Sunspots influence climate

UNIVERSITY AT Buffalo scientists working with ice cores have solved a mystery surrounding sunspots and their effect on climate that has puzzled scientists since they began studying the phenomenon. The research, published in the journal Geophysical Research Letters, provides striking evidence that sunspots — blemishes on the sun's surface indicating strong solar activity — do influence global climate change, but that explosive volcanic eruptions on Earth can completely reverse those influences.

"Knowing the mechanisms behind past climate changes is critical to our understanding of possible future changes in climate, such as global warming, and for assessing which of these changes are due to human activities and which arise naturally," explained co-author Michael Stolz of the Department of Physics in UB's College of Arts and Sciences.

According to the UB researchers, their work reveals two different mechanisms by which climate is affected by cosmic rays, charged particles that stream toward Earth and which are strongly influenced by solar activity.

To confirm any connection between sunspots and climate, a consistent correlation would have to be observed during many solar cycles, Michael Ram, professor of physics at UB explained. That's what he and his graduate students and co-authors have done with their study of ice cores, long cylinders of ancient ice from Greenland that serve as a frozen archive in that they record climate details from thousands of years ago.

Plain old dust, Ram added, holds the key in these experiments because it reflects how dry conditions were in a particular year. "Dust is a very sensitive parameter of climate," he explained.

Drawing on climate data derived from ice cores, the scientists used laser-light scattering techniques to determine the level of dust in the atmosphere for roughly the past 300 years, which is how far back sunspot data have been recorded.

The scientists started out with the assumption that a low level of cosmic rays on Earth resulting from high sunspot activity would lead to less cloud cover and less rain, with resulting high dust levels. "This was true for the first three or four solar cycles studied, from about 1930 to 1962, but then the correlation reversed itself, demonstrating that the mechanism couldn't be what we thought," said Ram.

It turned out that during those 32 years of positive sun/dust correlation, there was relatively little explosive volcanic activity worldwide. The researchers found that the same conditions existed between 1860 and 1882. Each of these relatively `quiet' periods came to an end with increased volcanic activity.

For example, in 1883, the Indonesian volcano Krakatau erupted in one of the deadliest volcanic disasters, killing 36,000 people. At the same time, the data started to exhibit low dust concentration whenever there was high sunspot activity, a correlation that violated the scientists' original assumptions.

"By carefully studying the timing of other volcanic eruptions, we found that they definitely coincided with all of the correlation reversals between sunspots and climate," said Ram.

"All energy comes from the sun, but the change in the visible radiation from the sun during any one of the solar cycle is less than one half of a per cent," explained Stolz. "Scientists have said it's impossible that so small a change could influence any signal in the climate.

But here we have evidence to show that it's not just radiation energy from the sun that is affecting climate, it's the solar-modulated cosmic rays that have a strong influence because of their impact on cloud cover."

With fewer clouds, and therefore less rain, the scientists reasoned, maximum sunspots should cause levels of atmospheric dust to rise.

But, the researchers discovered, during periods of high volcanic activity, high sunspot activity also results in high levels of atmospheric dust.

According to John Donarummo, co-author of the paper, it has long been known that volcanoes add more dust and more sulphates to the atmosphere.

The UB team discovered that these additional sulphates cause cosmic rays to have a pronounced effect on Earth by spurring the formation of small droplets in the atmosphere that, in turn, cause the formation of a type of cloud that does not produce rain. "During these times of high volcanic activity, the sunspot/climate correlation reverses and dust levels rise, even in the absence of high sunspots," explained Stolz.

I'm skeptical, on several levels. One, the cosmic ray to dust causal mechanism seems rather weak. In fact, every one of the causal links seems rather weak, putting most of the weight on the statistical analysis. That is rarely a good sign.

Two, it is easy to encounter spurious correlations in long times series. When you see "correlations" "reverse" numerous times in a 300 year time series, the most plausible explanation is not a complicated twiddle flipping on and off at irregular intervals, it is just that there isn't any real correlation at all. No correlation and rapidly and irregularing switch correlations look precisely the same.

And you'd expect to find irrelevant matches to imputed "flips" in correlations to any of dozens of other series over the same period. Like correlations between who wins the super bowl and which way the stock market goes, these mean nothing. But will automatically arise for some matches, just because each goes one of two ways every year.

A good test of whether one might be being fooled by such effects is the scale of the supposed flips in correlations compared to the overall length of the time series. You expect "runs" of length on the order square root of overall length, even from purely random, unreal relations. So if you see 15-20 years of x, and 15-20 years of y, in a 300 year time series, there is every reason to be suspicious that it is purely an artifact.

The article also notes 0.5% variations in solar activity over typical solar cycles. That amounts to approximately 2 watts per square meter (adjusted for only part of the earth's surface being illuminated, etc). Which incidentally is about the scale of modeled greenhouse effects from past observed CO2 changes, and about half those predicted for doubling atmospheric CO2.

There is also at least anecdotal evidence that the variations in solar activity over more pronounced solar cycles, less frequent and associated with more extreme changes in sunspot activity, may be somewhat larger, perhaps double. In particular, the "solar minimum" associated with the first half of the 1600s had astronomers reporting virtual no sunspot activity for extended periods, while tree ring data says climate got significantly cooler.

The most plausible explanation of these effects is not through a twiddle with dust and cloud formation, or any resulting amplification of signal, but simply through varied total solar output, directly to mean (and equilibrium - some short run transition effects) temperature. Unless the ice core data force an assumption of large amplification of solar variation signal, there is very little reason to suppose there is any.

Indeed, part of this looks to me like another "amplifier hunt", trying to find something - anything - in the climate system that can take a tiny input (of the scale of variations normally seen) and boost its climatic effects 10 fold. For those in Palm Beach who may think such things are a matter of course, that is not at all the case.

There are scads of mere allegations about possible mechanisms of that kind. But only allegations. The reason there are so many is the whole global warming crowd needs such amplifiers, because the mechanism they do have (CO2 direct greenhouse) are too small to support their scaremongering predictions. This results in a regular crop of "maybe there is this" or "maybe there is that", all amplifiers, whose sole motivation is to save the prediction, not to investigate the actual linkages among subsystems of the global climate.

But typically when such things are investigated by serious physicists, they don't show large scale amplification effects for anything like the scale of variations typically seen. Thus, some said "maybe cloud cover is so sensitive that is magnifies small changes in a power "driver" into large temperature effects". Maybe pigs have wings. Go look, and you find cloud cover over a period of decades changes by on the order of 1 percent, in the wrong direction, thus acting as a minute damping force but basically letting changes to power terms effect global mean temperature "as is". Go look, and pigs don't have wings, either.

To me this report looks like statisical data mining of artifacts out of long time series in support of allegations of climatic amplifiers. The fact that they link it to sun activity rather than CO2 variation might make naive readers think they are global warming debunkers, and individually they might be for all I know. But the general technique (time series mining) and characteristic conclusion (some complicated hypothetical twiddle with weak causal links is supposed to dramatically amplify minute power term changes) both stick out like sore thumbs, screaming "epicycle hunt."

Not kilowatts, watts, and that is for illuminated area. It is usual to track these things in total area, which is 1/4th as much. (The earth re-radiates heat in all directions while only being warmed on one side. "Tangential" or angled illumination produces less than straight overhead at noon, etc, thus the 1/4 figure rather than 1/2).

So 0.5% is ~1380 divided by 4 (re-radiating area) divided by 100 (percent) divided by 2 (half a percent) or ~1.7 watts per square meter. That is roughly the same order of magnitude as the predicted change in direct greenhouse effect from observed past changes in atmospheric CO2. So yes, it is the right order of magnitude for explanations about these things.

However, it is not the right order of magnitude for the predictions the scaremongers are interested in. Because the change in equilibrium mean temperature goes as the one-fourth power of the change in the power term. As per Boltzman's law, literally true for black bodies, the right first order approximation for most other things. E.g. the earth's albedo is on the order of 0.8, 1 being black-body.

So, change solar input to 1.005 of previously, and the equilibrium temperature goes 1.001247663, in degrees Kelvin. Or about 0.36 degrees C. Geez Louise, same order of magnitude as observed changes in mean temperture over century time scales. But the scaremonger predictions are changes of 3-5 degrees C, so they need 8-14 times as large a temperature change.

Meaning they need power changes on the order of 4-7%, or 14-24 watts per re-radiating square meter. They think they can get ~4W from direct greenhouse if they predict doubling of CO2 levels (along with other twiddles about other gases, because the latest on CO2 alone, in the UN's own climate report, is only about 2.4W even if it happens).

So they need amplifiers somewhere that take input power signal and boost its climatic effect 5 fold - by changing overall planetary albedo/blackness, or increasing water vapor based greenhouse, or anything else they can dream up (e.g. wetness to dust to cloud, here).

So the important thing to realize is that solar variation is big enough to explain observed *past* temperature changes on time scales of order 50 to a few hundred years - which have been minor. But it is not large enough to predict large *future* changes, which is what a lot of these characters want. So "not useful" has two meanings. Scientifically, solar variation explains quite a bit of past temperature change (though probably nothing like all - maybe half). But it doesn't help the scaremongers.

But amplifiers, in whatever context first "found"/invented, can help the scaremongers. Because they don't have a coherent power budget. Their own predictions of power effects from the greenhouse gas changes they decide to predict (which they mostly pick out of the air, but have to keep reasonably plausible) aren't sufficient to account for the temperature changes they also predict. They need 4/5ths of the power to pop out of the complexity of the climate system somewhere, "sensitively".

But, you will wonder, if they don't have 4/5ths of the needed power and don't know where it would come from, why in heck to they make that prediction? Because the prediction is practically constant; it is the theory that moves to save the prediction, not the other way around.

CO2 warming was originally proposed as a possible explanation for ice ages. Which show temperature changes on the order of 5 degrees C. The prediction that CO2 variation might cause temperature changes of that scale was first made more than 100 years ago, in the late 1800s, when effects like greenhouse could first be modeled theoretically (though still crudely - they knew nothing of quantum mechanics and little of energy levels etc).

Global climate models based on that idea were first built in the late 1960s and early 1970s. But shortly afterward, in the mid 1970s, the real explanation of ice ages was re-discovered (one fellow had figured in out much earlier, but his ideas had been overlooked). Long time scale variations in the earth's orbit around the sun (eccentricity changes, tilt shifts, precession, etc) lead to changes in total solar radiation received on the order of 7% over time scales of 10s of thousands of years.

So there was no 7% overall power change left in ice ages to be explained by CO2 variation. The original late 1800s idea was wrong as a solution to ice ages. But the idea still existed, some scale of greenhouse effect from CO2 variation was perfectly plausible, and models had been built based on it. The right way to proceed therefore would have been to accept the orbital explanation of ~5C changes - the largest seen in the past records - and then to expect CO2 changes to be smaller, second order terms explaining minor subvariations.

But there was no potential scaremongering it that. It was not done. Instead, they kept the scale of prediction from when CO2 variation was supposed to cause ice ages. Which means ice ages are "overexplained", twice. Meanwhile physicists went out and measured the scale of effect you could expect from direct CO2 greenhouse, and it was on the order 1-3 watts per re-radiating square meter. Exactly what you'd expect from a second order correction to the orbital variation model of ice ages. But not enough to save the 5C prediction.

So they kept the prediction instead of accepting what the physicist's data ought to have told them. And realized they'd need some mysterious twiddle of an amplifier somewhere, to turn small but real and verifiable power changes from direct greenhouse, into their hackneyed old predictions. Since the climate is complicated, they thought they might be able to do this.

They ran off looking for epicycle amplifiers in every complicated subsystem of the global climate. Maybe this, maybe that, maybe 4/5ths of the needed power will pop out through the vengeance of offended mother earth. It was generalized water vapor, then it was clouds, then it was seeding of clouds, then clouds were two varieties, then in was sulphates, aerosols, dust, volcanoes, ice caps, ozone - on and on, trying to spin out new explanations faster than they could be investigated and shot down.

They still don't have an energy budget. They just wave their hands and gesture toward some version of that complexity, and then say "well, it pops out of our models". That is, their models predict a temperature response to their own power terms 4 times as large as it should be, on the "naive" simple physics of it.

For all the world like they forgot Boltzman's law, maybe because a linear model is "simpler". For small changes, even a linear model would have been fine, if they had replaced the fourth root with a 1/4 times coefficient. (Since 1.0n ^ .25 is about 1.0n/4). But why put that in, when you are just going to do a regression to find all the coefficients in the linear model anyway? That their model thus predicts a linear relationship (with coefficient near 1) between power term and equilibrium temperature is can thus be explained, but as a gross error.

Complicated climatic twiddles are supposed to fill in between the simple physics screaming "you dropped a fourth root" and their old ice-age scale prediction.

Using Google we find:

Study of Dust in Ice Cores Shows Volcanic Eruptions Interfere with the Effect of Sunspots on Global Cli

PRESS RELEASE
Date Released: Wednesday, June 19, 2002
University at Buffalo

Study of Dust in Ice Cores Shows Volcanic Eruptions Interfere with the Effect of Sunspots on Global Climate

University at Buffalo scientists working with ice cores have solved a mystery surrounding sunspots and their effect on climate that has puzzled scientists since they began studying the phenomenon.

The research, published in a paper in the May 15 issue of Geophysical Research Letters, provides striking evidence that sunspots -- blemishes on the sun's surface indicating strong solar activity -- do influence global climate change, but that explosive volcanic eruptions on Earth can completely reverse those influences.

It is the first time that volcanic eruptions have been identified as the atmospheric event responsible for the sudden and baffling reversals that scientists have seen in correlations between sunspots and climate.

"Knowing the mechanisms behind past climate changes is critical to our understanding of possible future changes in climate, such as global warming, and for assessing which of these changes are due to human activities and which arise naturally," explained co-author Michael Stolz, doctoral candidate in the Department of Physics in UB's College of Arts and Sciences.

"For a long time people have tried to find out whether, for example, periods of maximum sunspots will influence the climate to behave in a certain way," said Michael Ram, Ph.D., professor of physics at UB and co-author on the paper.

"Whenever scientists thought they had discovered something, say, they were seeing a positive correlation between temperature and sunspots, it would continue like that for several years and, all of a sudden, there would be a reversal and, instead, they would start to see a negative correlation," said Ram.

"There seemed to be no consistent relationship between what the sun was doing and what the climate was doing," he said.

To truly confirm any connection between sunspots and climate, a consistent correlation would have to be observed over a long period, covering many solar cycles, Ram explained.

That's what he and his graduate students and co-authors have done with their study of ice cores, long cylinders of ancient ice from Greenland that serve as a frozen archive in that they record climate details from thousands of years ago.

"This is the beauty of working with ice cores," said Ram. "They go back 100,000 years, so we can study how dust concentrations vary along the ice core, reflecting past-atmospheric dust concentrations."

Plain old dust, Ram added, holds the key in these experiments because it reflects how dry conditions were in a particular year.

"Dust is a very sensitive parameter of climate," he explained.

Drawing on climate data derived from ice cores obtained through the Greenland Ice Sheet Project 2, (GISP2), the scientists used laser-light scattering techniques to determine the level of dust in the atmosphere for roughly the past 300 years, which is how far back sunspot data have been recorded.

"This was true for the first three or four solar cycles we studied, from about 1930 to 1962, but then the correlation reversed itself, demonstrating that the mechanism couldn't be what we thought," said Ram.

It turned out that during those 32 years of positive sun/dust correlation, there was relatively little explosive volcanic activity worldwide. The researchers found that the same conditions existed between 1860 and 1882. Each of these relatively "quiet" periods came to an end with increased volcanic activity.

For example, in 1883, the Indonesian volcano Krakatau erupted in one of the deadliest volcanic disasters, killing 36,000 people. At exactly the same time, the data started to exhibit low dust concentration whenever there was high sunspot activity, a correlation that violated the scientists' original assumptions.

"By carefully studying the timing of other volcanic eruptions, we found that they coincided with all of the correlation reversals between sunspots and climate," said Ram.

A chart in the paper shows how six major volcanic eruptions between 1800 and 1962 occurred during precisely the same years when there were reversals in the correlation between sunspot activity and climate.

That revelation provided a further insight into how sunspots affect climate.

"All energy comes from the sun, but the change in visible radiation from the sun during any one solar cycle is less than one half of a percent," explained Stolz. "Scientists have said it's impossible that so small a change could influence any signal in the climate. But here we have evidence to show that it's not just radiation energy from the sun that is affecting climate, it's the solar-modulated cosmic rays that have a strong influence because of their impact on cloud cover."

With fewer clouds, and therefore less rain, the scientists reasoned, maximum sunspots should cause levels of atmospheric dust to rise.

"That is true sometimes," said John Donarummo, Jr., UB doctoral candidate in the UB Department of Geology and a co-author on the paper.

But, the researchers discovered, during periods of high volcanic activity, high sunspot activity also results in high levels of atmospheric dust.

According to Donarummo, it long has been known that volcanoes add more dust and more sulfates to the atmosphere.

The UB team discovered that these additional sulfates cause cosmic rays to have a more pronounced effect on Earth by spurring the formation of small droplets in the atmosphere that, in turn, cause the formation of a type of cloud that does not produce rain.

"During these times of high volcanic activity, the sunspot/climate correlation reverses and dust levels rise, even in the absence of high sunspots," explained Stolz.

The work was funded in part by National Science Foundation.

This is of interest:

Dr. Michael F. Sheridan mfs@eng.buffalo.edu

Michael Sheridan is currently completing a 3-year project on volcanic risk assessment at Pico de Orizaba Mexico with funding from NASA. Bernard Hubbard just finished his Ph.D. on this project. Work in this area continues with a new M.A. student, Fernanda Scuderi, who will work on understanding the source of a giant debris avalanche and flow that originated from Las Cumbres volcano, located about 30 km north of Pico. He will continue working with civil protection authorities in Veracruz State to coordinate volcanic hazard mapping with public safety policy. A new project on the volcanic hazards of Las Tuxlas volcanoes south of Veracruz will probably begin next year. Dr. Sheridan is associated with risk assessment groups elsewhere in Mexico, including Popocatepetl and Volcan Colima, both of which are currently active. The focus in these projects is to develop better models for emplacement of volcanic debris flows. A project on the back burner is the development of a volcanic hazard map for El Chichon volcano in the state of Chiapas. Ricardo Molinero, a Ph.D. student is working on the Chichinautzin Volcanic Field that extends from Mexico City southward. This project will look into the relationship of volcanism and tectonism in this area, relating the sequence and volume of volcanic products to volcanic risk in Mexico City. Adam Stinton has begun his research project on a comparison of sector collapse of young Cascade Volcanoes. He will use GIS to determine likely areas of edifice collapse on Mt. Rainier and possibly other volcanoes.

John Donarummo is finishing his Ph.D. dissertation on an interpretation of dust/ash in the Greenland ice core. Potential new projects for the next 2 or 3 years include additional volcanic hazard work in Latin America. He and Morgan Salisbury, a M.A.

student, will begin work on Sabancaya Volcano in Peru to investigate the pyroclastic history of the volcano as it pertains to risk assessment. This study will focus on the pyroclastic history of the volcano and the large volcanic debris avalanche that slid from the volcano Hualca Hualca into the Colca valley. He will submit a proposal to study the pyroclastic flow deposits of Villarrica Volcano in Chile and develop a hazard map for that volcano as well. A study of lahars at Galeras Volcano, Colombia is a strong potential, also.

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