In geologic terms it's imminent. In biologic, maybe within a lifetime.
December 20, 2014 6:09 AM   Subscribe

Earth's Magnetic Field May Be About to Flip [summary] - "Earth's last magnetic reversal took place 786,000 years ago and happened very quickly, in less than 100 years -- roughly a human lifetime. The rapid flip, much faster than the thousands of years most geologists thought, comes as new measurements show the planet's magnetic field is weakening 10 times faster than normal and could drop to zero in a few thousand years." (via)
posted by kliuless (35 comments total) 17 users marked this as a favorite
 
Thanks, Obama.
posted by Wordshore at 6:25 AM on December 20, 2014 [60 favorites]


No magnetosphere, even temporarily, is bad news. Cosmic radiation is nasty stuff.
posted by leotrotsky at 6:30 AM on December 20, 2014


Can we not link to the Daily Mail on science subjects, though? Especially when it is using this to tell people to "forget global warming". That headline is not a rhetorical device, it's the point of the article.
posted by howfar at 6:31 AM on December 20, 2014 [50 favorites]


Between this and the periodic solar flares, you have to think that our electrical grid, as currently designed, is a catastrophe waiting to happen. Local power generation and less miles long conducting wires would be much more resilient.
posted by leotrotsky at 6:34 AM on December 20, 2014 [5 favorites]


Local power generation and less miles long conducting wires would be much more resilient.

Yes, but... but... my back yard!

Best not to think about it; I may well die before it's a real problem.
posted by GenjiandProust at 7:08 AM on December 20, 2014 [3 favorites]


Hopefully this will cure all the vaccine-related autism cases.
posted by blue_beetle at 7:12 AM on December 20, 2014 [1 favorite]


i guess now all the magnetically treated miracle health water will become toxic.
posted by ennui.bz at 7:24 AM on December 20, 2014 [6 favorites]


Is local power generation a euphemism for wind and solar, leotrotsky? We should not depend upon highly experimental distributed tiny nuclear reactor technologies. And local power generation with fossil fuels is disastrous for the environment, global warming, etc.

Wind and solar are by far our best sources of energy, but they do require either batteries or a smart grid. Batteries have their own environmental challenges. And a smart grid is not exactly avoiding the power lines.

In fact, we'll need far more long power distribution lines if we want to address global warming :
World’s first road-powered electric vehicle network switches on in South Korea

Wind and solar are more resilient int the sense that if the long wires blow up a base station or two, some local power generation capacity remains.
posted by jeffburdges at 7:27 AM on December 20, 2014 [4 favorites]


The best model might be a distributed network of wind and solar residential producers, who produce what they consume and store any excess in distributed but publicly subsidized (like public utilities) hydrogen battery banks for resale or use during non-peak production periods. We could use large scale renewable projects (wind farms, geothermal, hydrothermal, etc.) to provide some additional flexibility in capacity to offset yield gaps at the residential level.
posted by saulgoodman at 8:29 AM on December 20, 2014 [1 favorite]


They are related. Global warming affects the geodynamo through icecap melting that changes earth's moment of inertia by shifting mass toward the equator.
posted by BentFranklin at 8:31 AM on December 20, 2014


I'm skeptical about that last statement. Even it's true that global warming pumps more than a tiny amount of mass towards the equator I don't see what that has to do with earth's magnetic field.
posted by rdr at 8:48 AM on December 20, 2014 [2 favorites]


Yes. Given the vastly different orders of magnitude between the mass of the Earth and that of the ice sheets, I would, personally, be surprised if there were an effect. Is there geological evidence of periodic warming/cooling being correlated with shifts in the magnetic field?
posted by howfar at 8:57 AM on December 20, 2014


Just in case you needed an illustration depicting the protective effect of the magnetosphere.
posted by xtian at 8:59 AM on December 20, 2014 [1 favorite]


Although not *that kind* of geophysicist (my graduate classes on the geodynamo were some of the more traumatic academic experiences of my life), I don't believe that distribution of mass at the Earth's surface (particularly that of water and ice, the masses of which are orders of magnitude less than mantle density anomalies, let alone anything in the outer core) plays any effect at all. That said, some casual googling yields some suggestions of correlations, though the causality, if any, is probably the other way (variation in the magnetic field affecting climate).

Example: Courtillot et al 2007, needs a subscription for full access, which I don't have from here, and comment from Bard and Delaygue 2007 [pdf]. There are older papers relating mass extinctions, global climate change and the geodynamo from older geological time, but they are more speculative and, again, propose links between the geodynamo and major extinction and/or climate events via mantle convection (plumes, outpourings of flood basalts and so on).

Again, it's not my field, so if anyone has links or cites to relevant work, it would be great to share.
posted by bumpkin at 9:40 AM on December 20, 2014 [4 favorites]


Hmm... well, it looks like there has been several suggestions along this line:

Doake (1977) A possible effect of ice ages on the Earth's magnetic field, Nature

Rampino (1979), Possible relationships between changes in global ice volume, geomagnetic excursions, and the eccentricity of the Earth's orbit, Geology

It doesn't look like this had a lot of legs, though the Bard and Delaygue comment I cited above mentions a fair bit of work that modeled the effect of precession on the geodynamo, via tidal effects. Beyond modeling, it looks like it's a difficult story to establish since even establishing the temporal correlation between magnetic field and climate is pretty hard -- the temporal resolution of magnetic intensity and polarity variation being generally poorer than you would want or need. The FPP article -- which isn't about the magnetic field - climate link at all -- looks like a pretty notable contribution because they've managed to find a suitable collection of rocks to begin to approach the sub-millenial resolution you'd want. That said, even if you managed to establish a climate - magnetosphere correlation, what that would mean for causality (magnetic field -> climate or climate -> magnetic field) would still involve some hard work to establish.

tl;dr : the relationship between changes in ice volume on the surface and the geodynamo isn't a total non-starter, but it's far from established.
posted by bumpkin at 10:01 AM on December 20, 2014 [4 favorites]


Yes, but... but... my back yard!

My back yard is where I'm going to build my radiation shelter, with its six-foot-thick dirt walls & ceiling
posted by jjwiseman at 10:18 AM on December 20, 2014 [1 favorite]


Cosmic radiation is nasty stuff.

If comic books have taught me anything, it means we're all going to get some fantastic powers. One out of four of us might have some minor side effects, though.
posted by entropicamericana at 10:21 AM on December 20, 2014 [12 favorites]


tl;dr : the relationship between changes in ice volume on the surface and the geodynamo isn't a total non-starter, but it's far from established.

It's bound to have some effect, but given all the other influences that change over geologic time I would be surprised if it was in any way a predictable one. But it's a fun subject to search the web for, and there's this: Geomagnetic reversals from impacts on the Earth.
dust from the impact crater and soot from fires trigger a climate change and the beginning of a little ice age. The redistribution of water near the equator to ice at high latitudes alters the rotation rate of the crust and mantle of the Earth. If the sea-level change is sufficiently large (>10 meters) and rapid (in a few hundred years), then the velocity shear in the liquid core disrupts the convective cells that drive the dynamo.
posted by sfenders at 10:35 AM on December 20, 2014


If comic books have taught me anything, it means we're all going to get some fantastic powers. One out of four of us might have some minor side effects, though.

If Fox plays their cards right, maybe the can time the release of their FF/X-men crossover film to coincide with the flip.
posted by homunculus at 11:08 AM on December 20, 2014


I never seem to get over the thrill of realizing that life as we know it on Earth is only possible because the entire planet is surrounded by a magnetic force-field generated by a massive ball of iron at the Earth's core, shielding us from the constant bombardment of cosmic death rays from the sun.

I love the idea of aliens discovering our planet and thinking, That can't be natural, can it?
posted by straight at 12:30 PM on December 20, 2014 [15 favorites]


So much for my Long Now 10000 Year Compass proposal.
posted by benzenedream at 12:42 PM on December 20, 2014 [11 favorites]


Especially when it is using this to tell people to "forget global warming". That headline is not a rhetorical device, it's the point of the article.

This can't be stressed enough, IMO. Sneakily phrasing the real viewpoint as a seemingly tossed off joke or implicit assumption rather than plainly stating it is a technique I keep seeing in use by bad actors.
posted by the big lizard at 2:06 PM on December 20, 2014


The geodynamo comes from circulation of the molten core, not the solid iron core. Coriolis forces combined with MHD feedback effects create vortices that generate the magnetic field. When Earth's rotation changes, shear between the mantle and liquid core causes turbulence that disrupts the vortices until the new rotation propagates throughout the core. Then the vortices come back with a 50% chance of being oriented north or south. Pole reversals seem to occur about half as often as abrupt rotation changes. Rotation changes can occur for many reasons, not necessarily climate change.
posted by BentFranklin at 2:07 PM on December 20, 2014 [7 favorites]


786,000 years ago. Yet clearly some humans made it through last time.

Amish, I expect.
posted by IndigoJones at 4:53 PM on December 20, 2014


If this had happened around a thousand years ago humanity's history would have been very different. Without compasses there may have been no Age of Sail, because sailors (during the daytime at least) would have found it very hard to navigate when out of sight of land.(*)

(*) Yes, I know about the Polynesians and their impressive feats of compass-less navigation.
posted by Joe in Australia at 5:25 PM on December 20, 2014


The auroras will be spectacular.

I wonder what pole reversal would do to magnetic data, which is most computer data.
posted by theora55 at 6:23 PM on December 20, 2014


sailors (during the daytime at least) would have found it very hard to navigate when out of sight of land.

Not so difficult in the daytime as during a cloudy night with variable winds. But maritime navigation relied on the compass until quite recently, not just centuries ago. Radio navigation was invented sometime in the 1940's during the war I think, but it wasn't thoroughly ubiquitous until the 1980's. So I would say we're just barely beyond the period of maximum dependence on the magnetic field for navigation. Not so long ago it was hard enough even with a good compass; you never know precisely how much leeway the boat is making, or exactly how fast the current is going. When you came in sight of land or a lighthouse or something, you'd just hope you weren't too far off and could recognize your actual position from the charts. Or maybe I just wasn't very good at navigating, but I bet that if you can find data on the worldwide rate of shipwrecks per decade, it'll show a dramatic decrease from the 1960's on as it seems to do for the Great Lakes.

Anyway, the point is, if geomagnetic troubles wipe out all the GPS satellites as well as making the compass useless, we could always go back to LORAN-C.
posted by sfenders at 6:58 PM on December 20, 2014 [2 favorites]


I wonder what pole reversal would do to magnetic data, which is most computer data.

the short answer is "nothing". (does your computer lose data when you rotate it 180°?)
posted by russm at 7:15 PM on December 20, 2014 [5 favorites]


I think that somewhere along the way people started skipping a step in thinking about how Earth's magnetic field affects radiation and life here. Because really, most of the nastiest radiation from space that can harm living things doesn't care much about our magnetic field: a lot of cosmic radiation is in the form of gamma rays or uncharged neutrons that don't respond to magnetic fields, while those cosmic rays that do respond are "deflected" on curved paths that just change which incoming directions end up hitting the Earth, still almost as many particles are slamming into the upper atmosphere and releasing a shower of secondary radiation, some of which makes it to the ground and is why we build our sensitive particle detectors in mines or under the ice in Antarctica, or suspended on the bottom of the Mediterranean (if that one gets built). Meanwhile a lot of the harmful radiation from the sun is x-rays or ultraviolet light, completely unaffected by the magnetic field but partially blocked by the atmosphere.

What's mostly deflected by our magnetic field is the solar wind, that thin, high-speed plasma emitted from the sun. It's dangerous radiation, and it is deflected by the magnetic field... but while some of it is deflected away, other of it deflected into the Van Allen belts where they bounce back and forth for quite a while, radiating away some of their energy as radio waves before eventually, usually, coming in as concentrated beams aimed at Norway or wherever and making pretty northern lights (also southern). Notice yet again that it's the atmosphere doing the radiation-blocking, keeping those northern lights up high and beautiful rather than down at the surface giving us cancer.

That's the real benefit, the real reason why astrobiologists talk about magnetic fields being a prerequisite for a planet to support life: not because it blocks the deadly radiation, but because it blunts the energy of the solar wind before it strikes the atmosphere. Without it, the solar wind would have stripped away Earth's atmosphere long ago. And it's that atmosphere that does most of the radiation-blocking.

The electric grid and compasses and other tech might have problems with a weaker magnetic field, but we living organisms won't notice a change in the radiation one bit.
posted by traveler_ at 9:32 PM on December 20, 2014 [12 favorites]


Thanks to by BentFranklin and traveler_ for refining my astonishment. So actually the Earth is surrounded by a magnetic field generated by an enormous geodynamo created by the mass of molten iron at the planet's core which is keeping the Earth's atmosphere from being stripped away by wind from the Sun. Fantastic.
posted by straight at 12:05 AM on December 21, 2014 [3 favorites]


And that magnetic field is a consequence of the random motions of gas and dust molecules in the protoplanetary nebula that gave birth to our Solar System. Thanks to conservation of angular momentum all that random movement became a turning motion around the center of the nebula, and that eventually became the rotation of the planets which generates our magnetic field. (And also day and night, which keeps the planet from roasting on one side and freezing on the other.) So we are still directly benefiting from the kinetic energy contained in a dust cloud over five billion years ago.
posted by Kevin Street at 12:36 AM on December 21, 2014 [2 favorites]


I wonder what pole reversal would do to magnetic data, which is most computer data.

I think we'll be OK if we pick up all computers and hard disks and rotate them by 180 degrees.
posted by sour cream at 5:30 AM on December 21, 2014


It appears that destiny has finally caught up with us.
posted by SPrintF at 2:05 PM on December 21, 2014


Another interesting feature of pole shifts is that while the main field is disrupted, smaller dynamos will emerge, with many mini north and south poles at random locations all over the planet.
posted by BentFranklin at 6:19 PM on December 21, 2014


I wonder what pole reversal would do to magnetic data, which is most computer data.

the short answer is "nothing". (does your computer lose data when you rotate it 180°?)


Thanks for treating it as a stupid question. The magnetic field is expected to weaken dramatically, with various shifts. It's hard for me to believe the pole reversal will be perfectly tidy, but by all means, do snark.
posted by theora55 at 5:04 PM on December 26, 2014


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