At present, scientists are using GPS technology to track the movements of our modern continents. As you're reading this, the Americas are inching closer to Asia while Australia and Antarctica are shifting north.
Dr. J. Brendan Murphy, a geologist at St. Francis Xavier University, explains that if the Americas stick to their present course, "the Pacific Ocean will close and the Atlantic will widen" until we get an all-new supercontinent in 70 million years or so.
But maybe the Pacific isn't doomed after all. A different school of thought holds that it's the Atlantic Ocean whose days are numbered.
The argument goes like this: Oceanic crust gets denser with age. Eventually, the crust becomes so dense and heavy that it starts subducting. At the Atlantic's center is a mid-ocean ridge, which is the reason why the body of water is currently expanding. The ridge is constantly producing new crust on the sea floor that pushes older crust — which had previously been created by the same ridge — further and further outward. Hence, the Atlantic grows ever wider.
How long can this status quo persist? Some geologists think that the very old crust on the Atlantic's edges is bound to go under. Eventually, these scientists say, new subduction zones will emerge along the coasts of Africa and the Americas. As the zones devour old, dense ocean crust, the Atlantic will theoretically shrink, pulling the American continents backward until they slam into Europe and Africa.
Don't hold your breath waiting for that to happen, though. "The Atlantic's been expanding for 200 million years, so if you assume that the rate at which it will subduct is similar, it'd probably take [the same amount of time] to close," Murphy notes.
A third possibility was put forth in 2012. That February, a Ph.D. candidate at Yale University by the name of Ross Mitchell published his thesis, which centered on supercontinent formation. After evaluating prehistoric trends, he predicted an impending closure of both the Caribbean Sea and the Arctic Ocean. This means that the Americas would merge together and meet up with Eurasia somewhere around the North Pole.
Mitchell now works at Curtin University in Perth, Australia, where he is a member of the Earth Dynamics Research Group, which seeks to enhance our understanding of plate tectonics and supercontinents. Mitchell informs us via email that he’s sticking by the viewpoint expressed in his 2012 thesis. "Nothing has changed my mind yet," he says, "but hopefully some additional lines of evidence we have in the pipeline should help convince others."
For his money, Murphy says he thinks that of these three scenarios, the first one seems like the safest bet. But when all's said and done, there'd be no way to collect on that gamble — not unless somebody devises a way to live for 70 to 200 million years. "It's not really a testable hypothesis, that's for sure!" he says.