This illustration exhibits the place water rests and flows below the Antarctic ice, with blue dots indicating lakes and contours indicating rivers.
Credit score: Credit score: NSF/Zina Deretsky
Think about drifting over Antarctica’s icy expanse. A white continent extends beneath you, and it is smothered in sufficient frozen water to drown each shoreline on the earth in a 216-foot (66 meters) wave if it have been to soften. However scientists now consider that, deep beneath nearly 1.2 miles (2 kilometers) of ice and a comparatively skinny slice of rocky crust, one area of the frozen continent hides a column of red-hot magma, straining towards the floor, in response to a brand new examine.
Often, magma nears the floor solely on the edges of tectonic plates. And West Antarctica’s Marie Byrd Land, the place the plume is suspected to exist, is way from any such border areas. Nevertheless, there are locations on the earth the place magma reaches towards the floor removed from any tectonic border areas, NASA scientists stated in a Nov. 7 assertion. Yellowstone Nationwide Park is one. Hawaii is one other. All that magma pushes in opposition to the crust in these components of the world, inflicting it to bulge and pumping warmth up by the bottom.
That warmth provided scientists the primary clues that the Antarctic plume exists. [Photo Album: Antarctica, Iceberg Maker]
Regardless of its obvious icy stillness, Antarctica is alive with movement. Big lots of frozen water slip, slide and grind with huge stress in opposition to the continent beneath, their fixed movement lubricated by a fancy system of rivers and lakes beneath the ice.
However in Marie Byrd Land, researchers discovered much more of that exercise than the identified regional warmth sources might clarify. One thing else was cooking the ice shelf. About 30 years in the past, researchers first started to suspect magma plume is perhaps the trigger, given the domed form of the crust in that space.
Now, scientists know for positive.
Examine researchers Hélène Seroussi and Erik Ivins of NASA’s Jet Propulsion Laboratory constructed a mannequin of all of the identified melting and freezing below the ice within the area. Researchers haven’t got probes below the ice, however they will detect the exercise because of cautious measurements of the rise and fall of the floor from NASA’s ICESat satellite tv for pc and IceBridge flyover missions. [Extreme Antarctica: Amazing Photos of Lake Ellsworth]
Their mannequin confirmed the existence of a magma plume pumping about 150 milliwatts per sq. meter (or about 11 sq. toes) of warmth as much as the floor, and peaking at as a lot as 180 milliwatts per sq. meter in a area the place a rift within the crust could exist. (A milliwatt is one-thousandth of a watt.) For comparability, a typical stretch of land in america will get about 40 to 60 milliwatts per sq. meter of geothermal warmth, and Yellowstone will get about 200 milliwatts per sq. meter.
This magma plume is not an alternate doable explanation for latest upticks in melting alongside the West Antarctic Ice Sheet attributed to human-generated local weather change. The plume is way older than the latest interval of atmospheric warming; certainly, at 50 million to 110 million years previous, it is older than our species and the West Antarctic Ice Sheet itself. The plume has been an element within the ice sheet’s conduct all through its historical past, and up to date surges in melting are the results of all the extra warmth people have pumped into it.
The examine was printed on-line Sept. four within the Journal of Geophysical Analysis: Stable Earth.
Initially printed on Stay Science.