For decades, many scientists believed that most of the water in our planet came from space, transported by meteorites and comets during the first moments of the terrestrial formation. However, a new study published in Nature Communications, proposes a different idea: part of the water could have been formed inside Earth thanks to huge amounts of hydrogen kept in its core.
The study was led by researchers from the Peking University and ETH Zurich, who were able to recreate extreme conditions similar to those found deep within the Earth, they discovered that hydrogen can become trapped inside iron under very high pressure and temperature. So, let’s learn more about this study.
Discovery in the Earth’s core
The Earth’s core is located more than 1,800 miles under our feet. There, temperatures and pressures are extremely high and materials behave very differently to the surface.
Scientists recreated these extreme conditions using small samples of iron. They used advanced tools such as atom probe tomography and diamond anvil cells to observe how hydrogen interacts with iron under extreme conditions. This way researchers found that hydrogen can be incorporated into iron when exposed to these intense pressures and temperatures. In other words, hydrogen does not only exist in the atmosphere or on the surface of the planet—it can also be stored deep inside the Earth’s core.
According to the team, the core could contain between 0.07% and 0.36% of hydrogen by weight. Although the percentage seems small, the total amount would be equal to about 9 and 45 times more hydrogen than the one found in all oceans of the planet together.
Water on Earth
For many years, the most accepted theory about the origin of water on Earth had been this one: when the planet was being formed, meteorites and comets rich in water or materials containing water hit the planet. These impacts would have provided a great part of the water that fills rivers, oceans, and lakes today.
However, the discovery of huge hydrogen reservoirs in the core opens a new possibility. When hydrogen combines with oxygen, water is created. So, if the Earth’s core contains such vast amounts of hydrogen, it suggests that some water may have formed internally rather than being delivered entirely from space.
This process may have occurred during planetary accretion, the stage when Earth was forming and growing through the accumulation of materials. During this time, hydrogen could have become trapped inside iron as the core formed. Later, as hydrogen interacted with other elements such as oxygen, water may have been produced within the planet itself.
The meaning of this discovery
Beyond offering a new explanation for the origin of water, the study also helps explain another scientific puzzle. Hydrogen is the lightest and most abundant element in the universe. Yet, it is relatively scarce at Earth’s surface compared to what scientists might expect.
If large amounts of hydrogen are stored in the core, this could explain why less hydrogen is found on the surface. The discovery also provides new insight into the deep composition of the Earth and the long-term geochemical processes that have shaped the planet since its earliest beginnings.
Although further studies are needed to confirm and expand on these findings, the research represents an important step forward in understanding Earth’s internal structure and the processes that influence the global water cycle.
So…
It becomes clear that understanding the origin of water is understanding how our planet formed, how its interior works, and how its systems evolved over billions of years. Isn’t it incredible how we can learn new things about theories that were totally accepted?