There are several things that make Earth unique in the solar system. Plate tectonics is among those features, but it won’t be a characteristic of our planet forever. Researchers estimate that, based on changes over the last 3 billion years, tectonics will cease to happen roughly 1.45 billion years in the future.
Plate tectonics is the slow but continuous movement of large segments of the Earth’s crust, which are known as plates. Some plates sink beneath the others, whereas some move apart and some collide. These movements are responsible for the creation of mountain chains, can cause disastrous earthquakes, and can form volcanos.
It is unclear how tectonics started, but the potential for it to stop has been suspected for a while. In this latest work, published in the journal Gondwana Research, Cheng Qiuming from the China University of Geosciences tried to calculate when any major movements in the crust were likely to end.
They constructed a model of how the mantle activities have changed in the past and tried to extrapolate what that tells us about the future. The study shows both the intensity and repetition of major activity below the crust in the mantle over the past few billion years. The researcher has interpreted this as a general trend of mantle cooling. In 1.45 billion years, the temperature of the mantle won’t be high enough anymore for it to flow. Without this internal motion, activities on the surface such as plate tectonics will cease.
Plate tectonics is the mechanism by which the interior of our planet blows off heat, hence why the mantle is slowly cooling over time. Without plate tectonics, it won’t just be a goodbye to volcanos and earthquakes, which we could certainly do without. It will also be a goodbye to mountains. The inexorable movement of plate against plate as it pushes the crust literally to higher and higher peaks. Without it, erosion will take over and over the course of a few million years, even the tallest chain will be nothing but rolling hills.
[8/22, 3:08 PM] Solid My Bro: oscientists at Pennsylvania State University in the US conducted a study which implies that there may be more habitable planets in the universe than previously thought.
The study suggests that plate tectonics -- long assumed to be a requirement for suitable conditions for hosting life -- are in fact not necessary at all.
Why did scientists assume these conditions for a planet to be habitable?
Normally, scientists look for biosignatures of atmospheric carbon dioxide while searching for habitable planets or life on other planets.
According to the research published in the journal Astrobiology, on Earth, atmospheric carbon dioxide increases surface heat through the greenhouse effect.
"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, an assistant professor of geosciences at Penn State, adding that:
"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."
Most of Earth's volcanoes are found at the border of tectonic plates, which is one reason scientists believed they were necessary for life.
Another natural phenomenon which aids in carbon cycling is by subduction -- in which one plate is pushed deeper into the subsurface by a colliding plate, thus shoving carbon into the mantle.
Absence of tectonic plates on a planet
As reported by PTI, researchers said that planets without tectonic plates are known as stagnant lid planets.
On these planets, the crust is one giant, spherical plate floating on mantle, rather than separate pieces.
These are thought to be more widespread than planets with plate tectonicsIn fact, Earth is the only planet with confirmed tectonic plates
Life-cycle of a planet
Foley and Andrew Smye, another assistant professor at Penn State, created a computer model of the life-cycle of a planet.
They looked at how much heat its climate could retain based on its initial heat budget, or the amount of heat and heat-producing elements present when a planet forms.
After running hundreds of simulations to vary a planet's size and chemical composition, the researchers found that:
Stagnant lid planets can sustain conditions for liquid water for billions of years.
According to them, at the highest extreme, they (these planets) could sustain life for up to 4 billion years -- roughly Earth's lifespan to date.
"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."
According to the computer model, the presence and amount of heat-producing elements were far better indicators for a planet's potential to sustain life.
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