- Education and Science»
- Geology & Atmospheric Science
Pole Shift: Are The Earth's Poles Reversing?
One of the more popular doomsday scenarios being discussed in the pseudoscientific corners of the Internet is the threat of an impending Polar Shift. The premise of this theory is that an imminent astronomic calamity (powerful solar storm, close encounter with "Planet X," geomagnetic reversal, alien death ray) will cause the Earth's poles to completely reverse, flipping the planet upside-down in relation to the rest of the solar system.
According to some variants of the doomsday scenario, this would also suddenly stop the Earth's rotation and cause it to turn the other way, leading to massive continent-upheaving earthquakes and tsunamis and volcanoes and other forms of mass destruction, ultimately bringing about the end of the world as we know it. This scenario sounds a bit like a plot for a bad science fiction movie, and indeed it was the plot of a bad science fiction movie - the 2009 Roland Emmerich thriller 2012. And like all bad science fiction, this doomsday scenario is based partly in misunderstood facts and partly in complete fabrication.
The root of this Polar Shift doomsday hypothesis is in the work of some early 20th Century theorists. The most prominent of these was author Charles Hapgood, a college professor and historian who disagreed with the emerging theory of plate tectonics, instead proposing in his 1958 book The Earth's Shifting Crust that the weight of the polar ice caps can destabilize the outer crust and cause it to shift catastrophically. Later authors built on Hapgood's hypothesis, suggesting that such a crustal displacement was responsible for the disappearance of the "lost city" of Atlantis, among other wild ideas.
While more recent scientific discoveries in geology have shown most of Hapgood's ideas to be incorrect, some aspects of the Polar Shift scenario do seem plausible. The planet Uranus, for example, is tilted almost 90 degrees to its orbital plane, and Venus is flipped completely upside-down, rotating in the opposite direction of all other planets around our Sun. Assuming that the planets all formed spinning in the same direction - as do most models of planetary formation - something pretty cataclysmic had to have happened at some time in the past to flip their poles so drastically.
It is only natural to wonder if the same thing could happen to us, and what effect such a shift would have on our planet.
Magnetic Pole Reversal
One type of polar shift that is well-known to have happened frequently in the past is a geomagnetic reversal, or reversal of the Earth's magnetic poles. Unlike the geographic poles, which constitute the axis of Earth's rotation and are always located at 90 degrees north and south latitude, the magnetic poles are the positive and negative dipoles of the Earth's magnetic field, and are not located at true north and south. These magnetic poles are currently tilted about 11 degrees of latitude away from the geographic poles and are in constant motion, drifting by as many as 24 miles (40km) per year.
In addition to its obvious benefits for navigation, the magnetic field also helps shield and protect the Earth and from harmful radiation. The solar wind - the flow of charged particles generated by the Sun, can strip away our atmosphere's ozone layer, which helps protect us from harmful ultraviolet radiation. Moreover, the magnetic field also helps the planet maintain its atmosphere, as the flow of charged particles can strip away the outer layers of the atmosphere over time. Many astrophysicists believe that the reason Mars has such a thin atmosphere is that its magnetic field turned off many millions of years ago.
The magnetic poles are generated by the rapid rotation of the solid iron inner core inside the liquid iron outer core. This creates whirlpool-like convection currents in the liquid metal, and due to the high conductivity of liquid iron these convection currents produce an electric current. Electric currents produce a magnetic field, according to Ampere's Circuital Law, and magnetic fields produce electric currents according to Faraday's Law of Induction. The result of this positive feedback loop is a self-sustaining magnetic field generator, or geodynamo, producing our planet's strong magnetic field.
One of the curious quirks of this geodynamo is that it has a tendency to reverse polarity from time to time, flipping the North and South magnetic poles. The reasons why the magnetic pole flips, a process known as geomagnetic pole reversal, are not well understood. It is well known that the pole has reversed many times in the past, however, thanks to the permanent record of historical geomagnetic fields preserved in the rock as it solidified. Stripes of magnetized rock on either side of mid-ocean ridges, volcanic regions where new crust is being produced, preserve a record of the Earth's shifting polarity over the past 130 million years.
While geomagnetic reversals appear to have occurred frequently throughout much of Earth's history, for the last 780,000 years the polarity has remained the same. This has led some geologists and astrophysicists to speculate that we are long overdue for a reversal, a speculation that proponents of the Polar Shift catastrophe scenario have taken as evidence for their pseudoscientific claims.
How the Earth's magnetic field behaves during a reversal is another question that has plagued geologists and inspired pseudoscientists. The geomagnetic record indicates that the flips of the magnetic pole can take thousands of years to accomplish, presumably leaving the Earth without a magnetic field in the interim. If this is the case, there should be a record of extinction periods corresponding with magnetic pole shifts, as these periods would leave the Earth exposed to harmful radiation and solar wind. So far, studies have failed to find any such correlation.
More recent research, using computer modelling of a geodynamo system, has demonstrated that the transition period of geomagnetic reversal does not stop the Earth's magnetic field - merely fractures it into multiple North and South poles scattered around the planet. While confusing for individuals trying to navigate by compass, this would otherwise pose no danger to the planet. If the Earth is currently undergoing a geomagnetic reversal, it is certainly not something anyone other than compass manufacturers should lose sleep over.
Physical Pole Shifts
The Earth's axis is currently tilted 23.44° degrees from the ecliptic, or the plane of the planet's orbit around the Sun, with the North Pole aimed roughly in the direction of the star Polaris. However, since the Earth is not a perfect sphere but a slightly pear-shaped oblate spheroid, the gravity of the Sun, Moon, and other planets tugs unevenly on our northern and southern hemispheres, causing the orientation and tilt of the poles to change over time.
The largest effect of the gravitational pulls of the Sun and the Moon and planets is known as axial precession. The poles move in a slow circle over a period of 25,772 years, much like a spinning gyroscope rolling around one of its axes. This type of precession does not change the angle of the Earth's axis, but does change its orientation relative to the stars such that in the not-too-distant future the North Pole will no longer be pointing at Polaris. This type of polar shift is also known as precession of the equinoxes, and determines our current astrological age.
Obliquity of the Ecliptic
The gravitational tug of the Earth's celestial neighbors also causes slight variations in the inclination of the ecliptic, our orbit around the Sun. Since we measure the Earth's axial tilt in relation to the ecliptic, these shifts in the Earth's orbit change the measured angle of our tilt. These variations in the axial tilt, or obliquity of the ecliptic, occur in a 41,040-year cycle, the angle of Earth's axis ranging from 22.1 to 24.5 degrees. It should be clarified that this is not actually changing the tilt of our planet itself - this remains stable relative to its own inertia. It is merely the change in the angle of our orbit that changes the tilt relative to it.
While the change in Earth's obliquity is a relative change caused by the gravity of our Solar System neighbors, there is a set of shorter-term cycles changes that do affect the actual angle of tilt. These cycles are known as nutation. The most pronounced is an 18.6 year cycle that shifts the Earth's tilt by a total of 9 arc-seconds, or 9/3600ths of a degree. This translates to about 885 feet (270 meters) of movement over this 18 year period. In addition, there are other smaller cyclic shifts over time periods of six months to a year. The measurable effect of this is a slight shifting of the Tropic and Polar Circles from year to year, since these are defined by the position of the Sun at the summer and winter solstices.
While many of the forces acting on our planet's rotation are external, factors both inside and on the surface affect the poles as well. Sloshing oceans, melting ice caps, earthquakes, and motions in Earth's liquid outer core cause the pole to move in slow, circular wobbles of about 12 meters in diameter. Careful analysis of this motion by the International Earth Rotation Service has found two cyclic wobbles - one annual wobble, and another 435-day wobble known as the Chandler wobble for its discoverer, astronomer Seth Carlo Chandler. Combined, these overlapping wobbles cause the pole to trace out a spiral pattern over the course of a dozen years. While these effects are very small compared to the size of the planet, tracking them is important for applications such as GPS navigation that rely on precise measurements of geography.
How are you preparing for the coming global pole shift superpocalypse?
True Polar Wander
Cyclical changes such as precession, nutation, and polar motion are by now well-understood, and cause only minute shifts in the tilt of the Earth's axis over long periods of time. But has the Earth ever had any larger shifts throughout its history?
Some evidence does exist for periods of total polar wander in the Earth's distant past, during which the planet shifted by twenty degrees or more in a geologically rapid period of time. By studying the geomagnetic record stored in ancient lava flows and some sedimentary rocks, geologists can establish the relative locations of the North and South poles during different periods in geologic history. Piecing together the geomagnetic record across different parts of our current continents, geologists can determine how these land masses moved over time.
During some periods of the past, however, studies have found that that all of the continents appeared to have moved in tandem relative to the magnetic poles, suggesting that there was a shift in the entire Earth during these periods. This is known as True Polar Wander. If conclusively verified, these periods of true polar wander would appear to provide evidence in favor of the polar shift doomsday hypothesis.
However, the studies suggesting past periods of polar wander also show an extremely slow rate of wander- usually about one degree per million years. These changes also do not shift the axis of rotation itself - they instead shift the entire mantle of the Earth around the liquid outer core in response in order to balance the changing weight distribution of the continents.
Preparing for the Polar Shift
Though proponents of the Polar Shift doomsday hypothesis enjoy instilling fear and panic in their readers, their claims should not be taken seriously. Though there are some shifts in the pole that occur on the scale of years, centuries, millennia, and millions of years, none appear to be catastrophic in the short term. The doomsday scenario being hyped on the Internet has no basis in reality.
The only actual destruction known to result from the Polar Shift hypothesis is to the credibility of actors like John Cusack and Danny Glover for appearing in fearmongering films like 2012.
Sources and Further Information
- Introduction to Geomag
Geomagnetism is the study of the Earth's magnetic field. This includes the fields produced by the Earth as well as those interacting with the Earth. Internal dynamo processes within the Earth create slowly changing magnetic fields.
- Minds in Ablation Part Five: Charting Imaginary Worlds
Pole Shifts, Ice Sheets, and Ancient Sea Kings: A Digression that Simply Got Out of Hand.
- New evidence for extraordinarily rapid change of the geomagnetic field during a reversal
Coe, R.S.; Prévot, M.; Camps, P. Nature, 20 April 1995.
- Wandering of the Geomagnetic poles | ngdc.noaa.gov
Historical movement of the geomagnetic poles
- IERS: Earth rotation
Several space geodesy techniques contribute to the permanent monitoring of the earth's rotation by IERS.
- True polar wander and supercontinents
David A.D. Evans. Tectonophysics 362 (2003) 303 – 320
- Linking Deep and Shallow Geodynamics to Hydro- and Bio-Spheric Hypotheses
T. D. Raub, et al.
- Absolute plate motions and true polar wander in the absence of hotspot tracks. - ResearchGate
Bernhard Steinberger & Trond H. Torsvik. Nature, Vol 452. 3 April 2008.