TPreston Posted February 10, 2017 Share Posted February 10, 2017 (edited) The British Antarctic Survey is to pull all staff out of its space-age Halley base in March for safety reasons. The highly unusual move is necessary because the Brunt Ice Shelf on which the research station sits has developed a big new crack. BAS officials say neither staff nor the base are in any immediate danger but believe it would be prudent to withdraw while the situation is assessed. The plan would be to go back once the Antarctic winter is over, in November. Halley station comprises a series of hi-tech pods that are mounted on hydraulic legs and skis so that they can be moved periodically further inland, to get away from the shelf edge where icebergs are calved into the ocean. Unpredictable situation BAS is in the process of conducting such a move right now. The relocation is all but complete, with the last pod currently in the final stage of being shifted 23km to the new site. The move was necessitated by a chasm that had opened up in the shelf and which threatened to cut off Halley. But this huge fissure to the west of the station is not the cause of the temporary closure. Rather, it is another break in the ice some 17km to the north and east of the new base position. It has been dubbed the "Halloween Crack" because it was discovered on 31 October. "Changes to the ice, particularly the growth of a new crack, presents a complex glaciological picture that means that BAS scientists are unable to predict with certainty what will happen to the ice shelf during the forthcoming Antarctic winter," the research organisation said in a statement. "As a precautionary measure, BAS will remove its people before the Antarctic winter begins." http://www.bbc.com/news/science-environment-38643420 Draggendrop 1 Share Link to comment Share on other sites More sharing options...
Unobscured Vision Posted February 10, 2017 Share Posted February 10, 2017 Ouch. That's potentially bad. Link to comment Share on other sites More sharing options...
Draggendrop Veteran Posted February 11, 2017 Veteran Share Posted February 11, 2017 This one caught me off guard, as I was expecting it to be the Larsen C, but this one is on the east side of the Weddell Sea, the Brunt Ice Shelf. Weddell Sea as part of the Southern Ocean https://en.wikipedia.org/wiki/Weddell_Sea Some Antarctic ice shelves. https://en.wikipedia.org/wiki/Larsen_Ice_Shelf This appears to be a case of having two Halley bases moved.....They knew about Larsen C, she's gong to go soon...and now the major crack in the Brunt Ice field. The Brunt crack is real bad as well due to the runoff areas southwest...this one will go as well. Halley base forced to relocate as huge crack in Larsen C ice shelf grows 17 miles in two months A crack in Larsen C captured by Nasa scientists in 2015. It measured 70 miles long, more than 300 feet wide and about a third of a mile deep. Nasa/John Sonntag Quote Update 9/2/17: New aerial footage of the Larsen C ice shelf in Antarctica shows the crack recently grew 17 miles in just two months. The acceleration in the break forced British Antarctic Survey scientists at the Halley research station to relocate the base over fears the shelf would break and leave Halley at risk. Tractors were used to tow the base's eight modules at the start of February to move it 15 miles "inland". Now, it looks like that was the best move. The 100-mile long, two-mile wide crack only has to travel a further 20 miles for the break to occur, creating a mammoth iceberg. “The iceberg is likely to break free within the next few months,” Adrian Luckman of Swansea University in Wales, part of Project Midas which has been tracking the break,told the New York Times. “The rift tip has moved from one region of likely softer ice to another, which explains its step-wise progress.” http://www.wired.co.uk/article/a-5000-sq-km-glacier-is-about-to-break-off-antarctica Stunning Photos Show Huge Crack in Antarctic Ice Shelf Britain's Halley VI research station has to be moved to avoid being lost at sea. Quote Operation Icebridge, in its eighth year of conducting airborne survey of polar ice, flew two missions in November around the 88th parallel. The highly sophisticated aircraft is equipped with radars, lasers, digital imaging and infrared sensors. The Larsen ice shelf, in the East Antarctic, is of interest because two previous sections have broken off and disappeared into the sea. Larsen A collapsed in 1995. In 2002, Larsen B began to break apart. Within six weeks, a 1,235 square mile chunk of ice slipped away, which scientists attributed to warmer air temperatures. Prior to that, the Larsen B ice shelf had been stable for 12,000 years. Larsen C began thinning around the time that the other sections broke off, losing 13 feet between 1998 and 2012. But deterioration of the ice shelf has dramatically accelerated. When the dark of the Southern Hemisphere winter lifted in August, scientists were shocked to see that the rift in the ice had grown nearly 14 miles. "The growth of this rift likely indicates that the portion of the ice shelf downstream of the rift is no longer holding back any grounded ice," said Joe MacGregor, IceBridge deputy project scientist and glaciologist at NASA Goddard Space Flight Center. Ice shelves ride on water and are fed by glaciers and continental ice streams. Cracks and calving are normal, and the loss of a portion of an ice shelf will not contribute to sea level rise as it is already afloat on the ocean. However, an ice shelf such as Larsen C holds back land ice, acting as a buttress. When a shelf disintegrates, the glaciers behind it can flow out to sea, which will directly increase sea level. Long-term satellite observations show that Antarctic glaciers are rapidly retreating. In West Antarctica, they are losing 23 feet of elevation per year. As they slip away, they add up to 150 billion tons of water to the ocean, raising seas by about a tenth of an inch annually. One of those glaciers, the Pine Island Glacier, calved off a 225 square mile iceberg in 2015. Ohio State University researchers found that the rift began at the base of the glacier in 2013 and worked its way upward. "It's generally accepted that it's no longer a question of whether the West Antarctic Ice Sheet will melt, it's a question of when," said study leader Ian Howat, associate professor of Earth Sciences at Ohio State. and here is the confusion, the crack in the Brunt.... Quote A separate rift in the East Antarctic is forcing a British research station to relocate. It's on the wrong side of the crack and could be stranded out at sea. Antarctica holds more than half of the planet's fresh water in its snow, glaciers and ice formations. But conditions around the continent are worsening. The NASA mission also flew over Antarctic sea ice. It found coverage to be sparse in the Bellingshausen Sea, on the west side of the Antarctic Peninsula. http://www.ecowatch.com/nasa-antartica-larsen-c-2144755963.html This one shows the Larsen C crack forming... http://www.esa.int/spaceinimages/Images/2017/01/Larsen_crack British Antarctic Survey abandons polar base as worrying crack grows in ice Quote cientists at the British Antarctic Survey are abandoning their research station for the first time ever this winter after a new worrying crack developed in the ice sheet. The renowned Halley VI ice base, from which the hole in the ozone layer was first detected, was already scheduled to be relocated 14 miles across the Brunt Ice Shelf because of an encroaching fissure in the ice. But a new crack has been steadily growing to the north of the base, and computer modelling suggests that it could cause a large iceberg to calve away from the sheet, which could destabalise the area. Although the British Antarctic Survey (BAS) says nobody is immediate danger, they cannot be sure that conditions would not worsen during the difficult conditions of the southern polar winter when an evacuation would be impossible. “We want to do the right thing for our people,” said Captain Tim Stockings, the Director of Operations at the base. “Bringing them home for winter is a prudent precaution given the changes that our glaciologists have seen in the ice shelf in recent months. “The Halley VI Research Station sits on a floating ice shelf. It was designed specifically to move inland if required. The current work to relocate our station is going very well. This challenging engineering project is scheduled to complete as planned by early March 2017. http://www.telegraph.co.uk/science/2017/01/16/british-antarctic-survey-abandons-polar-base-worrying-crack/ The research station was moved from Larsen C and now, due to the Brunt Ice Field crack, she's moving again. I followed the Larsen B in 2002, ESA sat images and US recon images. The sat shots missed the event happening, but caught it shortly afterward. It was the size of Rhode Island, but was composed of 1000's of icebergs, some hanging around for several years. Larsen C and the Brunt field in the east side of the Weddell Sea are going to break off. The problem will be the exposed land supported fields, which when any melt occurs, now begins to raise sea levels. This is a double whammy and will make the Weddell Sea become a game of "dodge ball" with icebergs, for years. Link to comment Share on other sites More sharing options...
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