Hours, Days, or Weeks June 29, 2017

Hours, days, or Weeks. That’s the timeline for the next big ice shelf collapse on the Antarctic peninsula, which has been widely predicted after a large and rapidly growing crack was discovered in the area. I spoke to Glaciologist Eric Rignot about it in December.

Meanwhile, I’ll be on standby to report if/when this drops.

USAToday:

One of the world’s biggest icebergs ever recorded is “hours, days, or weeks” away from breaking off an Antarctic ice shelf, scientists announced Wednesday. “In another sign that the iceberg calving is imminent, the soon-to-be-iceberg part of Larsen C Ice Shelf has tripled in speed to more than 10 meters per day between June 24th and June 27th,” said Adrian Luckman of Project MIDAS, a British Antarctic research project that’s keeping watch on the ever-growing crack. “The iceberg remains attached to the ice shelf, but its outer end is moving at the highest speed ever recorded on this ice shelf. We still can’t tell when calving will occur — it could be hours, days or weeks,” he added. Once the iceberg breaks off, it “will fundamentally change the landscape of the Antarctic Peninsula,” he said.

– After the berg breaks off, Larsen C will be less stable than it was prior to the rift, and the ice shelf could eventually follow the dramatic example of its neighbor Larsen B, which disintegrated in 2002 following a similar rift-induced calving event. After that break, the number of glaciers behind it accelerated and are still flowing faster than before. Project MIDAS said there is no evidence to link the growth of this rift, and the eventual calving, to climate change. However, it is widely accepted that warming ocean and atmospheric temperatures have been a factor in earlier disintegrations of ice shelves elsewhere on the Antarctic Peninsula, most notably Larsen A in 1995 and Larsen B in 2002.

Project Midas:

In another sign that the iceberg calving is imminent, the soon-to-be-iceberg part of Larsen C Ice Shelf has tripled in speed to more than ten meters per day between 24th and 27th June 2017. The iceberg remains attached to the ice shelf, but its outer end is moving at the highest speed ever recorded on this ice shelf. We still can’t tell when calving will occur – it could be hours, days or weeks – but this is a notable departure from previous observations.

The most recent observations on 27th June do not cover the rift tip, but a low resolution Sentinel-1 image of just after midnight on 28th June shows clearly that the iceberg remains attached to the ice shelf at its western end – for now. When it calves, the Larsen C Ice Shelf will lose more than 10% of its area to leave the ice front at its most retreated position ever recorded; this event will fundamentally change the landscape of the Antarctic Peninsula. We have previously shown that the new configuration will be less stable than it was prior to the rift, and that Larsen C may eventually follow the example of its neighbour Larsen B, which disintegrated in 2002 following a similar rift-induced calving event. The MIDAS Project will continue to monitor the development of the rift and assess its ongoing impact on the ice shelf. Further updates will be available on this blog, and on our Twitter feed.