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Sun & climate: moving in opposite directions

What the science says...

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The sun's energy has decreased since the 1980s but the Earth keeps warming faster than before.

Climate Myth...

It's the sun

"Over the past few hundred years, there has been a steady increase in the numbers of sunspots, at the time when the Earth has been getting warmer. The data suggests solar activity is influencing the global climate causing the world to get warmer." (BBC)

At a glance

Thankfully for us, our Sun is a very average kind of star. That means it behaves stably over billions of years, steadily consuming its hydrogen fuel in the nuclear reaction that produces sunshine.

Solar stability, along with the Greenhouse Effect, combine to give our planet a habitable range of surface temperatures. In contrast, less stable stars can vary a lot in their radiation output. That lack of stability can prevent life, as we know it, from evolving on any planets that might orbit such stars.

That the Sun is a stable type of star is clearly demonstrated by the amount of Solar energy reaching Earth's average orbital position: it varies very little at all. This quantity, called the Total Solar Irradiance, has been measured for around forty years with high accuracy by sensitive instruments aboard satellites. Its average value is 1,362 watts per square metre. Irradiance fluctuates by about a watt either way, depending on where we are within the 11-year long sunspot cycle. That's a variation of no more than 0.15%.

From the early 1970s until today, the Solar radiation reaching the top of Earth's atmosphere has in fact shown a very slight decline. Through that same period, global temperatures have continued to increase. The two data records, incoming Solar energy and global temperature, have diverged. That means they have gone in opposite directions. If incoming Solar energy has decreased while the Earth continues to warm up, the Sun cannot be the control-knob of that warming.

Attempts to blame the sun for the rise in global temperatures have had to involve taking the data but selecting only the time periods that support such an argument. The remaining parts of the information - showing that divergence - have had to be ditched. Proper science study requires that all the available data be considered, not just a part of it. This particular sin is known as “cherry-picking”.

Please use this form to provide feedback about this new "At a glance" section, which was updated on May 27, 2023 to improve its readability. Read a more technical version below or dig deeper via the tabs above!

Further details

Our Sun is an average-sized main sequence star that is steadily using its hydrogen fuel, situated some 150 million kilometres away from Earth. That distance was first determined (with a small error) by a time consuming and complex set of measurements in the late 1700s. It led to the first systemic considerations of Earth's climate by Joseph Fourier in the 1820s. Fourier's number-crunching led him to realise a planet of Earth's size situated that far from the Sun ought to be significantly colder than it was. He was thereby laying the foundation stone for the line of enquiry that led after a few decades to the discovery of what we now call the Greenhouse Effect – and the way that effect changes in intensity as a response to rising or falling levels of the various greenhouse gases.

TSI Solar cycles

Figure 1: Plot of the observational record (1979-2022) on the scale of the TSIS-1 instrument currently flying on the space station. In this plot, the different records are all cross calibrated to the TSIS-1 absolute scale (e.g., the TSIS1-absolute scale is 0.858 W/m^2 higher than the SORCE absolute scale) so the variability of TSI in this plot is considered to be its “true variability” (within cross calibration uncertainties). Image: Judith Lean.

The Sun has a strong magnetic field, but one that is constantly on the move, to the extent that around every 11 years or so, Solar polarity flips: north becomes south, until another 11 years has passed when it flips back again. These Solar Cycles affect what happens at the surface of the Sun, such as the sunspots caused by those magnetic fields. Each cycle starts at Solar Minimum with very few or no sunspots, then rises mid-cycle towards Solar Maximum, where sunspots are numerous, before falling back towards the end. The total radiation emitted by the Sun – total solar irradiance (TSI) is the technical term – essentially defined as the solar flux at the Earth's orbital radius, fluctuates through this 11-year cycle by up to 0.15% between maximum and minimum.

Such short term and small fluctuations in TSI do not have a strong long term influence on Earth's climate: they are not large enough and as it's a cycle, they essentially cancel one another out. Over the longer term, more sustained changes in TSI over centuries are more important. This is why such information is included, along with other natural and human-driven influences, when running climate models, to ask them, “what if?"

An examination of the past 1150 years found temperatures to have closely matched solar activity for much of that time (Usoskin et al. 2005). But also for much of that time, greenhouse gas concentrations hardly varied at all. This led the study to conclude, " that at least this most recent warming episode must have another source."

TSI vs. T
Figure 2: Annual global temperature change (thin light red) with 11 year moving average of temperature (thick dark red). Temperature from NASA GISS. Annual Total Solar Irradiance (thin light blue) with 11 year moving average of TSI (thick dark blue). TSI from 1880 to 1978 from Krivova et al. 2007. TSI from 1979 to 2015 from the World Radiation Center (see their PMOD index page for data updates). Plots of the most recent solar irradiance can be found at the Laboratory for Atmospheric and Space Physics LISIRD site.

The slight decline in Solar activity after 1975 was picked up through a number of independent measurements, so is definitely real. Over the last 45 years of global warming, Solar activity and global temperature have therefore been steadily diverging. In fact, an analysis of solar trends concluded that the sun has actually contributed a slight cooling influence into the mix that has driven global temperature through recent decades (Lockwood, 2008), but the massive increase in carbon-based greenhouse gases is the main forcing agent at present.

Other studies tend to agree. Foster & Rahmstorf (2011) used multiple linear regression to quantify and remove the effects of the El Niño Southern Oscillation (ENSO) and solar and volcanic activity from the surface and lower troposphere temperature data.  They found that from 1979 to 2010, solar activity had a very slight cooling effect of between -0.014 and -0.023°C per decade, depending on the data set. A more recent graphic, from the IPCC AR6, shows these trends to have continued.

AR6 WGI SPM Figure 1 Panel p

Figure 3: Figure SPM.1 (IPCC AR6 WGI SPM) - History of global temperature change and causes of recent warming panel (b). Changes in global surface temperature over the past 170 years (black line) relative to 1850–1900 and annually averaged, compared to Coupled Model Intercomparison Project Phase 6 (CMIP6) climate model simulations (see Box SPM.1) of the temperature response to both human and natural drivers (brown) and to only natural drivers (solar and volcanic activity, green). For the full image and caption please click here or on the image.

Like Foster & Rahmstorf, Lean & Rind (2008) performed a multiple linear regression on the temperature data, and found that while solar activity can account for about 11% of the global warming from 1889 to 2006, it can only account for 1.6% of the warming from 1955 to 2005, and had a slight cooling effect (-0.004°C per decade) from 1979 to 2005.

Finally, physics does not support the claim that changes in TSI drive current climate change. If that claim had any credence, we would not expect to see the current situation, in which Earth's lower atmosphere is warming strongly whereas the upper atmosphere is cooling. That is exactly the pattern predicted by physics, in our situation where we have overloaded Earth's atmosphere with greenhouse gases. If warming was solely down to the Sun, we would expect the opposite pattern. In fact, the only way to propagate this myth nowadays involves cherry-picking everything prior to 1975 and completely disregarding all the more recent data. That's simply not science.

Longer-term variations in TSI received by Earth

It's also important to mention variations in TSI driven not by Solar energy output but by variations in Earth's orbit, that are of course independent of Solar activity. Such variations, however, take place over very long periods, described by the Milankovitch orbital cycles operating over tens of thousands of years. Those cycles determine the distance between Earth and the Sun at perihelion and aphelion and in addition the tilt the planet's axis of rotation: both affect how much heat-radiation the planet receives at the top of its atmosphere through time. But such fluctuations are nothing like the rapid changes we see in the weather, such as the difference between a sunny day and a cloudy one. The long time-factor ensures that.

Another even more obscure approach used to claim, "it's the sun" was (and probably still is in some quarters) to talk about, "indirect effects". To wit, when studies can't find a sufficiently large direct effect, bring even lesser factors to the fore, such as cosmic rays. Fail.

In conclusion, the recent, post 1975 steep rise in global temperatures are not reflected in TSI changes that have in fact exerted a slight cooling influence. Milankovitch cycles that operate over vastly bigger time-scales simply don't work quickly enough to change climate drastically over a few decades. Instead, the enormous rise in greenhouse gas concentrations over the same period is the primary forcing-agent. The physics predicted what is now being observed.

Last updated on 27 May 2023 by John Mason. View Archives

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Further viewing

Related video from Peter Sinclair's "Climate Denial Crock of the Week" series:

Further viewing

This video created by Andy Redwood in May 2020 is an interesting and creative interpretation of this rebuttal:

Myth Deconstruction

Related resource: Myth Deconstruction as animated GIF

MD Sun

Please check the related blog post for background information about this graphics resource.

Denial101x videos

Related lecture-videos from Denial101x - Making Sense of Climate Science Denial


Additional video from the MOOC

Expert interview with Mike Lockwood


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Comments 26 to 50 out of 1295:

  1. WA, incidentally, where are those money figures coming from?
  2. Money figures? the $6 Billion? thats what is in the federal budget currently. the $170 Million is what the budget was just before George H Bush decided to throw money at the problem, first two numbers per Richard Lindzen, but I remember the numbers myself from back then. John gives $2.4 in 1993 which is after my $2 billion and $5.1 billion for 2004 which is before the current $6 billion. I think those numbers are right he just chose different years. As to the research question, you're the one making the claim "but key to the argument is that they stated positions that were not supported by their research". In what way did Mr. Taylor's statements fly in the face of his own research? How does writting a paper on Regional Precipitation Frequency or Observer Bias contradict his opinion that the warming did not seem catastrophic? Of course it doesn't. He was fired because his statements were not fasionable for politicians in power. In the case of Michels your claim that his statements were not supported by his research is rediculous. While you may not like it, any reader here who does read his papers will know that. Newell's work in particular shows no sign of bias and I think was very well done. His only mistake as far as I can tell was honesty. When his results didnt match what the climate models predicted... the end.
  3. Wondering Aloud: "With $6 billion/year in the US alone tied to GW orthodoxy, most people who need to keep their jobs are pretty hesitant to be branded a `denier'." And somehow Al Gore The Antichrist managed to create a _world-wide_ conspiracy using the US's budget alone? The _entire_ _world's_ climate research -- from China to India, from Hungary to Sweden, from Canada to Brazil -- depend on this $6b/year from the US? Can't you at least cook up a more plausible conspiracy theory? Back to the "it's the sun" topic, I find this particularly hilarious... apparently the creators of the film "The Great Global Warming Swindle" decided in their infinite wisdom to fabricate their own data to "prove" that it's the sun's fault: -- Frank Bi,
  4. Wondering Aloud: You may want to check your logic. Because your present a paper that does not support position A - it does not follow that you do support position A. If Mr. Taylor wishes to make a statement about global warming, he should produce the evidence that backs up his claim. Thus he is obligated to produce the research that supports his position - not say, my research does not contradict this position. And, as I indicated in my last post - he still appears to be the state climatologist so he does not appear to be fired. reagrds, John
  5. First off... No Frank the other countries spend money the same way, many have systems that are more corrupt. But, the US is by far the biggest player in the actual funding. The entire sun question was most certainly not created in some film made last year. If you read various threads here you would know that solar affects are blamed for millions of years of climate change in the past and now treated by some as irrelevent that's just not logical.
  6. Gee now it's a conspiracy theory! And here all I had was a practicle observation of how scientists sometimes face ethical challenges. On a more serious note, John I am not the one who claimed anything about their results vs their statements. Their results from your own references clearly are not contradicted by their public positions. You said: "but key to the argument is that they stated positions that were not supported by their research. This is what I was commenting on, you made the very logic error you attribute to me. The research in question does nothing to support the idea of catastrophic antropogenic global warming. So their public position that they didn't see strong evidence for it was perfectly reasonable. The problem is with the supposed vs. actual consensus again. I think you would have to concede that someone who recieves publicity as a "denier" is likely to have more trouble with funding agencies. Newell and Michels are clearly examples. I am not familiar enough with Taylor to judge.
  7. "No Frank the other countries spend money the same way, many have systems that are more corrupt. But, the US is by far the biggest player in the actual funding." So, by a sheer stroke of coincidence, _all_ the governments in the world decided _independently_ to promote the Great Global Warming Scam and then band together to create the World Gaia Government and rally around Al Gore The Antichrist or something? "If you read various threads here you would know that solar affects are blamed for millions of years of climate change in the past and now treated by some as irrelevent that's just not logical." Um, excuse me, that's the _whole_ _point_ of the AGW theory. Rive and Friis-Christensen olar effects correlated _well_ with _past_ climate change, but from 1985 on there was _no_ correlation between solar activity and global climate. Again, the link:
  8. Regarding your link: Give me a break, cripes take an astronomy class or something. Or better yet thermodynamics. There is nothing there that convinces quite the contrary. There are numerous real references above maybe you should check them. Thank you for another personal attack as well. Do you really think your abuse is going to convince me or anyone else smart enough to understand this blog? Nor will your deliberate misunderstanding of everything that someone you oppose says. We are not idiots here. "Um, excuse me, that's the _whole_ _point_ of the AGW theory. Rive and Friis-Christensen olar effects correlated _well_ with _past_ climate change, but from 1985 on there was _no_ correlation between solar activity and global climate". Are you saying you think the whole point of AGW theory is that the sun caused climate cycles before but magically not now? So a thousand year wrong direction time lag for CO2 causing climate change is ok in your book? The fact that far larger CO2 changes in the past did not cause the climate change that is being attributed to todays tiny change is ok too? The heck with the entire paleo record, today is special? Meanwhile you think the suns effect is instant and only happens if the people you want to cite claim it does. Our host here, John and Phillippe are all obvious true believers in AGW, they are doing as good a job as can be done defending this position. You are showing a vicious political agenda and nothing else. I came here believing that the world was warming and Humans were largely the cause but doubting the catastrophic idea because it doesn't fit the historic record or the atmospheric physics very well. A few more posts from you and I might be convinced that it all really is a politically motivated hoax.
  9. Wondering Aloud, I searched through your 5 paragraphs of verbosum and I couldn't find a single grain of fact or logic in it. You continually ignore facts, promote your Worldwide Satanic Conspiracy theory, and then accuse others of "personal attacks". Well, here's a link you'll definitely be interested in reading. "Chad Tolman, a Sierra Club Delaware Chapter member, said that views held by Legates and other climate-change skeptics are fast becoming _irrelevant_, making direct action by the state unnecessary." (emphasis mine) Yeah indeed... if you keep pumping out the same junk day after day, people tend to stop listening to you.
  10. LOL Yup you got that right. The Sierra Club has been pumping out the same junk day after day for decades and so no one takes them seriously anymore, haven't for 30 years. If you have ever presented anything even close to logic or a fact here I can't find it. I have come to the conclusion that you are a "denier" trying to set up straw men to make glogal warming seem a hoax. Please let the debate go back to reality we were learning something here. I argue with Phillipe and John but I learn things from them.
  11. "If you have ever presented anything even close to logic or a fact here I can't find it." Here's the link again: Of course, in your supreme open-mindedness, you simply decided to ignore it.
  12. Well, solar flux doesn't need to be argued. It can be proved. The current solar theory is due to an interaction that has something to do with sunspots. So, if that is the case, then we can see if the global temperature will go down, assuming the present dearth of sunspot continues. Last year, there was a low amount of sunspots, and the earth's global temperature dropped a degree. We can see if it drops again. Also, in that vein, is it not possible to just create a carbon dioxide plume, turn it on, then turn it off, somewhere, and measure the radiative forcing that way? It seems to me that the RF is calculated based on another term that looks, honestly, like a fudge factor to make a computer model "work". If you created a carbon dioxide "bubble" on earth somewhere, then shouldn't you be able to measure a temperature increase on the ground proportionally to that increase?
    Response: 2007 cooling was not driven by solar forcing (or lack thereof) but by La Nina.
  13. That is one of my issues with AGW. The environmental fanatics has seized upon one and only one factor involved, CO2. Granted that CO2 is a greenhouse gas it is not logical that it is either the only contributer or even the primary factor in global warming. AGW is a fact that needs to be accepted but we can not be blind to the other influences or we skew the results and may take actions in the wrong direction. The most powerful force controlling the climate is the earth and it's weather. The ocean currents, the jet stream, the vulcanism that drives the weather, the clouds and their specific composition, the magma flow of the earths engine and moreso the sun and it's internal tides and resulting changes in force and solar wind. By leaving out even small factors in models we skew the data. We should not be making corrections for urban heat islands but discarding bad information. Do you realize that there is not even a theory for how El Nino is driven? Only a hypothesis and that is very recent, but the phenomenon is well documented and studied. AGW needs to be addressed but properly, fully aware of it's cause and effect. Otherwise we just make it worse.
    Response: The most powerful force controlling climate is radiative forcing. Whatever causes the planet to be in energy imbalance - to accumulate or lose heat - is what drives long term global warming or cooling. The factors such as ocean currents and El Nino are responsible for internal variations but have very little impact on long term energy imbalance.

    So what causes changes to the planet's energy imbalance? Not just CO2 - there are many forcings that drive climate (eg - aerosols, solar variations, cloud albedo). However, the reason for the focus on CO2 is because CO2 is the most dominant radiative forcing and is increasing faster than any other forcing.
  14. John I apologise for my outburst in your blog. I came to this blog in the hope of learning through intelligent discussion as I am about fed up with arogant alarmists that shout you down in the news blogs like CBS or ABC. I also read the papers and articles at Climate Debate Daily which has alarmist articles on the left and skeptical articles on the right. I see outright lies in both columns. But I also see a lot of excellent articles with links to papers. With the exception of one or two individuals, your responders to this blog seem to be both intelligent and educated and to them as well as you I apologise.
    Response: Your comment is appreciated. I always make it a point to address the science and avoid making personal comments about a person I disagree with. Ad hominem attacks are a form of mental laziness. It's always easier to attack a person than the argument they're making. It's also an indication that the arguer is more interested in winning the debate than finding the truth. I encourage both sides to exercise restraint and stick to the science - it makes for more constructive dialogue and you never know, both sides might learn something. :-)
  15. Quietman 'If the sun turns out to be a more powerful driver than CO2 and you take drastic action you just killed us all.' Ahem! I think you are mistaken! ."Ironically, even arch-skeptics Soon and Baliunas, who would like to lay most of the blame for recent warming at the doorstep of solar effects, came to a compatible conclusion in their own energy balance model study. Namely, any model that was sensitive enough to yield a large response to recent solar variability would yield an even larger response to radiative forcing from recent (and therefore also future) CO2 changes. As a result, their "best fit" of climate sensitivity for the twentieth century is comfortably within the IPCC range.
      This aspect of their work is rarely if ever mentioned by the authors themselves, and still less in citations of the work in skeptics' tracts such as that distributed with the "Global Warming Petition Project."
  16. Quietman The evidence for significant extraterrestrial sources – e.g. GCR & solar effects remain wanting and contradictory. Some studies have required variable ‘smoothing’ to achieve an excellent correlation, however the correlation vanishes with more data, and there were other ‘strange’ errors. e.g. the notorious and widely quoted by skepics, Friis-Christensen and Lassen 1991. As demonstrated by Damon and Laut 2004 ‘Pattern of Strange Errors Plagues Solar Activity and Terrestrial Climate Data’ The weight of evidence is on the side of CO2! Solar / GCR evidence remains inconclusive.
  17. ScaredAmoeba As I have mentioned elsewhere, Richard Mackey (Austrailia) published last year Rhodes Fairbridge and the idea that the solar system regulates the Earth’s climate in which he states "When the totality of the sun’s impact is considered, having regard to the relevant research published over the last two decades, the influence of solar variability on the earth’s climate is very strongly non-linear and stochastic. Recent research about the sun/climate relationship and the solar inertial motion (sim) hypothesis shows a large body of circumstantial evidence and several working hypotheses but no satisfactory account of a physical sim process." He procedes to explain how and why the IPCC data for solar influence could be incorrect. This research is now also supported by Oliver Manuel (Nuclear Chemistry, University of Missouri, Rolla, MO 65401 USA) and Hilton Ratcliffe (Astronomical Society Southern Africa, PO Box 354, Kloof 3640 SOUTH AFRICA) in their December 2, 2007 paper Fingerprints of a Local Supernova Personally I believe that there is more to it and have been reading up on the current hypothesis for the cause of El Nino / La Nina to see how the Fairbridge hypothesis would fit. I feel that it does but I am not a geologist that that is the field where this type of science would be applicable.
  18. I stand by my comment about solar influences. Even if the moving solar barycentre influences climate in some weird and mysterious manner, so far, this is not much more than a theory. My distinctly limited investigation leads me to believe that it has about as much relevance to climate change as astrology – i.e. not much. At most the influence can only be small. It is notable that AFAICT the scientific community doesn’t seem particularly convinced either. Once the scientific community takes it seriously, so will I. Until then, I'll treat as cuckoo science - intended to look convincing, deceive the unwary and postpone action and legislation to combat CO2 emissions. There’s a lot of cuckoo science around and strangely much of it can be traced back to sources funded by Exxon and the coal industry. The solar hypothesis remains distinctly unproven and remains far from convincing. More science is clearly required. You seem persistently to be looking for any possible excuse to ignore the ugly fact that we already have a cause for a substantial proportion of climate change that is supported by solid science. We have the mechanism, palaeoclimate studies, all supported by a wealth of observations and measurements using different methods and that is increasing atmospheric CO2 with an anthropogenic origin. We must reduce and phase-out fossil carbon emissions by all means possible at the earliest feasible time. We must not permit any new coal-powered plants to be built without tried and tested sequestration technology being incorporated. All non-sequestered emissions from coal-powered stations need to be stopped no later than 2030. That is easily enough time to have a tried and tested zero carbon generating capacity.
  19. ScaredAmoeba In The Pennsylvania Gazette, May 15, 2007, article An Inaccurate Truth? an interview of Professor Robert Giegengack of the Department of Earth and Environmental Science pretty much sums up my stance: AGW is real but not apocalyptic.
  20. From the Vostok ice core data, during glacial periods, often a rising temperature trend with a rising carbon dioxide level suddenly changed direction and became a falling temperature trend in spite of the carbon dioxide level being higher than when the temperature was increasing. This could not be if carbon dioxide causes a positive feedback. The Andean-Saharan Ice Age occurred when the carbon dioxide level was over ten times its current level. What is different now that could lead to run away temperature increase? The determination that non-condensing greenhouse gases have no significant influence on average global temperature is not refuted by any climate history. The assertion ‘it’s the sun’ appears to be too simplistic. Of course the sun is part of it but several other things affect the temperatures at the measuring sites. These other things may include solar wind, cosmic rays, UV, magnetic strength, relative humidity (propensity to form clouds), ocean turn-over, and possibly other factors. Apparently, no one has sorted all this out yet. Graphs of NOAA and other data (all referenced) are presented at One observation from these graphs is that the recent (last 130 years or so) average global temperature data has not been unusual.
  21. Quietman The Professor Giegengack’s accusation of exaggeration would have us believe that the IPCC and scientists have perpetrated a most serious fraud – if only it were true. The truth is that the Professor’s accusation of exaggeration is a straw man argument and completely dishonest. The Professor should know perfectly well that both the IPCC and the scientists, of which the IPCC is involved, are extremely careful to use ranges of future scenarios in which they have extremely high confidence. Therefore these projected scenarios tend to be very cautious and conservative. The IPCC, for instance has consistently published past projected future scenarios that have been proven by events not to be exaggerations. The fact that the Professor levels such a false accusation reveals more about him than the IPCC and the thousands of scientists involved that he wrongly accuses of exaggeration. There are a small number of scientists, who have chosen to accept money from the fossil fuel industry and who do not have a reputation for credibility worth preserving. So why is the Professor not telling the truth? I don’t know, but there are a small number of scientists who make very similar accusations at mainstream scientists and the IPCC. Most of the others have been funded by the fossil fuel industry. So perhaps, he too is being less than open and honest in terms of his conflicts of interest. Further evidence that Professor Giegengack was being disingenuous is another projection that supports the view that the IPCC’s estimates of future sea level rises of 28 to 43 cm by 2100 were over conservative, due to incompletely understood mechanisms of ice-melt. [Dr Jevrejeva's group’s projections have been submitted for publication in the scientific journal Proceedings of the National Academy of Sciences.] The new estimates suggest sea-level rise is likely to be in the range of 0.8 and 1.5 metres, which confirms another estimate of 0.5 and 1.4 metres by 2100 by Stefan Rahmstorf, but using a distinctly different methodology. IPCC exaggeration? – clearly not. However, the facts never got in the way of malicious allegations and lies.
  22. Dan Pangburn You failed to prove that CO2 cannot be the driver of temperature via feedback, by choosing to totally ignore that other factors are involved. But later-on in your argument, you acknowledge that single effects alone are too simplistic. Are you suggesting that the climate is driven by a sole factor, or by more than one? You seem to suggest that both cases are true? Your contradictory logic proves that your argument is logically flawed and is without merit. Please ask any objective climatologist. Objective means NOT being in the pay of a vested interest (e.g. fossil fuel industry)! They will tell you that the climate is driven by numerous forcings and feedbacks. They will also tell you that a factor that causes cooling such as aerosols (volcanic or man-made) can result in cooling, despite increasing CO2 concentrations that would result in warming.
  23. Solar temperatures should lag temperature changes on earth. That is what actually shows the real influence of the sun on climate. This the exact opposite of historical readings of C02 when C02 lagged temperatures suggesting the opposite correlation.
  24. mick What your first sentence actually means is rather unclear. Could you please explain what you meant? References please. As stated earlier, the solar hypothesis is wanting and satisfactory mechanisms remain unproven, especially since evidence for increasing solar output is unconvincing. More science is definitely required. The solar hypothesis is also vastly overhyped, especially by those with a fossil fuelled agenda or a political axe to grind. The lag of CO2 behind temperature only shows that CO2 is released by increasing temperatures. This does not disprove that CO2 is a GHG. CO2 is known to be infra red active, both as a feedback and as a forcing. The absorption spectra of CO2 and H2O are different and the absorption of CO2 can be detected by satellite. The warming from CO2 often leads to additional feedbacks from other sources e.g. water vapour. Annually adding ~ 28 Gt of CO2 from burning fossil fuels has artificially boosted atmospheric CO2 and started a warming phase. The fossil source of this carbon is demonstrated by the isotopic composition. The increasing temperatures will release further CO2 that will cause further warming. All this without requiring any change in solar output.
  25. ScaredAmoeba There is more than one solar hypothesis. Most of which are much more recent than the greenhouse hypothesis, of which there are also more than one. The simple fact is that the effect on temperature based solely on CO2 was only 50% of what the models predicted: Ohio State University Fact Sheet

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