Tidal Strength Study Predicts Earth's Return to Supercontinents

When you think of continents, you probably think of the seven you learn about in school. If you’re up to date on your science, you may even say there are eight. To us, the Earth is a collection of distinct land masses floating in the water; the days of supercontinents like Pangea and Rodinia millions of years behind us. However, according to a new study in Geophysical Research Letters, supercontinents are also in the planet’s future.

The position of Earth’s continents is known to be dependent on the shifting, sinking, and sliding of tectonic plates, as well as the size and shape of the ocean basins. But in a paper published Wednesday, researchers show that the movement of tectonic plates also dictates a super-tidal cycle that controls the strength of the ocean’s waves. This long cycle, in turn, creates changes in tidal energy that scientists argue is linked to the formation of supercontinents every 400 to 600 million years. Using statistical modeling, they determined that, in 250 million years, our individual continents will have once again shifted into a single supercontinent surrounded by ocean.

“Our simulations suggest that the tides are, at the moment, abnormally large,” Bangor University oceanographer and study co-author Mattias Green, Ph.D., explained in a statement released Wednesday. “And that really was our motivating question: If the tides were weak up until 200 million years ago, and they’ve since shot up and become very energetic over the past two million years, what will happen if we move millions of years into the future?”

So, Green and his team created a model that simulated millions of years of tectonic plate movements and changes in the resonance of ocean basins to answer that very question. They determined that the oceans will go through several tidal cycles before the next supercontinent smashes into the scene. Right now, we’re only at the beginning stages of the tidal energy maximum, and strong tides are expected to persist for another 20 million years.

Eventually, the North American and Eurasian plates will drift apart, and the Atlantic Ocean will morph and widen. If this model is correct, in 50 million years Asia will split, causing a new ocean basin to form, and in 100 million years, Australia will move north toward the lower half of Asia. As the continents merge into a single form, tidal energy will decline and, eventually, “a largely quiet sea” will surround the supercontinent.

We’ll all be dead by then, but hey, that’s pretty cool! And in the meantime, before shifting ocean tides make a continent house party happen, scientists can use this information on tidal strength to study the link between tides and sustainable ocean life.