Earth’s core has been cooling since Earth formed about 4.5 billion years ago, when the entire surface was covered in a magma ocean.
A study published Jan. 15 challenges scientific understanding of how fast this cooling occurs, showing that the process is moving much faster than scientists thought.
The findings, by researchers from Switzerland, Germany, the United States and Japan, add to support from a flurry of studies that radiation plays a larger role in extracting heat from Earth’s core than previously assumed.
The core-mantle boundary lies between Earth’s lower mantle and its liquid core. Scientists believe it is mainly composed of a mineral called bridgemanite, named after physicist Percy Bridgeman in 2014. Scientists believe that Bridgeman rock is the most abundant mineral on Earth.
“We finally found that [bridgmanite’s] previous thermal conductivity values were severely underestimated,” said Motohiko Murakami, professor of earth sciences at ETH Zurich and lead author of the study.
Takashi Murakami and his colleagues found that the thermal conductivity of Bridgemanite was 1.5 times higher than expected.
“Heat transfer from the core will be more efficient than previously thought, which ultimately causes the core to cool faster than expected,” Murakami said.
Complete News Source : DW
