The surface of the Earth is where we live. Yet our planet is a restless home, subject to earthquakes, volcanic eruptions, destructive floods, landslides, and other natural hazards. The Earth’s surface is always changing, in response to processes deep in the planet’s interior as well as to a complex suite of interactions among the solid Earth, atmosphere, oceans, hydrosphere, and biosphere. Understanding these changes poses a deep scientific challenge, but meeting that challenge can reap enormous practical benefit.


Here we go with the science again. You had better have a good excuse for this!


[You may have noticed, but probably didn’t, that we took some time off after the last blog because, frankly, we were ahead of schedule and had run out of ideas. Funny how that happens when you write a lot! Not that there weren’t plenty of things to write about. Donald Trump proposed to temporarily restrict immigration from some problem areas in the Middle East, and that, of course, was unthinkable. People overseas might be inconvenienced; our colleges, the ones that take in foreign students, tuition and fees, might suffer; and major companies, the ones that rely on foreign skilled [and inexpensive] labor might have to hire from the U.S. Oh the pain! Oh the horror! Don’t people understand? We haven’t had any foreign sponsored terror incidents this week, so that means we never will! And if we do, so what? How much are a few lives here really worth, compared to the needs of our economy?

I’m not saying that everyone who comes here is a psychopathic murderer. That would be silly. But it’s estimated that, out of every population, if tested, about 4% would emerge as psychopaths. Why is it a bad idea to look for them? And if it’s a good idea, why is it a bad idea to pause for a few months, analyze our current screening procedures, and improve them? Why is it a good idea to just assume everything is fine and blunder on into the future? It’s not as though the U.S. is well-loved in the world. The previous Administration developed an active program to exterminate terrorists, and those worthies continue to threaten grisly retaliation at every turn. We would be foolish not to take precautions. At least that’s what I think.

Of course the Europeans aren’t doing that kind of thing, are they? And they’re not having any terror incidents, are they? Oh, wait! There are terror attacks over there, and other criminal stuff as well, and our friends in Europe do seem to be getting a bit frosty about it. Or so say the recent polls. Are Europeans turning xenophobe? Should we be afraid?

And so it goes, blather, blather. So if everybody’s talking about this – Trump, immigration, foreign criminals, etc. – why should we? Do we have anything to add to the collective wisdom? No, not right now. That’s why last week I pushed the staff to come up with a different topic, and that’s why Fred asked: “What happens when the Earth’s magnetic poles shift? When south becomes north, and vice versa?”

I bet you never thought about that. I certainly didn’t until Fred spoke up. But it turns out that serious people are busy working the problem, some of them in NASA, and others in colleges that actually teach science. Who would have thought?]

Turbulent Earth

Who indeed? Well NASA worries about such things, along with some other geologists and earth scientists, and an assortment of preppers. Let’s leave the preppers out of the discussion for a bit, and talk about NASA. Back about 15 years ago NASA issued a report about our planet’s magnetic personality. It seems planetary magnetism, the magnetic field that surrounds us, is largely a product of unstable geology at the earth’s core. While our planet may seem eternal and unchanging to us, that’s not really the case. Its iron core actually is very hot, and the outer core is fluid.  The fluid is basically melted iron, moving upward to deliver its heat to cooler regions, and then sinking back again.

So ferrous stuff moves around down there, below the surface, and that in turn generates a magnetic field. Professionals call it a “dynamo effect.” [3] The magnetic field interacts with lots of other things, including crustal rocks it has magnetized and radiation from the Sun and beyond. The latter – the radiation part – is also called “space weather.”[4] [“Space weather,” that’s an overly cute name; normally I wouldn’t think of weather in a vacuum; but I guess we’re stuck with it. That’s the way it is with most bad decisions. Other people have to live with them.]

Shifting Poles

The point is that our planet’s magnetic field varies from time to time due to internal and external forces.[5] NASA thought that phenomenon ought to be studied further.[6] That was 15 years ago and apparently the recommendation was a good one. There’s now serious evidence that our planet’s magnetic field has weakened “significantly” in the last 150+ years.  If that continues, it’s said, the field might disappear in time; not permanently; but perhaps for as many as 200 years. Magnetic poles will flip as a part of that process.

The most disturbing views, that pole shifts are imminent, come from the popular press, which in turn attribute them to some NASA researchers .[7] Currently NASA officially confirms only that poles have shifted in the past.[8]

Pole flipping, by the way, also is called “geomagnetic reversal.” Most agree that it’s happened before and no doubt will again.[9]  That’s not to say, however, that there’s a clear and present danger that it will happen right now.  Nothing is certain. This is science, not politics or religion. Scientific theories are really only hypotheses, to be scrutinized, tested, verified or falsified. That’s always a work in progress, and not all scientists believe the same thing at the same time. Don’t panic, but be alert!

The Magnetic Field

If the poles flip, the maximum danger to Earth people will occur when the planet’s magnetic field disappears. No doubt those of you who follow NASA’s space travel initiatives already understand this. High energy Galactic Cosmic rays, from outside our solar system, and bursts of low energy particles from our sun are both dangerous to humans unprotected by magnetic fields. “This issue is known since the time of Werner von Braun: [S]everal studies attempted during the last 40 years to find practical ways to protect … astronauts from the sudden, very intense, low energy, Solar Particle Events and, at the same time, from the dose due to the continuous flux of penetrating, high energy Galactic Cosmic Rays.”[10]

One way to protect space travelers is to develop machines to generate high-strength magnetic fields to shield them from radiation. Unfortunately it’s pretty hard to build something like that to fit on a space ship; the machine has to be small, light and very powerful, and not dangerous to the people it’s supposed to protect. But current efforts do point to a solution for those of us who one day may be trapped on a non-magnetic planet. Space and resources are not so limited on the ground, so why not build dynamos all over the place, until there are enough of them to protect the people who really matter?

Of course we should also protect the less fortunate. They can take advantage of other, less expensive strategies like those being developed to settle the planet Mars.

Mars the Prototype

The planet-bound have other protections even if nothing around them generates a magnetic field. Consider Mars, for example. It has no magnetic field, but settlers there will have the mass of their planet to shield them from the sun’s radiation, at least before sunrise and after sunset. Then there’s the Martian atmosphere. It also can absorb solar radiation, and it’s especially effective doing that in the morning and late afternoon, when the sun is lowest on the horizon. That’s because radiation from a source to the side of your position on a planet travels through more atmosphere than radiation from directly overhead.[11]

So what else might we learn from Mars? Well, one way to further protect folks up there might be to simply bury the places where they live or work. One estimate is, for Mars, about 1.5 meters [about 5 feet] of regolith would do the job.[12] So if Martian settlers stay out of the sun, and stick close to home, they should be all right.

The calculations and examples I recite were done for Mars. Granted our Earth is closer to the Sun than Mars, larger than Mars, and has a thicker atmosphere. That means the numbers might [probably will] change; but the same general principles should hold true for both planets. Why wouldn’t they, if our planet becomes non-magnetic for a while?

Final Thoughts

Perhaps it’s time to start thinking about underground condos. Stories abound that the rich and/ or famous are doing that very thing, although the reasons vary and don’t seem to involve a fear of losing Earth’s magnetic field. The rich are more concerned with possible insurrections, etc., by an angry populace. But pay attention you preppers out there! This might be a project you can start for yourselves. How hard can it be to bury a house? And if you do that, drop us a line and tell us how it worked out.






[1] See NASA, Living on a Restless Planet, Solid Earth Science Working Group (SESWG) Report (2002), at p. 26 -27, available at

[2] G. Sallust is our disreputable founder, who gives orders even when he’s not here.

[3] See NASA, Living on a Restless Planet, Solid Earth Science Working Group (SESWG) Report (2002), at p. 26 -27, available at “The Earth’s magnetic field originates in the fluid outer core, where self-regenerating dynamo action maintains the field against decay.” Henceforth the report will be cited as Restless Planet at ___.

[4] Id. “This field gives rise to both permanent and induced magnetization in crustal rocks and also interacts with current systems in the ionosphere and magnetosphere (space weather).”

[5] Id. “These interactions give rise to fluctuating external electromagnetic fields that in turn induce electric currents in the Earth’s conducting interior. The induced electric currents produce time-variable electromagnetic fields at and above the Earth’s surface, and the field measured at any point represents the vector sum of contributions from the core field, the crustal field, the external field, and the induced electromagnetic field.”

[6] See Restless Planet at 26 – 27. “The induced electric currents produce time-variable electromagnetic fields at and above the Earth’s surface, and the field measured at any point represents the vector sum of contributions from the core field, the crustal field, the external field, and the induced electromagnetic field. The separation of these different signals is the greatest challenge for observational geomagnetism, yet the benefits from doing so will be great.” See also SESWG, What are the Dynamics of Earth’s Magnetic Field and Its Interactions with the Earth System? available at

[7] See Inquisitir, Didymus, NASA Warns Earth’s Magnetic Field Weakening, Poles Shift Imminent, Reversal Could Have Caused Neanderthal Extinction (November 8, 2015), available at According to Monika Korte with the Niemegk Geomagnetic Observatory at GFZ Potsdam, Germany, “It’s not a sudden flip, but a slow process, during which the field strength becomes weak, very probably the field becomes more complex and might show more than two poles for a while, and then builds up in strength and [aligns] in the opposite direction … When the polar shift happens, the Earth will have no magnetic field for about 200 years,” Jakosky said. … “Weakening of the Earth’s magnetic field [will have] serious consequences for life on Earth because the magnetic field acts as a shield that prevents dangerous solar radiation from passing into the atmosphere.” See also Express, no author, NASA: Earth’s magnetic poles are ‘switching’ with catastrophic consequences for humanity, available at

[8] See NASA, 2012: Magnetic Pole Reversal Happens All The (Geologic) Time (November 30, 2011), available at If you have something from  NASA that’s different and more recent, please let us know. We’ll add it to a blog and give you credit for the tip, if you want it.

[9] See the Wikipedia entry on the subject, available at

[10] See ESA, Battiston et al., Active Radiation Shield for Space Exploration Missions,  at Foreword, p. 5 (an archived report available at )

[11] See Selenian Boondocks, Stetter, Mars surface shielding from radiation (September 6, 2015)(hereafter cited as Mars Surface at __) available at  For more information, take a look at “The Looming Problem; Radiation Shielding for Space Travel — Collection of Important Literature”, available at . This is a very interesting archive that, we believe, is authentic. But these days, who knows for sure? We’re citing several things from this source.

[12] See Mars Surface at pp. 4-5 of 10.