The interior of the Earth is cooling faster than expected, according to a new study

Since the Earth formed about 4.5 billion years ago, our planet has been slowly cooling. Over millions of years, the Earth went from being covered by a deep ocean of magma to forming a brittle crust.

Since then, processes driven by heat from within the Earth have been extremely important in protecting our world and allowing life to thrive. For example, the rotating and convective dynamo inside the Earth is what generates its vast magnetic field. Similarly, it is believed that mantle convection, tectonic activity, and volcanism help support life by stabilizing global temperatures and the carbon cycle.

At what rate is the interior of the Earth cooling?

Although the constant cooling of the Earth’s interior is known, The question of how fast it cools has not yet been answered exactly. and when its interior will solidify, and therefore the end of the geological activity, possibly turning the Earth into barren rock, similar to Mars or Mercury.

Now, new research has revealed that this could happen sooner than previously thought. The study, conducted by ETH Zurich professor Motohiko Murakami and colleagues at the Carnegie Institution for Science, has been published in the journal Earth and Planetary Science Letters.

Thermal conductivity of bridgmanite

These experts have developed a measurement system in the laboratory that allows measure the thermal conductivity of a mineral known as bridgmanite, situated on the boundary between the outer iron-nickel core of the Earth and the lower mantle of molten fluid above it. The measurements were made under the pressure and temperature conditions prevailing inside the Earth.

“This measurement system allowed us to show that the thermal conductivity of bridgmanite is about 1.5 times higher than previously assumed,” says Murakami in an ETH statement.

This suggests that the heat flux from the core to the mantle is also greater than previously thought. The increased heat flux increases mantle convection and increases the cooling of the Earth.

It also causes plate tectonics to slow down faster than expected based on previous heat conduction values. Tectonics is responsible for the convective movements of the mantle. According to the researchers, these changes seem to lead to a cooling of the planet.

Postperovskite: higher thermal conductivity

And the process could be accelerating. When cooled, bridgmanite transforms into another mineral called posperovskite, which is even more thermally conductive. and thus the rate of heat loss from the core to the mantle would increase.

“Our results could give us a new perspective on the evolution of Earth dynamics,” Murakami said. “They suggest that Earth, like the other rocky planets Mercury and Mars, is cooling and going dormant much faster than expected.”

However, it cannot say how long it will take, for example, for convection currents in the mantle to stop. “We still don’t know enough about this type of event to pinpoint its timing,” said the planetary scientist. According to the statement, it would first be necessary to better understand how mantle convection works in spatial and temporal terms, among other factors. (I)