The oceans are in a perpetual state of flux, with water flowing in and out of the Earth’s mantle. The process, known as the deep water cycle, sees water slip under the planet’s tectonic plates only to come out later through underwater volcanoes and vents. About 70 percent of the Earth’s surface is covered in water and 97 percent of that water – more than 332,519,000 cubic miles – is found in the oceans. But the deep water process appears to be swallowing up more water than it is releasing back to the surface.
And if some scientific estimates are to be believed, there could be about three to four oceans-worth of water are trapped under the mantle.
The shocking revelation was presented by a team of geologists from Norway in the Journal Geochemistry, Geophysics and Geosystems.
The researchers found historical evidence of sea levels fluctuating by more than 656ft (200m) alongside so-called super continental cycles every 300 to 500 million years.
These drastic shifts in oceanic heights were determined by the volume of the ocean, which itself was determined by the movement of the continents.