The Earth has a fierce molten core that generates a magnetic field capable of defending our planet against devastating solar winds.

The protective field extends thousands of miles into space and its magnetism affects everything from auroras to power grids, the Daily Mail reports.

But this field, so important to life on Earth, has weakened by about 15 per cent during the past 200 years.

And this, scientists claim, could be a sign the Earth's poles are about to flip.

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In a new report, Daniel Baker, director of the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder, claims there are signs of a reversal.

He says if this reversal happens, it is likely to render some areas of the planet "uninhabitable" by knocking out power grids.

His comments were made in an in-depth Undark report written by Alanna Mitchell, who has a new book about the topic titled The Spinning Magnet: The Electromagnetic Force that Created the Modern World and Could Destroy It.

Mitchell writes: "The dangers: devastating streams of particles from the sun, galactic cosmic rays, and enhanced ultraviolet B rays from a radiation-damaged ozone layer, to name just a few of the invisible forces that could harm or kill living creatures."

Historically, Earth's North and South magnetic poles have flipped every 200,000 or 300,000 years.

A flip is overdue as the last one was about 780,000 years ago.

The latest satellite data, from the European Space Agency's Swarm trio which monitors the Earth's magnetic field, suggests a flip may be imminent.

The satellites allow researchers to study changes building at the Earth's core.

Their studies suggest molten iron and nickel are draining energy out of the core near where the magnetic field is generated.

While scientists aren't sure exactly why this happens, they describe the type of "restless activity" that could suggest the magnetic field is preparing to flip.

If a switch happens, we would be exposed to solar winds capable of punching holes into the ozone layer.

The impact could be devastating for mankind, knocking out power grids, radically changing Earth's climate and driving up rates of cancer.

"This is serious business", Richard Holme, Professor of Earth, Ocean and Ecological Sciences at Liverpool University told MailOnline in an earlier interview.

"Imagine for a moment your electrical power supply was knocked out for a few months – very little works without electricity these days."

The Earth's climate would change drastically. In fact, a Danish study believes global warming is directly related to the magnetic field rather than CO2 emissions.

The study claimed that the planet is experiencing a natural period of low cloud cover because of fewer cosmic rays entering the atmosphere.

Radiation at ground level would also increase, with some estimates suggesting overall exposure to cosmic radiation would double causing more deaths from cancer.

Researchers predict that in the event of a flip, every year 100,000 people would die from the increased levels of space radiation.

"Radiation could be three to five times greater than that from the man-made ozone holes. Furthermore, the ozone holes would be larger and longer-lived," said Dr Colin Forsyth, from the Mullard Space Science Laboratory at UCL.

The magnetosphere is a large area around the Earth produced by the planet's magnetic field.

Its presence means that charged particles of the solar wind are unable to cross the magnetic field lines and are deflected around the Earth.

Scientists have discovered that ancient pots can act as a magnetic time capsule.

This is because they contain an iron-based mineral called magnetite. When pots form, the magnetite minerals align with the Earth's magnetic field, just like compass needles.

By examining pottery from prehistory to modern times, scientists have discovered just how dramatically the field has changed in the past few centuries.

They've found that Earth's magnetic field is in a permanent state of flux.

Magnetic north drifts and every few hundred thousand years the polarity flips so a compass would point south instead of north.

If the magnetic field continues to decline, over billions of years, Earth could end up like Mars - a once oceanic world that has become a dry, barren planet incapable of supporting life.

But scientists claim the rate of decline is too fast for the Earth's core to simply burn out.

Instead, the story told by ancient pottery suggests the Earth's poles could be about to undergo another flip.

According to the British Geological Survey, the Earth's magnetic field has on average four or five reversals in polarity every million years and we're overdue for a similar event.

"At the moment, we cannot accurately determine whether or not the Earth's field is about to flip," said Dr Forsyth. "We have only been recording the Earth's field for around 170 years; about 1-15 per cent of the time a flip is expected to take."

If a flip occurs, it would cause the Earth's magnetic shield to be weakened for thousands of years, opening up our defences and causing cosmic radiation to get through.

"We have a double layer defence shield," said Jim Wild, a space scientists at Lancaster University.

"Space is full of stuff that's not great for biological tissue. If we didn't have an atmosphere, that stuff would be hitting us. It's the magnetic field [that] protects atmosphere from the solar wind."

WHAT COULD HAPPEN TO EARTH IF ITS POLES FLIPPED?

The Earth's magnetic field is in a permanent state of change.

Magnetic north drifts around and every few hundred thousand years the polarity flips so a compass would point south instead of north.

The strength of the magnetic field also constantly changes and currently it is showing signs of significant weakening.

Life has existed on the Earth for billions of years, during which there have been many reversals.

There is no obvious correlation between animal extinctions and those reversals. Likewise, reversal patterns do not have any correlation with human development and evolution.

It appears that some animals, such as whales and some birds use Earth's magnetic field for migration and direction finding.

Since geomagnetic reversal takes a number of thousands of years, they could well adapt to the changing magnetic environment or develop different methods of navigation.

Radiation at ground level would increase, however, with some estimates suggesting that overall exposure to cosmic radiation would double causing more deaths from cancer. "But only slightly," Professor Richard Holme said.

"And much less than lying on the beach in Florida for a day. So if it happened, the protection method would probably be to wear a big floppy hat."

Electric grid collapse from severe solar storms is a major risk. As the magnetic field continues to weaken, scientists are highlighting the importance off-the grid energy systems using renewable energy sources to protect the Earth against a black out.

"The very highly charged particles can have a deleterious effect on the satellites and astronauts," added Dr Mona Kessel, a Magnetosphere discipline scientist at Nasa.

In one area, there is evidence that a flip is already occurring. "The increasing strength of the South Atlantic anomaly, an area of weak field over Brazil, is already a problem," Prof Holme said.

The Earth's climate could also change. A recent Danish study has found that the earth's weather has been significantly affected by the planet's magnetic field.

They claimed that fluctuations in the number of cosmic rays hitting the atmosphere directly alter the amount of cloud covering the planet.

Henrik Svensmark, a weather scientist at the Danish National Space Centre who led the team behind the research, believes the planet is experiencing a natural period of low cloud cover because of fewer cosmic rays entering the atmosphere.