3 reasons to worry about that huge iceberg that broke off Antarctica

July 12, 2017, 11:34am

The iceberg that broke off the Larsen C ice shelf this week is a glimpse of what’s in store for Antarctica.

The trillion-ton block of ice, likely to be dubbed A68, is among the 10 largest icebergs ever recorded. It’s roughly the size of Delaware — enough ice to fill 463 million Olympic swimming pools and twice the volume of Lake Erie. And now this 2,240-square-mile behemoth is slowly floating away from the Antarctic Peninsula.

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A crack in the ice was first detected in the fall of 2010 and has progressed steadily across the iceberg for the last 7 years.

While there isn’t scientific consensus that global warming is responsible for the break — “cleaving,” or the breaking off of blocks of ice from Antarctic ice shelves is a natural process — there is consensus that events like this will take place more frequently as man-made global warming progresses.

But some scientists do think global warming is responsible: “This sort of evolution of ice is the direct signature of global warming,” University of California Glaciologist Eric Rignot told VICE News.

Here are three reasons why this iceberg’s bad news:

The Larsen C ice shelf is in bad shape

Larsen C, the fourth-largest ice shelf in Antarctica, is 12 percent smaller than it was before the iceberg broke off. Scientists think that it’s now less structurally sound.

“Although this is a natural event, and we’re not aware of any link to human-induced climate change,” Dr. Martin O’Leary, a Swansea University glaciologist said in a statement, “this puts the ice shelf in a very vulnerable position. This is the farthest back that the ice front has been in recorded history.”

Larsen A collapsed in 1995 and Larsen B almost fully disintegrated in 2002. The scientific consensus is that global warming was the culprit in both cases.

Glacial ice will contribute to rising sea levels

As icebergs break off and the ice shelves they’re a part of break down, more glacial ice will flow to the oceans, where it will melt and contribute to rising sea levels.

“Eventually the ice shelf will fall apart,” Rignot said. “We estimate that the ice front needs to retract by another 20 kilometers before the ice shelf is at risk of falling apart.” Scientists don’t yet have enough data to estimate when that might happen. The Larsen B ice shelf, Larsen C’s smaller neighbor to the north, collapsed suddenly over the course of about a month.

If the Larsen C ice shelf collapses, the twenty or so glaciers that flow into it will instead flow directly into the ocean. So while this iceberg won’t contribute to rising sea levels — it was already floating in water — the collapse of Larsen C could cause sea levels to rise by as much as four inches.

It’s a sign of things to come

Even the Larsen C ice shelf would make only a relatively small contribution to rising global sea levels compared to what would happen if larger ice shelves to its south were to collapse. The fate of our coasts is inextricably tied to the health of these ice shelves: The collapse of a few of them could result in several feet of sea level rise — and all it takes is two feet to put huge swathes of Miami underwater.

“The short message is that people need to look beyond this calving event — what is the big picture?” said Rignot. “And the big picture is that things are changing in the Antarctic. The giant is awake. He’s wide awake.”