Oceans may perhaps be shrinking — Science News, March ten, 1973

The oceans of the globe may perhaps be progressively shrinking, leaking gradually away into the Earth’s mantle…. While the oceans are continuously getting gradually augmented by water carried up from Earth’s interior by volcanic activity … some procedure such as sea-floor spreading appears to be letting the water seep away extra swiftly than it is replaced.

Update

Scientists traced the ocean’s leak to subduction zones, places exactly where tectonic plates collide and the heavier of the two sinks into the mantle. It is nevertheless unclear how considerably water has cycled amongst the deep ocean and mantle by means of 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 perhaps “rain” water back into the ocean, scientists reported in 2022. But given that Earth’s mantle can hold extra water as it cools (SN: six/13/14), the oceans’ mass may possibly shrink by 20 % every single billion years.