In Tom Cruise’s new movie Digger, the actor plays a crazed oil baron whose irresponsible drilling causes a massive iceberg to split off Greenland. Named Judy by climate scientists in the movie, the marauding ice barrels toward Europe, imperiling lives—but real climate scientists say this may be a little more fantastical than what we’d see if such an event really happened.

In the movie, Judy threatens to bring a tsunami to Norway. The plot point is dramatic, but it misunderstands how ice shelves work, says Nils Bochow, a climate scientist at the Alfred Wegener Institute in Potsdam, Germany. Ice shelves are already floating on the water, so “if [icebergs] break off, nothing much happens because they don’t cause any change in sea level.”

Icebergs can make waves if they break off ice shelves or glaciers, but these are typically confined to a range of a few kilometers (one km is 0.6 mile), Borchow says. “And they’re also moving very, very slowly. It’s not very spectacular.”

On supporting science journalism

If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Judy’s size is about 400 square miles—that’s likely much larger than any possible Greenland iceberg, Borchow says. For example, a recent large iceberg that broke free of Greenland’s Petermann Glacier was 29 square miles; it eventually collided with the country’s Joe Island. The largest Greenland iceberg in recent history broke off Petermann Glacier in 2010, and it was only a quarter the size of Judy.

In Antarctica, however, icebergs much larger than Judy break off ice shelves regularly. But again, these aren’t known to cause havoc to humans on land. (They have been known to trouble penguins, though.) In fact, many of these events are a natural part of an ice shelf’s life cycle rather than the result of climate change or human activity. For instance, in 2023 an iceberg 1.5 times as big as Judy broke off of Antarctica’s Brunt Ice Shelf. It was the fourth in a succession of large calving events off Antarctica—and it wasn’t even the largest: one iceberg that broke off another Antarctic ice shelf in 2017 was about 2,240 square miles.

“It’s unlikely that an iceberg would make its way to a major populated area [because icebergs] usually melt as they enter the warmer waters away from the ice sheet,” says Chris Stokes, who studies glaciers at the Durham University in England.

“However, they pose a serious hazard to shipping and other maritime human activities and there may be some local impacts on coastal settlements or tourist activities near the ice sheets,” he adds.

Icebergs aside, what is true is that human-driven climate change is causing ice at the planet’s poles to melt. The resulting destruction of critical ice sheets in Greenland and Antarctica will raise global sea levels.

Digger is, first and foremost, a parable—without spoiling the plot, its events are intentionally exaggerated to make a point about humans and climate change. But Borchow says that the movie misses one of the least recognized truths about climate change.

“I think a lot of people think that [climate change] is happening very fast, but these ice sheets are very, very slow,” he says. “We see this change, but it doesn’t seem urgent to most people… But everything that we do today has an influence on the future. It’s really hard to put that in a movie.”

Subscribe to Support Independent Journalism

Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.

When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.

Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber