Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Monday, July 13, 2015

Sunspots and ice ages

If there's one feature of media that drives me the craziest, it's the practice of appending the words "scientists claim" to any damn thing they want to in order to give it unwarranted credibility.

Take, for example, the story that appeared over at RawStory (and also, in similar forms, at The Telegraph and The Daily Mail).  Entitled "'Mini Ice Age' On the Way In 15 Years, Say Scientists," this article takes a piece of legitimate and interesting scientific research and puts a sensationalized spin on it that, if I were one of the researchers, would impel me to write a rebuttal comprised of a single sentence: "I DIDN'T SAY THAT."

First, a little background.  The number of sunspots, which are electromagnetic storms on the surface of the Sun, has been observed to fluctuate on a cycle of about eleven years, but also to be subject to a second (much longer-period) cycle of 370-odd years.  This is the proximal cause of the Maunder Minimum, a time of low sunspot activity that lasted from 1645 to about 1715.

Sunspots in September 2001 [image courtesy of NASA]

Thus far, this probably would merit nothing more than a "So what?" from everyone but astronomy buffs.  Why would popular media even report on something like sunspots?  But the Maunder Minimum, at least in part, coincided with low temperatures in Europe -- the article in RawStory refers (correctly) to the Thames freezing over in winter during that period (although, as you'll see, even that is only one cherry-picked piece of the truth).

So to put it bluntly, the whole purpose of this story is intended to cast doubt on anthropogenic climate change.  "Damn scientists!" you're left thinking.  "Can't even decide if the temperature is rising or falling!"

The problem is, this is a flaw in the media's reporting, not in the science itself.  Let's take this claim apart at the seams, okay?

First, let's look at the basis of the claim -- that the Maunder Minimum predicts extremely cold temperatures.  All it takes is a quick trip to Wikipedia to find out that it's not that simple:
Note that the term "Little Ice Age" applied to the Maunder minimum is something of a misnomer as it implies a period of unremitting cold (and on a global scale), which is not the case.  For example, the coldest winter in the Central England Temperature record is 1683-4, but the winter just 2 years later (both in the middle of the Maunder minimum) was the fifth warmest in the whole 350-year CET record.  Furthermore, summers during the Maunder minimum were not significantly different to those seen in subsequent years.  The drop in global average temperatures in paleoclimate reconstructions at the start of the Little Ice Age was between about 1560 and 1600, whereas the Maunder minimum began almost 50 years later.
If you want to go a little deeper than Wikipedia -- and you should -- check out this cogent and well-written summary of the problem with correlating sunspots and ice ages by Mike Lockwood, professor of space environment physics and a director of research at the University of Reading.  Lockwood writes:
There is very little evidence that the lower global mean temperatures between 1400 and 1800 were caused by solar activity - there's more evidence it was associated with volcanic activity and/or internal oscillations in the climate system...  Much of what has been written in the media and on the internet fails to appreciate the difference between regional and global climates.  My research looks at a potential link between low solar activity and cold European winters. That's a regional and seasonal effect and not a global effect.
If that wasn't unequivocal enough for you, Lockwood goes on to say, "What's more, there's no evidence that summers in the Maunder minimum were any colder than usual.  This is not a 'Little Ice Age' - it is not an ice age of any shape or form."

Second, let's check and see if the scientists cited in the RawStory article actually said anything about an ice age starting in fifteen years.  The lead researcher, Valentina Zharkova of Northumbria University, presented her findings at the National Astronomy Meeting in Llandudno, Wales last week, and a summary appeared in  Here are a few relevant paragraphs:
It is 172 years since a scientist first spotted that the Sun's activity varies over a cycle lasting around 10 to 12 years.  But every cycle is a little different and none of the models of causes to date have fully explained fluctuations.  Many solar physicists have put the cause of the solar cycle down to a dynamo caused by convecting fluid deep within the Sun. Now, Zharkova and her colleagues have found that adding a second dynamo, close to the surface, completes the picture with surprising accuracy. 
"We found magnetic wave components appearing in pairs, originating in two different layers in the Sun's interior.  They both have a frequency of approximately 11 years, although this frequency is slightly different, and they are offset in time.  Over the cycle, the waves fluctuate between the northern and southern hemispheres of the Sun.  Combining both waves together and comparing to real data for the current solar cycle, we found that our predictions showed an accuracy of 97%," said Zharkova... 
Looking ahead to the next solar cycles, the model predicts that the pair of waves become increasingly offset during Cycle 25, which peaks in 2022.  During Cycle 26, which covers the decade from 2030-2040, the two waves will become exactly out of synch and this will cause a significant reduction in solar activity. 
"In cycle 26, the two waves exactly mirror each other – peaking at the same time but in opposite hemispheres of the Sun.  Their interaction will be disruptive, or they will nearly cancel each other.  We predict that this will lead to the properties of a 'Maunder minimum'," said Zharkova.  "Effectively, when the waves are approximately in phase, they can show strong interaction, or resonance, and we have strong solar activity.  When they are out of phase, we have solar minimums.  When there is full phase separation, we have the conditions last seen during the Maunder minimum, 370 years ago."
Is it just me, or did she say nothing about "ice ages?"

But the Maunder Minimum was cold, right?  Couldn't we still see a drop in temperatures if the predicted minimum occurs?  To answer that question, let's go back to Lockwood:
Statistically, we found a significant link between the occurrence of cold winters in the long CET record and solar activity.  By "significant" we mean that there was only a five per cent chance that we were being fooled by a coincidence...  In a paper with scientists from the Met Office's Hadley Centre, we used an energy balance model to show the slowing in anthropogenic global warming associated with decline in solar irradiance to Maunder minimum levels.  We found the likely reduction in warming by 2100 would be between 0.06 and 0.1 degrees Celsius, a very small fraction of the warming we're due to experience as a result of human activity.
Which hits on the central point.  My suspicion is that the hype surrounding the Maunder Minimum and sunspots has one purpose: to reassure us that our activity isn't going to warm the Earth further, and push the climate more out of whack than it already is.  "Don't worry," the media tells us.  "Keep burning your fossil fuels.  The Earth is going to be just fine.  In fact, we might be heading into an ice age!"

And because few people read any deeper than what appears in popular media, they're left with the further impression that the scientists don't know what the hell they're talking about.  We hear about global warming, and then there's an article where "scientists claim" that everything is cooling off.  Is it any wonder that laypeople throw their hands in the air and stop listening?

Which, of course, is what a lot of the powers-that-be want.  Altering the status quo is expensive, and requires unhooking our government from the influence of the fossil fuel industry.  No way can we have that happen.

No way.

Easier to slip into the media misleading stories that subtly cast doubt on the research itself, along with those nasty little words -- "scientists claim."  After that, they can sit back and let natural cynicism and distrust do the rest.

1 comment:

  1. Well, here’s a radio interview with Zharkova that shows pretty clearly that she is directly contributing to Little Ice Age hype. I don't know that in this particular case we can blame the media exclusively for the misleading hype.