One of the paradoxes of this year’s trade tensions is that in many parts of the world, it doesn’t yet feel like a crisis.

For all the turmoil in emerging-market currencies, equity investors in major markets seem ... relaxed? The milestone passed with little fanfare, but the S&P 500 index closed at a record high of 2,914.04 on Aug. 29. The day before, India’s Nifty 50 did the same. Other indexes in developed markets are only moderately below their January peaks.

With President Donald Trump expected to start implementing the next round of tariffs on $200 billion of Chinese goods within hours, it’s tempting to think the global economy is riding out the turmoil. Tempting, but mistaken. Look closely: The slowdown has begun.

Take trade volumes. It’s been extraordinarily unusual for the momentum of global commerce to head anywhere but up in recent decades. The only notable occasions when the world trade monitor compiled by the CPB Netherlands Bureau for Economic Policy Analysis has turned down in a sustained way since 2000 have been on the eve of the 2001 and 2008 recessions, and during the 2015 commodity slump.

You can now add 2018 to that list, with the index coming in negative throughout the second quarter of this year. That drop is particularly striking given that commodities, one of the largest and most volatile subsets of globally traded goods, have been doing quite well – the CPB’s indexes of fuels and non-fuel commodities both reached the highest levels since 2014 in May. The weakness is coming not from materials but from manufactured goods, as global supply chains seize up.

That’s consistent with the picture emerging on the ground. U.S. manufacturers “reported higher prices and supply disruptions that they attributed to the new trade policies,” according to the Federal Reserve’s July Beige Book, in addition to “higher input prices and shrinking margins.” The next edition, due out next week, is likely to show further impact, judging by the warnings from business leaders on the eve of the current round of levies.

Even that probably understates the extent of the underlying slowdown. In the U.S., port traffic has been running at record levels in recent months, suggesting the effect of tax cuts and a favorable monetary policy are more than making up for any trade jitters. However, a chunk of the movements probably relate to businesses stocking up early in order to beat the tariffs, according to the National Retail Federation, an industry group.

The fact that previous trade slumps have often coincided with U.S. recessions doesn’t mean the coming one will. The declines in volumes tracked by the CPB are more likely to have been consequences rather than causes of previous economic contractions. Still, as Komal Sri-Kumar wrote for Bloomberg Opinion earlier this year, markets have a poor track record of picking up on the risks from rising tariff barriers in advance.

For a better picture of what lies ahead, have a look at the way the world’s container-shipping lines are planning for the future. Order books that ran in excess of 1,000 vessels before the 2008 financial crisis haven’t cracked one-fifth of that level since Trump came to power. If the global economy is going to ride out this latest round of tension, the merchant fleets on which trade depends aren’t seeing it.