Overheated Earth may be locked in place
Dramatic changes to the temperature of Earth's atmosphere could cause the planet's crust to become locked in place, research shows.
The Earth's crust is like a jigsaw of free-floating, rocky plates. Below those plates is a deep layer of flowing rock called the mantle, whose movements cause the plates to move slowly around.
Associate professor Louis Moresi of Monash University and colleagues wanted to understand better how atmospheric temperature might affect the characteristics of the mantle.
Their results appear in the journal Earth and Planetary Science Letters.
Using a combination of mathematical simulations and theory they found that if the Earth's surface temperature rose by around 100°C and stayed that way for a few million years, the mantle could become less viscous and stop moving the tectonic plates around.
"In practical terms, if you took the Earth and heated it up by 100°C then it would potentially make it very hard for these internal forces to break up the plates," Moresi says.
The lead author of the paper, associate professor Adrian Lenardic, from Rice University in the US, says the heat required for such a change is far beyond anything we expect from human-induced climate change.
"But things like volcanic activity and changes in the sun's luminosity could lead to this level of heating," he says.
The results have implications for the search for potentially life-friendly planets in our galaxy, the researchers say.
"Plate tectonics is the thing that provides many of the building blocks for life in the form of energy," Moresi says.
The findings also help explain why Venus, our near neighbour in the solar system, has evolved so differently to Earth.
The two planets are similar in terms of their size and makeup, but Venus has a carbon dioxide-rich atmosphere that has made its surface temperature more than 400°C hotter than Earth's.
It also lacks any outward signs of plate tectonic activity.
"The high temperature is very much the reason we don't have plate tectonics on Venus," Moresi says.