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Earth is like an onion: Layers

After decades of theorizing and searching, scientists are reporting that they've finally establish a massive reservoir of water in the Earth's mantle — a reservoir so vast that could fill up the Earth'southward oceans iii times over. This discovery suggests that Globe'south surface water really came from within, as role of a "whole-Earth water cycle," rather than the prevailing theory of icy comets hitting Earth billions of years ago. As always, the more we understand almost how the Earth formed, and how its multitude of interior layers proceed to function, the more accurately nosotros tin predict the future. Weather, sea levels, climatic change — these are all closely linked to the tectonic activity that incessantly churns abroad beneath our anxiety.

This new study, authored by a range of geophysicists and scientists from beyond the Usa, leverages data from the USArray — an array of hundreds of seismographs located throughout the US that are constantly listening to movements in the Globe's drapery and core. After listening for a few years, and carrying out lots of complex calculations, the researchers believe that they've institute a huge reserve of water that's located in the transition zonebetween the upper and lower mantle — a region that occupies between 400 and 660 kilometers (250-410 miles) below our feet. [DOI: x.1126/scientific discipline.1253358 – "Dehydration melting at the peak of the lower curtain"]

Earth's crust, cutaway diagram

As you tin can imagine, things are a lilliputian circuitous that far downward. Nosotros're not talking nearly some kind of water reserve that can exist reached in the same way equally an oil well. The deepest a human borehole has ever gone is but 12km — well-nigh one-half fashion through the Earth's chaff — and we had to cease because geothermal energy was melting the drill chip. 660 kilometers is a long, long way down, and weird stuff happens downwards there.

Basically, the new theory is that the Earth's drape is full of a mineral called ringwoodite. We know from experiments here on the surface that, under extreme force per unit area, ringwoodite can trap water. Measurements made by the USArray indicate that equally convection pushes ringwoodite deeper into the mantle, the increment in pressure forces the trapped water out (a process known as dehydration melting). That seems to be the extent of the report's findings. Now they need to try and link together deep-Earth geology with what actually happens on the surface. The Globe is an immensely complex car that generally moves at a very, very irksome step. It takes years of measurements to get anything even budgeted useful data. [Read: Is earthquake prediction finally a reality?]

Earth's underground ringwoodite ocean

Earth's underground ringwoodite body of water [Epitome credit: The Guardian]

With all that said, at that place could be massive repercussions if this study'southward findings are authentic. Even if the ringwoodite just contains around 2.half-dozen% water, the book of the transition zone means this underground reservoir could contain enough h2o to re-fill up our oceans three times over. I'm non saying that this gives u.s. the perfect excuse to continue our abuse of World's fresh water reserves, but it's definitely something to mull over. This would also seem to discount the prevailing theory that our surface h2o arrived on Globe via a bunch of icy comets.

Finally, hither's a fun idea that should remind u.s. that Earth'south perfect limerick and climate is, if yous look very closely, rather miraculous. One of the researchers, talking to New Scientist, said that if the water wasn't stored underground, "it would be on the surface of the Earth, and mountaintops would be the only land poking out." Maybe if the formation of Earth had be a petty different, or if we were marginally closer to the Lord's day, or if a random asteroid didn't land hither billions of years ago… you probably wouldn't be sitting hither surfing the web.