A massive iceberg has broken off from Antarctica’s Pine Island Glacier. The detached chunk of ice measures 103 square miles, which is over four times the size of Manhattan. There are concerns that this calving event could accelerate the loss of more ice from the glacier, and ultimately break down the barrier that prevents land-based ice from floating off into the ocean.
Pine Island Glacier is one of the largest ice streams on the West Antarctic Ice Sheet. It is melting faster than any other glacier in Antarctica and its rate of ice loss has been speeding up for 40 years. This event marks the second time in two years that a huge iceberg has retreated from Pine Island Glacier. This incident also closely follows one of the largest calving events ever recorded when an iceberg the size of Delaware broke off from Larsen C.
Although the iceberg will not directly contribute to sea level rise, it will have an indirect impact. These floating ice shelves create barriers that prevent land ice from floating off into the ocean. These barriers are broken down as the ice shelf splits, allowing land ice to glide away and expand the ocean. If Pine Island Glacier completely melted, sea levels would rise by as much as 1.7 feet.
Scientists believe that warming ocean waters are melting the icebergs from below, triggering them to detach and float away. There is also evidence that the warming sea is weakening the base of Pine Island Glacier and changing the patterns of ice loss. While icebergs usually break away from the sides, the rift that led to the latest calving formed in the center.
Dr. Stef Lhermitte is a satellite observation specialist from Delft University of Technology in the Netherlands. He was the first to report the news of the iceberg on Twitter.
“It’s the fifth large calving event since 2000,” said Dr. Lhermitte. “This one and 2015, they were much further inland than the previous ones. So there has been a retreat of the calving front, specifically between 2011 and 2015.”
Image Credit: NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey