Thread: Huge ice shelf in Antarctica to collapse by 2020

Huge ice shelf in Antarctica to collapse by 2020

Doyle Rice, USA TODAY4:37 p.m. EDT May 15, 2015


(Photo: NSIDC/Ted Scambos)


The last remaining section of Antarctica's Larsen B ice shelf, which partially collapsed in 2002, is quickly weakening and likely to disintegrate completely by 2020, said a new study out today.

Ice shelves are permanent floating sheets of ice that connect to a landmass, such as Antarctica, according to the National Snow and Ice Data Center.

When it goes, the ice shelf will shatter into hundreds of icebergs. Since it's already floating ice, the collapse of the ice shelf will not directly contribute to global sea-level rise.

However, ice shelves are the gatekeepers for glaciers flowing from Antarctica toward the ocean, according to NASA. Without them, glacial ice enters the ocean faster and accelerates the pace of global sea level rise.

The remaining section of the Larsen B ice shelf is roughly the size of 27 Manhattan islands.

"These are warning signs that the remnant is disintegrating," said study lead author Ala Khazendar of NASA's Jet Propulsion Laboratory, in a statement.

"Although it's fascinating scientifically to have a front-row seat to watch the ice shelf becoming unstable and breaking up, it's bad news for our planet," he said. "This ice shelf has existed for at least 10,000 years, and soon it will be gone."

The Larsen B Ice Shelf is on the eastern side of the Antarctic Peninsula, the part that looks like an arm reaching out toward South America. The peninsula has warmed 4.5 degrees Fahrenheit since 1950, making it one of the fastest-warming places on Earth.

Scientists think that the recent ice shelf collapses in both the Arctic and Antarctica are related to climate change.

Ice shelves are different from ice sheets. An ice sheet, which covers more than 97% of Antarctica, has built up over thousands of years as snow falls but never melts. As ice piles up, it slides slowly toward the continent's edge to form ice shelves attached to the ice sheet, but are floating in the ocean.

"This is certainly a warning," said Khazendar.

The study appeared in the journal Earth and Planetary Science Letters, and was written by researchers from NASA and the University of California at Irvine.

http://www.usatoday.com/story/weathe...ming/27386877/

Massive Antarctic Ice Shelf Will Be Gone Within Years, NASA Says

MAY 15, 2015 4:01 PM ET
SCOTT NEUMAN


A 2008 view of the leading edge of the Larsen B ice shelf, extending into the northwest part of the Weddell Sea. Huge, floating ice shelves that line the Antarctic coast help hold back sheets of ice that cover land.

Mariano Caravaca /Reuters/Landov

In 2002, NASA released dramatic images that showed a portion of Antarctica's Larsen B ice shelf collapse and disappear. Now, the space agency says what's left of the massive feature will be gone before the end of the decade.


As NPR's Christopher Joyce reported in March, climate change has been accelerating the pace of disintegration of the 625-square-mile, 1,600-foot-thick Larsen B.

Now, a team led by Ala Khazendar of NASA's Jet Propulsion Laboratory has found that the ice is melting so fast that the shelf will be gone before 2020.

"This ice shelf has existed for at least 10,000 years, and soon it will be gone," Khazendar says.

"What is really surprising about Larsen B is how quickly the changes are taking place," he says. "Change has been relentless."

NASA writes:

"Ice shelves are the gatekeepers for glaciers flowing from Antarctica toward the ocean. Without them, glacial ice enters the ocean faster and accelerates the pace of global sea level rise. This study, the first to look comprehensively at the health of the Larsen B remnant and the glaciers that flow into it, has been published online in the journal Earth and Planetary Science Letters.
"Khazendar's team used data on ice surface elevations and bedrock depths from instrumented aircraft participating in NASA's Operation IceBridge, a multiyear airborne survey campaign that provides unprecedented documentation annually of Antarctica's glaciers, ice shelves and ice sheets. Data on flow speeds came from spaceborne synthetic aperture radars operating since 1997."

http://www.npr.org/sections/thetwo-w...ears-nasa-says