sunspot theory of global warming

[gib65]

Is there anything to the sunspot theory of global warming.

[iNow]

This study was published July of this year in the Procedings of the Royal Society:

 

 

http://www.journals.royalsoc.ac.uk/content/h844264320314105/fulltext.html

There are many interesting palaeoclimate studies that suggest that solar variability had an influence on pre-industrial climate. There are also some detection-attribution studies using global climate models that suggest there was a detectable influence of solar variability in the first half of the twentieth century and that the solar radiative forcing variations were amplified by some mechanism that is, as yet, unknown. However, these findings are not relevant to any debates about modern climate change. Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified.

[bascule]

Solar luminosity's effect on the climate system is well understood, as is the solar cycle's effect on solar luminosity. Solar forcing have not dominated climate change for decades:

 

[ecoli]

shame your graph only goes up to 1990... any more recent data?

[bascule]

That's the only graph I've seen that shows forcing inputs graphed over time. It's based on Meehl et al. (2004)

 

There's other graphs on the attribution of climate change to various forcings. This is the one I've seen the most, showing attribution of 20th century climate change:

 

[Chris C]

here is a more up to date graph on relative radiative forcings (Collins et al 2006; IPCC, 2007)

 

 

From Foukal et al (2006)Here is the abstract:

 

Variations in the Sun's total energy output (luminosity) are caused by changing dark (sunspot) and bright structures on the solar disk during the 11-year sunspot cycle. The variations measured from spacecraft since 1978 are too small to have contributed appreciably to accelerated global warming over the past 30 years. In this Review, we show that detailed analysis of these small output variations has greatly advanced our understanding of solar luminosity change, and this new understanding indicates that brightening of the Sun is unlikely to have had a significant influence on global warming since the seventeenth century.

 

Looks like Solar irradiance has decreased over the past few decades and is poorly correlated with temperature trends over the last 100 years, and the trends are too small to have outweighed the anthropogenic signal especially from 1950 onwards (early century warming can be associated with higher magnitudes of solar forcing) . (Gilgen et al., 1998; Crowley, 2000; Stanhill and Cohen, 2001; Max Plank Institute, 2004; Foukal et al., 2006; Lockwood and Frohlich 2007; IPCC, 2007)

 

Moreover, we know from the IPCC TAR that night temperatures are increasing at a faster rate than daytime temperatures, which is inconsistent with a primary external influence from the sun and consistent with increase in greenhouse gases. Moreover, the troposphere is warming while higher layers (Stratosphere, mesosphere, theremosphere) are cooling, which again, is not consistent with the primary influence from the sun.

 

In short, The decrease in lower stratospheric temperatures is the result of decreased ozone concentrations at the tropopause and greater insulation by greenhouse gases in the troposphere. The lower stratosphere has cooled primarily due to ozone depletion, while the troposphere has warmed from the enhanced greenhouse effect.

 

The thermal profile of the stratosphere is the result of a balance between radiative heating and cooling rates due to greenhouse gases(ie CO2, O3, water vapor). The reason the stratosphere cools with increase of CO2 is the balance in the stratosphere is between absorption of solar radiation by O3 and cooling by infrared emission. As you increase CO2, there is radiative cooling, therefore, the stratosphere cools to come back into balance. Increase of greenhouse gases at the troposphere creates an increased temperature gradient so that anything below will generaly warm, while anything above will cool. This is also consistent with temperature trends at the mesosphere and thermosphere (see Lastovicka et al., 2006) and a comparison made by the study-

 

"The increase in global surface air temperature during the 20th century has been attributed mainly to the increasing atmospheric concentrations of greenhouse gases. In the upper atmosphere, the radiative effects of greenhouse gases, particularly CO2, become more pronounced and produce a cooling rather than a warming effect. This effect is demonstrated by the CO2-dominated atmosphere of Venus, where the troposphere is more than twice as warm as Earth's and the thermosphere is 4 to 5 times as cold "

 

Addition as well- numerous studies now demonstrate that over the last 60 years or so the anthropogenic signal is strongly detectable and overwhelms "natural" external forcings (Ammann et al 2007) and that if there was a strong solar forcing to come it would only be of more concern as the radiative physics behind more CO2 in the atmosphere is well known.

 

Much is known about the physics of climate change, and this paradigm, developed from many parts of science over the decades, has repeatedly proven to be successfully predictive as well as explanatory with high confidence. Much work remains to fully understand paleoclimatic templates (such as "tipping points" or abrupt climate change), feedbacks, and to assess possible implications for the future, but the foundations for this work are remarkably solid.

 

Chris

[Fred56]

Isn't there new research that indicates there is a bigger forcing from the solar cycle than previously believed, and that the next cycle should help to measure or calibrate this effect now they understand it better?

[1veedo]

The sun hasn't gotten any "stronger" sense at least the mid-1970's (I think 1976 which is when we first started recording direct solar irradiance from a satellite). There's also some data suggesting the sun has cooled off sense about the 40's and has definitely gotten cooler in the last 8,000 years.

[Fred56]

"A bigger forcing" doesn't imply that the sun is getting hotter. I'm referring to the variation in solar activity during the 11-year cycle. This variation has, until now, been believed to have no, or an insignificant, effect. The new research appears to indicate that there could be 0.2 degrees of extra forcing at the top of the cycle. This should be borne out, or not, by the next cycle (which starts real soon). Apparently they will be able to calibrate the measurements better, or something. If you're really interested, I could try to find a good link to this.

[Chris C]

See my graph above from the AR4...sun is in a "positive forcing" but not that significant in relation to greenhouse gases, and not much in relation to the peaks vs. drops in the 11-year cycle. I want to point out that the change in the mean is ~ 0.05% or about 0.5 W/m^2, much less than the variation within a cycle.

 

If the ACRIM data changes in the mean insolation are correct, then the inferred increase in solar radiance would account for ~10% of the temperature anomaly over 1990-2000 compared to previous decades:

 

 

The highest attribution of warming to the 1950-2000 period to solar activity I've seen is about 25% (http://www.agu.org/pubs/crossref/2005.../2005GL023849.shtml). this is very likely a high end figure, but even still, it leaves 75% left to other forcings. But if new and updated TSI data are used, then the trends they calculate vanish. The Foukal et al. paper (http://www.nature.com/nature/journal/v443/n7108/abs/nature05072.html) also show there is no positive evidence for a longer term forcing larger than seen over the 11 year cycle, as we also see in the Lockwood and Frohlich 2007 paper- http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf. Trends over the past few decades not doing what it should to explain warming, or even coming close to the magnitude of warming, as has been shown by countless studies all demonstrating the vast majority of post-1950 warming due to anthropogenic forcing. This still brings into question the stuff like stratospheric cooling which I brought up in my last post.

 

Chris

[bascule]

This variation has, until now, been believed to have no, or an insignificant, effect.

 

Here's RealClimate's take on the 11 year solar cycle:

 

http://www.realclimate.org/index.php/archives/2005/07/the-lure-of-solar-forcing/

 

This is not to say that there is no solar influence on climate change, only that establishing such a link is more difficult then many assume. What is generally required is a consistent signal over a number of cycles (either the 11 year sunspot cycle or more long term variations), similar effects if the timeseries are split, and sufficient true degrees of freedom that the connection is significant and that it explains a non-negligible fraction of the variance. These are actually quite stiff hurdles and so the number of links that survive this filter are quite small. In some rough order of certainty we can consider that the 11 year solar cycle impacts on the following are well accepted: stratospheric ozone, cosmogenic isotope production, upper atmospheric geopotential heights, stratospheric temperatures and (slightly less certain and with small magnitudes ~0.1 deg C) tropospheric and ocean temperatures. More marginal are impacts on wintertime tropospheric circulation (like the NAO). It is also clear that if there really was a big signal in the data, it would have been found by now. The very fact that we are still arguing about statisitical significance implies that whatever signal there is, is small.

 

If you're really interested, I could try to find a good link to this.

 

That would be helpful

[Fred56]

OK found a couple. The team is Camp & Tung and it's based on an analysis of >50 yrs of data.

 

http://www.upi.com/NewsTrack/Science/2007/08/02/math_used_in_new_climate_change_assessment/3629/

http://scienceandpublicpolicy.org/sppi_originals/the_unruly_sunne_cannot_be_ruled_out_as_a_cause_of_recent_climate_variation.html

 

And here's some of the content:

1.

Camp and Tung said that while the existence of a long-term trend in solar output is controversial, its periodic change within an 11-year cycle has been measured by satellites.

 

To assess how that oscillatory forcing affects climate on Earth, Camp and Tung compared the Earth's surface temperature measurements between years of solar maximum and years of solar minimum.

 

They determined that times of high solar activity are on average 0.2 degrees Celsius warmer than times of low solar activity, and that there is a polar amplification of the warming.

 

That finding is believed the first to document a statistically significant globally coherent temperature response to the solar cycle, the authors note.

2.

"Though Lockwood and Frohlich present data indicating no correlation between solar and temperature variability, such correlations have been recently reported.

 

Fig. 5, for instance, documents an interesting new result by Camp and Tung (2007) demonstrating a correlation between the 11-year solar activity cycles and the global surface temperature variations during more than half a century between 1959 to 2004:

 

 

 

"Since the [solar] forcing is global, theoretically one should expect a global-scale response. When globally and annually averaged and detrended, but otherwise unprocessed, the surface air temperature since 1959 (when the modern radiosonde network was established) is seen in [Fig. 5] to have an interannual variation of about 0.2ºK, somewhat positively correlated with the solar cycle, although the signal also contains a higher frequency (of 3-5 year period) variation of comparable magnitude, possibly due to El Niño-Southern Oscillation (ENSO). What is surprising is that a solar-cycle signal is already apparent in this "raw" data. An isospectral Monte-Carlo test shows that the correlation coefficient, ρ = 0.47, between the global temperature and the TSI is statistically significant at 98.4% confidence level. This is obtained without any filtering of the global mean signal, and gives confidence that the solar signal is not an artifact of our filtering to be presented below."

Fig. 5 Half a century of correlation between solar activity (TSI) and detrended global mean surface air temperature (T). From Camp and Tung (2007).

 

The availability of scientific results such as those of Camp and Tung suggests that Lockwood and Frohlich have founded their conclusion upon selected data, and that conclusions other than theirs are possible."

[1veedo]

All it says is that during the 11-year peak temperatures are on average .2C warmer then the trough. The sun does effect temperatures on the planet but it's not causing global warming.

[SkepticLance]

There appears to be a lot of confusion here. The effect of sunspots on global average temperature does not appear to be a result of direct changes in solar irradiance. In fact, apart from normal 11 and 22 year cycle changes, sunspot activity has been relatively steady for most of the past 50 odd years. There was a big increase in sunspot activity after 1910, and it fell again about 1941. From about 1955 there has been little overall change.

 

However, sunspots are assocated with a couple of changes in solar output other than irradiance.

1. Magnetic effects.

2. Increased ultra violet output.

 

The magnetic effects may act through cosmic ray flux. It has been known for some time now that cosmic ray intensity reaching the Earth's atmosphere drops off when sunspot activity is high. This appears to be a result of high magnetic effects, since cosmic rays are very high energy charged particles and are deflected by magnetic fields.

 

Thus, a hypothesis has been formed that suggests that at times of high sunspot activity, and lowered cosmic ray flux, there are fewer charged particles in the atmosphere to act as nucleation sites for clouds. Since low altitude clouds reflect heat and are a cooling influence, this means warmer conditions. There is a little empirical evidence available from satellite studies that show fewer clouds when sunspot activity is high, but I do not believe we can say this hypothesis has sufficient evidence to be accepted.

 

A second hypothesis depends on the ozone generating effect of ultra violet. Since ozone is a potent greenhouse gas, this may be a means by which high sunspot activity can result in warmer temperatures. Again, this is a mere hypothesis and remains unproven.

 

The point is that measuring irradiance is quite unhelpful in determining the effects of sunspots on global temperature.

 

It is also quite unhelpful to talk about changes in sunspot activity over the past 50 years. The big changes have been at other times.

[Fred56]

All it says is that during the 11-year peak temperatures are on average .2C warmer then the trough. The sun does effect temperatures on the planet but it's not causing global warming.

It also says that Lockwood and Frolich are wrong, maybe.

It is also quite unhelpful to talk about changes in sunspot activity over the past 50 years. The big changes have been at other times.

So Camp & Tung are providing "unhelpful" research?

[SkepticLance]

To Fred

 

All honest and competent scientific research should be regarded as helpful. I do not include unwarranted deduction as honest research. Good research must include solid empirical data - not deduced data, unless the calculations are based only on proven material rather than uncertain assumptions.

 

What I meant by 'unhelpful' was discussing minor changes in sunspot activity in this thread when the real impact has been during times of major sunspot activity change.

[Fred56]

the real impact has been during times of major sunspot activity change.

And this conclusion is based on what solid empirical data?

[SkepticLance]

Fred asked about empirical evidence for the large sunspot changes and associated large global temperature changes.

 

These come from a variety of studies. I am not sure if I have a single reference to put it all together. A good general discussion can be found on Wiki at http://en.wikipedia.org/wiki/Solar_variation

 

A good graph relating sunspots to temperature back to 1860 can be found on

http://www.mps.mpg.de/images/projekte/sun-climate/climate.gif

 

This shows the relationship quite convincingly.

 

http://pubs.giss.nasa.gov/abstracts/1998/Lean_Rind.html

 

http://www.solarstorms.org/CloudCover.html

[iNow]

But doesn't current sunspot activity imply that global temperatures should presently be decreasing, which it's not?

[Chris C]

I Just e-mailed Tung himself, here is his response:

 

......................

 

Dear Chris,

Thank you for your inquery. The solar cycle signal goes up and down on a

11-year periodicity. So there should not be a secular trend in the global

mean temperature if the beginning and end years are at the same phase of the solar cycle, i.e. from solar max to solar max, or from solar min to solar

min. If you see a secular trend, then it must be attributed to something

else, possibly CO2. The solar-cycle signal is on top of any CO2 secular

trend, so it adds or subtracts 0.2 C depending on the period. For the next

5 years it will add 0.2 C on top of any CO2 warming.

 

--KK Tung

 

................................

 

I really hadn't seen what the point of referencing this study was- I had thought it was clear that Tung showed how CO2 sensitivity will match IPCC projections and even eliminate low-end sensitivity. I hope this ends this discussion here regarding Tung and Camp (2007) since we know what it really means (ie http://environment.newscientist.com/channel/earth/climate-change/mg19526164.800).

 

It has been extremely well documented now that solar changes since about 1950 have a very minimal forcing, and maybe even negative (solar irradiance also declined from 1960 to about 1990 from Gilgen et al 1998; Stanhill and Cohen, 2001) and I have already supplied a great deal of references on this subject.

http://www.pnas.org/cgi/reprint/104/10/3713

http://www.nature.com/nature/journal/v443/n7108/abs/nature05072.html

http://www.ucar.edu/news/releases/2006/brightness.shtml#

http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf

http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2004/pressRelease20040802/

 

These two go over the temperature profiles of the layers of the atmosphere which I've gone over as being indicative of a greenhouse warmed planet and not a solar warmed planet:

http://www.climatescience.gov/Library/sap/sap1-1/finalreport/default.htm

http://www.sciencemag.org/cgi/content/summary/314/5803/1253

 

As we know though, if a strong natural forcing is to become apparent we will get just more forcing on top of CO2 as we know the physics behind CO2 increase. There are still countless other journals on the impacts of higher CO2, and what kind of forcing we get from that, and the explanatory and preditive power of the greenhouse warmed planet

 

Wrote this earlier in another forum so I will reproduce it here:

 

Remember, Earth's climate system is based on a radiative balance between absorbed visible radiation "A" and longwave radiation emitted at the Top-Of-Atmosphere "B"...so A≈ B. . At all times, globally averaged, A and B equal each other. As more solar radiation goes in than IR goes out, you get warming; if more IR goes out, than solar radiation comes in, you get cooling. This equilibrium isn't the case regionally-there is more solar radiation than outgoing IR at the equator, and more outgoing radiation than solar incoming at the poles. The only reason the two areas don't contine to warm (equator) and cool (poles) toward infinity is because of oceanic and atmospheric currents which transport heat from the equator to the poles keeping a stable temperature profile. Globally averaged, the radiative balance is in equilibrium and so temperature remains stable. So, the heat content of the climate system is something like dH/dt = A−B. However, when we speak of "global warming" we refer to some "forcing" which disrupts one side of the equation. As is well documented in the scientific literature, the increase in greenhouse gases have allowed more solar radiation going in than infrared going out (A > B) on a GLOBAL scale (which is the problem), but we know we aren't getting more solar radiation but we're delaying the IR out, and we know primary radiative forcing driving the increase in surface temperature is an increase of downward sky infrared from the atmosphere to the surface- sun is not forcing, and the temperature trends in the portions of the atmosphere (cooling in the stratosphere and above, and warming in the troposphere and below) are what we expect from more greenhouse gases and not more solar radiation) or the fact night temperatures are increasing faster than day temperature indicative of greenhouse gases and not the sun, so the explanatory and predictive power is there.

 

To achieve a new radiative balance, the Earth must warm. Greenhouse gases work on the "energy loss" side of the equation: IR loss to space, not absorption of solar radiation. The CO2 forcing is simple physics- I think you do something like dT = 6.3 ln (C/Cx) where C and Cx are your final and initial CO2 levels, where the IPCC gets the ~1.6 W/m^2 radiative forcing from. Doesn't matter if "something else" will go positive, because we know what happens if you put in more CO2- if anything, it just gives more cause for alarm if we have stronger natural forcings because temperatures should increase even more.

 

From this point, I hope intelligent conversation is possible on the subject, but right now the scientific data shows clearly that the anthropogenic signal has dominated the second half of this century in its warming trends, and not just because of lack of other forcings but because we know how CO2 works as well and what forcing we will get with a given addition. The IPCC 2007 report gives greater justice to all these topics as well, and from pgs 188-192 goes over the solar variability very well, with an enormous load of other references which readers can review for additional insight on the topic- http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch02.pdf

 

I cannot possibly do justice to all of the literature and knowledge on both solar variation and the physics of more CO2, paleoclimate consistency, etc but I can try my best to lay out an overview of what we know. I am not trained as an astrophysicist, and I can get a bit more technical but not too much- I strongly encourage people to read the relevant literature and avoid secondary sources from blogs and other wingnut sites, full of misdirected claims which can easily be refuted

 

Chris

 

But doesn't current sunspot activity imply that global temperatures should presently be decreasing, which it's not?

 

Pretty much. We keep rising becuase of the greenhouse dominance, and it looks like we will get ~3 C per 2x CO2; I think Camp and Tung just show we might get more as we head toward solar maxima coming up.

 

[Fred56]

I hope this ends this discussion here regarding Tung and Camp

No problem. I brought it up because this thread is about sunspots and so is their research.

Just in closing: one of the implications of their findings (and Tung appears to imply something like this in his email) is that the next cycle should push atmos. temp. upwards over the next 5-6 years, possibly resulting in a few years of highest recorded temp. Which Chris C has also stated, sort of. The other thing is that I think a study that is apparently "believed the first to document a statistically significant globally coherent temperature response to the solar cycle" isn't irrelevant to the discussion at all.

[SkepticLance]

iNow asked

 

"But doesn't current sunspot activity imply that global temperatures should presently be decreasing, which it's not?"

 

As I have said before, sunspot activity has not changed much over the past 50 odd years, apart from the 11 and 22 year cycles. Over the past 30 years, temperature rise correlates closely with greenhouse gas rise, and this is doubtless the best explanation for the current rise in global temperature.

 

The point I made about sunspot activity driving warming and cooling applies to an earlier time - before 1976.

[Fred56]

OK. I make the following observations about the direction this thread has gone so far:

The initial query was about what substance there is to the idea the warming trend is due to solar activity, or sunspots.

My post was about some research that specifically refutes this idea (but some may have initially believed I was trying to do something else with it), although it does find a bigger forcing, apparently. The relevance of Camp & Tung's work to this discussion is that it suggests other results may be incorrect, and that they could find no secular trend in over 50 years of instrumental data.

Assumptions about “someones loyalty” or otherwise, to the “cause”, appear to have coloured my contribution. This isn't especially saddening, or anything (it happens a lot, anyway).

Just thought I'd let you all know.

 

“Beware the Jubjub bird, and shun

The frumious Bandersnatch!”

[Chris C]

yay

[jryan]

So what is causing the observed ice melts on Mars and the moons of Saturn and Jupiter?