The volcanic debris, by disrupting air travel in the surrounding region, has also disrupted a range activities in the United States and other globally connected economies far from the ash cloud itself.
Among the sectors affected: the flow of visitors to tourist hot spots such as New York City, high-profile sporting events including a car race in Japan, and trade in goods including US- and Canadian-caught seafood.
The slowdown in global transport has even had an effect that many consumers may welcome: a modest dip in the price of oil.
How big the impacts are will depend on the behavior of the Eyjafjallajökull volcano itelf. The longer its ash-spewing eruption continues, the higher its cost to global economic activity.
Airlines, some of the businesses hardest hit, on Monday succeeded in persuading European regulators to partially lift a ban on flights affecting a large swath of the Continent. The industry, citing successful test flights over the weekend, argued that on many routes the ash poses no safety hazard.
The new arrangement, if it works as hoped, should begin to ease a logjam of stranded air travelers in the British Isles and elsewhere – including passengers waiting to return to Europe from US cities.
Yet, with air lanes not fully open, the activity of a single Icelandic volcano is serving as a reminder of how dependent the global economy is on transportation – even in an age of iPhones and digital networks. Some examples:
Tourism. Several million stranded travelers are struggling to get home, and many of these are Europeans in America, in addition to the hordes in London's Heathrow Airport. There's also the question of whether people with vacation plans later this month will be able – or willing – to fly.
The potential effect on one American city hints at the revenue at stake across the US and world. In a worst-case scenario, 160,000 visitors could cancel their trips to New York over a two-week period, costing the local economy as much as $250 million in revenue, according to NYC & Co., which promotes tourism to the city.
Airline revenues. The industry says it is has been losing about $200 million per day because of all the grounded flights. The most affected airlines are those based in Europe. But because each region of the world depends to some extent on traffic to all the other regions, the damage extends to carriers based in the US, Asia, Africa, and beyond.
On Sunday alone, US-based airlines were planning to send 337 nonstop flights to Europe, and 310 were canceled.
Sporting and other events. Abdellah Falil, one of the world's elite runners, didn't earn any prize money from the Boston Marathon Monday: He was among dozens of runners who couldn't make it to Boston. News reports have also cited a range of sporting and other events affected at least marginally by the travel jam-ups.
In motor sports, Japan was poised to host the MotoGP race next weekend, but officials postponed the event because of car drivers who couldn't take to the skies to get there. The volcano has been a boon for videoconferencing services, however, as some businesses scrambled to find alternatives to in-person meetings.
Goods shipments. By weight, the bulk of world trade travels by sea or land. But some of the most valuable shipments – perishables, time-sensitive items, or even hot-selling gadgets – go by air.
A few days of delay are generally not a major problem for most of the affected industries, but any lingering outages could affect both the revenue of producers and the price or availability of goods for consumers.
Dutch growers want to ship tulips to America. African farmers want to send fruit to London.
"I do not have any more scallops," seafood supplier Christophe Malysse said in a Friday report by GlobalPost. He normally would be flying them in to European restaurants, providing revenue for the fishing industry in the US and Canada.
For a rough gauge of US airborne trade with Europe, consider that in February of this year, the US trade with Europe included $27 billion in imports and nearly $21 billion in exports. Judging by an IHS Global Insight study last year, as much as 27 percent of that dollar value may have traveled by air – or about $13 billion.
On Monday, FedEx issued a statement hinting at the challenges shippers are navigating. The company said it "has begun limited flying to airports in Southern Europe in an effort to move freight that is currently in its system." Customers should wait until full service is resumed before shipping perishable items, FedEx recommended. And European customers "should expect delays in shipments."
A lot depends on keeping those air lanes open.
• Material from the Associated Press was used in this report.