The Pacific Ocean Is Shrinking and Will Form a New Supercontinent, Scientists Say

The Pacific Ocean is shrinking. Every year, it gets about an inch smaller as the tectonic plates that the Americas sit on are pushed westward. Now, thanks to calculations by a supercomputer, scientists say that a new “supercontinent” will eventually emerge due to this process: Amasia. 

The current world map, with its recognizable pattern of continents and oceans, is just one snapshot of our planet in time. Earth has tried on all kinds of continental configurations over its 4.5-billion-year lifespan, including periods where almost all of Earth’s land consolidates into one giant supercontinent.

We currently live in the broken remains of the supercontinent Pangaea, which formed 335 million years ago and disintegrated during the rise of the dinosaurs. The existence of even older supercontinents, such as Rodinia and Columbia (Nuna), suggest that Earth is locked into a “supercontinent cycle” that sees the formation and destruction of these immense landmasses on a rough timeline of 600 million years. The cycle raises the question of what kind of new supercontinent might emerge millions of years from now, prompting scientists to propose future landmasses with names like Novopangaea, Aurica, and Amasia. 

To shed light on this mystery, researchers led by Chuan Huang, a geophysicist at Curtin University in Australia, simulated the future of Earth with a supercomputer. The results suggest that a new supercontinent, Amasia, will form when the Pacific Ocean shrinks into nothingness some 200 million years from now, causing North America to slam into Asia, according to a recent study published in National Science Review.

The future emergence of Amasia, a portmanteau of America and Asia, has been discussed by scientists for more than a decade, but there is debate over whether this supercontinent would form “inside in,” a process known as introversion, or “outside in,” which is called extroversion. Introversion involves the closure of younger post-Pangaea oceans, such as the Indian or Atlantic, whereas extroversion indicates the closure of the Pacific Ocean, which is the oldest ocean on Earth and is shrinking at a rate of about one inch per year. 

“Earth's known supercontinents are believed to have formed in vastly different ways, with two endmembers being introversion and extroversion,” said Huang and his colleagues in the study. “The former involves the closure of the internal oceans formed during the break-up of the previous supercontinent, whereas the latter involves the closure of the previous external superocean.” 

“With our modelling results, we speculate if the next supercontinent will likely assemble through the closure of the Pacific Ocean,” which would be extroversion, “or the Indo-Atlantic oceans,” which would be introversion, the team added.

As Huang and his colleagues ran their supercomputer simulations, they noticed the strength of the lithosphere, the stiff top layer of Earth that encompasses the crust and surface, is an overlooked variable in the emergence of the next supercontinent. The oceanic lithosphere has been weakening over time as a result of Earth’s slow cooling, a shift that clearly predicts the rise of Amasia from extroversion, or the closure of the Pacific Ocean. 

“Our results show that the yield strength of the oceanic lithosphere plays a critical role in determining the assembly path of a supercontinent,” the researchers said. “We found that high oceanic lithospheric strength leads to introversion assembly, whereas lower strength leads to extroversion assembly.” 

“This predicts that the next supercontinent Amasia could only be assembled through the closure of the Pacific Ocean,” the team concluded.

In this way, the new study offers a glimpse of our planet some 200 to 300 million years from now, when an enormous landmass could unite over the ashes of the long-lived Pacific Ocean. It’s a reminder that humanity has existed for a mere split-second in geological time, and that our planet in the deep past and far future may as well be an alien world.

"Earth as we know it will be drastically different when Amasia forms,” said Zheng-Xiang Li, a professor at Curtin’s Earth Dynamics Research Group who co-authored the study, in a statement. “The sea level is expected to be lower, and the vast interior of the supercontinent will be very arid with high daily temperature ranges." 

"Currently, Earth consists of seven continents with widely different ecosystems and human cultures, so it would be fascinating to think what the world might look like in 200 to 300 million years' time," he concluded.