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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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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 1026 to 1050 out of 1302:

  1. KR and marsupial Thank you for your input. I understand your points. From the information provided to me, I did not have the information on the Heartland funding. I will look for data on global cloud cover. Does anyone have any links to such data? Thank you both for your time.
  2. I have been able to find some data on global cloud cover. I also see that it is a bit complicated with low clouds cooling Earth and high clouds warming Earth. Will take some figuring out. Again, thanks for your time.
  3. SirNubwub - I would suggest looking at Ari Jokimäki's list of Papers on global cloud cover trends, in particular Eastman et al 2011.
  4. SirNubWub: You really need to get more specific in just what it is you're looking for. Although not totally useless, "sunshine hours" is awfully simplistic. It used to be commonly measured by devices such as the Campbell-Stokes Sunshine Recorder, and is defined formally as the amount of time where direct solar radiation exceeds 120 W/m^2. It depends on cloud, other atmospheric conditions, sun angles, etc., and is only very loosely related to solar energy received at the earth's surface. Likewise "cloud cover". Cloud is not something that is easily summarized in one number. What type? What altitude? What time of day? all this changes the effect that "one tenth cloud cover" will have on solar radiation. If you are interested in energy received at the surface, it is better to look directly at the measurements, such as those archived at The Baseline Surface Radiation Network. Note that the "fake skeptics" that are trying to mislead people (or are misleading themselves) will often ignore real, direct readings of importance (e.g. radiation) and focus on indirect, approximate readings of loosely-related factors (e.g., sunshine, cloud cover). This is another form of cherry-picking. Regardless of whether it is intentional or the result of confirmation bias or motivated reasoning, it is not good science.
  5. Bob, Thanks for the info. I see that the graph I posted is fairly useless. I will have to dive deeper into the subject of radiation. I appreciate the link.
  6. @ Bob Loblaw #1029: SirNubWub's posts on this thread and others suggest to me that his primary purpose is not to learn, but rather, it is to provoke SkS authors into saying something intemperate. Therefore, be careful not to take the bait.
  7. John, You have me wrong and I am a bit ticked by you accusation. All of my discussions have been based on data from referrenced links. I have admitted that I have been wrong on two occassions now in the past few days. If that and my reply in line 1030 is not what you want to see from all skeptics, then please tell me how you hope I would reply.
    Response: [DB] Point taken. Dialogue and discussion in good faith should be accorded respect from all parties. The point of this site is to disseminate and foster civil discussion of the primary literature of climate change and to overcome misperceptions and misinformation about it.
  8. @ SirNubwub #1032 I'd be very pleased if you were to proove me wrong. If you do, I will apologize.
    Response: [DB] SirNubwub should be accorded the benefit of the doubt, as per his/her recent comment above. Comments made in good faith on these threads are what matter.
  9. SirNubwub - While I feel it inappropriate to speculate on others motives, I would like to point out some issues with your previous postings. Your first posting on SkS, as far as I have found, asked "Can I now present to my classes that the hockey stick argument has been discarded by the AGW proponents? ". I recall another one (can't find it at the moment) asking why there was no significant warming in 15 years. You've also recently put forth the proposition that climate science is driven by the money, rather than the data. And in this thread you open up by stating "I am not here to debate a point. I have read the report, but I am not knowledgeable enough in the topic to try to defend it. I just want to learn the alarmist side of the point", then showing a graph of cherry-picked data, from a bad source, arguing directly against the point of the opening post. So, in context, you have presented a series of 'skeptic'/denial talking points, asking about the "alarmist side", usually with an air of "Doesn't this prove all of the science wrong?". The support for these points (IIRC) has been from newspaper articles, blog postings, and sources like the NIPCC. Bad sources, bad phrasing in your questions, all of which unfortunately can lead to a perception that you are more interested in propping up denial memes than investigating the data. It also appears clear to me that you have not read the opening post(s) on the threads you have joined, or looked over the list of 'skeptic' arguments, all of which quite frankly answer the questions you have raised. If you wish to be taken as someone actually interested in answers, I would suggest several things: (1) read the opening post(s), (2) critically evaluate your sources, and (3) ask questions, rather than dropping these "Aren't all of you wrong?" statements. Because, quite frankly, anyone involved enough in climate science and the public discussion to be present on a website like this has already heard enough"Silver Bullet" arguments from 'skeptics' to find them quite antagonizing.
    Response: [DB] The thread in question leads up to this comment by SirNubwub here. Fixed link & text per request.
  10. DB, thank you.
  11. (Continued from here) Dikran Marsupial, Falkenherz - Foster and Rahmstorf 2011 (discussed here) examined atmospheric responses to various forcings, namely aerosols, MEI/ENSO, and insolation, using multiple linear regression to examine their contributions. The steady increase in CO2 forcing was not associated with a time lag: as a near-linear trend, it doesn't have the necessary variations to be time-matched to temperature changes (no 'teeth' to match). For that component F&R 2011 just used a linear rising trend. [Source] The atmosphere, in particular the upper troposphere (RSS/UAH) responds quite quickly to changes in TSI. Overall effects (larger temperature swings) will occur over longer periods due to the thermal buffering of the oceans, but there is a fairly immediate and detectable atmosphere response.
  12. The atmosphere, in particular the upper troposphere (RSS/UAH) responds quite quickly to changes in TSI. Overall effects (larger temperature swings) will occur over longer periods due to the thermal buffering of the oceans, but there is a fairly immediate and detectable atmosphere response.
    Indeed - as the seasonal changes in response to annual hemispherical insolation changes suggest.
  13. As Bob explained to me up thread there are various time constants for warming of lower layers of the ocean. There should thus be a roughly exponential rise in GAT (atmosphere) based on those time constants after the immediate GAT rise. The annual cycle of solar means it can only perturb the mixed layer before cycling back. A secular rise in solar would affect the deeper layers for which we would have to derive time constants.
  14. Interesting article on this topic: Steinhilber et al 2012, "9,400 years of cosmic radiation and solar activity from ice cores and tree rings". They use Be10 and C14 isotopes from ice cores and tree rings to reconstruct total solar irradiance over that period, taking advantage of some more recent ice cores for cross-checking. They then compare that to the Asian climate record, and find good coherence - albeit with periods of very low coherence, which they state are "...pointing to other forcings like volcanoes and greenhouse gases and their corresponding feedbacks. Their forcing data will apparently be made available at the NOAA server for paleo datasets, although only his 2009 revision is currently up.
  15. New Research for the topic: Evidence of recent causal decoupling between solar radiation and global temperature "We have shown that there is an evident causal decoupling between total solar irradiance and global temperature in recent periods. Our work permits us to fix the 1960s as the time of the loss of importance of solar influence on temperature. At the same time greenhouse gases total radiative forcing has shown a strong Granger causal link with temperature since the 1940s up to the present day. ..." Well, eyeballing MarkIII the TSI/Temperature Graph gives a similar impression, but scientific proof of it gives a way better argument.
  16. That chart shows temperatures continuously and sharpely increasing since 1980, that is pure nonsense.  The most accurate measurements, satellite measurements, the ones the Clinate Scientists seem to choose to ignore shows flat temperatures from 1980 to 2000, with a few spikes. Then the reletively volcano free 2000 through today shows an increase of 0.2 degrees. As recent as 2008 we were at or below the level of 1980. If the best the (-snip-)highlighted by the original article starting this thread.

    Response: (Rob P) Inflammatory snipped.
  17. "The most accurate measurements, satellite measurements, the ones the Clinate Scientists seem to choose to ignore shows flat temperatures from 1980 to 2000, with a few spikes"

    Nonsense.  UAH, a satellite measurement from climate "skeptics" Roy Spencer and John Christy, shows about .22*C of warming from 1980 to 2000.  From 1980 to the present it shows about .42*C.  You are completely wrong. 

    "As recent as 2008 we were at or below the level of 1980."

    Nonsense again.  2008 was no where near as cool as 1980. 

    " If the best the (-snip-) can do is rely on highly innacurate ground measurements they don't have much of a case."

    The ground measurements agree very well with the satellite data, which you are obviously are unfamiliar with.  Nothing you said above is true.  Talk about a . (-snip-) 

    Response: (Rob P) Inflammatory snipped.
  18. Robert Wagner @ 1042, those same satellite measurements you claim to be accurate show a TOA energy imbalance: more energy entering the Earth system than leaving it. What do you think is happening to all that extra energy Earth is absorbing, if it is not warming the biosphere?

  19. Robert Wagner @1041, below are 11 year running averages of Gistemp (as used in figure 1 above) post 1950, along with 11 year running averages of RSS and UAH data, all offset to have a common baseline of 1981-2010.  As can clearly be seen, the trends of the three are virtualy indistinguishable.  Your primary claim is, therefore, patently false.

    I will also note that your supposition that the satellite records, by virtue of being satelite records, are more accurate records is unfounded.  It is well known that the surface temperature record needs adjustment for the Urban Heat Island (UHI) effect, Time of Observation (TOBS), along with changes of instruments over time.  The satellite record, however, invovles adjustments for changes of instruments (as one Satellite is replaced by another), for the fact that the raw data includes a large measure of the cooling stratosphere in its observations, for the fact that the time of observation at any location changes as the satellite orbits , for bias arising from the properties of different surfaces, and their altitudes; and so on.  Far more, and far more mathematically challenging mathematical adjustments are required to take raw satellite records and turn them into a temperature record than are required for the surface record.

    Below are a list of the main corrections of the main, known errors in the UAH record that have been needed over time (and acknowledged by Roy Spenser).  There has been a scientific paper published pointing out yet another apparently needed correction that Dr Spencer does not yet agree with.  Only time will tell if he has finally got it about right, or whether yet more corrections will be needed before UAH can finally be considered as accurate as the surface record:

  20. Why are people even debating this The empirical evidence in favor of the solar explanation is overwhelming.

    Dozens of peer-reviewed studies have found a very high degree of correlation (.5 to .8) between solar-magnetic activity and global temperature going back many thousands of years (Bond 2001, Neff 2001, Shaviv 2003, Usoskin 2005, and many others listed below). In other words, solar activity “explains,” in the statistical sense, 50 to 80% of past temperature change.

    Such a high degree of correlation over such long time periods implies causality, which can only go one way. Global temperature cannot be driving solar activity, so there must be some mechanism by which solar activity is driving or modulating global temperature change. The high degree of correlation also suggests that solar activity is the primary driver of global temperature on every time scale studied (which is pretty much every time scale but the Milankovitch cycle).

    In contrast, records of CO2 and temperature reveal no discernable warming effect of CO2. There is a correlation between atmospheric CO2 and temperature, but with CO2 changes following temperature changes by an average of about 800 years (Caillon 2003), indicating that it is temperature change that is driving atmospheric CO2 change (as it should, since warming oceans are able to hold less CO2). This does not rule out the possibility that CO2 also drives temperature, and in theory a doubling of CO2 should cause about a 1 degree increase in temperature before any feedback effects are accounted, but feedbacks could be negative (dampening rather than amplifying temperature forcings), so there no reason, just from what we know about the greenhouse mechanism, that CO2 has to be a significant player. The one thing we can say is that whatever the warming effect of CO2, it is not detectable in the raw CO2 vs. temperature data.

    This is in glaring contrast to solar activity, which lights up like a neon sign in the raw data. Literally dozens of studies finding .5 to .8 degrees of correlation with temperature. (-snip-). RF for CO2 is entered as ___ W/m^2 while RF for total solar effects is entered as ___ W/m^2. [I'm not going to quote the actual numbers, but yeah, the ratio is an astounding 40 to 1, up from 14 to 1 in AR4, which listed total solar forcing as 0.12 W/m^2, vs. 1.66 for CO2.]

    So the 50% driver of global temperature according to mountains of temperature correlation data is assumed to have 1/40th the warming effect of something whose warming effect is not even discernable in the temperature record. (-snip-).



    Response: [DB] Off-topic and inflammatory rhetoric snipped.
  21. Sabre, you did read the intermediate and advanced articles tabbed above, yes?  Yes, global temp track solar variation quite well until about 1960. Where is it argued that it doesn't?  What happens after 1960, as TSI drops from the modern max, and temp just keeps on rising.  You're familiar with Pasini et al. (2012), yes?  And the same Usoskin (2005) points out "during these last 30 years the solar total irradiance, solar UV irradiance and cosmic ray flux has not shown any significant secular trend, so that at least this most recent warming episode must have another source." 

  22. DSL,

    Apparently some people don't feel uncomfortable commenting on posts they haven't read. It gets a bit ridiculous when the post you'd provide them with a link to in order to dispel their misconception is the one they've commented on!

  23. Just out of curiosity, what's the most-commented post here at SkS? This would have to be a contender, which strikes me as amazing because it's one of the most obviously wrong myths yet apparently one of the most fervently argued.

  24. Sabre @1045...  Do you honestly believe that the broad scientific community hasn't already considered everything you've stated here before coming to the overwhelming conclusion that human are primarily responsibe for the rise of global temperature of the past 40 years?

    Just curious.

  25. JasonB...  I was thinking exactly the same thing.  Literally, this is probably THE most clearly debunked myths there is in the climate debate.  It's stunning that anyone is still clinging to it.

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