Wandering magnetic field may point to change

Like everything else about the biosphere that is our planet, the Earth, the magnetic field is part of a subtly balanced and interconnected system.

And a series of studies showed that the amount of ice lost on the continent of Greenland was 267 gigatonnes in 2017. In 1996, there were 97 gigatonnes. To put this in perspective, a single gigatonne is an ice cube 1 km wide, 1 km high and 1 km long.

This change was measured by satellites. Some photograph the thaw, others use lasers to measure the height of the ice. Some feel the diminution decrease in gravity caused by mass loss.

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As the ice recedes, the ocean currents are changing course. New shipping routes are being opened to northern Canada. The salinity of the surrounding sea is being reduced.

But now there seems to be more going on.

Greenland is not as heavy as it was.

This means that the pressure applied to the pulsating magma veins below the Earth's surface has been reduced.

And this mass of molten iron is changing.

Faster.

In new directions.

This could explain the highly erratic shift in magnetic north position.

But it could also give the whole planet an unexpected change.

"TRUE POLAR WANDER"

This light blue dot wandering through space is locked in an internal feedback loop.

What happens to one aspect of this small world affects another, which in turn affects another.

A 2018 study in the journal Geophysical Research Letters examined the fossil signatures found deep in the oceanic sediments around the Hawaiian Islands.

He suggests that the Earth's magnetic field is not the only thing that occasionally undergoes a dramatic change.

The same can be said of the surface of the Earth.

"The Hawaiian hot spot was set about the axis of rotation from about 48 million years ago to about 12 million years ago, but it was set at a farther north latitude we find today," said Daniel Woodworth , graduate student. of Rice University. "By comparing the Hawaiian hot spot with the rest of the Earth, we can see that the change of location has been reflected in the rest of the Earth and is superimposed on the movement of the tectonic plates. This tells us that the whole earth has moved, relative to the axis of rotation, which we interpret as a true polar wandering. "

Essentially, the Earth's surface was thrown out of order.

And this was probably caused by a "blur" of magma in the mantle beneath the crust.

Generally, everything is held relatively consistent by the rotational spinning effect of the Earth's rotational force. But not always.

The magma flows can change. Their consistency in certain places may change.

"Imagine you have a very, very cold syrup, and you're putting in hot pancakes," Gordon, W.M. Keck, a professor at Earth University, Environmental and Planetary Science at Rice University, said. "As you dump, you temporarily have a small stack in the center where it does not instantly flatten due to the viscosity of the cold syrup. We find that the dense anomalies in the mantle are like that small temporary pile, only the viscosities are much higher in the lower mantle. Like syrup, it will eventually deform, but it takes a long, long time to do it. "

If these drops of magma are large enough, they can destabilize the rotation of the planet. Although the angle of the Earth relative to the Sun does not change, the position of the continents changes.

Essentially, the centrifugal force pulls that "drop" of magma closer to the equator. From the perspective of the continents, the equator seems to change.

The study said that the last time this happened 3.2 million years ago, it changed Greenland and parts of Europe and North America to the north.

"This may have triggered what we call the ice age," said Professor Gordon.

GEOLOGICAL PRESSURE KITCHEN

Less than 100 years ago, the idea that Earth's continents could change positions was considered ridiculous. But the discovery of tectonic plates changed that almost overnight.

The Earth's outer crust is a system of solid plates floating in a super-high and highly pressurized rock mantle. These cycles constantly, as well as the continents they contain, through the tectonic forces expressed through volcanoes and earthquakes. It may only be a matter of a few centimeters per year. But it was enough for the GPS network to have to be redefined to avoid navigation errors.

It is easy to forget the driving force of all this, for it is far, far from sight.

The flow and reflux of molten metals from the Earth's mantle and core.

As our planet revolves around its axis, this liquid iron is agitated.

And that's a good thing.

The constant interaction of iron in the iron generates electric currents that feed the magnetic field that protects the Earth's surface. This "skips" the worst of the sun's radiation and even powerful cosmic rays.

In the same way, there is a constant interaction between the molten core and the solid crust.

The magma can move, shift and cool as the above crust changes.

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This can result in more or less dense areas of magnetic material.

And this can affect the circulation of molten magma around it.

Such changes may explain the mysteries, such as the powerful magnetic anomaly of the South Atlantic, which has claimed several satellites in recent years.

It also alters the "balance" of the Earth's magnetic field, causing the location of the north and south poles to "wander".

They can even "turn."

"In other words, if you were alive about 800,000 years ago, and staring at what we call the north with a magnetic compass in hand, the needle would point to the south," says a NASA commentary.

But the implication now is that the balance of the Earth's crust may be unstable if the magma below changes and changes in unexpected ways.

ANTARCTIC WILDCARD

Just as plate tectonics react to changes in Greenland's weight, they will also be affected by Antarctica. And ice is melting in Antarctica faster than ever – about six times more per year than it was 40 years ago.

As this ice lies on land, the runoff leads to ever higher sea levels around the world.

The Antarctic melt has already raised global sea levels by more than 1.4 centimeters between 1979 and 2017, a report published in this week's issue of the National Academy of Sciences (PNAS) scientific journal Proceedings.

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An increase of 1.8 meters by 2100, as some scientists predict in the worst scenarios, would flood many coastal cities that house millions of people around the world, previous research has shown.

It would also greatly reduce the weight of the ice sitting in Antarctica and redistribute that weight to the bottom of the ocean – and the magma below.

For the current study, researchers embarked on the longest ice mass assessment in Antarctica in 18 geographic regions. The data came from high-resolution aerial photographs made by NASA airplanes, along with satellite radars from various space agencies.

Researchers have found that from 1979 to 1990, Antarctica lost an average of 40 billion tonnes of ice per year. In the years 2009 to 2017, ice loss has increased more than sixfold to 252 billion tons per year.

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Even more troubling, the researchers found that areas that were once considered "stable and immune to change" in Eastern Antarctica are pouring much ice, too, the study said.

The total amount of ice in Antarctica, if all melted, would be enough to raise sea level by 57 meters. By far, most of the ice in Antarctica is concentrated in the east, where there is enough sea ice to drive 52 meters of sea level rise, compared with about 5 million across the entire West Antarctic ice sheet.

The latest research shows that the melting of Eastern Antarctica deserves "greater attention," according to the PNAS report.