Underneath the Pine Island Glacier Ice Shelf, in the West Antarctica, stronger ocean currents have been melting the glacier.
In a public release from the Earth Institute at Columbia University; “The glacier is currently sliding into the sea at a clip of four kilometers (2.5 miles) a year, while its ice shelf is melting at about 80 cubic kilometers a year – 50 percent faster than it was in the early 1990s – the paper estimates.”
Research has shown that this rapid rate of Antarctic ice melting is caused by an ocean current known as upwelling.
Ocean currents, sometimes called earth’s conveyor belt, flow clockwise in the northern hemisphere and counter – clockwise in the southern hemisphere. Upwellings are different. These are vertical currents that bring the water up from the bottom.
The strong ocean currents have been eroding the underneath side of the Pine Island Glacier, creating a cavity which allows warmer water, created by an upwelling to become trapped in the cavity of the iceberg, causing it to melt at a faster rate. The water is warmest where the ice is the thickest, thus intensifying the melting. This melting process then turns around and nurtures the ongoing rise in sea levels overall.
In 2009, Stan Jacobs with an international team of scientists, in the Amundsen Sea had the opportunity of observing an upwelling first hand. They described this incident as the ocean water “appearing to boil just like a pot on the stove.”
On this same trip with Stan Jacobs was researcher Adrian Jenkins of the British Antarctic Survey. He and his team sent a robot submarine under the ice shelf to reveal an underwater ridge. They assumed that the glacier broke off from this ridge sometime before the 1970s. Because of the upwelling sea current, it allowed warm water underneath, which gained access to the deeper parts of the glacier. As time went on, a cavity grew, allowing more warm water to be exposed to the glacier.
There are other glaciers in the Amundsen area that are suffering the same fate as the Pine Island Glacier. The Thwaites glacier, which is an unusually large glacier flowing into the Pine Island Bay. It is about 50 kilometers wide and has gradually shortened due to ice-calving, which is the process by which icebergs break off from an ice shelf or glacier.
The Getz Ice Shelf extends many miles into the ocean from the Getz glacier. The vertical face of the Getz Ice Shelf is approximately 200 feet high, and is thought to extend another 1,000 feet below the surface. There are several islands either partially or wholly embedded into this ice shelf.
The research being done by Stan Jacobs and Adrian Jenkins, along with their teams is showing that there are ocean currents that are melting the Antarctic ice, and these currents are doing so at quite an alarming rate.
Resources:
http://www.ldeo.columbia.edu/news-events/ocean-currents-speed-melting-antarctic-ice
http://www.nasa.gov/mission_pages/icebridge/multimedia/fall10/GetzIceShelf.html
