By Neelabja Adkuloo
A NASA study has confirmed that there is a gigantic geothermal heat source sitting beneath the Antarctic glacier. This may help to explain why Antarctica is so unstable today, and is melting at a rate higher than was expected.
Mantle plume activity
The motion of Antarctica’s ice sheet helps the scientists estimate how much ice is melting at the base and where. The ice sheet is known to rise and fall because the bedrock of the glacier is laced with rivers, which fill with and then drain water. This explains the continual gain and loss of glacial ice. Recent investigations, however, suggest that the sheet has suffered a sharp loss of volume that cannot be explained by natural factors.
NASA’s satellite and airborne observations have proposed that a hot ‘mantle plume’, a collection of scorching hot rocks which rise from beneath the earth, is responsible for the ice loss. The suggestion—that a mantle plume exists beneath the glacier—was first made 30 years ago by Wesley E LeMasurier, a scientist from the University of Colorado. The NASA survey has now offered concrete evidence to support the claim.
The NASA team used the Ice Sheet System Model (ISSM) to look at the natural source of heating. The ISSM is a climate model which employs quantitative methods to study the evolution and dynamics of ice sheets. The area above the plume was recognised on the survey as a hotspot. The heat measured at that spot was a whopping 1800 degrees.
According to the study, the mantle plume has been present in the Marie Byrd Land region of Antarctica for more than 50 million years. This is evidence that the plume came into existence long before the Antarctic glacier formed. A similar geological feature is also present at the Yellowstone National Park in the United States. The presence of the Antarctic plume explains why the ice is vulnerable in specific areas. The NASA researchers now have a tough task ahead: Trying to understand how the glacier was able to stay frozen despite the hot mantle plume beneath it.
Huge implications for the planet
Ice sheets contain about 99% of the earth’s freshwater. During the last ice age, a major part of the Earth was covered by ice sheets. Today, however, only two ice sheets remain: the Antarctic ice sheet and the Greenland ice sheet, with the Antarctic being the larger of the two.
If the glaciers disappear, the earth’s landscape would change drastically. Melting ice sheets would put coastal regions at a greater risk of flooding. Large icebergs that broke off from the Antarctic glacier would create hazards for shipping. Melting ice would also add tonnes of freshwater to the oceans, which would impact its salt content. It would also make the survival of many marine animal and plant species, especially corals and krills, impossible.
The seismic imaging conducted by NASA scientists has established that the meltdown is an imminent issue. The amount of water beneath the Antarctic glacier has had a significant impact on its stability. The liquid water acts as a lubricant, reducing the ice friction. This allows the glaciers to slide more easily and collapse into the oceans. Antarctica is currently undergoing a period of sustained ice loss. Understanding the future of the Antarctic ice sheet is absolutely essential for gauging the rate at which ice may be lost in the future.
Featured Image Source: Wikimedia Commons
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