(Image above: Larsen C icebergs seen using a thermal imaging instrument aboard a NASA satellite.)
In July, one of the largest icebergs ever recorded — measuring in at about the size of Delaware and containing a volume of ice twice the size of Lake Erie — broke off the Larsen C Ice Shelf in northwest Antarctica.
The event, which took place during the frigid blackness of the Antarctic winter, was detected using satellite instruments that could pierce the darkness to sense the ice below. As the austral spring dawns, scientists are now being granted their first glimpses of the new iceberg during the daytime.
And the images are incredible.
The first daytime satellite photo to be released by NASA came on Sept. 11, via an instrument on NASA’s Terra satellite, which is known as the Moderate Resolution Imaging Spectroradiometer, or MODIS.
It revealed the massive iceberg, which dwarfs Manhattan yet somehow has taken on its shape, in all its glory.
Satellite image showing the massive Antarctic iceberg and its smaller sibling on Sept. 16, 2017. / IMAGE: NASA
The new data shows how the massive iceberg has split into smaller pieces since it cleaved off from the floating ice shelf last summer, and reveals that it has begun to push away from the ice shelf that birthed it, thanks to offshore winds.
The original iceberg weighed about 1 trillion tons, according to a team of researchersaffiliated with a U.K.-based research project, known as Project MIDAS. While the iceberg calving event itself is likely mostly natural, it nevertheless threatens to speed up the already quickening pace of ice melt in the region due in large part to global warming.
In its original shape, the iceberg was about 2,200 square miles in area, Project MIDAS researchers said in a blog post on July 12. In late July, the main iceberg, known as A-68A, lost several chunks of ice as it began to slowly drift out to sea.
One of those large chunks is now known as A-68B, according to the National Ice Center, which tracks large icebergs because they pose a danger to ships.
Around the same time, scientists revealed that new cracks were developing on the Larsen C ice shelf, potentially signaling additional breakup events in the coming months to years.
Scientists are closely monitoring the Larsen C Ice Shelf because of the warming occurring in that region, and the unsettling history of other ice shelves in the area.
The icebergs in natural color (left). Thermal image (right) reveals where the colder ice ends and warmer water begins. / IMAGE: NASA
The Antarctic Peninsula, which is where the Larsen C Ice Shelf is located, is one of the most rapidly warming parts of the Earth. Two of its neighbors, Larsen A and Larsen B, have already collapsed. (The rapid breakup of Larsen B inspired the opening scene in the disaster flick, The Day After Tomorrow.)
Because of that history, there is tremendous scientific interest in seeing how Larsen C responds to losing about 12 percent of its area in a single, trillion-ton iceberg. While the iceberg calving event itself is not likely caused specifically by climate change, it nevertheless threatens to speed up the already quickening pace of ice melt in the region by leaving the ice shelf behind it in a weakened state, with new cracks that may develop additional icebergs in the future.
The melting of the ice shelf does not affect global sea levels directly, since the ice was already floating, like an ice cube in a glass, before the calving event. However, when ice shelves like Larsen C melt, they can free up land-based ice behind them to flow faster into the sea, which does raise sea levels.
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