Get the drift?: A look at the supercontinents of the future

What does our collective future look like? Well, that depends on how far ahead you want to look.

PREMIUM (HT Imaging)

The first-ever supercomputer-generated continental-shift models are out, and the projections they share are dramatic. But they also hold out new hope: they could help in our search for habitable planets beyond our solar system.

First, the troubles at home.

The Asia of the far future could be a boiling, uninhabitable wasteland, with temperatures between 45 and 55 degrees Celsius and weather conditions too extreme for most mammals, about 250 million years from now. Conditions on the rest of the planet would not be much better.

As all of Earth’s landmasses merged into a supercontinent named Pangea Ultima (Pangea, also the name of the last supercontinent, is Greek for All Lands), the coasts would be sweltering and swamp-like, akin to the inside of a hot, wet plastic bag, researchers at the University of Bristol have said. Away from the climate-moderating oceans, things would be worse, as land temperatures soared by at least 14 degrees Celsius.

Any mammalian species still clinging to life will do so in the 8% of the supercontinent that was still habitable, near the poles. Surviving humans would necessarily live here too.

“Daily extremes, compounded by high levels of humidity, would ultimately seal our fate” elsewhere on Pangea Ultima, Alexander Farnsworth, a senior research associate at University of Bristol and lead author of the study (published in the journal Nature Geoscience), said in a statement.

Fissure price

We’ve known that this was coming.

In 1858, the French geologist Antonio Snider-Pellegrini first proposed that all the world’s continents were once part of a united landmass, a theory based on the fact that identical plant fossils had been found in Europe and North America.

In 1912, German meteorologist Alfred Wegener then proposed the concept of continental drift. These landmasses, once part of a single continent that he named Pangea, were still drifting, he said. Sadly, Wegener’s theory was ignored for decades, in large part because he had no data to explain how the drift was occurring.

By the late 1960s, advances in seafloor mapping and seismology solved that problem. Fresh data showed that the continents do indeed sit on massive tectonic plates (which are pieces of planetary crust and upper mantle) that are moving at an average rate of 1.5 cm a year.

On a geological timescale, that is rapid enough to give the Earth regular makeovers.

Collision control

So how often has this cycle of drift and accretion occurred?

It turns out Pangea (which existed about 300 million years ago) was only the last in a long line of supercontinents, going back 3 billion years.

By analysing geological features, plate movements and magnetic patterns in the ocean crust, scientists theorise that…

* An original supercontinent, Vaalbara, likely formed about 3 billion years ago, as the molten planet cooled.

* Vaalbara drifted apart and was reunited as Columbia aka Nuna, 1.7 billion years ago.

* Then came another period of drift, followed by the largely barren Rodinia (from the Russian Rodina, or Motherland), a massive and roughly circular landmass that likely existed 1 billion years ago.

* Pannotia, a horseshoe-shaped clump, is said to have existed about 600 million years ago. Just before things drifted apart again, and then reunited, to form Pangea.

Evidence suggests we are now about halfway through the next 500-million-year cycle of drift and accretion.

Mass movement

There are many ways it could play out.

If the Atlantic Ocean narrows rapidly, it could bring the Americas, Europe and Africa back together, to form Pangea Ultima.

If the Atlantic Ocean continues to widen instead, as it is currently doing, and the Pacific Ocean continues to narrow, the Americas could collide with the northward-drifting Antarctic plate, and then into the already-stitched-together Africa-Eurasia, to form what is being called Novopangea.

If both the Pacific and Atlantic Oceans narrow, Earth could end up with a ring-shaped, or atoll-like, supercontinent, surrounded by a super Pacific Ocean, with the Atlantic and Indian Oceans becoming inland seas. This would be the supercontinent Aurica, with the former continents of Australia and the Americas at its centre.

Aurica would be a balmy place, with a very dry interior but tropical coasts.

If the Pacific Ocean narrows, forcing the Pacific plate into a collision with Eurasia and the Americas, meanwhile, all Earth’s continents except Antarctica could drift northwards to form a frozen, icy Amasia, shaped around the North Pole.

Under pressure

But that would come later. First, as the continents crashed, we would have global climate chaos akin to what followed the Chicxulub impactor strike about 66 million years ago.

Volcanic eruptions would release large amounts of carbon-dioxide into the air, heating the planet over time.

“The newly emerged supercontinent would effectively create a triple whammy, comprising the continentality effect, hotter climate and more CO2 in the atmosphere,” Farnsworth has said. “The result would be a hostile environment largely devoid of food and water sources.”

How does it help us to know this now? As the researchers have pointed out, these projections could find application today, in the search for habitable planets outside our solar system. Continents are likely shifting on other worlds, and if we know what a sea of magma or a frozen tundra could reshape itself as, a few million years down the line, well, that’s another way to answer the question: Could this be home?