The Earth is cooling faster than expected. ETH Zurich geologists have now been able to detect this using the thermal conductivity of the Earth’s mantle. Thus, the core converts 50% more heat to the mantle than previously thought.
A warm center is a basic need for life on Earth
Life on Earth is possible because there is life on the planet. Not only does the Earth’s warm center trigger plate changes, but mountains and volcanoes can also be rediscovered from this appearance. In addition, the valuable safety factor of the Earth’s magnetic field should not be forgotten. It is also structured by currents in the earth’s interior. The metal-bearing volcanic layers flow together, turning the planet into a giant dynamo and blocking dangerous radiation from space with a strong magnetic field. According to some researchers, the complete cooling of the Earth’s core, for example, will cause our own planet the same fate as Mars.
This may one day come due to the natural thermal conductivity of the line. Bridgemanite is the most abundant mineral in the transition zone between the mantle and the center of the earth. This viscous layer of rock is in constant contact with lava containing iron and nickel, but at temperatures as high as 1000 C. “Due to its steep temperature gradient, this is the Earth’s largest temperature range,” say researchers at ETH Zurich, which raises the question of how quickly the Earth loses heat and how long it is dynamically active. In fact, the typical heat loss of an entire planet should be based on this range.
The researchers had to reflect the conditions at the center of the earth
Until now, measuring the thermal conductivity of bridgemanite has caused a significant problem. To determine how much heat the mineral absorbs and re-emits, scientists must follow the process inside the Earth and take into account the same conditions in terms of pressure and temperature. Swiss researchers have now been able to create precisely such a structure by making monocrystalline crystals from high pressure and heat from bridzmonite and subjecting them to a pressure of 80 gigapascals by the diamond anvil cell. A laser can be used to heat the crystals to a temperature of about 2200 degrees Celsius.
The measurement can finally be carried out using a spectroscope. With this tool, the emitted radiation can be measured and conclusions can be drawn about the crystal lattice, thermal conductivity and heat.
About 5.3 watts per meter and transmitted by the mineral Kelvin (W / mK). The researchers estimate that the total thermal conductivity should be 15.2 W / mK. The new results are 1.5 times higher than previous geophysical estimates.
“Our results may give us a new perspective on the evolution of the Earth’s dynamics,” says geologist Motohiko Murakami. “They report that Earth, like other rocky planets Mercury and Mars, is cooling and crashing faster than expected.”
However, scientists have not been able to make any conclusions about how long the Earth will be cold. “In the current state of knowledge, the timing of such events cannot be limited,” says the geologist. This will require additional knowledge of the radioactive decay of the elements at the center of the earth and the process of mantle accumulation.
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