North
Pole Moves as Ice Sheets Melt
The
North Pole’s surprise trip toward Greenland is due to Earth's
rapidly melting ice sheets, a new study finds.
A
true-color image taken on May 5, 2000, by an instrument aboard NASA's
Terra spacecraft, over the North Pole, with sea ice shown in white
and open water in black.
CREDIT:
Image by Allen Lunsford, NASA GSFC Direct Readout Laboratory; Data
courtesy Tromso receiving station, Svalbard, Norway
15
May, 2013
The
distribution of mass across the planet determines the position of
Earth's poles. Because Earth is a bit egg-shaped, the North
Pole
is always slightly off-center. It's also been slowly drifting south,
responding to long-term changes since the last Ice Age, as the
enormous ice sheets that once covered large swaths of the planet
melted and parts of the Earth rebounded from the lost weight.
But
in 2005, the pole suddenly started making a beeline east for
Greenland, moving a few centimeters eastward each year. The cause?
Rapid melting of the Greenland Ice Sheet, finds a study published May
13 in the journal Geophysical Research Letters. Ice loss and the
associated sea-level rise account for more than 90 percent of the
polar shift, Nature
News reported.
Melting
ice moves mass around by adding water to the oceans and lightening
the load on ice-covered crust. Although global ice melt plays a role
in the pole's shift, Greenland itself is the primary contributor to
the eastward movement, the researchers found. "Both of [those
factors] are contributing, but now we can say glacial melting in
Greenland produces an observable polar motion," said Clark
Wilson, a study co-author at the University of Texas, Austin.
The
change is small, dwarfed by the pole's broad wandering circles, which
are caused by Earth's bulging midriff (the 14-month Chandler
wobble)
and an annual wobble related to seasonal shifts. However, "if
you remove those effects, you'll see a long-term drift," Wilson
told LiveScience.
Using
data from NASA's GRACE satellite, which measures Earth's gravity
field, the researchers tested whether Greenland's ice loss changed
the pole position. The data can track how water and ice shift across
the planet. "Mass is moving around all the time," Wilson
said.
Knowing
the precise location of the North Pole has become a critical part of
modern life. It's the foundation of GPS, which guides people with
mapping
apps,
as well as military systems and planes.
June
3, 2013 – EARTH –
The
discovery by NASA rover Curiosity of evidence that water once flowed
on Mars – the most Earth-like planet in the solar system – should
intensify interest in what the future could hold for mankind.
The
only thing stopping Earth having a lifeless environment like Mars is
the magnetic field that shields us from deadly solar radiation and
helps some animals migrate, and it may be a lot more fragile and
febrile than one might think.
Scientists say earth’s magnetic field
is weakening and could all but disappear in as little as 500 years as
a precursor to flipping upside down. It has happened before – the
geological record suggests the magnetic field has reversed every
250,000 years, meaning that, with the last event 800,000 years ago,
another would seem to be overdue.
“Magnetic north has migrated more
than 1,500 kilometers over the past century,” said Conall Mac
Niocaill, an earth scientist at Oxford University.
“In the past 150
years, the strength of the magnetic field has lessened by 10 percent,
which could indicate a reversal is on the cards.”
While the effects
are hard to predict, the consequences may be enormous. The loss of
the magnetic field on Mars billions of years ago put paid to life on
the planet if there ever was any, scientists say. Mac Niocaill said
Mars probably lost its magnetic field 3.5-4.0 billion years ago,
based on observations that rocks in the planet’s southern
hemisphere have magnetization.
The northern half of Mars looks
younger because it has fewer impact craters, and has no magnetic
structure to speak of, so the field must have shut down before the
rocks there were formed, which would have been about 3.8 billion
years ago.
“With the field dying away, the solar wind was then able
to strip the atmosphere away, and you would also have an increase in
the cosmic radiation making it to the surface,” he said. “Both of
these things would be bad news for any life that might have formed on
the surface – either wiping it out, or forcing it to migrate into
the interior of the planet.”
---Extinction Protocol
Lost
in migration: Earth's magnetic field overdue a flip
The
discovery by NASA rover Curiosity of evidence that water once flowed
on Mars - the most Earth-like planet in the solar system - should
intensify interest in what the future could hold for mankind.
3
June, 2013
The
only thing stopping Earth having a lifeless environment like Mars is
the magnetic field that shields us from deadly solar radiation and
helps some animals migrate, and it may be a lot more fragile and
febrile than one might think.
Scientists
say earth's magnetic field is weakening and could all but disappear
in as little as 500 years as a precursor to flipping upside down.
It
has happened before - the geological record suggests the magnetic
field has reversed every 250,000 years, meaning that, with the last
event 800,000 years ago, another would seem to be overdue.
"Magnetic
north has migrated more than 1,500 kilometres over the past century,"
said Conall Mac Niocaill, an earth scientist at Oxford University.
"In the past 150 years, the strength of the magnetic field has
lessened by 10 percent, which could indicate a reversal is on the
cards."
While
the effects are hard to predict, the consequences may be enormous.
The loss of the magnetic field on Mars billions of years ago put paid
to life on the planet if there ever was any, scientists say.
Mac
Niocaill said Mars probably lost its magnetic field 3.5-4.0 billion
years ago, based on observations that rocks in the planet's southern
hemisphere have magnetisation.
The
northern half of Mars looks younger because it has fewer impact
craters, and has no magnetic structure to speak of, so the field must
have shut down before the rocks there were formed, which would have
been about 3.8 billion years ago.
"With
the field dying away, the solar wind was then able to strip the
atmosphere away, and you would also have an increase in the cosmic
radiation making it to the surface," he said.
"Both
of these things would be bad news for any life that might have formed
on the surface - either wiping it out, or forcing it to migrate into
the interior of the planet."
RIGHT
HERE, RIGHT NOW
Earth's
magnetic field has always restored itself but, as it continues to
shift and weaken, it will present challenges - satellites could be
more exposed to solar wind and the oil industry uses readings from
the field to guide drills.
In
nature, animals which use the field could be mightily confused -
birds, bees, and some fish all use the field for navigation. So do
sea turtles whose long lives, which can easily exceed a hundred
years, means a single generation could feel the effects.
Birds
may be able to cope because studies have shown they have back-up
systems that rely on stars and landmarks, including roads and power
lines, to find their way around.
The
European Space Agency is taking the issue seriously. In November, it
plans to launch three satellites to improve our fairly blurry
understanding of the magnetosphere.
The
project - Swarm - will send two satellites into a 450 kilometre high
polar orbit to measure changes in the magnetic field, while a third
satellite 530 kilometres high will look at the influence of the sun.
DESCENT
INTO CHAOS
Scientists,
who have known for some time the magnetic field has a tendency to
flip, have made advances in recent years in understanding why and how
it happens.
The
field is generated by convection currents that churn in the molten
iron of the planet's outer core. Other factors, such as ocean
currents and magnetic rocks in the earth's crust also contribute.
The
Swarm mission will pull all these elements together to improve
computer models used to predict how the magnetic field will move and
how fast it could weaken.
Ciaran
Beggan, a geomagnetic specialist at the British Geological Survey in
Edinburgh, said studies have also refined our understanding of how
the field reverses.
They
have focused on lava flows. When these cool and form crystals the
atoms in iron-rich molten rock align under the influence of the
magnetic field, providing a geological memory of the earth's field.
But
that memory looks different in various locations around the world,
suggesting the reversal could be a chaotic and fairly random process.
"Rather
than having strong north and south poles, you get lots of poles
around the planet. So, a compass would not do you much good,"
said Beggan.
While
the whole process takes 3,000-5,000 years, latest research suggests
the descent into a chaotic state could take as little as 500 years,
although there are significant holes in scientific understanding.
"Although
electricity grids and GPS systems would be more vulnerable, we are
not really sure how all the complex things that are linked together
would react," Beggan said.
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