Scientists say Earth’s core may store enough hydrogen to form up to 45 oceans, potentially influencing volcanic activity and the planet’s evolution.
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| A new study finds hydrogen trapped in Earth’s core could equal nine to 45 oceans of water, with implications for mantle chemistry and volcanism. Image: CH |
Science Desk – February 11, 2026:
Earth’s oceans cover more than 70 percent of the planet’s surface, yet new research suggests far larger quantities of water’s key ingredient—hydrogen—may be locked deep inside the planet’s core.
In findings published February 10 in Nature Communications, researchers report experimental evidence that Earth’s core could contain enough hydrogen to form between nine and 45 oceans. The discovery could significantly alter scientific understanding of how water circulates within the planet and how internal processes shape surface geology over billions of years.
Hydrogen does not exist as liquid water in Earth’s core, where temperatures and pressures are extreme. Instead, it is believed to be chemically bound within metallic materials. Over time, some of this hydrogen may migrate upward into the mantle, where it reacts with oxygen-rich minerals to form water.
According to study co-author Motohiko Murakami, a geodynamicist at ETH Zurich, this deep hydrogen cycle could influence mantle melting, magma formation and ultimately volcanic activity at the surface.
Water lowers the melting point of rocks. Even small increases in mantle water content can make it easier for magma to form, potentially affecting the frequency and intensity of volcanic processes.
Previous attempts to estimate hydrogen in the core relied on indirect measurements, such as tracking how iron expands when hydrogen is added. These approaches produced widely varying results.
To obtain more precise data, Murakami and his colleagues recreated the extreme conditions thought to exist during Earth’s formation, when the planet was covered by a global magma ocean.
The team sealed iron samples inside hydrogen-rich glass and compressed them using a diamond anvil cell—a device capable of generating immense pressures. They then heated the materials with a laser to temperatures reaching 4,826 degrees Celsius.
Under these conditions, the materials melted into droplets of iron containing silicon, hydrogen and oxygen—similar to the molten material believed to have sunk and formed Earth’s early core.
After rapidly cooling the samples, researchers used advanced imaging techniques to examine their internal structure. They identified tiny inclusions composed of silicon and hydrogen in a one-to-one atomic ratio.
That ratio is significant because earlier research suggests the core contains between 2 and 10 percent silicon by weight. Using this benchmark, the team calculated that hydrogen likely accounts for roughly 0.07 to 0.36 percent of the core’s total mass.
While the percentage appears small, the immense size of the core means the total hydrogen content would be enormous—equivalent to enough hydrogen to create approximately nine to 45 Earth oceans of water.
The findings raise broader questions about the origin and long-term stability of Earth’s water. Traditionally, scientists have debated whether much of Earth’s water was delivered by comets or asteroids. The possibility of a massive internal hydrogen reservoir suggests that deep planetary processes may also play a significant role in sustaining surface water over geological timescales.
If hydrogen has been slowly leaking from the core into the mantle for billions of years, it may represent a subtle but continuous source influencing Earth’s hydrological and volcanic systems.
The study may also inform research into other rocky planets. Understanding how hydrogen behaves under extreme pressures could help scientists assess water potential on distant exoplanets or better interpret the geological evolution of planets like Mars and Venus.
For now, the research highlights how much remains unknown about Earth’s deep interior. While oceans dominate the visible planet, an even larger story may be unfolding far below—hidden in the metallic heart of the world.
As scientists continue probing Earth’s inaccessible depths, the possibility that dozens of oceans’ worth of hydrogen lie trapped within the core underscores a profound scientific reality: the planet’s most influential reservoirs may be the ones we cannot see.