Oceans may well be shrinking — Science News, March ten, 1973
The oceans of the globe may well be progressively shrinking, leaking gradually away into the Earth’s mantle…. Even though the oceans are consistently becoming gradually augmented by water carried up from Earth’s interior by volcanic activity … some approach such as sea-floor spreading appears to be letting the water seep away far more swiftly than it is replaced.
Update
Scientists traced the ocean’s leak to subduction zones, regions exactly where tectonic plates collide and the heavier of the two sinks into the mantle. It is nevertheless unclear how a lot water has cycled among the deep ocean and mantle via the ages. A 2019 evaluation suggests that sea levels have dropped by an typical of up to 130 meters more than the final 230 million years, in component due to Pangea’s breakup developing new subduction zones. Meanwhile, molten rock that bubbles up from the mantle as continents drift apart may well “rain” water back into the ocean, scientists reported in 2022. But due to the fact Earth’s mantle can hold far more water as it cools (SN: six/13/14), the oceans’ mass may well shrink by 20 % each billion years.
