In the decades leading up to 2020, we were warned repeatedly about a global pandemic, a once-in-a-century occurrence, the likes of which hadn’t been seen since 1918-1919. The Obama administration understood that it was only a matter of time and had the presence of mind to try and prepare us, but the current occupant ignored and dismantled that preparation, leaving us vulnerable, and so here we are, beyond 180,000 deaths in the U.S.
Another catastrophe is in the making, and once again it really is only a matter of time. We WILL at some point be hit with a once-in-a-century geomagnetic storm caused by the Sun, as we were in 1859 and 1921 (and very nearly were in 2012). Only this time, because of our absolute dependence on an aging electrical grid, the cost will be in the trillions of dollars. Many millions of people in densely populated areas like Washington, D.C., New York, and Boston could be without power for up to 2 years. It’ll make coronavirus look like a walk in the park.
We’d better sincerely hope that Donald Trump, or anyone like him, isn’t president when it happens.
Catastrophes, although terrifying, of course pique our curiosity as well, because they can be objectively fascinating. September 1 marks the first time a solar flare was directly observed, back in 1859. And this wasn’t just any solar flare; it was the cause of a barnburner called the Carrington Event, and it set the benchmark for what a huge solar storm can do here on Earth.
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Sunspot records are a little bit older than the U.S.A., dating back to 1755, the beginning of Solar Cycle 1. There is a cycle about every 11 years, and we are now entering Solar Cycle 25. “Gen XXV”, as it were. This one is being predicted by most (but not all) to be comparable to the last cycle in terms of sunspot activity:
Forecast for Solar Cycle 25 by an international panel co-chaired by NOAA/NASA
The Earth’s magnetic poles reverse erratically every few hundred thousand years or so — the last time it happened was 780,000 years ago — but the Sun does it reliably every 11 years. The Sun will have relatively clean magnetic North and South Poles reestablished in the mid-2020s, and that will be the peak of solar activity for Cycle 25.
Sunspots generally come in pairs, with an arch of magnetic field lines running from one to the other.
Hale’s polarity laws, dating from 1919, say that each sunspot pair within the Northern or Southern solar hemisphere has the same magnetic polarity pattern, but they show opposite polarity patterns between the two hemispheres, and these polarity patterns switch every cycle.
Typical arrangement of sunspot pairs and their magnetic polarities
Here in 2020, new sunspots are showing the expected polarity reversal. Thus, Solar Cycle 25 is underway:
Yellow circles = positions of sunspots of Solar Cycle 24. Red and blue triangles = identified magnetic regions which conform to the polarity orientation expected from Solar Cycle 25.
The above is called a “butterfly diagram”, where we plot the latitude of sunspots over time. At the beginning of a cycle, they tend to show up at higher latitudes, then they drift toward the equator as the cycle goes on. This happens over and over, as you can see from this butterfly diagram for the last 150 years:
Top: sunspot latitudes over time; Bottom: sunspot area over time
Solar Cycle 25 last said hello with a little burp of charged particles on August 16 that passed by Earth August 20. No biggie. But these burps will get bigger over the course of the cycle.
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The magnetic field lines that run between sunspots occasionally meet each other and “reconnect”. If they are oriented the right way with respect to each other, you get a violent ejection of charged particles from the Sun, or a coronal mass ejection.
The first coronal mass ejection to be witnessed directly was during the total eclipse of July 18, 1860:
Drawing of the July 18, 1860 total eclipse, showing a coronal mass ejection (at lower right) in progress
The Sun, especially its corona, is so hot that atoms don’t hold together anymore. They split up into protons (positive charge) and electrons (negative charge), and those just float around in a state of matter called plasma, or a gas full of charged particles. When charged particles move around, as they’re always doing within the Sun, they induce a magnetic field. That’s represented by the lines in the main diary picture.
Each line in a magnetic field is something that charged particles flow around and around in little spirals. If you hold out your right hand and give the “thumbs up”, the direction of the magnetic field line points the way your thumb does, and the charged particles flow in the direction the rest of your fingers are pointing, around and around.
Two magnetic field lines pointing in opposite directions will repel each other, but if they are pushed together and do connect, that repulsion energy gets manifested as explosive outflow:
So all that plasma circling the magnetic field line gets ejected very rapidly, and you get a coronal mass ejection. This has actually been caught on film! NASA demonstrates:
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The first solar flare ever directly observed was by English astronomer Richard Carrington on September 1, 1859. That was no ordinary solar flare, either; it gave rise to the Carrington Event, the strongest geomagnetic storm to hit Earth on record:
While engaged in the forenoon of Thursday, September 1, in taking my customary observation of the form and positions of the solar spots, an appearance was witnessed which I believe to be exceedingly rare. The image of the Sun’s disk was, as usual with me, projected on a plate of glass with distemper of a pale straw color, and at a distance and under a power which presented a picture of about 11 in. diameter. I had secured diagrams of all the groups and detached spots . . . when within the area of the great north group (the size of which had previously excited general remark), two patches of intensely white and bright light broke out, in the positions indicated in the appended diagram by the letters A and B, and of the forms of the spaces left white.
My first impression was that by some chance a ray of light had penetrated a hole in the screen attached to the object-glass, by which the general image is thrown into shade, for the brilliancy was fully equal to that of direct sun-light; but, by . . . causing the image to move by turning the R.A. handle, I saw I was an unprepared witness of a very different affair. I thereupon noted down the time by the chronometer, and seeing the outburst to be very rapidly on the increase, and being somewhat flurried by the surprise, I hastily ran to call some one to witness the exhibition with me, and on returning within 60 s, was mortified to find that it was already much changed and enfeebled. Very shortly afterwards the last trace was gone, and although I maintained a strict watch for nearly an hour, no recurrence took place. The last traces were at C and D, the patches having traveled considerably from their first position and vanishing as two rapidly fading dots of white light. The instant of the first outburst was not 15 s different from 11 h:18 min Greenwich mean time, and 11 h:23 min was taken for the time of disappearance.
The most obvious effects were brilliant auroras at unusually low latitudes, as far south as Hawaii:
Shortly after midnight on September 2, 1859, campers in the Rocky Mountains were awakened by an "auroral light, so bright that one could easily read common print. Some of the party insisted that it was daylight and began the preparation of breakfast", according to the Rocky Mountain News.
The Earth’s magnetic field was distorted by the force of the ejection, and a changing magnetic field induces an electric current wherever electrons are able to flow. This happens in whatever complex orientations the magnetic field might have over a particular area and can affect wires running in different directions differently and unpredictably.
Fortunately, large electrical wires at that time were carried mainly only within telegraph transmitters, but many of them got fried irreversibly, shocked their operators, and in some cases started fires. The Carrington Event is still the strongest known geomagnetic storm to hit us, although there have been a few other strong examples in the last 100 years:
1) Carrington event, September 2, 1859 (Dst = -1600)
2) Great Storm of May 14-15, 1921 (Dst = -900)
3) March 13, 1989 Superstorm (Dst = -589)
4) November 20, 2003 (Dst = -472)
5) Halloween Event, October 30, 2003 (Dst = -401)
What is the Dst?
The Disturbance Storm Time (Dst) index is a measure of geomagnetic activity used to assess the severity of geomagnetic storms. It is expressed in nanoTeslas (nT) and is based on the average value of the horizontal component of the Earth's magnetic field measured at four near-equatorial geomagnetic observatories. It measures the growth and recovery of the ring current in the Earth's magnetosphere. The lower these values get, the more energy is stored in Earth's magnetosphere.
Earth’s magnetosphere, always distorted away from the Sun by a regular stream of charged particles called the solar wind, but much more so during a coronal mass ejection
Number 2 on the list, The Great Storm of 1921, was still quite serious:
from the New York Times, May 16, 1921
Around 02:00 GMT on May 15th, a telegraph exchange in Sweden burst into flames. About an hour later, the same thing happened across the Atlantic in the village of Brewster, New York. Flames engulfed the switch-board at the Brewster station of the Central New England Railroad and quickly spread to destroy the whole building. That fire, along with another one about the same time in a railroad control tower near New York City’s Grand Central Station, is why the event is sometimes referred to as the “New York Railroad Superstorm.”
The 1989 “superstorm” caused a 12-hour blackout throughout the entire province of Québec and loss of communication with many satellites for several hours. It also fried some transformers in the U.S.:
The copper core of the "generator step up" (GSU) transformer at the New Jersey Salem One Nuclear Plant melted during the 1989 Storm
Even the Halloween Event of 2003, for its part, led to red aurorae over Maryland:
Red aurorae over Mt. Airy, Maryland, October 2003 (three combined 8-second exposures)
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We’ve been very lucky in the 21st Century so far. Two Carrington-like events have occurred, but neither happened to be pointed at Earth.
Coronagraph image (blocking the Sun at center) from NASA’s Solar and Heliospheric Observatory (SOHO) satellite
Even though Solar Cycle 24 doesn’t look like much, it contained the very powerful July 23, 2012 event, which was comparable to 2001. Here we get a much more dramatic feel for the power of it. At 0:20 the charged particles erupt out of the coronagraph, and near the end (0:48), we see a few little burps followed by the massive ejection, shown with respect to Earth’s position (the blue dot at right) and the position of the STEREO-A spacecraft, which recorded the event. Whew! We dodged a major bullet here:
Daniel Baker of the University of Colorado studied the 2012 event along with NASA and had this to say about it:
I have come away from our recent studies more convinced than ever that Earth and its inhabitants were incredibly fortunate that the 2012 eruption happened when it did. If the eruption had occurred only one week earlier, Earth would have been in the line of fire. In my view the July 2012 storm was in all respects at least as strong as the 1859 Carrington event. The only difference is, it missed.
The odds that a Carrington-class storm will actually hit Earth in any upcoming ten-year period are about 12%. According to a study by the National Academy of Sciences, the total economic impact of such an event, just in the first year, could exceed $2 trillion. Another study for Lloyd’s of London put the figure at $0.6-$2.6 trillion.
Part of the reason it would be so costly is that people all along the East Coast of the U.S. (among other places) could be without power for one to two YEARS, disabling not only electrical power but water distribution. The Lloyd’s report puts it this way...
Areas most likely to be without power for an extended period (up to 2 years) in the event of a Carrington-like solar storm. Red, orange, and yellow areas would have significant outages, with red the worst
...while the National Academy of Sciences report is a little less nice about it:
Regions susceptible to power grid collapse during a 4800 nT/min geomagnetic field disturbance at 50° geomagnetic latitude, where the densest part of the U.S. power grid lies. The affected regions are outlined in black. Analysis of such an event indicates that widespread blackouts could occur, involving more than 130 million people. A disturbance of such magnitude, although rare, is not unprecedented: analysis of the May 1921 storm shows that disturbance levels of ~5000 nT/min were reached during that storm.
The same geographic emphasis was also found in a study from earlier this year. Here is a map of the induced electric field for transmission lines projected in a once-in-a-century geomagnetic storm that takes into account the conductivity structure of Earth's interior. Blank areas aren’t zero; they just weren’t analyzed:
Major problems in major population centers
It just so happens that there is an anomalously high degree of electrical resistance within the upper mantle that lies underneath the region of yellow along the Eastern seaboard, where population density and power consumption are high. Just our luck.
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We still understand only little about how the magnetic field of the Sun is formed, and we can’t predict when the next coronal mass ejection will take place. When it does, we’ll have perhaps 24 hours to prepare and try to minimize the damage. It’s very unlikely we’ll spend all the money it’d take to modernize the electrical grid so that it can actually withstand another Carrington event. We won’t do that now at least, but the Sun will eventually force our hand.
It really is a new age of solar astronomy, with new space probes, Earth-based telescopes, and observation techniques being developed rapidly. But even if we learn enough about the Sun to predict solar storms, until we radically alter our electrical infrastructure, we really are sitting ducks. One heck of a crisis awaits a president of the not-too-distant future.
Can we please pick competent ones from now on?
