Doyle Rice

USA TODAY

A crack in an ice shelf in Antarctica grew by six miles in the past few weeks, British scientists say, and now measures more than 100 miles long.

Once the crack is complete, a giant iceberg larger than Rhode Island will break or "calve" off of Antarctica. The iceberg would be one of the biggest on record.

The break "will fundamentally change the landscape of the Antarctic Peninsula," according to Project MIDAS, a British Antarctic research project that's tracking the crack.

Only a final 12 miles of ice now connects the future iceberg to its parent ice shelf.

Ice shelves are permanent floating sheets of ice that connect to a land mass, according to the National Snow and Ice Data Center.

Most of the world's ice shelves hug the coast of Antarctica. The Larsen C shelf is on the Antarctic Peninsula, the portion of the continent that juts out toward South America.

If the iceberg did break off, it wouldn't contribute to sea-level rise since it's already floating, said Ted Scambos, a scientist with the data center. (If a chunk of ice that big did drop into the sea, it would raise sea levels about 1/16 of an inch, he said.)

However, once that iceberg breaks off, land ice that had been blocked by the berg would plop into the sea. It's that ice that would eventually raise sea levels, NASA scientist Thomas Wagner said. "Ice shelves serve a critical role in buttressing ice that's on land," he said.

You can literally bet on when a massive iceberg will break off Antarctica

There is not enough information to know whether the split is a result of climate change or not, but there is "good scientific evidence" climate change has caused thinning of the ice shelf, the British researchers say.

Once the iceberg sheared off, it would float along the coast of Antarctica, then head out into the Southern Ocean.

"As it moved north, ocean temperatures both at the surface and at the base of the berg would begin to thin it and erode it from the edges," Scambos said. It would eventually break apart into smaller chunks that would melt into the ocean.