Earth’s water originated close to home, lava analysis suggests

Deuterium levels in mantle argue against comets as H2O source

volcanoes

WATERY WORLD  Water molecules embedded inside lava spewed by volcanoes in Iceland (like the one shown) and Canada suggest that Earth’s H2O originated from water-laden dust.

Magnús Tumi Guðmundsson

Molecules entombed inside pristine magmas suggest that Earth’s water came from soggy dust, not icy comets.