Next supercontinent may form when the Pacific Ocean disappears

By Ashley Strickland, CNN

The world may have a new supercontinent within 200 million to 300 million years as the Pacific Ocean shrinks and closes.

Researchers at Curtin University in Australia and Peking University in China used a supercomputer to model the evolution of Earth’s tectonic plates and the formation of a future supercontinent. The journal National Science Review published their findings on September 28.

“Over the past two billion years, Earth’s continents have collided together to form a supercontinent every 600 million years, known as the supercontinent cycle. This means that the current continents are due to come together again in a couple of hundred of million years’ time,” said lead author Dr. Chuan Huang, a research fellow in Curtin’s Earth Dynamics Research Group and the School of Earth and Planetary Sciences, in a statement.

The formation of supercontinents has occurred in widely varying ways, scientists believe.

The team’s simulation showed that due to the fact that Earth has been cooling for billions of years since its formation, the thickness and strength of the tectonic plates beneath the oceans have reduced over time.

This natural process would hinder the next supercontinent from forming as a result of the shrinking of the Atlantic or Indian oceans, which scientists consider to be relatively young oceans. These oceans likely formed when the most recent supercontinent on Earth broke apart and the various pieces slowly drifted from one another.

Called Pangaea, the land mass formed around 320 million years ago, according to the study authors. It broke apart between 170 million and 180 million years ago, when dinosaurs walked the Earth.

In contrast, the Pacific Ocean is the oldest ocean on Earth. This vast body of water is actually the remnant of the Panthalassa superocean that started to form 700 million years ago as a supercontinent even more ancient than Pangaea began to break apart.

The study team found that when the tectonic plates diminish in strength and thickness, the formation of a new supercontinent is more likely to happen by the closing up of a former superocean that had surrounded a past colossal land mass. Reducing by a few centimeters per year, the Pacific Ocean began shrinking during the age of the dinosaurs. Based on the new simulation, the Pacific Ocean’s current reach of 10,000 kilometers (6,213.7 miles) will close up in less than 300 million years.

“The resulting new supercontinent has already been named Amasia because some believe that the Pacific Ocean will close (as opposed to the Atlantic and Indian oceans) when America collides with Asia. Australia is also expected to play a role in this important Earth event, first colliding with Asia and then connecting America and Asia once the Pacific Ocean closes,” Huang said.

Australia is currently drifting toward Asia at a rate of about 7 centimeters (2.8 inches) per year, while Eurasia and the Americas move at slower rates toward the Pacific Ocean, said study coauthor Zheng-Xiang Li, distinguished professor in Curtin’s School of Earth and Planetary Sciences.

What will this world be like?

Changes in the distribution of continents and oceans will cause changes in climates, “particularly when ocean currents are stopped by continental collision, or new ocean currents are formed when continents break apart,” Li said.

An example of this phenomenon is when Australia broke away from Antarctica 45 million years ago, triggering the formation of the Antarctic polar ice cap.

Researchers also expect more earthquakes as the continental plates collide. Seismic activity has periodically occurred where India and Eurasia’s plates have been colliding for the past 55 million years, Li said. The initial impact formed the Tibetan plateau and the Himalayas.

Surrounded by a new superocean, the newly formed supercontinent will also have decreased biodiversity.

“Earth as we know it will be drastically different when Amasia forms. The sea level is expected to be lower, and the vast interior of the supercontinent will be very arid with high daily temperature ranges,” Li said. “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 million to 300 million years’ time.”

Scientists are still trying to understand Earth’s supercontinent cycle, which is driven by heat and gravity. The research team wants to establish how Earth’s plate tectonics started and when the first continents formed, as well as what kicked off the supercontinent cycle.

“We are only starting to look at the entire Earth system, from its core to its atmosphere, as a closely linked system that evolved together,” Li said.

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