Scientists have uncovered new evidence for an ancient heat source beneath the West Antarctic ice sheet.

The underground mantle plume is thought to be driving some of the melting seen beneath the ice, giving rise to lakes and rivers.

It’s thought to have formed 50-110 million years ago, long before the ice sheet itself, and has likely played a role in rapid collapses that took place during past periods of climate change – and, it could help explain the instability seen today.

The underground mantle plume is thought to be driving some of the melting seen beneath the ice, giving rise to lakes and rivers. The illustration shows flowing water under the Antarctic ice sheet, with blue dots indicating lakes, while lines show rivers

MANTLE PLUME According to NASA, mantle plumes are narrow streams of hot rock, which spread like a ‘mushroom cap’ beneath Earth’s surface. As the material is buoyant, it pushes the crust upward. The study found that the energy flux from the mantle plume must not exceed 150 milliwatts per square meter – compared, for example, to a heat flux of 490 to 60 milliwatts in regions with no volcanic activity, and an average 200 milliwatts per square meter beneath Yellowstone. When the researchers simulated a greater heat flow, they found it resulted in too much melting. Advertisement

The suspected geothermal heat source is situated deep beneath Antarctica’s Marie Byrd Land.

While it’s not a new phenomenon, it could help scientists better estimate the rate of future ice loss in the area, as the meltwater helps to lubricate the glaciers.

A scientist at the University of Colorado Denver first suggested the presence of a mantle plume beneath Marie Byrd 30 years ago.

This could explain volcanic activity and the dome feature.

‘I thought it was crazy,’ said Hélène Seroussi of NASA's Jet Propulsion Laboratory in Pasadena, California, of when she first heard the idea.

‘I didn’t see how we could have that amount of heat and still have ice on top of it.’

In a new study, however, researchers used numerical modelling with the Ice Sheet System Model to study the plume, revealing natural sources of heating and heat transport from a number of processes.

They scientists also used observations of changes in the altitude of the ice sheet surface, captured by NASA’s IceSat satellite and airborne Operation IceBridge campaign.

‘These place a powerful constraint on allowable melt rates – the very thing we wanted to predict,’ said Erik Ivins of JPL.

Scientists have uncovered new evidence for an ancient heat source beneath the West Antarctic ice sheet (pictured). It’s thought to have formed 50-110 million years ago, long before the ice sheet itself

The study found that the energy flux from the mantle plume must not exceed 150 milliwatts per square meter – compared, for example, to a heat flux of 490 to 60 milliwatts in regions with no volcanic activity, and an average 200 milliwatts per square meter beneath Yellowstone.

When the researchers simulated a greater heat flow, they found it resulted in too much melting.

To work with the space-based data, they found the heat flow must be between 150 and 180 milliwatts per square meter.

According to NASA, mantle plumes are narrow streams of hot rock, which spread like a ‘mushroom cap’ beneath Earth’s surface.

As the material is buoyant, it pushes the crust upward.

The researchers say the plume beneath the Marie Byrd Land may have helped drive rapid ice loss at the end of the last ice age, around 11,000 years ago.