Uh, what does that fluctuation in that plot prove?
It proves that the solar output in that band of the EUV varies by over a factor of three during the solar cycle. That is a huge variation and as such should be included in the measurements of the total solar irradiation. But it is not. For example, ACRIMSAT measures only the 2000 nm to 200 nm window.
x-rays and EUV don't make it to the surface of the Earth anyway
True, they get absorbed in the very upper layers of the atmosphere. However, roughly 50% of the energy does reach the earth's surface through secondary effects such as fluorescence, ionisation-recombination emission, heating and conduction, heating and thermal emissions, and so on. The physics behind this is perfectly analogous to why of the infrared radiation captured by greenhouse gases about half the energy still ends up in space instead of being reflected back to earth.
And we know it's not an increase in solar output causing the warming we've observed.
Sorry, we do not know that. The conclusion that it cannot be because of the sun is based on space-based measurements of the total solar irradiance (TSI). These found a fairly stable 1365 W/m^2 (see for example here). But these measurements are wrong! Why? Because the EUV and X-ray part of the solar spectrum is not included.
Take for example ACRIMSAT. It is sensitive only down to 200 nm and as such it wholly misses out on the EUV and X-Ray bands. Moreover, to properly observe the whole x-ray flux you have to capture a fairly wide field of view that includes the corona as this X-ray image of the sun shows.
A predicted 6 degrees Celsius rise in a century? Oh, how scary! Let's introduce onerous carbon-curbing measures.
But wait, the models that make these predictions all have CO2 as the driving factor behind climate change. The historical record shows, however, that the atmospheric CO2 concentration follows changes in global temperature instead of leads it. Not surprising: higher temperature -> oceans heat up -> less dissolved CO2.
Moreover, there is a perfectly plausible alternative explanation for what is causing the rapid climate fluctuations (historically going both up and down on a fairly short timescale): the sun. If you include the EUV and X-Ray bands of the spectrum, it becomes obvious that the sun's output changes much more than it is being given credit for: http://www.usc.edu/dept/space_science/sem_data/SEM%20Data%20Graphs/SEM_1996-2009.jpg
Another good writeup on the leaked emails can be found here. Summary: manipulation of evidence, private doubts about whether the world really is heating up, suppression of evidence, fantasies of violence against prominent Climate Sceptic scientists, attempts to disguise the inconvenient truth of the Medieval Warm Period , and communications discussing how best to squeeze dissenting scientists out of the peer review process.
Such high-frequency photons are absorbed in the very upper layers of the atmosphere. However, roughly 50% of the secondary energetic effects (heating, fluorescence, ionization-recombination emission, etc.) will reach ground level instead of going back out into space.
If something here on earth is varying with the solar cycle, the first cause to consider is therefore the solar EUV and X-ray flux.
Every climate model that utilizes atmospheric chemistry uses UV since it plays an important role in ozone and methane in the atmosphere.
Please do read before commenting: I was referencing EUV, not UV. That stands for extreme UV. Recent space-based observations of the sun have shown that the EUV and X-Ray components of the solar spectrum are highly variable, are not caused by the short-wavelength tail of the black-body spectrum of the solar surface, but instead are correlated to the solar corona, solar magnetic fields, and solar wind.
Has this variation in the short-wavelength part of the solar spectrum, which is obviously highly relevant to climate change, been included in the models you fawn about? No, it has not.
You can read the various refutations of the guys claims.
So predictable: when the official dogma is in danger, the heretic has to be burned.
Do you really think there is a worldwide conspiracy for climate change?
In 1993, the Club of Rome published the book "the First Global Revolution" in which they explained their reasoning behind pushing the environmental agenda. Quoting:
"It would seem that humans need a common motivation...either a real one or else one invented for the purpose....In searching for a new enemy to unite us, we came up with the idea that pollution, the threat of global warming, water shortages, famine and the like would fit the bill. All these dangers are caused by human intervention, and it is only through changed attitudes and behavior that they can be overcome. The real enemy then, is humanity itself."
He's an expert in dowsing as well as an expert on geophysics.
Good for him. I am sure that, being a proper scientist, he has more interesting and valid things to say about dowsing than that circus-act magician (the Amazing Randi) you link to.
But let me guess, you just know that there can be no truth to any claim of extra-sensory perception. Well, time to be enlightened: http://www.youtube.com/watch?v=qw_O9Qiwqew.
There is an ironic analogy with global warming: another case where the mainstream view has been turned into dogma with alternative views being taboo even though they are supported by extensive experimental and observation evidence.
If you cannot argue with the science attack the person, eh?
I want a model, skeptics. I want a scientifically valid atmospheric dynamics model that shows that increasing the amount of CO2 does not impact global climate and yet still explains our observational data.
Ah yes, shift the burden of evidence. The fact of the matter is that the climate models that favor CO2-induced anthropogenic global warming are woefully incomplete and as such not scientifically valid.
To see that that is so, take for example this observation: http://www.usc.edu/dept/space_science/sem_data/SEM%20Data%20Graphs/SEM_1996-2009.jpg. That's our Sun changing its EUV output in a broad wavelength band by a factor of three on a timescale of five or so years. That graph makes obvious that any reasonable model for global climate change will have to include the EUV part of the solar spectrum. Guess what: current models ignore the short-wavelength range of the solar spectrum.
Now calculate how many gallons of water will be added to the ocean when the ice on top of Alaska and Greenland finishes melting. A small delta can be extremely relevant.
It is only going to be relevant if the ice on top of Alaska and Greenland is actually going to melt substantially. Please do show us some credible data to that effect.
In the mean time, let me show you some data on Antarctica, which holds 90% of the world's land ice and as such is the most interesting place to look at when it comes to anticipating sea level rise or fall: http://wattsupwiththat.com/2009/10/08/antarcticas-ice-story-has-been-put-on-ice/. Guess what, Antarctica has been fattening up with ice of recent, and the global warming alarmists try to hide the data.
Is it really that hard to directly test the microwaves they're interested in
What makes you assume that their experiment was motivated by an interest in microwaves? Studying the physiological effects of 60 Hz fields is mighty interesting, as that is the power-line frequency.
The linked article talks about magnetic (not EM) fields at 60 Hz. Looks like it would relate more to the power grid than to cell phones, if at all.
There is a relation. What the experiments at 60 Hz show is that EM fields with very low photon energies (the photon energy is proportional to the frequency) can still cause biochemically appreciable effects such as DNA breakage.
The main reason that microwave-frequency EM radiation (which cell phones emit) has been claimed to be safe, at least in the low-power non-heating range, is that microwave photon energy is still way too low to break chemical bonds. This claim has been refuted by the 60 Hz results since they show that DNA breakage is definitely possible in the low-photon-energy regime, presumably by an indirect mechanism.
Except that the study that you link to is not about low frequency EM radiation, i.e. it has nothing to do with cell phones.
You don't understand. The main argument against cell-phone-induced damage is that the microwave photon energy (which is proportional to the frequency) is insufficient to break chemical bonds. However, that argument goes out the window if even much lower frequency EM radiation is found to still be able cause DNA breakage.
Powerwatch is a good overview site dealing with health issues surrounding microwave and lower frequency electro-magnetic radiation. It may surprise many of you, but there have been clear-cut studies showing DNA damage on acount of EM fields, even at low frequencies: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1241963
The "explanation" shifts the blame to "nanoflares". Why? Well, because "These temperatures can only be produced by impulsive energy bursts". But just because that is the only mechanism James Klimchuk can think of does not mean that there is no other mechanism. Indeed, anomalous extreme temperatures have been observed in coronal-alike plasmas under laboratory conditions: http://arxiv.org/ftp/physics/papers/0509/0509127.pdf. No "nanoflares" in that 0.4 Torr Pyrex cylinder.
This is typical overconfidence in theory. The reasoning is: nature must obey our currently accepted theories, and within the context of those theories I see only one possible cause, so that must be it. Such hubris. The accepted theories are likely to be incomplete, and might be downright wrong in places.
Then there is the title of the post: "Mystery of Sun's Outer Atmosphere Solved" Finely tuned to plant the mistaken belief in the mind of the Slashdot crowd that it has been figured out. Nothing more to see here. Please move along. After all, we don't want people to get a clue as to what is actually producing all that energy needed to keep the corona piping hot, do we?
At minimum, we have had solar output data from satellites for decades, now, which is more than enough to determine if there's a correlation between the observed increase in global mean temperature and solar output.
No we have not had that. Realize that measuring the solar flux in the EUV and X-ray spectrum is not that easy even when in space. These wavelengths are easily absorbed: lenses and mirrors cannot be used to focus those photons on a detector. You need tricky instruments like grazing-incidence spectrometers. Also, early on people were not aware of the importance of the short-wavelength part of the solar spectrum and as such were not sending up the right instruments.
Anyway, it's clear you're unwilling to listen to actual reason, so I'm done here.
That's funny when you are ignoring observations of obvious relevance. I showed you a graph with a factor of three variation in the solar flux in a fairly broad wavelength band. At the very least that should have made you think twice.
Hopefully anyone reading this thread will see how disjoint and irrational the arguments of some of the anti-AGW folks really are.
I think anyone reading this thread is quite capable of perceiving that your argument is the shrill sounding one, and that you are unwilling to consider basic physics and observational data.
I guess part of the confusion lies in that we use a different meaning for "global warming". What I mean is an increase in the average global atmospheric temperature, something which can have many causes. I think you mean something more narrow: anthropogenic greenhouse-gas driven global warming.
Then look at the solar output over the last 50 years.
Obviously, there are more factors to be considered. For example, that the decrease in global temperatures started a bit earlier than the maximum in that graph is likely because 1997-1998 were El Niño years.
And unless you can provide evidence that said flux has shown an increasing trend over the last 50 years (okay, let's say the last 20 or so, since we've had reliable satellite data), your supposition that those bands are linked to GW is baseless.
I am sure you can agree that simple physics dictates that variations in the solar flux must drive global average temperatures. After all, the energy present in the solar radiation reaching the earth is mostly absorbed by the earth's atmosphere, surface, and sea. This heats the earth's atmosphere directly and indirectly on a global scale. An increase or decrease in the solar output will therefore cause a matching increase or decrease in atmospheric heating and hence warm or cool the earth.
What you must be doubting, therefore, is whether changes in the solar flux are the main factor in increasing or (as is the case currently) decreasing global average temperatures.
You can answer this question for yourself by seeing what fraction of the total solar energy output lies in the variable UV/EUV/X-ray part of the spectrum.
Hint #1: it is a much larger number than you may suspect from the black-body spectrum derived from the solar surface temperature. The corona is excessively hot and responsible for most of the EUV and X-ray emissions.
The full disk extreme ultraviolet (EUV) solar radiation is a major energy source, whose magnitude is required in modeling the scattering, ionization, and heating of planetary atmospheres, moons, comets, and the inflowing interplanetary/instellar medium.
Oh FFS, so you admit, then, that the variations in these other bands are linked to the solar cycle.
Yes they are linked, but not in the simple way you seem to suggest. The linking mechanism to the solar cycle I described is indirect. Also, UV/EUV/X-ray output variation have been observed to occur on much shorter timescales than the 11 year solar cycle. Part of that has of course to do with solar flares, but there are also medium-timescale (days/weeks) variations that correlate to changes in the solar wind proton and neutral atomic hydrogen flux.
Moreover, the precise origin of the UV/EUV/X-ray coronal flux is enigmatic at best: the temperature of the solar corona is 1-2 million degrees Kelvin and there are no good quantitative explanations for how it can sustain that high temperature in spite losing energy rapidly (through that very UV/EUV/X-ray flux radiating out into space).
In short, it is a complex mess with many theoretical unknowns. But the observations make clear that the UV/EUV/X-ray flux constitutes an important fraction of the solar output, and that this flux varies strongly on multiple timescales.
How ironic. You accuse me of stupidity while, apparently, not understanding the term "mean global temperature".
Imagine the solar output doubles. What do you figure will happen to the mean global temperature? Assume it halves. What will happen? In what way is that not a correlation?
We've had satellites studying the sun for decades.
The variations are definitely correlated to the solar cycle which is not surprising: coronal conditions are strongly influenced by the entangled magnetic field loops pinned to sunspots since the charged particles in the corona track those loops on account of the Lorentz force. And it is known that the sunspot number rises and falls as to sun goes through the solar cycle maximum and minimum. However, the current cycle has an anomalously low number of sunspots and an extended minimum.
To get some idea as to what fraction of the short wavelength flux stems from the corona, have a look at the following images: http://umbra.nascom.nasa.gov/images/
And that's why you see a strong correlation between solar output and global mean temperature! Except, of course, there is no such correlation.
Don't be stupid. As any child knows, the sun heats the earth so there is obviously a correlation between solar output and earth temperature.
However, the highly variable part of the solar output is mostly in the UV/EUV/X-ray range and as such is not easy to measure on earth. No correlations of global temperature with ground-based or narrow-band solar flux measurements are to be expected.
It is related to global warming/cooling as follows: the required low temperatures in the upper atmosphere are only attained if the solar UV/EUV/X-ray flux, mostly originating from the solar corona, is very low: that part of the spectrum does not penetrate well and hence is absorbed in the upper atmosphere.
Since this UV/EUV/X-ray flux is a significant fraction of the solar output and varies strongly with coronal conditions, it is the most important driver of global warming/cooling. The solar corona is a very dynamic system which currently is in a quiescent state on account of the anomalously low number of solar spots. As a consequence it has been cooling in recent years, in spite of all the bullshit being published to the contrary: the raw data does not lie.
Wikipedia says that the mesosphere extends from 50 to 80-85 km up, and the thermosphere from 80-85 to over 640km, and that the mesopause (the boundary between the two layers, at 80-85km) "is the coldest place on Earth, with a temperature of 100C".
Make that -100C, but yes, true, it is well below freezing. However, the somewhat more physically complete explanation than simply "the upper atmosphere is getting colder" is that less energy is being put into the upper atmosphere on account of unusually low UV and X-ray emissions of the sun.
During the current solar minimum, which has extended well beyond the time it should have, there have been very few sunspots. The number of sunspots is strongly correlated to the UV and X-ray emissions of the solar corona which constitute a significant fraction of the overall solar flux. This strongly variable component of the solar output is the main driver of global warming or, as happens to have been the case since about 1998, global cooling.
Slashdot Mirror
Uh, what does that fluctuation in that plot prove?
It proves that the solar output in that band of the EUV varies by over a factor of three during the solar cycle. That is a huge variation and as such should be included in the measurements of the total solar irradiation. But it is not. For example, ACRIMSAT measures only the 2000 nm to 200 nm window.
True, they get absorbed in the very upper layers of the atmosphere. However, roughly 50% of the energy does reach the earth's surface through secondary effects such as fluorescence, ionisation-recombination emission, heating and conduction, heating and thermal emissions, and so on. The physics behind this is perfectly analogous to why of the infrared radiation captured by greenhouse gases about half the energy still ends up in space instead of being reflected back to earth.
Sorry, we do not know that. The conclusion that it cannot be because of the sun is based on space-based measurements of the total solar irradiance (TSI). These found a fairly stable 1365 W/m^2 (see for example here). But these measurements are wrong! Why? Because the EUV and X-ray part of the solar spectrum is not included.
Take for example ACRIMSAT. It is sensitive only down to 200 nm and as such it wholly misses out on the EUV and X-Ray bands. Moreover, to properly observe the whole x-ray flux you have to capture a fairly wide field of view that includes the corona as this X-ray image of the sun shows.
A predicted 6 degrees Celsius rise in a century? Oh, how scary! Let's introduce onerous carbon-curbing measures.
But wait, the models that make these predictions all have CO2 as the driving factor behind climate change. The historical record shows, however, that the atmospheric CO2 concentration follows changes in global temperature instead of leads it. Not surprising: higher temperature -> oceans heat up -> less dissolved CO2.
Moreover, there is a perfectly plausible alternative explanation for what is causing the rapid climate fluctuations (historically going both up and down on a fairly short timescale): the sun. If you include the EUV and X-Ray bands of the spectrum, it becomes obvious that the sun's output changes much more than it is being given credit for: http://www.usc.edu/dept/space_science/sem_data/SEM%20Data%20Graphs/SEM_1996-2009.jpg
Another good writeup on the leaked emails can be found here. Summary: manipulation of evidence, private doubts about whether the world really is heating up, suppression of evidence, fantasies of violence against prominent Climate Sceptic scientists, attempts to disguise the inconvenient truth of the Medieval Warm Period , and communications discussing how best to squeeze dissenting scientists out of the peer review process.
Though there is little variation at visible and near UV wavelengths, the solar flux has a huge (factor of three) variation with the solar cycle in the extreme UV: http://www.usc.edu/dept/space_science/sem_data/SEM%20Data%20Graphs/SEM_1996-2009.jpg.
EUV and X-ray photons constitute a marked fraction of the total solar output. A much larger fraction than you would expect from the short-wavelength tail of the black-body spectrum of the solar surface. Indeed, these emissions are mostly from the corona, not the surface: EUV at 171A http://www.lmsal.com/YPOP/ProjectionRoom/latest_TRACE_171.html, and an X-ray image http://www.lmsal.com/YPOP/ProjectionRoom/latest/sxt/full/sxtdag_512.gif.
Such high-frequency photons are absorbed in the very upper layers of the atmosphere. However, roughly 50% of the secondary energetic effects (heating, fluorescence, ionization-recombination emission, etc.) will reach ground level instead of going back out into space.
If something here on earth is varying with the solar cycle, the first cause to consider is therefore the solar EUV and X-ray flux.
Please do read before commenting: I was referencing EUV, not UV. That stands for extreme UV. Recent space-based observations of the sun have shown that the EUV and X-Ray components of the solar spectrum are highly variable, are not caused by the short-wavelength tail of the black-body spectrum of the solar surface, but instead are correlated to the solar corona, solar magnetic fields, and solar wind.
The EUV flux graph I linked to shows the variability. To observe the mentioned correlations, have a look at the following EUV (171A) and X-ray images of the sun: http://www.lmsal.com/YPOP/ProjectionRoom/latest_TRACE_171.html, http://www.lmsal.com/YPOP/ProjectionRoom/latest/sxt/full/sxtdag_512.gif.
Has this variation in the short-wavelength part of the solar spectrum, which is obviously highly relevant to climate change, been included in the models you fawn about? No, it has not.
So predictable: when the official dogma is in danger, the heretic has to be burned.
In 1993, the Club of Rome published the book "the First Global Revolution" in which they explained their reasoning behind pushing the environmental agenda. Quoting:
"It would seem that humans need a common motivation...either a real one or else one invented for the purpose....In searching for a new enemy to unite us, we came up with the idea that pollution, the threat of global warming, water shortages, famine and the like would fit the bill. All these dangers are caused by human intervention, and it is only through changed attitudes and behavior that they can be overcome. The real enemy then, is humanity itself."
Good for him. I am sure that, being a proper scientist, he has more interesting and valid things to say about dowsing than that circus-act magician (the Amazing Randi) you link to.
But let me guess, you just know that there can be no truth to any claim of extra-sensory perception. Well, time to be enlightened: http://www.youtube.com/watch?v=qw_O9Qiwqew.
There is an ironic analogy with global warming: another case where the mainstream view has been turned into dogma with alternative views being taboo even though they are supported by extensive experimental and observation evidence.
If you cannot argue with the science attack the person, eh?
Ah yes, shift the burden of evidence. The fact of the matter is that the climate models that favor CO2-induced anthropogenic global warming are woefully incomplete and as such not scientifically valid.
To see that that is so, take for example this observation: http://www.usc.edu/dept/space_science/sem_data/SEM%20Data%20Graphs/SEM_1996-2009.jpg. That's our Sun changing its EUV output in a broad wavelength band by a factor of three on a timescale of five or so years. That graph makes obvious that any reasonable model for global climate change will have to include the EUV part of the solar spectrum. Guess what: current models ignore the short-wavelength range of the solar spectrum.
It is only going to be relevant if the ice on top of Alaska and Greenland is actually going to melt substantially. Please do show us some credible data to that effect.
In the mean time, let me show you some data on Antarctica, which holds 90% of the world's land ice and as such is the most interesting place to look at when it comes to anticipating sea level rise or fall: http://wattsupwiththat.com/2009/10/08/antarcticas-ice-story-has-been-put-on-ice/. Guess what, Antarctica has been fattening up with ice of recent, and the global warming alarmists try to hide the data.
Quite so. But if you listen/look carefully, you can still find some truth from scientists willing to speak out. See for example this interview on the sea-level fraud: http://www.climatechangefacts.info/ClimateChangeDocuments/NilsAxelMornerinterview.pdf. Turns out that sea levels have not been rising.
The following interview Dr. Nils-Axel Morner, a Swedisch expert on sea-level geophysics, explains how the data has been misrepresented to feed the global warming scare http://www.climatechangefacts.info/ClimateChangeDocuments/NilsAxelMornerinterview.pdf. The reality is that little has happened to the sea level over the past decades.
Check out the following articles and there references contained therein: http://www.examiner.com/x-18425-LA-County-Nonpartisan-Examiner~y2009m10d14-Medical-research-of-the-flu-vaccine-zero-statistical-difference-in-death-rate, http://www.naturalnews.com/023902.html, http://www.whale.to/vaccine/ott.html, and http://www.whale.to/vaccines/gbs.htm
To understand what lies behind this, watch the following talk: http://video.google.com/videoplay?docid=6890106663412840646&hl=en#
What makes you assume that their experiment was motivated by an interest in microwaves? Studying the physiological effects of 60 Hz fields is mighty interesting, as that is the power-line frequency.
There is a relation. What the experiments at 60 Hz show is that EM fields with very low photon energies (the photon energy is proportional to the frequency) can still cause biochemically appreciable effects such as DNA breakage.
The main reason that microwave-frequency EM radiation (which cell phones emit) has been claimed to be safe, at least in the low-power non-heating range, is that microwave photon energy is still way too low to break chemical bonds. This claim has been refuted by the 60 Hz results since they show that DNA breakage is definitely possible in the low-photon-energy regime, presumably by an indirect mechanism.
You don't understand. The main argument against cell-phone-induced damage is that the microwave photon energy (which is proportional to the frequency) is insufficient to break chemical bonds. However, that argument goes out the window if even much lower frequency EM radiation is found to still be able cause DNA breakage.
Powerwatch is a good overview site dealing with health issues surrounding microwave and lower frequency electro-magnetic radiation. It may surprise many of you, but there have been clear-cut studies showing DNA damage on acount of EM fields, even at low frequencies: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1241963
The "explanation" shifts the blame to "nanoflares". Why? Well, because "These temperatures can only be produced by impulsive energy bursts". But just because that is the only mechanism James Klimchuk can think of does not mean that there is no other mechanism. Indeed, anomalous extreme temperatures have been observed in coronal-alike plasmas under laboratory conditions: http://arxiv.org/ftp/physics/papers/0509/0509127.pdf. No "nanoflares" in that 0.4 Torr Pyrex cylinder.
This is typical overconfidence in theory. The reasoning is: nature must obey our currently accepted theories, and within the context of those theories I see only one possible cause, so that must be it. Such hubris. The accepted theories are likely to be incomplete, and might be downright wrong in places.
Then there is the title of the post: "Mystery of Sun's Outer Atmosphere Solved" Finely tuned to plant the mistaken belief in the mind of the Slashdot crowd that it has been figured out. Nothing more to see here. Please move along. After all, we don't want people to get a clue as to what is actually producing all that energy needed to keep the corona piping hot, do we?
No we have not had that. Realize that measuring the solar flux in the EUV and X-ray spectrum is not that easy even when in space. These wavelengths are easily absorbed: lenses and mirrors cannot be used to focus those photons on a detector. You need tricky instruments like grazing-incidence spectrometers. Also, early on people were not aware of the importance of the short-wavelength part of the solar spectrum and as such were not sending up the right instruments.
That's funny when you are ignoring observations of obvious relevance. I showed you a graph with a factor of three variation in the solar flux in a fairly broad wavelength band. At the very least that should have made you think twice.
I think anyone reading this thread is quite capable of perceiving that your argument is the shrill sounding one, and that you are unwilling to consider basic physics and observational data.
I guess part of the confusion lies in that we use a different meaning for "global warming". What I mean is an increase in the average global atmospheric temperature, something which can have many causes. I think you mean something more narrow: anthropogenic greenhouse-gas driven global warming.
That cannot be done. We do not have that data. A lot of the solar output is in the EUV. It has only recently started to be measured: http://www.usc.edu/dept/space_science/missions/SEH-3/SEH-3.html. However, within the context of that limited data you may discern a tentative correlation between the recent decrease in global temperature, the current occurrence of noctilucent clouds, and this graph: http://www.usc.edu/dept/space_science/sem_data/SEM%20Data%20Graphs/SEM_1996-2009.jpg
Obviously, there are more factors to be considered. For example, that the decrease in global temperatures started a bit earlier than the maximum in that graph is likely because 1997-1998 were El Niño years.
Also, given how politicized climate science has become, I do not have much confidence in the accuracy of the global temperature data sets being foisted on us: http://wattsupwiththat.com/2009/07/24/uk-met-office-and-dr-phil-jones-pay-no-attention-to-that-man-behind-the-curtain/
I am sure you can agree that simple physics dictates that variations in the solar flux must drive global average temperatures. After all, the energy present in the solar radiation reaching the earth is mostly absorbed by the earth's atmosphere, surface, and sea. This heats the earth's atmosphere directly and indirectly on a global scale. An increase or decrease in the solar output will therefore cause a matching increase or decrease in atmospheric heating and hence warm or cool the earth.
What you must be doubting, therefore, is whether changes in the solar flux are the main factor in increasing or (as is the case currently) decreasing global average temperatures.
You can answer this question for yourself by seeing what fraction of the total solar energy output lies in the variable UV/EUV/X-ray part of the spectrum.
Hint #1: it is a much larger number than you may suspect from the black-body spectrum derived from the solar surface temperature. The corona is excessively hot and responsible for most of the EUV and X-ray emissions.
Here is a good place to start http://www.usc.edu/dept/space_science/missions/SEH-3/SEH-3.html. Quoting:
Yes they are linked, but not in the simple way you seem to suggest. The linking mechanism to the solar cycle I described is indirect. Also, UV/EUV/X-ray output variation have been observed to occur on much shorter timescales than the 11 year solar cycle. Part of that has of course to do with solar flares, but there are also medium-timescale (days/weeks) variations that correlate to changes in the solar wind proton and neutral atomic hydrogen flux.
Moreover, the precise origin of the UV/EUV/X-ray coronal flux is enigmatic at best: the temperature of the solar corona is 1-2 million degrees Kelvin and there are no good quantitative explanations for how it can sustain that high temperature in spite losing energy rapidly (through that very UV/EUV/X-ray flux radiating out into space).
In short, it is a complex mess with many theoretical unknowns. But the observations make clear that the UV/EUV/X-ray flux constitutes an important fraction of the solar output, and that this flux varies strongly on multiple timescales.
Imagine the solar output doubles. What do you figure will happen to the mean global temperature? Assume it halves. What will happen? In what way is that not a correlation?
Indeed, and guess what: we have found strong variations in UV output http://www.ingentaconnect.com/content/klu/sola/1998/00000177/00000001/00134956?crawler=true. The shorter the wavelength, the more extreme the variations.
The variations are definitely correlated to the solar cycle which is not surprising: coronal conditions are strongly influenced by the entangled magnetic field loops pinned to sunspots since the charged particles in the corona track those loops on account of the Lorentz force. And it is known that the sunspot number rises and falls as to sun goes through the solar cycle maximum and minimum. However, the current cycle has an anomalously low number of sunspots and an extended minimum.
To get some idea as to what fraction of the short wavelength flux stems from the corona, have a look at the following images: http://umbra.nascom.nasa.gov/images/
Don't be stupid. As any child knows, the sun heats the earth so there is obviously a correlation between solar output and earth temperature.
However, the highly variable part of the solar output is mostly in the UV/EUV/X-ray range and as such is not easy to measure on earth. No correlations of global temperature with ground-based or narrow-band solar flux measurements are to be expected.
For the recent trend in global temperatures, see here: http://www.canadafreepress.com/index.php/article/12865.
It is related to global warming/cooling as follows: the required low temperatures in the upper atmosphere are only attained if the solar UV/EUV/X-ray flux, mostly originating from the solar corona, is very low: that part of the spectrum does not penetrate well and hence is absorbed in the upper atmosphere.
Since this UV/EUV/X-ray flux is a significant fraction of the solar output and varies strongly with coronal conditions, it is the most important driver of global warming/cooling. The solar corona is a very dynamic system which currently is in a quiescent state on account of the anomalously low number of solar spots. As a consequence it has been cooling in recent years, in spite of all the bullshit being published to the contrary: the raw data does not lie.
Make that -100C, but yes, true, it is well below freezing. However, the somewhat more physically complete explanation than simply "the upper atmosphere is getting colder" is that less energy is being put into the upper atmosphere on account of unusually low UV and X-ray emissions of the sun.
During the current solar minimum, which has extended well beyond the time it should have, there have been very few sunspots. The number of sunspots is strongly correlated to the UV and X-ray emissions of the solar corona which constitute a significant fraction of the overall solar flux. This strongly variable component of the solar output is the main driver of global warming or, as happens to have been the case since about 1998, global cooling.