The Titanic hit an iceberg 900 miles east of Cape Cod. Could that happen today?

Here’s what to know.

Icebergs, large hunks of freshwater ice, break off or “calve” from glaciers in Greenland, and drift south down Iceberg Alley past Labrador and Newfoundland on the eastern coast of Canada into the North Atlantic. Their yearly visits have even become a tourist attraction.

The icebergs can be huge and also very deceptive. As much as 90 percent of an iceberg can be beneath the surface. Trapped by sea ice, frozen saltwater that floats on the surface, they are released when the sea ice begins to melt in March. May is typically the peak season, Ice Patrol officials said in an e-mail.

The Ice Patrol works with the Canadian Ice Service to monitor icebergs and create and distribute daily warning products for mariners. The Ice Patrol, formed more than a century ago in the wake of the Titanic disaster, uses satellite imagery, aircraft overflights, reports from mariners, and computer modeling to determine where the danger is, defining an “iceberg limit” that mariners are advised to steer clear of.

The severity of iceberg seasons has been highly variable. It is “difficult to understand and predict,” the Ice Patrol says on its website. Experts said the seasons could vary depending on the number of icebergs calved and the currents and winds that steer the icebergs. The Ice Patrol notes some variation could also be due to its reporting methods.

The Ice Patrol ranks the seasons by the number of icebergs that cross south of the 48th parallel, where they endanger transatlantic shipping. The 2020, 2021, and 2022 seasons were considered “light.” This year is considered “moderate.” But 2019 was considered “extreme,” with 1,515 icebergs floating too far south, including some that made it to the 40th parallel, south of where the Titanic sank, which was around the 42nd parallel.

Several factors are expected to influence the severity of future seasons. The obvious one is that the warmer water should cause the icebergs to melt quicker as they roam the ocean. But another factor is that the warmer climate will cause more icebergs to separate from their glaciers in the first place.

“There is some evidence that glaciers, particularly in Greenland, are having more icebergs due to increased warm water coming in at depth and undercutting the glaciers, which makes them more likely to calve,” said Alexander Robel, an assistant professor in the School of Earth & Atmospheric Sciences at Georgia Tech.

At the same time, a decline in sea ice caused by global warming could unlock more icebergs and let them wander away, he said.

Sea ice may not just be important because it keeps icebergs from floating free. In a recent paper in the journal Nature Communications, Robel suggested that the sea ice and icebergs locked in a mixture at the base of a glacier tend to buttress glaciers and keep them from calving in the first place.

While the icebergs may be set free, he said, the water will be warmer and the lack of sea ice may mean that they have a shorter lifespan because waves will erode them.

“Waves are actually one of the most effective mechanisms for eroding icebergs from the sides. And that’s because they basically are really good at bringing heat from far away in the ocean environment to the iceberg,” he said. When the sea ice is gone, it “makes an environment in which icebergs will deteriorate more quickly as they drift away from glaciers.”

Some researchers, he said, are “actually seeing fewer icebergs reaching those lower latitudes, because they’re melting before they get that far.”

Scientists have been raising the alarm about Arctic sea ice losses due to climate change. A recent study found that the Arctic may be completely free of sea ice each September, the month that sees the least sea ice, as early as the 2030s. That’s a far cry from the historical sea ice area in September, roughly 2.7 million square miles, according to NASA.

The Ice Patrol said if the Titanic were to sail today, it would be advised, just as today’s modern commercial and cargo vessels are advised, to stay outside the area the Ice Patrol has identified as the iceberg zone. It added, “No vessel that has heeded the warnings of [the Ice Patrol] has struck an iceberg since our inception” two years after the Titanic disaster.

Robel noted, however, there may be new dangers ahead from icebergs in a nearby region.

“We’re a lot more capable of avoiding icebergs than we were before,” thanks to satellites, radar, and computer models, he said. But, he said, as sea ice in the Arctic Ocean has been retreating due to climate change, there has been increased shipping activity at the top of the world.

It’s becoming “more enticing for shipping companies and other people to go through these risky routes,” he said.

“The less sea ice there is, the more mobile icebergs are. And so it becomes a more challenging problem to contend with at those high latitudes,” he said.

Martin Finucane can be reached at martin.finucane@globe.com.