Keeping up with Earth’s Magnetic Field
There has been a flurry of research and discussion about how to better characterize the Earth’s magnetic field in recent months and years. This heightened interest isn’t simply due to curiosity. In fact, it is because we depend on our magnetic field to sustain our way of life- and even life itself. This article is a brief overview on Earth’s magnetic field and why it is so important to “keep up with it”.
Earth’s magnetosphere provides a protective shield which deflects harmful solar radiation away from our planet. Without a magnetosphere Earth’s surface might look a lot more like that of Mars: devoid of both air to breathe and protection from harmful solar radiation. The planet would likely not have developed complex life either. Although we have been aware of the Earth’s magnetic field for centuries, its complexity and dynamic nature has continued to challenge our understanding and prediction of its ever-changing behaviour. We depend on our magnetic shield to sustain life, but even minor changes to the field have consequences in our everyday lives.
In the 17th century, the deflection of a suspended magnetic needle allowed for crude delineations of iron ore bodies, and observations that there was a strongly vertical “pole” in the Canadian Arctic [1]. The first recognized portable magnetometer for measuring the absolute field intensity was invented by Carl Friedrich Gauss in 1833 [2]. Although Gauss’ fundamental contributions to the field of mathematics and physics is widely recognized today, the applicability of a portable magnetometer was not fully realized until World War II, when they were used to track enemy submarines [3]. This war-time advancement opened the door for widespread research into the Earth magnetic field. The long-debated concept of plate tectonics eventually used the magnetic stripes of seafloor crust to prove the controversial theory in the 1950s.
In the following decades, land, sea, air, and space-borne platforms have been used to characterize and monitor the magnetic field. The World Magnetic Model developed jointly by US and British institutions is now an internationally adopted spatial model of Earth’s magnetic field. We rely upon accurate updates to this model (every five years) to navigate ships and aircraft, and is even used by your cellphone! However, of late, five-year intervals are inadequate. This is because the North geomagnetic pole is accelerating in position faster and less predictably than in previous decades [4].
You’ve probably heard of the inevitable “pole reversal”. The last reversal (Matuyama-Brunhes) occurred around 784,000 years ago [5]. Historical data tells us this will undoubtedly occur again, and that we are actually quite overdue (by about twice the average time between previous reversals). What does this mean for humankind? Contrary to some doomsday hypotheses, certainly not the end of all life on Earth. Reversals are not instantaneous occurrences; they usually happen slowly over thousands of years [5], although this is still lightning fast in geological time scales. While the reversal process can weaken our protective magnetosphere, it will probably not disappear entirely [6], but only change its geometry and intensity. We also have our ozone layer, which may take a serious beating from solar radiation, but will provide some sort of buffer as long as we don’t destroy it beforehand.
That is not to say that we shouldn’t care about a pole reversal. In fact, we should care a lot. During a pole reversal, our magnetosphere will resemble less of a bar magnet, and more like several bar magnets battling for magnetic supremacy. Besides exposing us to increased radiation, we would experience navigation turmoil and interruptions or losses in power grids and tele-communications. From animal migration patterns to Google Maps, society will at the very least have to adapt to a new way of life, perhaps for few hundred lifetimes.
This phenomenon is unlikely to happen in our lifetime, and may not happen this millennium. The truth is, we don’t know how humans will fare if we are around when it happens. While we shouldn’t panic, we should take this as a wakeup call that we depend on our magnetic shield for life as we know it. We need much more research and modelling to prepare for major changes to our precious magnetic field, including novel technologies that allow us to collect more (and better) data, and not only from observatories, but every citizen scientist or traffic light. At SBQuantum we are working on innovating the way that we collect and use magnetic data both on Earth and space-borne platforms. Through projects like MagQuest [7] we aim to contribute nascent magnetic technology for applications in defense, navigation, and magnetic forecasting. As the North geomagnetic pole lurches forward, so do we in the scientific quest to understand our ever-changing Earth and protect all of it’s inhabitants.
References:
[1] J. C. Ross, “III. On the position of the North Magnetic Pole,” Philosophical Transactions of the Royal Society of London, vol. 124, pp. 47–52, Jan. 1834, doi: 10.1098/rstl.1834.0005.
[2] K. F. Gauss, “Intensitas vis magneticæ terrestris ad mensuram absolutam revocata,” Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London, vol. 3, pp. 166–174, Jan. 1837, doi: 10.1098/rspl.1830.0095.
[3] E. P. Felch, W. J. Means, T. Slonczewski, L. G. Parratt, L. H. Rumbaugh, and A. J. Tickner, “Air-borne magnetometers,” Electrical Engineering, vol. 66, no. 7, pp. 680–685, Jul. 1947, doi: 10.1109/EE.1947.6443620.
[4] P. W. Livermore, C. C. Finlay, and M. Bayliff, “Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation,” Nat. Geosci., vol. 13, no. 5, pp. 387–391, May 2020, doi: 10.1038/s41561–020–0570–9.
[5] B. S. Singer, B. R. Jicha, N. Mochizuki, and R. S. Coe, “Synchronizing volcanic, sedimentary, and ice core records of Earth’s last magnetic polarity reversal,” Sci Adv, vol. 5, no. 8, p. eaaw4621, Aug. 2019, doi: 10.1126/sciadv.aaw4621.
[6] P. A. Mason and P. L. Biermann, “Astrophysical and Cosmological Constraints on Life,” in Habitability of the Universe Before Earth, R. Gordon and A. A. Sharov, Eds. Academic Press, 2018, pp. 89–126. doi: 10.1016/B978–0–12–811940–2.00005–8.
[7] Luminary Labs, “Home — MAGQUEST,” magquest.com. https://www.magquest.com/ (accessed Aug. 16, 2021).
