The Earth's Core Might Be Cooling Much Faster Than We Previously Thought

Scientists say it 'is cooling and becoming inactive much faster than expected.'
Chris Young
An illustration of Earth's coreRost-9D/iStock

The Earth's molten interior is likely cooling a lot faster than previously estimated, and it will speed up even more dramatically in the distant future according to scientists.

Researchers from Carnegie and ETH Zurich made the discovery after investigating the heat conduction properties of an abundant deep-Earth mineral, a report from New Atlas reveals.

Investigating 'the evolution of the Earth's dynamics'

The scientific community has long known that the Earth will gradually cool until even the volcanic activity that makes life on our planet possible ceases to exist. Though it will take millennia for this to happen, scientists don't have any way of accurately knowing exactly when the Earth's core will completely cool down and solidify.

To gain a better understanding of our Earth's cooling process, the team of researchers from Carnegie and ETH Zurich decided to investigate bridgmanite, a magnesium silicate or calcium silicate mineral that is abundant in the boundary layer between the Earth's outer core and its lower mantle. The team placed bridgmanite samples in a diamond anvil cell that was then heated using a laser to simulate the high-pressure and high-temperature environment found underneath the Earth's crust. Afterwards, they measured the thermal conductivity of the bridgmanite using an optical absorption system.

"Our results could give us a new perspective on the evolution of the Earth’s dynamics," said Motohiko Murakami, a corresponding author of the study explained in a press statement. "They suggest that Earth, like the other rocky planets Mercury and Mars, is cooling and becoming inactive much faster than expected."

The Earth will cool down at an increasingly fast pace

The scientists discovered that bridgmanite was roughly 1.5 times better at conducting heat than previously estimated. This means that heat must transfer more easily from the core to the mantle than had been previously believed. This faster transfer equals a higher cooling rate, meaning the Earth's core will cool down faster than once thought. What's more, as it cools bridgmanite turns into a mineral called post-perovskite, which conducts heat at an even faster rate. So the inner Earth could start to cool at an increasingly accelerated rate once bridgmanite starts forming into post-perovskite,  a crystal structure following the formula ABX₃.

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It is important to note that the Earth's cooling will still likely take billions of years to occur, even at the newly-estimated accelerated rate. We also know remarkably little about the interior of our own planet. Just last year, for example, it was discovered that the Earth's core is gradually becoming lopsided, and scientists are not sure why. In any case, in the many many years before our Earth's core loses the last of its heat, any number of other cataclysmic events have the potential to wipe us out for good. 

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