Understanding how planets evolve over billions of years is cool, but as humans who’ve only been around for hundreds of thousands of years, we tend to think on shorter timescales and to think a bit more selfishly about things like how we can prevent ourselves from going the way of the dinosaurs.

Geologists, paleontologists, and others who study the history of our planet as told by rocks and bones have identified numerous times in our planet’s history when there are massive die-offs. It had initially been thought that these extinction events were randomly occurring, but in new research appearing in Geoscience Frontiers and done by Michael R. Rampino, Ken Caldeira, and Yuhong Zhu, this team finds that global scale destructive geologic events occur on a 27.5 million year scale, with the most recent set of events occurring about seven million years ago. This both means we’re safe for another twenty-some-odd million years and that the last event was far enough back in time to be hard to study. They also found some evidence for a shorter period of nine to ten million years. 

In total, they examined 89 major geologic events over the last 260 million years. According to their paper: These events include times of marine and non-marine extinctions, major ocean-anoxic events, continental flood-basalt eruptions, sea-level fluctuations, global pulses of intraplate magmatism, and times of changes in seafloor-spreading rates and plate reorganizations.

When trying to identify why this is happening, they added: These cyclic pulses of tectonics and climate change may be the result of geophysical processes related to the dynamics of plate tectonics and mantle plumes, or might alternatively be paced by astronomical cycles associated with the Earth’s motions in the Solar System and the Galaxy.

This is basically a fancy way of saying we don’t know if this destruction is triggered from inside the planet or from something out there beyond our atmosphere. Again, we have twenty million or so years to figure this out.

More Information

NYU press release

“A pulse of the Earth: A 27.5-Myr underlying cycle in coordinated geological events over the last 260 Myr,” Michael R. Rampino, Ken Caldeira, and Yuhong Zhu, 2021 June 17, Geoscience Frontiers