Reversal of Earth's magnetic poles not global warming may have triggered Neanderthal extinction -- and it could happen again

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(CNN)The reversal of Earth's magnetic poles, along with a temporary
breakdown of the world's magnetic field about 42,000 years ago, could have
triggered a raft of environmental changes, solar storms and the extinction
of the Neanderthals, according to a new study.

The Earth's magnetic field protects us, acting as a shield against the
solar wind (a stream of charged particles and radiation) that flows out
from the sun. But the geomagnetic field is not stable in strength and
direction, and it has the ability to flip or reverse itself.

Some 42,000 years ago, in an event known as the Laschamp Excursion, the
poles did just that for around 800 years, before swapping back -- but
scientists were unsure exactly how or if it impacted the world.

Now, a team of researchers from Sydney's University of New South Wales and
the South Australian Museum say the flip, along with changing solar winds,
could have triggered an array of dramatic climate shifts leading to
environmental change and mass extinctions.

Scientists analyzed the rings found in ancient New Zealand kauri trees,
some which had been preserved in sediments for more than 40,000 years, to
create a timescale of how Earth's atmosphere changed over time.

Using radiocarbon dating, the team studied cross sections of the trees --
whose annual growth rings served as a natural time stamp -- to track the
changes in radiocarbon levels during the pole reversal.

"Using the ancient trees we could measure, and date, the spike in
atmospheric radiocarbon levels caused by the collapse of Earth's magnetic
field," Chris Turney, a professor at UNSW Science, director of the
university's Earth and Sustainability Science Research Center and co-lead
author of the study, said in a statement.

The team compared their new timescale with site records from caves, ice
cores and peat bogs around the world.

'End of days'
Researchers found that the reversal led to "pronounced climate change."
Their modeling showed that ice sheet and glacier growth in North America
and shifts in major wind belts and tropical storm systems could be traced
back to the period of the magnetic pole switch, which scientists named the
"Adams Event."

"Effectively, the Earth's magnetic field almost disappeared, and it opened
the planet up to all these high energy particles from outer space. It
would've been an incredibly scary time, almost like the end of days,"
Turney said.

Researchers say the Adams Event could explain many of Earth's evolutionary
mysteries, including the extinction of Neanderthals and the sudden
widespread appearance of figurative art in caves worldwide.

The phenomenon would have led to some dramatic and dazzling events. In the
lead-up to the Adams Event, the Earth's magnetic field dropped to only 0%
to 6% of its strength, while the Sun experienced several long lasting
periods of quiet solar activity.

"We essentially had no magnetic field at all -- our cosmic radiation
shield was totally gone," Turney said.

The weakening of the magnetic field meant that more space weather, such as
solar flares and galactic cosmic rays, could head to Earth.

"Unfiltered radiation from space ripped apart air particles in Earth's
atmosphere, separating electrons and emitting light -- a process called
ionisation," said Turney in a statement. "The ionised air 'fried' the
Ozone layer, triggering a ripple of climate change across the globe."

During this time, Earth's inhabitants would have been subjected to some
dazzling displays -- northern and southern lights, caused by solar winds
hitting the Earth's atmosphere, would have been frequent. Meanwhile, the
ionized air would've increased the frequency of electrical storms --
something that scientists think caused humans to seek shelter in caves.

"The common cave art motif of red ochre handprints may signal it was being
used as sunscreen, a technique still used today by some groups," Alan
Cooper, honorary researcher at the South Australian Museum, said in a

"The amazing images created in the caves during this time have been
preserved, while other art out in open areas has since eroded, making it
appear that art suddenly starts 42,000 years ago," Cooper, co-lead author,

An upcoming reversal
In the paper, published in the journal Science, experts say there is
currently rapid movement of the north magnetic pole across the Northern
Hemisphere -- which could signal another reversal is on the cards.
"This speed -- alongside the weakening of Earth's magnetic field by around
nine per cent in the past 170 years -- could indicate an upcoming
reversal," said Cooper.

"If a similar event happened today, the consequences would be huge for
modern society. Incoming cosmic radiation would destroy our electric power
grids and satellite networks," he said.

Human activity has already pushed carbon in the atmosphere to levels
"never seen by humanity before," Cooper said.

"A magnetic pole reversal or extreme change in Sun activity would be
unprecedented climate change accelerants. We urgently need to get carbon
emissions down before such a random event happens again," he added.

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