18 May 2017, New York Times Antarctic Dispatches: Miles of Ice Collapsing Into the Sea. The acceleration is making some scientists fear that Antarctica’s ice sheet may have entered the early stages of an unstoppable disintegration. Because the collapse of vulnerable parts of the ice sheet could raise the sea level dramatically, the continued existence of the world’s great coastal cities — Miami, New York, Shanghai and many more — is tied to Antarctica’s fate. Four New York Times journalists joined a Columbia University team in Antarctica late last year to fly across the world’s largest chunk of floating ice in an American military cargo plane loaded with the latest scientific gear. Inside the cargo hold, an engineer with a shock of white hair directed younger scientists as they threw switches. Gravity meters jumped to life. Radar pulses and laser beams fired toward the ice below. On computer screens inside the plane, in ghostly traces of data, the broad white surface of the Ross Ice Shelf began to yield the secrets hiding beneath. Read More here
Tag Archives: Antarctica
12 April 2017, Nature, Antarctica’s sleeping ice giant could wake soon. The massive East Antarctic Ice Sheet looks stable from above — but it’s a dangerously different story below. These first direct observations confirmed a fear that researchers had long harboured: that warm waters from the surrounding ocean can sneak underneath the floating glacier tongue and eat the ice away from below1. “This could explain why Totten has been thinning in the past few decades,” says Rintoul. Findings such as these are revealing some scary truths about East Antarctica — the vast, remote landmass to the east of the Transantarctic Mountains (see ‘Ice king’). This region is about as big as the entire United States and the majority of it stands on a high plateau up to 4,093 metres above sea level, where temperatures can plunge to −95 °C. Because the East Antarctic Ice Sheet seems so cold and isolated, researchers thought that it had been stable in the past and was unlikely to change in the future — a stark contrast to the much smaller West Antarctic Ice Sheet, which has raised alarms because many of its glaciers are rapidly retreating. In the past few years, however, “almost everything we thought we knew about East Antarctica has turned out to be wrong”, says Tas van Ommen, a glaciologist at the Australian Antarctic Division in Kingston, near Hobart. By flying across the continent on planes with instruments that probe beneath the ice, his team found that a large fraction of East Antarctica is well below sea level, which makes it more vulnerable to the warming ocean than previously thought. The researchers also uncovered clues that the massive Totten glacier, which holds about as much ice as West Antarctica, has repeatedly shrunk and grown in the past2 — another sign that it could retreat in the future. Read More here
1 March 2017, Thomas Reuters Foundation, Antarctica hits record high temperature at balmy 17.5°C (63.5°F). An Argentine research base near the northern tip of the Antarctic peninsula has set a heat record at a balmy 17.5 degrees Celsius (63.5° Fahrenheit), the U.N. weather agency said on Wednesday. The Experanza base set the high on March 24, 2015, the World Meteorological Organization (WMO) said after reviewing data around Antarctica to set benchmarks to help track future global warming and natural variations. “Verification of maximum and minimum temperatures help us to build up a picture of the weather and climate in one of Earth’s final frontiers,” said Michael Sparrow, a polar expert with the WMO co-sponsored World Climate Research Programme. Antarctica locks up 90 percent of the world’s fresh water as ice and would raise sea levels by about 60 metres (200 ft) if it were all to melt, meaning scientists are concerned to know even about extremes around the fringes. The heat record for the broader Antarctic region, defined as anywhere south of 60 degrees latitude, was 19.8°C (67.6°F) on Jan. 30, 1982 on Signy Island in the South Atlantic, it said. And the warmest temperature recorded on the Antarctic plateau, above 2,500 metres (8,202 feet), was -7.0°C (19.4°F) on Dec. 28, 1980, it said. Wednesday’s WMO report only examined the highs. The lowest temperature set anywhere on the planet was a numbing -89.2°C (-128.6°F) at the Soviet Union’s Vostok station in central Antarctica on July 21, 1983. (Reporting by Alister Doyle; Editing by Louise Ireland) Read More here
21 December 2016, Climate News Network, Antarctic rifts launch giant icebergs. Satellite images reveal clue to the hidden cause of fractures in Antarctic shelf ice that are calving huge icebergs into the south polar seas. Scientists in the US have identified an ominous trend in the Southern Ocean − the creation of enormous icebergs as rifts develop in the shelf ice many miles inland. And although three vast icebergs have broken from the Pine Island glacier in West Antarctica and drifted north in this century alone, researchers have only just worked out what has been going on. Their first clue came from a telltale shadow in the south polar ice, caught by a NASA satellite and visible only while the sun was low in the sky, casting a long shadow. It was the first sign of a fracture 20 miles inland, in 2013. Two years later, the rift became complete and the 580 sq km iceberg drifted free of the shelf. Significant collapse “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,” says study leader Ian Howat, a glaciologist in the School of Earth Sciences at Ohio State University in the US. “This kind of rifting behaviour provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see significant collapse of West Antarctica in our lifetimes.” The scientists report in Geophysical Research Letters journal that they had discovered that although shelf ice could be expected to wear at the ocean edge, something else was happening in West Antarctica. The Pine Island glacier is grounded on continental bedrock below sea level, which means that warming ocean water could penetrate far inland beneath the shelf, without anyone being conscious of any change. Read More here