Scientists have been concerned for many years that the collapse of a continental glacier on Greenland or the Antarctic could result in a rapid and dangerous rise in sea levels, and now the surprising condition of an Antarctic glacier has seriously increased that concern.
A group of international scientists recently led a two month-long expedition to one of Antarctica's most remote regions to measure the rate of ice melt under the 50km-long Pine Island Glacier, and the results have concerned glaciologists worldwide. The glacier, which thins out towards the Amundsen Sea at a rate of about 2.5 miles (4 kilometers) each year, has been carefully monitored by scientists because it has been identified as one of the most rapidly melting ice masses in the world.
The recent expedition bored 500 meters (1640 feet) down under the ice shelf in order to obtain the first conclusive measurements of the melt-rate beneath it. Sensors were installed inside the bore holes at various intervals across the glacier to measure ocean temperatures, salinity (or salt content), and the movement of warm-water flowing underneath the massive ice mass.
The findings of this latest research study, conducted by scientists at New York University’s Courant Institute of Mathematical Sciences, the Naval Postgraduate School (NPS) in Monterey, Calif., the University of Alaska, Pennsylvania State University, NASA, and the British Antarctic Survey, have been published recently in Science magazine, show that warm water currents under the glacier are melting the ice at a rate of approximately 2.4 inches (6 centimeters) per day.
These are worrying results, as the Pine Island glacier currently acts as a protective shield holding back the massive West Antarctic Ice Sheet and regulating global sea-levels, so its fate could potentially affect the lives of millions of people. The rate of melt under the ice shelf has been named as the “biggest source of uncertainty in global sea level projection“ by glaciologists.
"Intensive melting under the Pine Island ice shelf, as observed in our study, could potentially lead to the speed up and ultimate break-up of the ice shelf,” says David Holland of NYU’s Courant Institute and one of the paper’s co-authors. “That’s important, as this ice shelf is currently holding back inland ice, and without that restraining force, the Pine Island catchment basin could further contribute to global sea-level rise.”
Scientists have been concerned since the late 1980s that the glacier was being slowly undermined causing an increased flow of glacial ice into the Amundsen Sea. A previous study, published in the November 2012 issue of the journal Science, claimed that ice melt from the Antarctic and Greenland ice sheets was responsible for a fifth of the 2.2 inches (5.59 cm) of sea-level rise observed since 1992.
“Fresh water forms every time [the sea] injects heat into the shelf,” said NPS Research Professor Tim Stanton. “The warm water starts to melt the ice at the grounding line and creates a buoyant plume called a boundary layer current. We measured the effects of that current for the first time.”
“What we have brought to the table are detailed measurements of melt rates that will allow simple physical models of the melting processes to be plugged into computer models of the coupled ocean/glacier system,” he added. “These improved models are critical to our ability to predict future changes in the ice shelf, and glacier-melt rates of the potentially unstable Western Antarctic Ice Sheet in response to changing ocean forces.”
The results of the study have been published just two months after a massive iceberg measuring about 278 square miles (720 square kilometers) broke away from the Pine Island Glacier and drifted out into the Amundsen Sea. This evidence appears to provide definitive proof of 'global warming', as it is our oceans which retain the majority of the excess heat created by greenhouse gases.
How will global warming really affect us? Well, it appears that rising sea levels caused by climate change have produced the first 'global warming refugee': Iaone Teitiota from Kiribati, an island in the Pacific, has applied for refuge in New Zealand based on his claims that rising sea levels are making Kiribati uninhabitable.
Kiribati is made up of 33 small islands which, at just under 2 meters above sea-level ( 6.5 feet), are highly vulnerable to rising sea levels. The island's president has actually advised residents to leave, as increasingly high tides are destroying crops and contaminating drinking water. Many residents have already been forced to move to higher ground. Scientists have confirmed that Kiribati will soon become totally uninhabitable and suggest that governments should plan to evacuate its citizens over the next few years.
Evacuating a whole chain of Pacific Islands is quite an undertaking, and this scenario is a perfect small-scale illustration of the effects we can expect to witness if seas continue to rise. Evacuating much larger land masses will be much more difficult.
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