Plate tectonics are not necessary for human life, study says

A new study suggests that plate tectonics might not be needed to support life, which contradicts previous beliefs.

Tyler MacDonald | Oct 11, 2019

With recent research suggesting that our universe contains more habitable planets than we thought, a new study suggests that plate tectonics are not necessary.

Scientists often used biosignatures of carbon dioxide in the search for habitable planets. Atmospheric carbon dioxide typically increases the Earth's surface heat via the greenhouse effect, and carbon makes its way from the subsurface to the atmosphere due to natural processes.

"Volcanism releases gases into the atmosphere, and then through weathering, carbon dioxide is pulled from the atmosphere and sequestered into surface rocks and sediment," said Bradford Foley, co-author of the study. "Balancing those two processes keeps carbon dioxide at a certain level in the atmosphere, which is really important for whether the climate stays temperate and suitable for life."

And since most of our planet's volcanoes are located at tectonic plate borders, scientists previously believed that they were needed for life. But using a computer model of planetary lifecycles, the team examined how much heat planets can retain based on the amount of heat and heat-producing elements at the moment of planet formation.

Hundreds of simulations later, and the team found that stagnant lid planets can maintain liquid water conditions for billions of years. At the most, up to 4 billion years, which is the Earth's current approximate life span.

"You still have volcanism on stagnant lid planets, but it's much shorter lived than on planets with plate tectonics because there isn't as much cycling," Smye said. "Volcanoes result in a succession of lava flows, which are buried like layers of a cake over time. Rocks and sediment heat up more the deeper they are buried."

The findings were published in Astrobiology.