After studying stalagmites hidden deep in a cave in China, an international team of scientists from Australia, Taiwan, and China have learned that the Earth’s magnetic polarity can shift much more rapidly than previously thought, and in as little as just one century.

As Phys.org report, scientists are well aware that the Earth’s magnetic field can abruptly reverse polarity. Fortunately for modern humans, the last time that this occurred came before we had satellites and other electronic devices to worry about. However, reversals are exceedingly common.

According to NASA, “Reversals are the rule, not the exception. Scientists estimate reversals have happened at least hundreds of times over the past three billion years. And while reversals have happened more frequently in recent years, when dinosaurs walked Earth a reversal was more likely to happen only about every one million years.”

Because so much of modern society today hinges upon these electronic devices and satellites, scientists study changes to the magnetic polarity of the Earth to determine when it happened in the past, and how often. By analyzing these shifts, it helps us to prepare for the future.

In the most recent study on the Earth’s magnetic polarity, scientists visited Sanxing Cave, which is located in the Guizhou Province of China. Here they were able to obtain different specimens of stalagmites which have faithfully recorded all of the changes that have taken place over the years to our planet’s magnetic field.

If you’re curious about what causes the Earth’s magnetic field, just imagine liquid metal sitting 1,700 feet below the surface of where you are right now and swirling away. The swirling of this liquid metal is not always the same, however, and when it changes, so does the magnetic field.

With previous research suggesting that a total reversal would most likely occur over thousands of years, there wasn’t too much to be concerned about. This new study on stalagmites shows that the process can happen much faster than that.

How fast? Scientists discovered that 98,000 years ago there was a full magnetic reversal which took just a century and a half to complete, making the process an astonishing 10 times faster than scientists previously thought possible. This was discovered thanks to the use of a high-resolution cryogenic magnetometer, whose sensitivity and precision detects even the smallest changes to the Earth’s magnetic field over hundreds of thousands of years.

The new study which demonstrates that the Earth’s magnetic polarity can shift in just a century and a half has been published in Proceedings of the National Academy of Sciences.