Fragmented ice floes near the coast of West Antarctica
There is something mysterious and hot lurking beneath the surface of the Antarctic ice.
Now Nasa says that it might have found the source of that strange heating - a "mantle plume" - or upwelling of abnormally hot rock, that lies deep beneath the surface.
The heat is causing the surface of the ice to melt and crack, resulting in rivers and other disruption to Antarctica.
Around 30 years ago, a scientist at the University of Colorado Denver said that there might be a mantle plume under a region of the continent known as Marie Byrd Land. That hypothesis helped explain some strange features seen on the ice, like volcanic activity and a dome.
Mantle plumes are narrow streams through which hot rock rises up from the Earth's mantle, and then spreads out under the crust. Because the material itself is hot and buoyant, it makes the crust bulge upwards.
They explain how some places - like Hawaii and Yellowstone - have huge amounts of geothermal activity despite being far from the edge of a tectonic plate.
But it was also an idea that was hard to believe, since the ice above the plume is still there. "I thought it was crazy," said Helene Seroussi of Nasa's Jet Propulsion Laboratory, who helped the lead work. "I didn't see how we could have that amount of heat and still have ice on top of it."
Now scientists have used the latest techniques to support the idea. The team developed a mantle plume numerical model to look at how much geothermal heat would be needed to explain what is seen at Marie Byrd Land, including the dome and the giant subsurface rivers and lakes present on Antarctica's bedrock.
They compared the theoretical model with data brought back from Nasa's missions over the Antarctic, to ensure it was realistic. It led them to believe there was a mantle plume, packed with huge amounts of pressure and heat, beneath the surface. It would have formed 50 million to 110 million years ago, long before the ice sheet itself came into being.
Comment: A reader comments:
I have been doggedly explaining to them for a decade now, that non-dipole magnetic shifts at the core mantle boundary are the cause of this melting and climate change. We are heading towards a full reversal (always going towards or away from one, but now quite close. As a result of the last one, the icecap in Antarctica melted totally, seas rose 50 metres. Might be awkward, but cutting down smoking won't help)
The antique mantle plume yarn has some merit, but there is no effective material flow upwards in the mantle. That is about four orders of magnitude too slow. At least. The geomagnetic shift, gravity shift, eustatics and geodetics maps plus the seismic tomography, all match, while the lower troposphere CO2 maps don't, but show most CO2 is from the deep oceans, and also, oddly, from the deep sedimentary basins.
AGW is not a conspiracy, just the new world religion. It results from almost all climate scientists being geomagnetic illiterates, and also, they can't read multilayered time-series contour map shifts. It is an obscure set of skills.