From the Daily Mail:
Researchers at Ohio State University believe the same amount of water that currently fills the Pacific Ocean could be buried deep inside the planet right now.
The new study is helping to answer a longstanding question that has recently moved to the forefront of earth science: Did our planet make its own water through geologic processes, or did water come to us via icy comets from the far reaches of the solar system?
The answer is likely 'both,' according to the team, who are to present their work at the American Geophysical Union (AGU) meeting in San Francisco tomorrow.
They found a previously unknown geochemical pathway by which the Earth can sequester water in its interior for billions of years and still release small amounts to the surface via plate tectonics, feeding our oceans from within.
'When we look into the origins of water on Earth, what we're really asking is, why are we so different than all the other planets?' Wendy Panero, associate professor of earth sciences at Ohio State said.
'In this solar system, Earth is unique because we have liquid water on the surface.
'We're also the only planet with active plate tectonics.
'Maybe this water in the mantle is key to plate tectonics, and that's part of what makes Earth habitable.'And another article from today:
Geologists have revealed that they have found water that is up to 2.7 billion years old in sites all over the world.
They now estimate that there could be around 2.5 million cubic miles (11 cubic million km) of this water buried beneath the ground.
This is more than all of the world's rivers, swamps and lakes put together.
The scientists have also found tantalising hints that the highly salty water, which is spread out through tiny vein-like networks through the rock, could be home to life.
The water appears to be reacting with the rock to produce large quantities of hydrogen in a similar way to what occurs around deep sea vents.