. NASA warned Thursday that Larsen B, the Antarctic’s largest ice shelf, was rapidly losing strength and would probably be destroyed completely by 2020, scientists at NASA’s Jet Propulsion Laboratory in Pasadena (California). Researchers discovered that the last section of Antarctica’s Larsen B Ice Shelf is now flowing faster and becoming more fragmented. They also noted that two of the ice shelves’ tributary glaciers were flowing faster and thinning more quickly. Glaciers will be more likely to flow into the ocean when the entire ice shelf is gone. Image: NASA. Dr. Ala Khazendar from JPL’s Radar Science Group stated that these are signs the remnant of ice is eroding. 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.” “This ice shelf has existed for at least 10,000 years, and soon it will be gone.” Ice shelves are glacier gatekeepers Ice shelves are like gatekeepers, they stop glaciers from flowing from Antarctica into the sea. The ocean will rise faster if glacial ice is not contained on the shelves. Their latest research was the most comprehensive to date and examined the health of Larsen B, the remnant of Larsen B glaciers, as well as the glaciers which flow into it. Their findings were published in Earth and Planetary Science Letters, an academic journal (citation below). Dr. Khazendar, along with his colleagues, collected and analysed data about surface elevations, bedrock depths, and other information from aircrafts that participated in NASA’s Operation IceBridge. This airborne survey campaign provides unparalleled information on Antarctica’s glaciers and ice sheets. Satellite observations (synthetic aperture radios) provided data on flow speeds. Scientists pointed out that the scientists’ estimate of Antarctica’s Larsen B Ice Shelf life span was based upon the possibility that an enormous, expanding rift would crack across the groundline. Dr. Khazendar predicts the free-floating remnant would break apart into hundreds of floating icebergs, allowing the glaciers unimpeded to shift at an increasing rate to the ocean. Larsen B remnant, two tributaries in trouble Three major tributary glacies feed it, with their own tributaries farther inland. Dr. Khazendar stated that Larsen B’s rapid changes were truly remarkable. The pace of change has been constant.” Larsen B’s major tributary glaciers, Flask, Starbuck, and Leppard are named after Moby Dick characters. Scientists believed that the glaciers’ thicknesses and flow speed did not change after the 2002 partial collapsing. However, according to the study’s findings, the Leppard and Flask glaciers have thinned by 20-22 metres (65-72 feet) and accelerated significantly in in the intervening years. By 2012, the fastest-moving part of Flask Glacier had reached a flow speed of 700 metres (2,300 feet) per year – an acceleration of 36% – like a car speeding up from 55 mpg to 75 mph. Flask’s acceleration could indicate that the remnant is weakening and will accelerate further when it disintegrates. The glaciers that surrounded the partially collapsed section of Larsen B’s shelf in 2002, saw their speed increase by eight, much like a car going from 55 to 440. Starbuck is the smallest glacier. It hasn’t changed too much. Starbuck’s channel has a narrower width than the channels of the two other glaciers. The scientists believe that the channel is strong anchored to the groundrock which explains the relative stability of the glacier. Principal scientist at JPL’s Radar Science and Engineering Section Professor Eric Rignot was also a co-author. He said that the study of Antarctic Peninsula glaciers provided insights into how other ice shelves further south will respond to warming. 10ft sea level rise by 2100? Princeton scientists claim that Antarctica’s glaciers are melting more quickly each year. After simulating events over millions of years, researchers have found that the sea level could rise by nearly ten feet (3 meters) by the close of this century if no drastic steps are taken to cut emissions. The Antarctica’s huge ice sheet lost almost twice the amount of ice it had in its west over the last decade than the eastern part. Citation: “The emerging instability of the remnant Larsen B Ice Shelf (and its tributary, glaciers”),” Ala Khazendar and Christopher P. Borstad. Eric Rignot, Helene Seroussi, Bernd Scheuchl and Bernd Scheuchl. Earth and Planetary Science Letters (June 2015).). DOI: DOI: 10.1016/j.epsl.2015.03.014. Video: Antarctica’s Larsen B Ice Shelf
