The outer layer of the Earth, the solid crust we walk on, is made up of broken pieces, much like the shell of a broken egg.
These pieces, the tectonic plates, move around the planet at speeds of a few centimetres per year.
Every so often they come together and combine into a supercontinent, which remains for a few hundred million years before breaking up.
The plates then disperse or scatter and move away from each other, until they eventually – after another 400-600 million years – come back together again.
The last supercontinent, Pangea, formed around 310 million years ago, and started breaking up around 180 million years ago.
It has been suggested that the next supercontinent will form in 200-250 million years, so we are currently about halfway through the scattered phase of the current supercontinent cycle. The question is: how will the next supercontinent form, and why?
There are four fundamental scenarios for the formation of the next supercontinent: Novopangea, Pangea Ultima, Aurica and Amasia.
How each forms depends on different scenarios but ultimately are linked to how Pangea separated, and how the world’s continents are still moving today.
The breakup of Pangea led to the formation of the Atlantic ocean, which is still opening and getting wider today.
Consequently, the Pacific ocean is closing and getting narrower.
The Pacific is home to a ring of subduction zones along its edges (the ‘ring of fire’), where ocean floor is brought down, or subducted, under continental plates and into the Earth’s interior.
There, the old ocean floor is recycled and can go into volcanic plumes.
The Atlantic, by contrast, has a large ocean ridge producing new ocean plate, but is only home to two subduction zones: the Lesser Antilles Arc in the Caribbean and the Scotia Arc between South America and Antarctica.
Of these four scenarios we believe that Novopangea is the most likely.
It is a logical progression of present day continental plate drift directions, while the other three assume that another process comes into play.
There would need to be new Atlantic subduction zones for Aurica, the reversal of the Atlantic opening for Pangea Ultima, or anomalies in the Earth’s interior left by Pangea for Amasia.
Investigating the Earth’s tectonic future forces us to push the boundaries of our knowledge, and to think about the processes that shape our planet over long time scales.
It also leads us to think about the Earth system as a whole, and raises a series of other questions – what will the climate of the next supercontinent be? How will the ocean circulation adjust? How will life evolve and adapt?
These are the kind of questions that push the boundaries of science further because they push the boundaries of our imagination.
Mattias Green, Reader in Physical Oceanography, Bangor University; Hannah Sophia Davies, PhD Researcher, Universidade de Lisboa , and Joao C. Duarte, Researcher and Coordinator of the Marine Geology and Geophysics Group, Universidade de Lisboa
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