Earth's interior is likely to cool faster than expected
The Earth’s core emits heat to the Earth’s mantle (orange to dark red), which contributes to the slow cooling of the Earth. ETH researchers simulated this in the lab and now hypothesize that the planet is “dying” much faster than expected. (press photo)

Keystone

While humans are concerned about Earth’s climate, scientists are looking into the depths and into the far future: For example, ETH researchers in the lab have shown that the planet’s interior is likely to cool much faster than assumed.

It is difficult to conduct an empirical examination of the temperatures in the Earth’s interior for obvious reasons: the Earth’s core begins at a depth of about 3000 km and has a temperature of plus/minus 6000 K, which is about 5000 to 6000 degrees Celsius. So the ETH scientists simulated the boundary layer between Earth’s core and Earth’s mantle in the lab.

This boundary layer is relevant because here the viscous mantle rock is in direct contact with the hot iron
Nickel melts from the Earth’s outer core. The temperature gradient between the two layers is quite large, so there is likely to be a lot of heat flowing here. The boundary layer is mainly composed of the mineral bridgemanite.

ETH Professor Motohiro Murakami and colleagues at the Carnegie Institution for Science have developed a sophisticated measurement system that makes it possible to measure the thermal conductivity of bridgemanite in the laboratory, under conditions of pressure and temperature prevailing inside the Earth.

In the future a “dead” planet like Mars

“Using this measurement system, we were able to show that the thermal conductivity of bridgemanite is one and a half times higher than assumed,” Murakami says. This leads to the conclusion that the heat flow from the core to the cladding is also higher than previously thought. This could lead to the movement of tectonic plates, which is continued by convective motions in the mantle, and oscillates faster than previously assumed.

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“Our results may open a new perspective on the evolution of Earth dynamics. They point out that Earth, like the other rocky planets Mercury and Mars, is cooling and becoming inert much faster than expected,” explains Murakami.

* DOI Publication Number: 10.1016 / j.epsl.2021.117329

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