Why does the Earth's interior cool faster?
About 4.5 billion years ago, a large amount of cosmic dust and gas coalesced under the force of gravity to form our planet. However, the young Earth at that time was nothing like its current appearance. The Earth's environment was particularly hostile, with very high temperatures and oceans of magma bubbling up from its surface.
It took millions of years for the Earth to cool down and evolve into a habitable world. However, many layers beneath our feet, the Earth's interior is still hot, with a layer of molten metal, almost as hot as the Sun! And the cooling process is still ongoing, gradually continuing over time as we move towards the Earth's core.
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The core is the heart of the planet and is essential to life, as it provides Earth with its protective magnetic fields. One day, the core will eventually cool and become solid. Scientists believe that when this happens, Earth will become similar to Mars, affecting every planetary process as we know it.
Recently, scientists estimated that the Earth's interior is cooling faster than expected. And that's worrying for life as we know it on our planet.
"Our results could give us a new perspective on the evolution of Earth's dynamics. They suggest that Earth, like other rocky planets such as Mercury and Mars, is cooling and becoming inert much faster than expected," explains Professor Motohiko Murakami at ETH Zurich and lead author of this new study.
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Scientists came to this conclusion by studying Bridgmanite, a mineral commonly found at the boundary between Earth's core and the heat-conducting mantle. This mineral could be a key source for answers about how quickly the core will cool.
The boundary layer is the place where the thick rock of Earth's mantle comes into direct contact with the hot iron-nickel melt of the planet's outer core, the statement from ETH Zurich explains. Simply put, this is where the interaction of the planet's internal heat takes place.
The team conducted a laboratory experiment to determine how much bridgmanite is transported from the Earth's core to the mantle. Their laboratory environment mimics the conditions inside the Earth. It allowed them to measure the thermal conductivity of bridgmanite.
"This measurement system allows us to show that the thermal conductivity of bridgmanite is about 1.5 times higher than the hypothetical one," says Professor Murakami.
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This simply means a higher heat flow from the core to the mantle. This means the core is cooling much faster than previously assumed. But how long will it take for the Earth's core to solidify?
According to Professor Murakami: “We still don’t know enough about these kinds of events to determine their timing.” However, the cooling will not be rapid enough to have an impact on our immediate future on a human scale.
