Will Earth’s next supercontinent form by closing the Pacific Ocean or the Atlantic Ocean?

Earth’s unique plate tectonic system has made it the only known habitable planet. To understand how plate tectonics works, one needs to understand why and how all the continents periodically (every ~600 million years) collide together to form a globally singular supercontinent, only to break-up again after, on average, a couple of hundred of million years, constituting what scientists call the supercontinent cycle.

Following the supercontinent cycle prediction, the current continents scattered around Earth (Fig. 1b) are due to all come together again in a couple of hundred of million years’ time, and the resulting new supercontinent has already been named Amasia because some believe that the Pacific Ocean will close by having the Americas colliding with Asia (Fig. 1c).

Figure 1. Amasia — Figure 1. Changes in Earth’s surface landscape from supercontinent Pangea and superocean Panthalassa 200 million years ago (a) to the present-day configuration (b), and three possible ways of forming the next supercontinent Amasia: (c) Extroversion — through the closure of the Pacific Ocean, which is what is left of the Panthalassa superocean during Pangea time (a); (d) Orthoversion — neither major oceans closes; and or (e) Introversion — through the closure of internal young oceans formed during the break-up of Pangea, i.e., the Atlantic and Indian oceans.

However, not everyone agrees with such a prediction. Some researchers think Amasia may form by closing the Atlantic and Indian oceans instead of the Pacific (Fig. 1e). Others thought perhaps none of these major oceans need to be closed after all (Fig. 1d). How could we tell which of the predictions hold more water, scientifically speaking?

Researchers from Curtin University’s Earth Dynamics Research Group addressed this question by using a supercomputer to simulate forces that control the episodic assembly and dispersal of supercontinents. They found that because the Earth has been cooling for billions of years, the thickness and strength of the plates under the oceans reduce with time, causing it to be impossible to assemble the next supercontinent by closing the geologically “young” oceans such as the Atlantic and Indian oceans. Instead, it will be easier to do it by closing the Pacific Ocean.

“The Pacific Ocean is what is left of the Panthalassa superocean that started to form some 700 million years ago. It is the oldest ocean we have on Earth, and it started shrinking from its size maxima since the dinosaur time”, said Professor Zheng-Xiang Li of Curtin’s Earth Dynamics Research Group and a co-author of the paper.

“It is currently shrinking in size by a few centimeters per year”, said Professor Li. “Its current dimension of about ten thousand kilometers is predicted to take two to three hundred million years to close”.

Having the whole world dominated by a single continental mass will surely dramatically alter Earth’s ecosystem and environment, if what happened during the geological past is of any indication, not to mention the massive potential geopolitical implications. But few of us could live that long to see or worry about that.

Contact person: Prof Zheng-Xiang Li, Earth Dynamics Research Group, Curtin University.

Relevant publication:

Huang, C., Li, Z.X., Zhang, N., 2022. Will Earth’s next supercontinent assemble through the closure of the Pacific Ocean? National Science Review, nwac205. https://doi.org/10.1093/nsr/nwac205

Read the Curtin University Media Release:

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