Antarctica's Colossal New Iceberg Is Doomed — Here's What Will Happen Next

A photo illustration of an Antarctic iceberg at sunset.Shutterstock

 

Danielle Andrew 16/07/2017, 20:39

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

The block of ice was unceremoniously given the name of A68 by the US National Ice Center, whose abbreviations denote both an iceberg's location and its order of discovery.

Iceberg A68 now begins a long journey into the Southern Ocean and toward its doom: 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, the 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.

Diti Torterat/Wikipedia (CC BY 2.0)

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

Ice shelves like Larsen C, and their icebergs, come from snow that has covered Antarctica over thousands of years and compacted into ice. In many places, the ice is a mile thick down to bedrock.

Antarctica is the fifth-largest continent.NASA

Source: NASA Goddard Space Flight Center

But the ice doesn't sit there. Gravity tirelessly pulls it toward the sea, where it floats on the water to form gigantic ice 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.

Adrian Luckman/MIDAS Project

"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 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 over Larsen C to get a closer look. Satellite images suggest the crack formed around 2010, but it suddenly and rapidly started growing in 2016.

A 300-foot-wide, 70-mile-long rift in Antarctica's Larsen C ice shelf, as seen in November.John Sonntag/IceBridge/NASA Goddard Space Flight Center

"Rifting 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.

John Sonntag/IceBridge/NASA Goddard Space Flight Center

Source: Business Insider

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

Mike Nudelman/Business Insider

Source:Business Insider

Its thickness was about 620 feet, or more than double the height of the Statue of Liberty.

Mike Nudelman/Business Insider

Source: Business Insider

And its volume seemed to be about 277 cubic miles 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 colossal iceberg calved from Larsen C.


Source: Business Insider

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 (via Twitter)

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

NASA; Business Insider

Source: Business Insider

Yet 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.

NASA Scatterometer Climate Record Pathfinder; Dave Mosher/Business Insider

Sources: Business Insider, Scatterometer Climate Record Pathfinder

Some are big enough to reach South Georgia and the South Sandwich Islands before vanishing.

St. Andrews Bay on South Georgia Island.Shutterstock

"It'll probably take a year or two for the berg to get that far, and it will be melting a little as it goes," said Martin O'Leary, a colleague of Luckman's at Swansea University and Project Midas.

Project MIDAS/Swansea University

Source: Reddit/r/IAmA

Iceberg A68 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.

Caption

Mike Nudelman/Business Insider
The 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's major loss of ice could trigger a quick collapse of the whole ice shelf in the coming months or years. It wouldn't be unprecedented — the Larsen B ice shelf collapsed after an iceberg calved in 2002.

Larsen B once extended hundreds of kilometers over the ocean. Today, one of its glaciers runs straight into the sea.Amin Rose/Shutterstock

"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 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 breakup of the Larsen B shelf in the Southern Ocean.


Source: NASA

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

A tabular iceberg floats near the coast of West Antarctica, as seen from a window of a NASA Operation IceBridge airplane on October 27.Mario Tama/Getty Images

Source: Business Insider

The second-biggest was iceberg B15, which broke off Antarctica's Ross ice shelf in 2000. It had a surface area of 4,200 square miles — about twice the area of A68.

B15A, a large fragment of iceberg B15.Josh Landis/NSF

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. That's twice as large as Connecticut.

A tabular iceberg in the Weddell Sea near the Antarctic Peninsula.Shutterstock

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 B15. That water will eventually evaporate, making its way into clouds, rain, snow, more icebergs, and living beings.

Associated Press

The process began as early as July 14, when Luckman noticed in a NASA satellite image that iceberg A68 "has broken into two pieces."

Adrian Luckman/Twitter; NASA/Suomi

Source: Adrian Luckman (via Twitter)

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

Caption

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

The increasingly rapid melting of long-lived ice sheets, glaciers, and other frozen bodies is raising sea levels and changing coastlines all over Earth. Some of our most famous cities may cease to exist as we know them within our kids' lifetimes.

Google Earth/Climate Central

Source: Business Insider

 

Read the original article on Tech Insider. Copyright 2017.

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