There’s something alluring about a phenomenon or object named after at least one surname, though it’s better when there are two. ‘Look Around You’ knew about this when it mentioned the Beaumont Grille in the vegetable orchestra or whatever it was. The Helvetica Scenario is a bit different. If you didn’t already know what it was, the Carrington Event would be one of these. Here I run up against my usual problem of not knowing whether other people know stuff, so I’m going to run the risk of boring you all stiff by going into it.
The Carrington Event was a CME (coronal mass ejection: horrendous Sun kablooie, to paraphrase Calvin and Hobbes) occurring on the 1st and 2nd September 1859. It caused aurora australis to be visible as far north as Queensland and aurora borealis as far south as the Caribbean. This might be the kind of spectacular celestial display many people would kick themselves for having missed, but it had another more serious effect on human technology, namely the telegraphy network. Operators reported receiving electric shocks from their equipment, it caused pylons to emit sparks and it was even possible to send telegrams over wires with no technological source of current. It’s thought that the auroral event was associated with a previous CME which cleared a path for a second one against which Earth was then less protected. The magnetometer at Kew showed the strength of the event and the amateur astronomers Richards Carrington and Hodgson became the first people to observe a solar flare, hence the name. It’s possible that ice cores show traces of this event via concentrations of nitrates, although there can be other causes for this such as forest fires.
The Sun has a roughly eleven year cycle involving sunspots and other activity. Sunspots are cooler vortices on the visible solar surface which tend to proliferate and die down over this period, caused by a “winding up” of the magnetic field, and the latitude and quantity of the spots also varies. At the maxima, solar flares are more likely to occur, and the overall brightness of the Sun is slightly greater, which puzzles me a bit because sunspots are dimmer than the rest of the photosphere (surface). There’s also a longer cycle responsible for the likes of the Mediæval Warm Period, which lasted from 950-1100 CE. I don’t know if the Little Ice Age was connected. Climate change denialists have attempted to propagandise the public using this fluctuation, but in fact if you take it into consideration it shows that the overall temperature of the planet rose while the Sun was weaker and that the troposphere warms while the stratosphere cools because heat is being trapped close to the ground, whereas were it due to the Sun increasing its output it would heat the upper atmosphere more than the lower.
This was a geomagnetic storm. The Sun gives off a constant stream of charged particles called the solar wind. This fluctuates in intensity from time to time, and various events on the Sun drive these storms, such as CMEs. Because the magnetic field of the Sun is twisted during a solar maximum, spirals can form in the photosphere which then become realigned and the excess energy drives a large volume of more intense plasma away from the surface of the star at high speed. When it reaches our own magnetic field, it pushes it down on the sunlit side and increases the length of the tail on the dark side. This causes a similar tension in the magnetosphere here as it did on the Sun’s, and this has various effects. For instance, it can improve radio transmission by increasing the charge in the ionosphere, off which terrestrial radio waves can be bounced to increase their range, but also disrupt radio, damage electrical cables and cause power cuts and damage to satellites.
The Carrington Event is the strongest geomagnetic storm to affect Earth since it became possible to record such events reliably, but there have been earlier events which seem to have been similar. For instance, on the 4th November 1174 CE, a red light was seen across Europe and in December 940, red lights described as like ranks of soldiers in the sky were described in the annals of the Abbey of Sens. The difference, needless to say, is that the Middle Ages in Europe were not noted for their sophisticated electronic gadgetry, and unsurprisingly, religious interpretations were put onto these events. They were also probably not all associated with CMEs.
Back in the day, we had no electrical or electronic equipment. Although the filament lamp had been invented by 1859, said filament was made of platinum and the bulbs were ridiculously expensive and unreliable. The time for Joseph Swan’s patent was still a decade in the future, and telephones were even further off. As for mains power, that wouldn’t be happening anywhere until 1886, when Godalming got it. Hence we were more resilient back then. Life could just carry on as it always had with the minor detail of a few telegrams not getting through. It’s hardly even worth mentioning that this is no longer how things are.
If something like this happened today, it could destroy the internet, the GPS system and the cellular radio network. Moreover, if it was able to induce current in disconnected telegraphy systems, it wouldn’t be any good just to unplug everything, because delicate electronics could still be burnt out by the event. Two questions therefore arise. How often do they happen? How could we build in resilience to a world which has never encountered such a catastrophe when all the stuff is already out there?
In 2012, there was a somewhat similar event. On 23rd of July, a CME of about the same strength as the Carrington Event took place, crossing our orbit nine days away from the position of the planet. There are two solar observation satellites, STEREO-A and STEREO-B, one ahead of and one behind Earth. STEREO-A was able to observe and send back data from near the location, and was not damaged by the event, producing this I think famous image:
This doesn’t look like what one normally thinks of as a solar flare, which in my mind’s eye at least look more like this:
However, because the flare is heading directly for the satellite, it’s foreshortened and looks as if it surrounds the Sun. We’re seeing the Sun, or rather the blanked out bit where the Sun would be, through the CME. This is called a “halo” CME because it’s seen head-on, and that would be significant for us but there’s no real difference other than perspective. It’s interesting, incidentally, that this happened in 2012, that well-known apocalyptic year, because if we’d been just a little bit further along in our orbit or it had come out of a different bit of the Sun, we really would’ve experienced a major devastating event that year.
On 13th March 1989, a geomagnetic storm affected us strongly enough to have significant consequences. The auroræ almost reached the tropics, causing some to worry about nuclear war. Some satellites, and the space shuttle which was in orbit at that time, were also affected. Most notably, Quebec suffered a nine-hour powercut. It was affected more strongly due to the nature of the rock underneath the power lines and the fact that they were unusually long. Other power lines were protected because action was taken to ensure this, which is a bit reassuring.
The strongest storm of the twentieth century occurred from 13th-15th May 1921, causing fires and affecting undersea telegraph cables.
The risk per decade of a Carrington-level event is estimated at one in eight, clearly greater towards the maxima. They’re likely to induce currents in long metal structures, which as well as including powerlines and telecommunications cables also means gas and oil pipelines, so explosions and loss of fossil fuel supply seem likely to me but I’m not an expert of course. One suggestion for coping with them is to isolate transformers on the power grid and turn off satellites for the duration, which is several days. This would cause disruption in itself, but not as much as all the satellites and electrical devices being zapped out of existence permanently. A warning of some kind would be necessary and there would currently have to be enough of a workforce to facilitate this, meaning that currently this would be more dangerous during a holiday period. Aircraft would also be affected.
It’s important to note that CMEs don’t travel anywhere near the speed of light, meaning that satellites located at one of the points of balance between the Sun’s and Earth’s gravity, known as Langrange Points, would have time to transmit a warning of about an hour, and there are satellites located there for that very purpose. The specific risk to transformers is with step-up transformers, which overheat if there is a continuous supply of electrical current on the other side such as a hydroelectric power station, because the current has nowhere to go.
In fact, then, given forewarning it looks like we aren’t doomed after all, provided mitigating technologies are installed, and there are other risks such as flooding and hurricanes which are a more immediate threat. But that’s we humans. The Sun is a particularly stable star, and it’s in any case a given that we’ve come this far no matter how improbable it is because of the very large number of apparently habitable planets in the Universe. What isn’t clear is whether this is a potential Great Filter.
The Fermi Paradox is of course “where is everyone?”. There seem to be a very large number of suitable locations in the Universe for tool-using intelligence to appear and achieve space travel, but we are not aware of any intelligent aliens. Various explanations have been offered for this and one of them is stellar flares. We may have got lucky with our Sun being unusually stable. Over the past 140 years, apparently Sun-like stars fluctuate an average of five times as often as ours. If a civilisation developed electronics and became dependent upon them early enough, it might well not have put any such measures in place, and it’s possible that what’s happening is that civilisations are developing fine up until they reach twentieth century levels of technology, at which point they get damaged and have to start rebuilding from a much lower level. In fact, it could even be that the Sun is only unusually quiet right now and will later become more like a typical Sun-like star, with Carrington Events happening about once every twenty years or so.
Another issue here is with red dwarfs. Red dwarfs are the most common type of star and are cool and dim. However, they may be particularly suitable for Earth-like planets, because although such a planet would have to orbit so close to the star that there would be no relative rotation and it would be eternal day on one side and eternal night on the other, it turns out that the twilight zone would be at a comfortable temperature. However, red dwarfs are very often also “flare stars”. Proxima Centauri, Wolf 359 and Barnard’s Star are all flare stars. These are stars whose proportionate activity ramps up dramatically and frequently, which is not surprising considering their low mass: a flare on a red dwarf would be proportionately a much larger even than on the Sun. Because otherwise habitable planets are orbiting so close to them, this would be a much more destructive event which would also heat the planet up beyond habitable temperatures, at least to the twilight zone.
In conclusion then, the Carrington Event may not be as big a threat as it seemed at first. We’re aware of them and have taken steps to protect the infrastructure. However, at some point they may become much more frequent without warning, and they may have led to a situation where even widespread intelligent technological life finds it difficult to get beyond early industrial phase technology. In the apparently most suitable environments of all for life, CMEs may be so severe that they prevent the evolution of complex life even if that’s likely. Also, we may have just got lucky here, and lady luck has no memory, so that luck could end at any time.
A Box Of Chocolates 