Earth was formed 4.5 billion years ago. It's been cooling on the inside.
The molten interior of our planet has been cooling for the entire time it has been on the planet.
That is not a glib metaphor. Scientists believe the magnetic field is caused by the rotating, convecting dynamo deep inside Earth, an invisible structure that protects our world and allows life to thrive. The stabilization of global temperatures and the carbon cycle is thought to be aided by mantle convection, tectonic activity and volcanism.
Earth's interior is still cooling and will continue to do so, meaning that eventually the interior will solidify and the geological activity will cease, possibly turning Earth into a barren rock like Mars or Mercury. It has been found that it may happen sooner than previously thought.
The boundary between the outer iron-nickel core and the molten fluid lower mantle could be the key. How quickly the boundary mineral conducts heat will affect how quickly heat comes through the core and out into the mantle.
It's not easy to determine the rate of bridgmanite in ambient atmospheric conditions. It is vastly different deep inside our planet when it comes to thermal conductivity.
A team of scientists led by planetary scientist Motohiko Murakami of the ETH Zurich in Switzerland irradiated a single crystal of bridgmanite with pulsed lasers, simultaneously increasing its temperature to 2,440 Kelvin and pressure to 80 gigapascals, close to what we know.
The measurement system allowed us to show that the thermal conductivity of bridgmanite is 1.5 times higher than assumed.
This means that the heat flow from the core to the mantle is higher than we thought, and that the rate at which Earth's interior is cooling is faster than we thought.
The process could be speeding up. The rate of heat loss from the core into the mantle would increase when bridgmanite becomes post-perovskite, because it is more thermally conductive.
"Our results could give us a new perspective on the evolution of Earth's dynamics," he said. They think that Earth is cooling and becoming inactive more quickly than expected.
It's not clear how much faster that is. We don't understand the cooling of an entire planet. Mars is cooler than Earth because it's smaller, but there are other factors that may play a role in how quickly the planetary interior cools.
The decay of radioactive elements can 888-269-5556 888-269-5556 888-269-5556. One of the major sources of heat in the Earth's mantle is the elements.
"We don't know enough about these kinds of events to know when they're happening," he said.
It won't be a fast process on human scales, either way. It is possible that Earth will become uninhabitable by other mechanisms. We might have time to figure out the problem.
The team's research has been published.