The world's biggest iceberg is on the move. What does that mean for sea levels?

Warming ocean temperatures are causing historically icy land masses to break off. Climate scientist David Holland says if massive bergs continue to flood our oceans, sea levels will rise dangerously high.

A23A won't reach N.L. shores any time soon, but its movement offers scientists a glimpse of the future

A headshot of David Holland in the CBC studio in St. John's.
New York University climate scientist David Holland says if massive icebergs continue to flood the world's oceans, sea levels will rise dangerously high. (CBC)

The biggest iceberg in the world, known as A23A, is on the move for the first time in 40 years.

After being grounded on a shoal for decades, the massive berg broke free last week. 

David Holland, a New York University climate scientist, says A23A is now floating in the Antarctic circumpolar current, the world's strongest current, located in the Southern Hemisphere. 

And while that's certainly nowhere near the Iceberg Alley that attracts attention in Newfoundland and Labrador every spring and summer, Holland said A23A's movement is helping scientists all over the world look to the future. 

"This phenomena, I would say, almost definitely is a completely natural event," he said. "It offers us scientists an opportunity to glimpse into the future where, as people know, the atmosphere is warming. The waters around Newfoundland are at record warm [temperatures], and that's because greenhouse gas heat is going into the ocean."

Holland said areas that are accustomed to cold water are experiencing warming, and because of that scientists are seeing disintegration of historically icy land masses. 

"What we're thinking is in the future, we may see not one but thousands of icebergs coming out of these places."

A satellite photo of the massive berg surrounded by dark blue ocean.
At almost 4,000 square kilometres, A23A is the world's biggest iceberg. (CBC)

Doomsday iceberg

On the other side of Antarctica, a berg about the size of the United Kingdom made contact with warm water and has become unstable. 

Scientists believe that once it starts to break up, it will produce an enormous amount of icebergs. 

WATCH | Big 'berg! Professor David Holland talks about one of the biggest in the world: 

Not an ordinary ‘berg: This one is 3 times the size of Manhattan

3 months ago
Duration 2:48
Newfoundland is no stranger to icebergs, but this one is a behemoth that has broken off the Antarctic shelf after more than 30 years of being grounded. New York University Prof. David Holland breaks down where it is, the possible complications and why this one has scientists keeping a close eye.

"It would raise global sea level by about a metre, which would wipe out certain countries," Holland said.  

"That is a concern both from the sea level point of view, but also these bergs … if they scatter themselves around Antarctica, what will happen to the marine life that's not ready for such a rapid change?"

Holland said sea levels rising that much would certainly affect the province, particularly on Newfoundland's south coast. 

He, along with other scientists from Canada, the United States, the United Kingdom and South Korea, are working on creating a forecast to determine when those significant changes will happen.

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With files from Here & Now