Tech: One of the largest icebergs in history just broke off Antarctica — here's what will happen next

Here's the story of the Larsen C ice shelf's iceberg A68, which scientists say has left "the landscape of the Antarctic Peninsula changed forever."

Antarctica shed an iceberg of mind-boggling size from its Larsen C ice shelf this week .

The block of ice — one of the largest ever documented — will likely be given the unceremonious name of A68 by the US National Ice Center, whose abbreviations denote both an iceberg's location and order of discovery.

Iceberg A68 now begins a long journey into the Southern Ocean and toward its doom: as liquid in Earth's vast and complex system of water.

Here's how scientists discovered the giant iceberg, how it calved, and how it will eventually die — and be reborn.

In 2015, glaciologist Daniela Jansen discovered a growing crack in Antarctica's Larsen C ice shelf, which was then the fourth-largest ice shelf on the continent. The shelf is hundreds of years old, maybe more.

Sources: The Conversation (via Business Insider); The Cryosphere

Ice shelves like Larsen C formed after millennia's worth of snow covered Antarctica in a mile-thick sheet of ice from its bedrock to its surface.

Source: NASA Goddard Space Flight Center

Gravity tirelessly pulls that ice toward the sea, where it pushes onto water to form gigantic shelves.

Scientists like Jansen and Adrian Luckman, both glaciologists at Swansea University and the MIDAS Project, study Antarctica's changing ice shelves and melting surface.

"We spent many weeks camped on the ice investigating melt ponds and their impact — and struggling to avoid sunburn thanks to the thin ozone layer," Luckman hs said. "Our main approach, however, is to use satellites to keep an eye on things."

Source: The Conversation (via Business Insider)

In November, NASA flew a survey airplane to fly over Larsen C. Although satellite images suggest the crack formed in 2010, it seemed to grow suddenly and rapidly starting in 2016.

"[R]ifting of this magnitude doesn't happen so often, [so] we don't often get a chance to study it up close," Joe MacGregor, a glaciologist and geophysicist at NASA's Goddard Space Flight Center, told Business Insider in an email.

Source: Business Insider

What they found was epic in proportions. The crack measured more than 70 miles long, and at points it was more than 300 feet wide.

Source: Business Insider

By June 2017, the rift had grown dozens of miles — close enough to a breaking point for researchers to estimate the new iceberg's area at roughly the size of Delaware.

Source: Business Insider

It had an estimated thickness of about 620 feet (190 meters), which is more than double the height of the Statue of Liberty.

Source: Business Insider

Its volume was estimated to be at about 277 cubic miles (1,155 cubic kilometers) of ice. That's enough to fill Lake Erie more than two times.

Source: Business Insider

By late June, Luckman and others said it would be just days, or perhaps hours, until the epic iceberg calved from Larsen C.

Source: Business Insider

Then — sometime between July 10 and July 12 — the iceberg finally broke off.

Source: Business Insider

Subzero temperatures during Antarctica's winter prevent flights from February through mid-November. But multiple satellites photographed the event.

Sources: The Atlantic, Business Insider, Adrian Luckman/Twitter

Scientists today aren't sure where iceberg A68 will float. But some think it could drift more than 1,000 miles north — to the Falkland Islands.

Source: Business Insider

Most icebergs that calve from the Antarctic Peninsula get caught up in wind and water currents that drag them clockwise around the Southern Ocean as they move north.

Sources: Business Insider, Scatterometer Climate Record Pathfinder

Some are big enough to reach the South Georgia and South Sandwich Islands before breaking up and melting.

The iceberg made up about 12% of the Larsen C ice shelf's area. Luckman and others say the calving is a natural process, and that it won't contribute much to sea level rise.

"This event is ... a spectacular episode in the recent history of Antarctica's ice shelves, involving forces beyond the human scale, in a place where few of us have been, and one which will fundamentally change the geography of this region," Luckman said.

Sources: The Conversation (via Business Insider), The Guardian

Still, Larsen C loss of the iceberg may trigger a relatively rapid collapse of the whole ice shelf in the coming months or years. It wouldn't be unprecedented — Larsen B ice shelf collapsed after an iceberg calved in 2002.

"Our work has highlighted significant similarities between the previous Behaviour of Larsen B and current developments at Larsen C, and we have shown that stability may be compromised," Luckman has said. "Others, however, are confident that Larsen C will remain stable."

Sources: MIDAS Project, The Conversation (via Business Insider)

Satellites were able to capture the break up of the Larsen B shelf in the Southern Ocean.

Source: NASA

Iceberg A68 is technically a tabular iceberg, which takes a slab-like form. It's the third largest iceberg ever recorded.

Source: Business Insider

The second-biggest was iceberg B-15, which broke off Antarctica's Ross Ice Shelf in 2000. It had a surface are of 4,200 square miles (11,00 square kilometers) — about twice the area of A68.

Source: Chicago Tribune

The largest iceberg ever recorded calved from Antarctica in 1956. A passing ship recorded its size at about 12,000 square miles (31,000 square kilometers). That's twice as large as Connecticut.

Source: USA Today

Ultimately, iceberg A68 will break up into smaller and smaller pieces until the entire iceberg melts. The process could take years, as it did for iceberg B-15. That water will eventually evaporate, making its way into clouds, rain, snow, and living bodies.

A68's birth is most likely not tied to climate change, Luckman and others have said. But there's a lot of melting ice around the world that researchers have connected to human activity — and that's cause for alarm.

Sources: The Conversation (via Business Insider), The Guardian, Business Insider

The increasingly rapid melting of long-lived ice sheets, glaciers, and other frozen bodies will eventually raise sea levels and change the coastlines of Earth. Some of our most famous cities may cease to exist as we know them within our kids' lifetimes.

Source: Business Insider

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