More than 400 icebergs have drifted into the North Atlantic shipping lanes over the past week in an unusually large swarm for this early in the season, forcing vessels to slow to a crawl or take detours of hundreds of kilometres.

Experts are attributing it to uncommonly strong counter-clockwise winds that are drawing the icebergs south, and perhaps also global warming, which is accelerating the process by which chunks of the Greenland ice sheet break off and float away.

As of Tuesday, there were about 450 icebergs near the Grand Banks of Newfoundland, up from 37 a week earlier, according to the United States Coast Guard's International Ice Patrol. Those kinds of numbers are usually not seen until late May or early June. The average for this time of year is about 80.

In the waters close to where the Titanic went down in 1912, the icebergs are forcing ships to take precautions. Instead of cutting straight across the ocean, transAtlantic vessels are taking detours that can add around 650km to the trip - a day and a half of added travel time for many large cargo ships.

Close to the Newfoundland coast, cargo ships owned by Oceanex are throttling way back to 5.5-7.5km/h as they make their way to their home port in St John's, said executive chairman Captain Sid Hynes.

One ship was pulled out of service for repairs after hitting a chunk of ice, he said.
"It makes everything more expensive," Hynes said yesterday.

"You're burning more fuel, it's taking a longer time, and it's hard on the equipment." He called it a "very unusual year".

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