Plate Tectonics not needed for Sustaining Life

Plate Tectonics not needed for Sustaining Life

05 Dec 2012, Russia — Tolbachik Volcano erupting, Kamchatka, Russia — Image by © Sergey Gorshkov/Minden Pictures/Corbis

Latest research clearly signifies that the presence and quantity of heat-producing elements is a much better indicator to judge a planet’s potential to sustain life than the tectonic plates.

The climate of Earth is becoming more and more hostile towards life and experts are worried that we need to find an alternative habitat for humanity pretty soon if we want to save our species from extinction. Astronomers are exploring different avenues of our universe in this quest but they have not succeeded in their efforts until now. Generally, it is considered that existence of liquid water is the only requirement for life but that is not true. There are a number of factors that contribute to offer suitable conditions for life. For a very long time, scientists believed that plate tectonics is an essential requirement but a recent study of geoscientists from the Penn State proved that it is not necessary.

Atmospheric Carbon Dioxide is a biological indicator which helps scientists to distinguish whether life is possible on a planet or not. The facts that Carbon Dioxide is a greenhouse gas and it increases the temperature of the surface play an instrumental role in keeping water in the liquid state. All of us are aware of the greenhouse abilities of this gas as it is one of the root causes behind the global warming we are experiencing on our planet. Bradford Foley, an Assistant Professor of Geosciences at the Penn State University, said,

Volcanism releases gases into the atmosphere, and then through weathering, carbon dioxide is pulled from the atmosphere and sequestered into surface rocks and sediment. 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.”

The concept of plate tectonics was associated with life, for so long, because most of the volcanoes of Earth are found near tectonic plates. Similarly, the fact that ‘Subduction’ helps in carbon cycling created quite a lot of doubts. It refers to a process where a plate is pushed deeper into the mantle by a colliding plate.

A massive reason why astronomers failed in finding signs of life anywhere else in the universe was that they were looking for planets with tectonic plates. Most of the planets in our universe are without these plates and are known as ‘Stagnant Lid Planets’. After a series of simulations, it was determined that these planets can also sustain liquid water for as long as 4 billion years at the highest extreme. Andrew Smye, who is also an Assistant Professor of Geosciences described their findings in the following words:

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. 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.”

Both of these assistant professors collaborated to develop a computer model which could create a lifecycle of a planet. They analyzed the heat-retaining ability of a planet on the basis of its total heat and heat-producing elements at the time of its formation. The term ‘Heat-producing Elements’ points towards those elements that release heat while they decay. For example, Uranium turns itself into Thorium by releasing sufficient amount of energy. Similarly, Thorium decays to form Potassium and a lot of heat is released during that as well.

According to this research, ‘Degassing’ (a process in which Carbon Dioxide escapes from the subsurface rocks and comes to the surface of the planet) is pretty much possible if ideal temperature and pressure is available. Smye quoted that such a procedure is observed on Earth, with water, in subduction fault zones. He also mentioned that the intensity of the degassing process is dependent on the quantity of heat-producing elements in a planet. However, there is a maximum limit for that after which it becomes these elements become irrelevant. Foley described that by saying,

There’s a sweet spot range where a planet is releasing enough carbon dioxide to keep the planet from freezing over, but not so much that the weathering can’t pull carbon dioxide out of the atmosphere and keep the climate temperate.”

Latest research clearly signifies that the presence and quantity of heat-producing elements is a much better indicator to judge a planet’s potential to sustain life than the tectonic plates.

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