Melting of a major glacier system in western Antarctica may be caused by underwater volcanoes, and not by global climate change, according to new research.
Thwaites Glacier, a massive outlet for ice that empties into Pine Island Bay, is flowing at a rate of one-and-a-quarter miles per year. The bay opens up into the Amundsen Sea.
The Thwaites Glacier has been the subject of scrutiny by climatologists in the last few years, as new information about the severity of the melting becomes available. Traditional models had assumed heating from subterranean sources was fairly even around the region. New data provides details about areas where little was previously known.
University of Texas researchers studied how water moves underground in the region. They found liquid water was present in a greater number of sources than previously believed, and it is warmer than estimated in previous studies.
"It's the most complex thermal environment you might imagine. And then you plop the most critical, dynamically unstable ice sheet on planet Earth in the middle of this thing, and then you try to model it. It's virtually impossible," Don Blankenship, senior research scientist at the University of Texas, said.
Dusty Schroeder, lead author of the article announcing the results, helped lead a team that used aerial surveys to create radar maps capable of penetrating the surface of the ice. They found two bodies of water under the glacier which interacted with each other, distributing heat in the process.
The source of heating is believed to be a tearing apart, or rifting, of the crust under the Antarctic ice sheet. This allows movement of magma and creates volcanic eruptions, melting the ice. Liquid water and geological activity under the sheet allows the massive feature to slip off the continent.
The Thwaites Glacier is roughly the size of Florida, and is about 2.5 miles thick. Most climatologists estimate that if this structure were to melt, global sea levels would rise by between three-and-a-half and seven feet. The feature is considered one of the greatest factors in modeling rising sea levels. If the entire West Antarctic ice sheet were to melt, that amount could double.
Many climatologists believe the geological feature is already melting, and this new study shows the effect could be greater than previously estimated.
Understanding how geothermal processes are contributing to melting of the ice sheet in Antarctica could help researchers better understand how to model the region. Warming oceans off the coast of the southern continent could also contribute to loss of the ice sheet.
Study of the role of geothermal sources on melting in western Antarctica was published in the journal Proceedings of the National Academy of Sciences.
