Magnetic Pole's of our Planet on the Run!

Studies have shown that we might have a new entrant to wobble the already shaken climatic system of our planet. We have another loud and clear alarm from nature before we put an axe to our own foot. As you read and I write something strange is happening deep down the womb of the earth which has the potential to disrupt various technologies across the globe, some of which have already started to take corrective steps. The magnetic poles have started to move at unprecedented speeds and possibly we are standing at the doorstep of the magnetic polar flip, i.e. when earth’s magnetic north pole today would become magnetic south while the earth’s magnetic south becoming magnetic north. The poles have moved so much that at present both our north and south magnetic poles of our planet are in the eastern hemisphere. Note that magnetic south is actually earth’s magnetic north while the magnetic north is earth’s magnetic south. Run your brains! (Hint: A freely hanging magnet, like one in the compass, will be attracted by the south pole of the external magnet)

Unlike the usual pictorial representation of Earth’s magnetic field as a solid bar magnet, our magnetic field is actually produced by a complex flow of molten particles from the core of our planet nearly 3000 km beneath the earth’s surface. The two poles, therefore, wander independently and are not directly opposite to each other on the globe. Magnetic poles basically are the places at which the compass needle becomes vertical, and due to the motion of the earth resulting in the convoluted motion of the inner core, magnetic poles differ from the geographic poles i.e. 00 latitudes and longitudes. The planet's core suffers immense heat (~5000 degrees C) and pressure causing the metals in its inner part to turn solid. However, relatively relaxed the outer part of the core is liquid at about 3000-4000 degrees C and mainly consists of molten Iron and Nickel particles. The temperature and pressure differences along with the earth's rotational motion cause convection currents in the outer core of molten iron. The flowing soup of liquid metal thereby generates current. This swirl of this electric current lead to the production of our magnetic field (Ampere’s law). The particles passing through these generated magnetic fields further produce electric currents (which is also the basic principle behind working of the dynamo and the electric generation today). Thus there exists a self-sustaining loop, named as geodynamo. 

Studies have shown that once in every 200,000-300,000 years Earth's magnetic poles tend to flip. The moving iron patches in the outer core have a tendency to reverse align. When these reverse patches grow to a point that they dominate the core, the magnetic field flips. Simulations using supercomputers have shown that even the inner core plays an important role in this process. Essentially, inner core resists any reversal and only one out of 10 reversal attempt is successful. This might explain the Lashamp event which was a brief complete reversal that occurred only 41,000 years ago but lasted only about 440 years. So, one can realize that the flip would first lead to a declination of field strength (since the reverse field will tend to cancel the existing field) which will later get back on its feet again (when the field has flipped). Over the millions of years, our poles have flipped several hundred times. The stretching mid-Atlantic ridge has allowed geologists to go deep and collect igneous rocks which are like the geographic imprints of our planet. Minerals embedded in the lava are sensitive to earth magnetic field giving rise to “thermoremanent magnetization” and their study could provide information about earth’s magnetic field over thousands of years. The lava, however, takes 100 or 1000's of years to cool down, therefore giving an imprecise estimation of occurrence of the event. Recently Geologists have realized that the study of ancient pottery might help them overcome this problem of precision. When potters threw their clay, the minerals in the clay interacted with the earth’s magnetic field and as they cooled they froze into place like tiny compasses containing information about direction and strength of the magnetic field. The icing on the cake is many such pottery articles have a time stamp on them. Cheers to the Geologists! (Sorry Sheldon Cooper). Using this technique geophysicists and geologists have found that around 8th century BC, the core of our planet went crazy. “It was the strongest it’s been, at least in the last 100,000 years, but maybe ever. We call this phenomenon the Iron Age spike”, Ben-Yosef, an archaeologist and a part of a group of geophysicists who are creating a record of earth’s magnetic fields activity. But then it weakened quickly after 732 BC, losing about 30% of its intensity in just 30 years. Through these studies, scientists have learned that the reversal can happen at a relatively faster time scale than previously thought (of 1000’s of years).

Scientists know that the last flip occurred around 780,000 years ago. Thus, we are more than 2 times late for the flip. At present, scientists have observed that the magnetic North pole is literally running in the northern hemisphere, travelling at around 55 km/hr towards the northwest. Further, it’s losing its strength quickly, losing almost 10% of its strength. In 2018, it crossed the international date line into the eastern hemisphere. In the Southern hemisphere, the magnetic pole has already left Antarctica.

Position of Earth’s north magnetic pole. Image source: Wikipedia

Hurst, 'Magnetic field - The magnetic field and its direction', Te Ara - the Encyclopedia of New Zealand

The motion has created an area as large as 20% of earth surface centred over South America known as South Atlantic Anomaly. In this region, the weakened magnetic field causes energetic particles to approach Earth at much lower altitudes. Over the last 60 years, this region has grown to twice its size and is moving towards the west. This phenomenon forced the worlds geomagnetism experts into the sudden move. They usually meet every 5 years to update the worlds magnetic model which describes planets field and dictates the modern navigation but the magnetic poles are shifting so quickly that they decided to update it in 2019 against 2020 as per the usual schedule. The possibility of magnetic flip in our lifetime cannot be denied. Due to the scale of the phenomenon and the disastrous impacts, it might have, several agencies including NASA and ESA and scientists across the globe are keeping a sharp eye for it. 

Correlation between global temperature anomalies and motion of earth's magnetic poles. Data sources: Mandela, M., and E. Dormy. "Asymmetric behaviour of magnetic dip poles." Earth, planets and space 55.3 (2003): 153-157; Thébault, Erwan, et al. "International geomagnetic reference field: the 12th generation." Earth, Planets and Space 67.1 (2015): 79; NASA's Goddard Institute for Space Studies (GISS). Credit: NASA/GISS

This magnetic field is extremely important for our survival since it protects us from strong and lethal charged particles from the solar wind. Our modern technology like flight navigations, radio communications, electric grids and satellites all are linked to the magnetic fields in some way or other. Researchers from the University of Cambridge’s Centre for Risk Studies, along with several other institutions have estimated that a single solar storm can cost around $41.5 billion dollars a day to the US economy alone. To check if the phenomenon has any correlation with global warming, a crude test was performed. Data were obtained for the past 100 years (1900-2015) for temperature anomalies in northern and southern hemispheres and the velocity of earth’s magnetic north pole. Since the data for velocity has been collected at 5 years intervals, we smoothened the temperature anomalies through averaging over 5 years.  

The results show a correlation between the motion of the northern magnetic pole and northern hemispheric temperature anomalies. In the southern hemisphere however such correlation wasn’t observed. Literature review shows that even researchers now believe that the correlation may be more significant than previously realized. Although any comment upon causality cannot be made, however, it can be said with certainty that the repercussions of such an event will not be positive on the already dented economics of climate change.

Even the Royal Swedish Academy of Sciences awarded Nobel Prize for Economics in 2018 for the Economics of climate change saying it to be “our time’s most basic and pressing question about how we create long term sustained and sustainable economic growth.” One of the Nobel Laureate William Nordhaus’s work “is now widely used to weight the cost and benefits of curbing greenhouse gas emissions against those of inaction.” His studies are helpful to determine the social cost of greenhouse emissions. With merely a decade in hand before our temperature goal slips away, I hope their work enable us to transform the age-old debates into constructive actions.

References:

1. Earth's Poles Will Eventually Flip, So What Then?, Simon Worrall, February 1, 2018
2. Earth’s magnetic field, Wikipedia, accessed January 24, 2019
3. What If Earth's Magnetic Poles Flip?, Natalie Wolchover, February 10, 2012
4. Iron Age Potters Carefully Recorded Earth's Magnetic Field — By Accident, Rae Ellen Bichell, February 14, 2017
5. Reversals: Magnetic flip, British Geological Survey