This is how what happens in the center of the Earth affects the weather and climate

Geologists often remember that we humans know more about outer space than we do about the heart of our own planet.

We tend to think that the Earth works as a compact system with perfect synchronization, but it is not like that, as a new study has just reminded us that it has confirmed that the inner core of the Earth has slowed down in recent years.

These are the basic questions and answers about what has been discovered and how it affects people's daily lives.

The find

Since 2009, the rotation rate of the inner core, a 1,200-kilometer-radius sphere of metal located at the center of the Earth, has slowed.

The same thing happened in the early 1970s, and then its speed picked up again.

What this shows is that the inner core does not rotate exactly at the same rate as the crust, the outermost layer of the planet where humans inhabit and which has a much larger radius: 6,378 kilometers.

It is possible that the core follows a cycle of fluctuations that can span about seven decades.

Does this mean that the core of the planet has stopped?

Xiaoming Song, lead author of the study, explains it this way: “When we look at the Earth from space, the inner core rotates almost at the same rate as the mantle and the surface, in an easterly direction and in a 24-hour cycle.

We already knew from previous studies that the rotation speed of the inner core is not exactly the same.

In our new study, using Earth's surface as a reference point, we infer that the inner core rotated eastward and faster than the crust from the mid-1970s until 2009. Since then, the inner core has stopped and now it turns a little towards the west, that is to say, slower than the surface”.

The effect

The impact of this phenomenon at the planetary level is very, very small.

The Earth completes a 360 degree turn on itself every day.

The differences detected by the study are of the order of 0.1 degrees per year.

This asynchrony can affect the length of the day, but imperceptibly to humans.

The study authors calculate that the day may be a thousandth of a second longer or shorter than it was about 50 years ago, depending on the speed of the core's rotation.

These effects have no direct impact on the lives of Earthlings, but they can force the planet's most precise atomic clocks to be adjusted, introducing leap seconds, for example.

A penguin colony in the South Sandwich Islands, where the earthquakes analyzed in the study occurred.British Antarctic Survey

The observed effect can cause minimal deformations in the earth's crust, which could in turn influence sea level, according to Song.

In addition, effects on Earth's magnetic field could have an impact on climate, the study authors argue.

But for the moment these effects are just a hypothesis that will now have to be confirmed with more studies, according to Maurizio Mattesini, a CSIC geophysicist specializing in the internal structure of the Earth.

“It is suspected that the observed effect may have an impact on the climate, but there is no evidence.

The authors suggest that there is and, of course, now it will have to be investigated”, adds Mattesini.

the earth slows down

The Earth's core is one of the most unknown and violent places imaginable.

The solid metallic sphere of the inner core floats in a vast liquid ocean of molten iron and other metals, the outer core.

His behavior is governed by two great forces.

First, the force of gravity generated by the rotation of the crust and mantle drags the core with it.

Furthermore, the rotation of the solid nucleus within the liquid nucleus generates a powerful magnetic field that influences the speed of rotation.

The interaction of these and other forces explains why the inner core rotates at a slightly faster or slightly slower rate than the crust, and this in turn has an impact on the magnetic field.

The Earth rotates on itself more and more slowly.

In part it is because the rise and fall of the tides caused by the force of gravity of the Moon generates friction that slows down the crust.

These gravitational forces also cause the Moon to move away from Earth at a constant rate of about 3.8 centimeters per year, which also slows down the Earth's crust.

In this case, the effects are also very, very small: 100 years from now, a day will be 1.4 thousandths of a second longer.

Even if it recedes, the Moon will most likely never escape Earth's pull, at least not before the dying Sun lays waste to the Earth in about 7 billion years.

a distant future

4,500 million years ago, our planet was a mass of liquid and gaseous particles at high temperatures, but with hardly any consistency.

Over millions of years the planet has cooled.

The heavier compounds such as iron sank towards the innermost areas to form the nucleus, while the minerals that make up the mantle and crust remained in the most superficial parts.

No one knows exactly when the nucleus was formed, although the most recent estimates suggest that it happened 1,000 million years ago, explains Puy Ayarza, director of the Department of Geology at the University of Salamanca.

Every year, part of the liquid metals in the outer core solidify and swell the inner core, whose radius grows by one millimeter per year.

There will come a time when the entire liquid core solidifies and the Earth's magnetic field disappears, which will mean an apocalypse for life on the planet.

In any case, remember Ayarza, this will not happen for billions of years.

The geologist provides another example of the magnitude of these phenomena.

In December 2004, a magnitude 9.2 earthquake in Sumatra and the ensuing tsunami caused thousands of deaths in Asia.

“That earthquake made the Earth vibrate for four months.

It even shifted its axis of rotation a bit.

However, no one found out about it.

These are imperceptible changes.

In the same way, the oscillation of the inner core has already passed and it will happen again without us noticing it, ”she highlights.

The new study has opened new avenues of research to better understand the behavior of the Earth and its future.

But it also makes very clear the limitations of human technology to achieve this.

About the only way to understand how the inner core works, more than 5,000 kilometers deep, is to study planet-traversing earthquakes.

According to Song, a geologist at Peking University's Institute of Theoretical and Applied Geophysics in China, two big questions now remain to be addressed.

The first is to build computer models capable of accurately simulating the multi-decade cycles that the Earth's core appears to be following, a challenge for current computing.

In addition, more data is needed for earthquakes that traverse the entire Earth.

The current record only goes back to the mid-1960s, Song says.

“It is expected that the inner core will continue to rotate to the west relative to the surface in the coming years, even decades.

Seismic waves remain the best method to study the core, so improving high-quality seismic networks should be our priority,” she adds.

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