Amazing stuff! In the age of so called "climate change" and global warming hoax when cooler heads will hopefully prevail!
"New experiments suggest Earth’s iron core could be more than 1000°C cooler than longstanding estimates, potentially resolving a puzzle that has vexed geophysicists for decades.
By squeezing iron to nearly 2 million atmospheres between diamond anvils and heating it with rapid electrical pulses, researchers measured iron’s melting point at corelike conditions and found it melts at much lower temperatures than previous studies suggested. The result could help explain the so-called “new core paradox.”
Earth’s magnetic field has existed for at least 4 billion years. But many thermal models indicate the solid inner core—which as it slowly freezes today helps power the magnetic dynamo in the molten outer core—formed only about 500 million years ago.
The new measurements suggest the core lost heat more slowly than previous models assumed, allowing heat-driven convection alone to power the magnetic dynamo for most of Earth’s history, without requiring an ancient inner core. ..."
"... Today, that dynamo is sustained mainly by the slow freezing of the inner core, which releases heat and buoyant light elements into the liquid metal above. But some models of Earth’s cooling history suggest the inner core began to form just over half a billion years ago, raising the so-called “new core paradox”: What kept the dynamo running for the 3.5 billion years before the arrival of the inner core? ..."
From the abstract of the oral presentation:
"The melting temperatures and electrical resistivity of iron at high pressure are essential for understanding the thermal history and dynamics of Earth’s core, but significant differences in experimental results have led to divergent Earth models. We developed a pulsed Joule heating system to investigate the melting temperature and electrical resistivity of iron under the high pressure of Earth’s core. The system heats metal samples to temperatures exceeding 4000 K at pressures exceeding 2 Mbar. Precise sample fabrication, combined with a novel 5-color multianode spectroradiometer, enables high-precision heating control and temperature measurement (~ ±30 K) with sub-microsecond time resolution. Plateaus in temperature-time traces due to the latent heat of melting show outstanding reproducibility.
Our findings on the high-pressure melting curve of iron, based on more than 200 melting measurements extending to over 2 Mbar, reveal lower melting temperatures and a shallower Clapeyron slope relative to previous studies.
By extrapolating these to inner-core pressure and combining them with our measured resistivity of liquid iron (~75 μΩ cm), we propose that a relatively low adiabatic outer-core heat flow of < 10 TW and relatively low core-mantle boundary temperatures.
Our results indicate that thermal convection alone may have powered the geodynamo before the formation of the inner core, and that today’s lowermost mantle is likely to be fully solid."
Earth’s core may be far cooler than scientists thought (partial public access)
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