Good Morning James,
The recent coronal mass ejection (CME) began interacting with the terrestrial magnetosphere earlier today. Though initially that interaction was rather subdued a rapid fall-off in the proton particle counters is actually leading to some rather elevated readings over at the Rice.edu monitor site. Polar convection, density and velocity are all registering in the yellow band, while the Interplanetary Magnetic Field (IMF) magnitude, angle and the dynamic pressure are all passed up into the red zones. It is worth remembering that a CME consists of hot, charged particles (ionized hydrogen primarily) and as such the situation is similar to the current in the wall of your house when a light switch is flipped on. At the fundament then a "current" of hot gas passing around the earth interacting with the geomagnetic field of same is virtually identical to an electric motor though the geometry seems different. It is the case that the total effect perpetrated on us, on the planet, by the passing of the electrically conductive cloud of hot gas and further, that gas's interaction with the geomagnetic field is an inductive phenomena.
It is easy to forget that when talking about induction we're not talking about relative magnitudes of the flow of the gas but instead the instantaneous rate-of-change of that flow as being central to the effects we here witness. Most especially the preceding applies when focusing on the magnetic aspects. To be sure, the incoming stream interacts with, and in part, is trapped by the Earth's magnetic field, altering it's velocity and transferring momentum as it does so to form the Van Allen belts above or heads, but it is the resulting magnetic fluctuations induced throughout that drive the actual changes in "earth currents" that were so ferocious during the Carrington Event.
If an X-20 erupted on the face of the Solar disk, even very near to the center thereof, the total effect upon us here some few minutes later (light-travel time scale) would be negligible though the subsequent arrival of the mass of ejected gas would be have frightening effects on our civilization.
If, on the other hand, an extremely high magnitude flare occurred - virtually anywhere on the face of the visible disk - say, an X-40 or greater - then a resulting EMP (like the detonation of a 20 megaton thermonuclear device high in the stratosphere) would likely have near-instantaneous effects on the distribution grid on the sun-facing side of the planet. It might well be the case that the installed safety subsystems at most generating facilities would act in time to prevent a catastrophic, effectively incinerating, effect on the facilities themselves, but it is a near certainty that the Very High Voltage transformers which upconvert energy from the generating facilities to voltages making long-distance transmission of electrical energy practical would be summarily annihilated. The problem that would arise in this circumstance is that there are now only two manufacturing
concerns left operating globally at present that manufacture these extraordinary pieces of machinery and the minimum lag-time from order to delivery is two years (presuming that all of the requisite materials are already on hand without supply chain interruptions and that they themselves have ample electricity available to them for the manufacturing itself). Simply losing the grids over one hemisphere would be bad, but losing them globally would be an incalculable catastrophe. Consider that if there is no way available to transmit electricity long distance point-to-point then how would we be able to remanufacture replacements for these units?
Leaving aside the fact that the effects would be the worst in the developed world, resulting in "flash" starvation of hundreds of millions of people - if not billions - as our wondrously efficient, woefully interconnected and critically dependent supply chains vanished like smoke in the wind, how could this happen then?
It could happen as the consequence of a large magnitude X-Flare followed by a subsequent - and necessarily, geoeffective - high magnitude CME. When the mass began interacting with the terrestrial magnetosphere enormous ground currents would be induced by the action of the hot sea of gas flowing around the planet. Also, as a consequence, large voltage potentials would be induced in the ground plane - to which every electrical device on Earth is directly connected. It would not be enough to simply throw the breakers in your fuse panel to isolate your house, business and so forth from Earth voltages and grid fluctuations. Fluctuations on the ground plane itself could/would easily destroy whatever yet remained attached. Disconnecting the ground strap from your your panel(s) to the ground plane would be equally necessary until the large scale fluctuations subsided beyond the event. The actual events involved in this would come upon us rather stealthily. As the ground currents surged there would be no blinding, instantaneous grid-wide failure, no. Instead, the currents through the ground plane traveling into the transformers would slowly, steadily heat the cores in their oil baths until the frail windings began to boil their insulating coatings off at which point massive shorting would occur. Given that the Earth itself is non-homogeneous in it's make-up, it is also the case that the pattern of failure would be equally heterogeneous. Specifically, places like the eastern seaboard, especially, Eastern Canada would see the first failures (Canadian Electric companies have installed strip-mall sized buffers after the 1989 loss to Solar activity and are now relatively safe) due to the hard-rock underlying the region, the Laurentian Shield. But as one failure occurred there would be another, and another, ad infinitum as a cascade of failures shifted further of the burden to the remaining operational grid. The logical conclusion of this process would be the destruction of virtually every High voltage unit globally inasmuch as unlike a Solar EMP which would effect the "day side" only (approx.) the ground currents in the CME case would be global in character.
An enormous "buzz" has developed over the last few years relative to "EMP" events of Solar or instrumental origin but in the case of solar this particular effect would be limited except as noted above. Thankfully, we have a vast distance between us and our warm, somewhat tempestuous neighbor and it is this distance that along with the atmosphere and magnetic field in which life here is mainly cocooned that preserves us. The initial open-air testing of the hydrogen bomb in the 1950s early 1960s in the South Pacific is of course when first we became aware of the effects that an EMP pulse might have upon us. I have read a report - somewhere, it escapes me at the moment - that during one of the tests, in which one of the larger devices was detonated, that parts, if not all, of the island of Hawaii lost power, had equipment failures virtually simultaneously as the weapon was detonated. It is for this reason that I call "bull" on those harping on the possibility of a middle eastern agency deploying an "atom" bomb over the US to destructive effect. Hear me out.
Fission bombs have an upper limit beyond which - no matter how much more fissile material is added - simply doesn't produce any further corresponding yield. Our scientists ran into this problem rather early on during America's primal nuclear efforts, this led to the development of the H bomb, [fusion] thermonuclear weapons as it were. H-bombs don't really have an effective upper limit as to the amount of yield which can be obtained...just build a bigger bomb. However, there is a catch: H bombs are really, really difficult to engineer. Without going into detail, suffice it to say that the geometry of the device and the timing of the explosives necessary to coax a fusion reaction out of ordinary, cold matter are formidable--extremely so. The largest thermonuclear device ever tested was the infamous "Czar Bomba", the "King of Bombs" detonated by the Soviet Union circa 1960, which was designed to produce a yield of 100+ megatons TNT equivalent, but was actually only tested with two of it's four cores in place for a nominal yield of 52 megatons. For any who need more about this just traipse over to YouTube and search for "Czar Bomba", great footage BTW. But I digress, the probability that someone other than a major nation-state could develop atom bombs is crazy-high, it is only necessary to laboriously render out enough fissile material from uranium and then slap it together. But the converse is equally and inversely true for thermonuclear devices for the reasons lined out above.
As an aside, while I've been typing this, the polar convection graph over at stanford.edu has shot right up, as has the graph for interplanetary magnetic field. The figure being shown for the convection is nearly off the graph as it is currently scaled. It's about 02:30 CST [Sunday, July 15, 2012] and as I look now the Polar convection is actually above the numbered range on the graph, like when your going faster than your speedometer can show you, the IMF being 'way up there too. I expect that there might be some unhappy northern latitude utility company executives in the morning, the polar convection figure is still getting worse. If I read it right, pushing 280 Kv or more, been up there for quite a while now.
As always, May the Lord Bless and Keep us, His Children, everyone. - J.E.B. in Missouri