cuts, while increasing the federal deficit. That could lift imports.

On top of that, Mohi-uddin said, Germany is making a historic shift away from frugality toward spending. And Japan approved $135 billion of stimulus to boost economic growth.

Such support, combined with a weak dollar and a potential Federal Reserve rate cut, means the global economy might stay on its feet in 2026, provided the AI boom doesn’t fizzle. “The environment for investors is actually still good," Mohi-uddin said.

Write to Stu Woo at Stu.Woo@wsj.com