23 July, 2015

Another fine-tuned parameter for Earth’s plate tectonics

Otis from the RTB Houston Chapter writes:
 
An article in Science Daily reports on research that has found another fine-tuned parameter that is necessary for Earth's plate tectonics.  Without plate tectonics there would be no carbon-silicate feedback loop that stabilizes global climate thereby allowing a planet to be habitable over billions of years.
 
There are two parts to this new research.  First, it was found that Earth's composition of uranium, thorium and potassium abundance should be reduced 30% from that of previous models.  Second, a model of Earth's geodynamics shows that the new reduced composition makes plate tectonics possible whereas the previously assumed composition does not.  In the words of one of the researchers, "The new compositional model gives Earth a sweet spot of its own where its interior is neither too hot nor too cold.  . . .  there's another dial that's important to turn."
 
I have not yet read the original research article which is in Nature Geoscience.  However, based on the Science Daily article, I think that the takeaway message is this: Earth is very special. Planetary habitability is very fragile and cannot be determined by simply computing a star's current heat flux on a planet.
 
Otis
 
You can read the Science Daily article via the link below.
 

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