Last August I wrote about Solar Cycle 24, and I continue to get requests for an update on what is happening with sunspots and the geomagnetic cycle of the sun. The original August 3 post on The Agonist can be found here: http://tiny.cc/A3M40.
The quick answer is that the sun remains in an unusually extended solar minimum. The sun’s geomagnetic field reverses polarity roughly every 11 years. At the peak of this solar cycle, the field is very active, represented by the frequency with which the field breaks through the sun’s surface, causing sunspots, solar flares, and an active solar wind which brings electromagnetic radiation to the earth. This radiation interferes with satellite transmissions, causes brilliant displays of the aurora around the earth’s poles, and can pose risks to passengers on airplanes flying above a certain altitude. During the solar minimum all of this activity is much reduced or disappears completely for awhile until the new cycle kicks in.
The recently completely Solar Cycle 23 ended in 2008, and by now the sun should be displaying more geomagnetic activity each month. There should be, for example, about 50 sunspots appearing by now each month, peaking at around 250 a month in 2013. The cycle would normally ramp down after that until the next solar minimum is reached around 2019 when a new cycle will commence.
The problem – if it can be described this way – is that while the new cycle 24 has kicked in, it remains in a minimum stage. While there should be have been 50 sunspots in December, there were only 16. During some months last year there were no sunspots at all. At this pace of slow growth in the cycle, by the time we reach 2013 there likely will not be 250 sunspots per month. Half of that number may even be unlikely.
Mankind has studied sunspots for centuries, and the solar cycle has been plotted against historical weather data to indicate that earth’s temperature heats up when the cycle is very active, and cools down when the cycle is very quiet. This makes sense, because less radiant heat is reaching the earth if the sun lacks sun flares, and if the solar wind that pulses through the solar system is more subdued than normal. While scientists agree it makes sense for earth to be colder now during an extended solar minimum, they lack evidence establishing just how strong this link really is. For example, does a cooling effect from the solar minimum cancel out any man-made warming as a result of carbon dioxide buildup?
Anecdotally, from China to Britain to the U.S., winter this year seems to be much colder than usual with heavier snowfalls, just as autumn and summer were cooler than normal. The extended solar cycle minimum the sun is now experiencing many not be the principal or direct cause of our winter weather, but many would agree it is at least a factor, and a growing number of scientists think it could well be the principal contributor to a harsh winter.
Hence many more eyes than usual are watching this current solar cycle. There have been other instances where the solar minimum is extended for years – the longest cycle in fact was for 16 years. There have been two specific instances where the sun went extremely quiet, in hibernation really, for over 50 years, and weather on earth was decisively cooler. One such event during much of the 17th century seems tied to what is known as the Little Ice Age. This is yet another reason to monitor the solar cycle carefully, in case we are at the beginning of one of these hibernation periods.
Due so with caution, however. Watching the solar cycle can give you a sense of complete helplessness. Short of a comet or asteroid hitting the earth, and possibly including man-made effects like global warming or a nuclear winter, nothing is more important to life on this planet than what happens with the sun.