Earth ‘pulses’ every 27.5 million years, study finds — and we don’t know why

Most scientists agree that major geologic events on Earth such as mass extinctions, volcanic eruptions and tectonic plate movements have occurred randomly across time, and will continue to in the future. But a new study suggests these episodes are more organized than previously thought.

Thanks to advancements in techniques used to date materials such as rocks, a team of geologists from New York University discovered that activity on Earth follows a 27.5 million-year cycle, giving the planet a “pulse,” or extremely slow heartbeat, if you will.

But researchers don’t know what’s causing it.

They speculate that cycles of climate and movement of giant slabs of Earth may be the rascal behind the planet’s mysterious pulse. Similar cycles within Earth’s orbit in space that run about every 32 million years could also be setting the stage for these events.

“Whatever the origins of these cyclical episodes, our findings support the case for a largely periodic, coordinated and intermittently catastrophic geologic record, which is a departure from the views held by many geologists,” Michael Rampino, study lead author and a geology professor at NYU, said in a statement.

NYU researchers found that global geologic events are generally clustered at 10 different timepoints over the 260 million years, grouped in peaks or “pulses” of roughly 27.5 million years apart.

Because dating techniques have improved over the years, scientists now have clearer data on the timing of Earth’s past events. So, Rampino and his colleagues analyzed 89 “well-dated major geological events,” including “sea-level fluctuations,” “volcanic outpourings” and both marine and land extinctions, over the last 260 million years.

They learned these global events bunched at 10 different periods, pulsing or peaking every 27.5 million years or so. The most recent cluster of events happened about 7 million years ago, which means the next major phenomenon will occur in about 20 million years, the researchers said.

The study was recently published in the journal Geoscience Frontiers.