13 July 2017

Antarctica, melting

Rico's friend Kelley (who voted for Trump, sorry to say) sent this Yahoo article by Taylor Rogers:

A large portion of an ice shelf that was said to be “hanging by a thread” last month has broken off from the Antarctic mainland, creating one of the world’s largest icebergs, according to a report by the British Antarctic research group Project Midas.
The iceberg, which is estimated to have separated from the Larsen C ice shelf between Monday and Wednesday, will be named A68. It weighs a trillion tons and contains twice the volume of water held in Lake Erie, the report said. It is measured at nearly six thousand square kilometers, making it nearly twice the size of Rhode Island (see illustration, above).
The ice shelf’s calving has been expected for some time. Project Midas wrote that it was “watching with bated breath” after the rift separating the iceberg from the main shelf grew eleven miles in six days in late May of 2017. At the time, Adrian Luckman, lead investigator of Project Midas, wrote that the separation of the ice shelf would “fundamentally change the landscape of the Antarctic Peninsula”. The initial rift branched off several times, but only one iceberg can be seen at this time, Luckman told The Guardian.
“The iceberg is one of the largest recorded, and its future progress is difficult to predict,” Luckman said in a statement on the group’s website. “It may remain in one piece, but is more likely to break into fragments. Some of the ice may remain in the area for decades, while parts of the iceberg may drift north into warmer waters.”
Dr. Martin O’Leary, a glaciologist at Swansea University and a Midas member, said, though the calving was not apparently tied to manmade climate change, it was nevertheless concerning. “Although this is a natural event, and we’re not aware of any link to human-induced climate change, this puts the ice shelf in a very vulnerable position,” he said on the website. “This is the furthest back that the ice front has been in recorded history. We’re going to be watching very carefully for signs that the rest of the shelf is becoming unstable.”
According to NASA, IceBridge scientists measured the Larsen C fracture to be about seventy miles long, more than three hundred feet wide, and about a third of a mile deep.
Rising sea levels endanger heavily-populated coastal cities such as New York City, San Francisco, New Orleans, and Miami, and are predicted to cause over thirteen million Americans to relocate from coastal areas by 2100. This iceberg will not “immediately” influence sea levels, according to Project Midas, but if Larsen C continues to disintegrate, sea levels could be affected by glaciers flowing off the land behind the ice shelf into the ocean.
The scientific community first became concerned about the possibility of the Larsen C disintegrating after two nearby ice shelves, Larsen A and Larsen B, disappeared in 1995 and 2002, respectively. “In the ensuing months and years, the ice shelf could either gradually regrow, or may suffer further calving events which may eventually lead to collapse; opinions in the scientific community are divided,” Luckman said. “Our models say it will be less stable, but any future collapse remains years or decades away.”
Justin Worland has a Time article on Antarctica:

The stunning visual of an Antarctic ice shelf the size of Delaware breaking off into the ocean has struck wonder and worry in those all across the world who have seen the image. Scientists mostly attribute the occurrence to cleaving, the process in which a large portion of ice separates from the larger shelf, but disagree about the extent to which climate change contributed
Scientists say Larsen C will not directly contribute much to devastating sea-level rise, as the ice shelf was already floating, so when it melts, waters will not rise significantly, but nonetheless the image of a trillion-ton iceberg floating away from Antarctica has raised new concerns over climate change, and rightfully so. If the entire Antarctic ice sheet melted, sea levels would rise by two hundred feet globally, according to National Snow and Ice Data Center data.
That scenario almost certainly will not happen in the lifetime of anyone living today, but scientists warn that some parts of Antarctica's ice sheet are relatively close to collapse. One of the most vulnerable areas may be the Thwaites Glacier in the western part of the continent. A 2014 study published in the journal Science suggests that the glacier is likely in the early stages of collapse, with the glacier losing a fraction of a millimeter of ice annually. The researchers found that the glacier will likely begin rapid collapse as soon as two hundred years, though potentially as long as nine hundred, years from now.
But many variables remain undetermined and some scientists have warned that ice melt in West Antartica could actually occur much faster than previously anticipated if humans continue to emit greenhouse gases at current rates. A controversial study released last year from famed climate scientist James Hansen and a team of others suggested the world could see several feet of sea level rise by the end of the century, in large part due to ice melt in West Antarctica. Larsen C looks large today, and it is. But the worst-case scenario ice loss of the next century that could come from climate change would dwarf the ice shelf.
Rico says that Trump is so wrong... (But how can melting on this scale not be connected to global warming?)

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