Earth fever every 27.5 million years, but we have no idea what causes it

(ORDO NEWS) — Over the past 260 million years, dinosaurs have come and gone, Pangea has split into the continents and islands we see today, and humans have rapidly and irreversibly changed the world we live in.

But it seems that the Earth did not waste time. A recent study of ancient geologic events shows that our planet has a slow, steady “heartbeat” of geologic activity every 27 million years or so.

This pulse of clustered geological events – including volcanic activity, mass extinctions, plate reorganization and sea level rise – is an incredibly slow, 27.5-million-year cycle of catastrophic ebb and flow. But, fortunately for us, the research team notes that we still have 20 million years before the next “pulse”.

“Many geologists believe that geological events are random in time,” Michael Rampino, an NYU geologist and lead author of the study, said in a 2021 statement.

“But our study provides statistical evidence for a common cycle, suggesting that these geologic events are correlated rather than random.”

The team analyzed the ages of 89 well-known geological events over the past 260 million years.

As you can see from the graph below, some of these times were harsh – more than eight of these world-changing events clustered together in geologically small time spans, forming a cataclysmic “momentum”.

Earth fever every 27 5 million years but we have no idea what causes it 2

“These events include the timing of marine and non-marine extinctions, major oceanic anoxic events, continental flood-basalt eruptions, sea level fluctuations, global pulses of within-plate magmatism, and the timing of changes in seafloor propagation rates and plate reorganization,” the team writes in their paper. article.

“Our results suggest that global geologic events are generally correlated and appear to occur in impulses with a main ~27.5-million-year cycle.”

Geologists have long been studying the potential cyclicity of geological events. Back in the 1920s and 30s, scientists of that era assumed that the geological record had a cycle of 30 million, and in the 1980s and 90s, researchers used the most dated geological events at that time to obtain a range of “impulse” durations from 26, 2 to 30.6 million years.

Now everything seems to be falling into place – 27.5 million years is just what we expected. A study published in late 2020 by the same authors suggests that this 27.5 million year mark is when mass extinctions occur.

“This work is pretty good, but I actually think the best work on this phenomenon was the [2018 work] by Muller and Dutkiewicz,” tectonic geologist Alan Collins of the University of Adelaide, who was not involved in the study, told ScienceAlert in 2021. .

That 2018 paper, written by two researchers at the University of Sydney, looked at the Earth’s carbon cycle and plate tectonics and also concluded that the cycle lasts roughly 26 million years.

Collins explained that in the latest study, many of the events that the team drew attention to are causal—meaning that one directly causes the other, so some of the 89 events are linked, such as anoxic events that cause the extinction of marine organisms.

“However,” he added, “this 26-30 million year cycle seems to actually exist, and over a longer period of time, but it is also not clear what is its root cause!”

Other studies by Rampino and his team suggest that comet impacts could be the cause, and one space explorer even suggested that Planet X was to blame.

But if the Earth does have a geological “heartbeat,” it could be caused by something closer to home.

“These cyclic impulses of tectonics and climate change may be the result of geophysical processes associated with the dynamics of plate tectonics and mantle plumes, or they may be driven by astronomical cycles associated with the movement of the Earth in the solar system and the galaxy,” the team of researchers wrote in their study.


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