The interior of the Earth cools much faster than we expected

The evolution of the Earth is the story of its cooling. About 4.5 billion years ago, extreme temperatures prevailed as an ocean of magma covered its surface. Over millions of years, the surface cooled and formed the crust, but the enormous thermal energy emitted from the Earth’s interior created tectonic plates and volcanoes that in turn sustained life by stabilizing the carbon cycle and global temperatures. In addition, this constant movement of molten material inside the Earth creates the huge magnetic field that protects the Earth and allows life to flourish.

The Earth will continue to cool and in the very distant future scientists expect that its interior will solidify, stopping any geological activity, turning the planet into a barren rock, like Mercury or Mars.

Now, scientists at ETH Zurich in Switzerland believe that this will happen much faster than we expected. Powerful lasers targeted a silica perovskite crystal, a rock on the edge of the mantle and core, momentarily raising its temperature to 2,440 Kelvin and pressure to 80 gigapascals to simulate the conditions at the deepest point of the mantle.

Evaluating the thermal conductivity of the perovskite, they were able to estimate that it was 1.5 times higher than they thought. This means that the heat transferred from the core to the mantle is higher and thus the rate at which the Earth’s interior cools is faster. In fact, when perovskite is cooled, it is converted to another mineral, known as meta-perovskite, which is even more conductive and increases the rate of heat loss from the core to the mantle.

The results give us a new perspective on the evolution of the Earth. They show us that the Earth, like the other rocky planets, cools and becomes inactive, much faster than we expected.

But we do not know what “very fast” means. Our knowledge of the cooling of an entire planet is limited, but in any case it does not concern the human scale of time. After all, it is very likely that the Earth would become unfit for life by other mechanisms long before.

Unboxholics

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