5X5 Episode 35

No sunspots in August - will this lead to a period of solar cooling?
S: This is the SGU 5x5 and tonight's topic is. We are joined for this podcast by from Astronomy Cast. Pamela, thanks for joining us

PG: Oh, thanks for inviting me.

S: So we are just coming out of our solar minimum, meaning the 11-year cycle of the sunspots, and the month of August had no recorded sunspots and this is the first time that has happened in almost a century.

PG: Yeaaaaaah... This is one of the problems. The sun is a star and stars are intemperate objects. Even Shakespeare acknowledged them as being inconstant... Our sun has a magnetic field; it likes to flip itself inside-out every, oh, 11 years or so, and in the middle of the flip, it is busy and coated in sunspots. But once it has its fields aligned, it tends to have very few sunspots on the surface. The sunspots are just places where the magnetic field lines stick themselves out and go back in. Our sun seems to have a nice happy magnetic field right now that isn't interested in turning itself back inside-out. One month isn't all that long to worry; it's if this keeps going and keeps going that we start to be concerned. And that has happened before.

R: What's all this about an ice age?

PG: (laughs) Well&mdash;

R: I'm being frightened.

PG: Well, you shouldn't be, at least not yet. Especially with global warming. Back from 1645-1715, there was what we call the "". This is a period in time when there were very few sunspots recorded. Under 10 per decade, basically, during that period. And it just happened to coincide with a mini-ice age, where for various reasons, the northern hemisphere, specifically Europe, was much, much colder during the winter than it normally was, although recorded temperatures show that... or at least, recorded estimates of temperature based on what the people reported, say that during summer, it was just fine. So it seems to be that with a lack of magnetic activity from the sun, the decided to move itself too far south during the winter and so Europe got more cold than really was comfortable for anyone.

S: What do you think about the theory that the sun's magnetic field helps protect the Earth from ? So with a more stable or decreased magnetic field, there is more cosmic rays, which increases the cloud formation on the Earth, which then reduces the temperature by blocking out more of the sun. And that was causally related to the mini-ice age.

PG: I think it is a complicated process and we're still trying to figure things out. Magnetic fields are one of the most complicated things for any astronomer or physicist to work with. And the Earth has its own magnetic field, and what we don't know is what were the temperature gradients on the planet? What were the... what was the rate of ice falling into the North Atlantic? Other things can affect a lot of this, just by introducing more fresh water into the sea you can change all sorts of things. The&mdash;what was the Earth's magnetic field doing? The sun's magnetic field definitely did have something to do with it. Saying any one thing in particular is difficult. There is also evidence that there is a lot more volcanism going on in the period. So we are trying to decouple too many different things to say that any one thing caused, for instance, cloud cover. Clouds could just as easily have come from having extra volcanic ash in the air. There's too many different things to uncouple.

E: Yeah, according to this article, it says that this could possibly also be affecting things such as: wavelengths in the far ultra-violet, affecting ozone production, and natural production of isotopes such as, which apparently might also be tied to the solar activity.

B: Yeah, just for comparison, when things are running normally, when the sun is active, we might see a hundred or more sun-spots in a given month. And at the other end of the spectrum, normally when the sun is very inactive, it'll briefly drop to near zero and then quickly the sunspots will return as a new cycle begins. That's what we usually see.

S: But this year it's been, like, less than three per month, and again, August has seen zero spots by some observers and I think like a half a point or a half a spot by some other observers, but essentially no sunspot activity. And it's, again, just a little bit longer than normal, or average, we should say, and just really I guess, it will depend on how long this is going to last. But one of the interesting things is the potential irony of the solar forcing of the climate perhaps now moving in a direction that might counter balance human forcing through man-made greenhouse gases and global warming. Wouldn't it be ironic if the man-made contribution ended up helping stabilize our climate because we just happen to be going through a solar period of cooling.

E: That would be the ultimate irony. I would say.

(laughter)

S: But as&mdash;Pamela, I think I agree from what I've read so far, it's so complicated, basically, that at this point it is not possible to make any kind of reliable predictions.

PG: But the nice thing is that if it does cause a mini-ice age, well at least now we have the tools to measure it. So, I'm all about the sun doing cool things that we can discover. There is lots of Ph.D.s hidden in this research; it's just waiting to see what is happening is the annoying part.