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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...

Select a level... Basic Intermediate Advanced

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, "...so 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

and

Additional video from the MOOC

Expert interview with Mike Lockwood

Comments

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Comments 1301 to 1317 out of 1317:

  1. Trying to find responses to Connolly et al 2021 in RAA on solar contribution to GW.

  2. cgfree59 @1301,
    The best initial assessment of any work by the Connolly brothers or Willie Soon is to assume it is yet another pile of their usual nonsense (I was much surprised recently seeing an NSIDC blog actually citing one of their papers for real!!) and given the lengths they go in obfuscating and misdirecting folk, this is not entirely a falacious use of an ad hominem argument.

    There are responses to this particular serving of nonsense Connolly et al (2021) 'How much has the Sun influenced Northern Hemisphere temperature trends? An ongoing debate' (thus a layman's efforts or a reply from the numpties themselves to a criticism of press coverage of their paper) but I do not see anything here at SkS.


    The conculsions of Connolly et al (2021) are to assert that the IPCC is premature with its conclusions as it ignores certain estimates of TSI and thus solar forcing which provide radically different results to the global warming attribution reached by the IPCC.

    "Different TSI estimates suggest everything from no role for the Sun in recent decades (implying that recent global warming is mostly human-caused) to most of the recent global warming being due to changes in solar activity (that is, that recent global warming is mostly natural)."

    You could expend time and effort trawling though Connolly et al (2021), picking out the obfuscation and misdirection they employ but the crux of it is the crazy method they use. That is they the employ blind curve-fitting of their preferred solar-caused climate forcing onto some crazy NH temperature estimates and only after this first-step into the lunatic asylum do they then get to attributing the left-overs of any temperature trends to anthropogenic forcings.


    So the results are pure nonsense.


    Further a rather telling observation is that of these TSI estimates which they claim are being ignored (TSI High Variability Estimates all plotted out in their Fig 3), only two would allow any naive correlation between rising global temperature with TSI through the all-important "recent decades."
    One of these two exceptional TSI estimates was scaled from a postage-stamp-size graphic in Ammann et al (2007), a paper which contradicts the muppets in that it concludes:-

    "Although solar and volcanic effects appear to dominate most of the slow climate variations within the past thousand years, the impacts of greenhouse gases have dominated since the second half of the last century.

    The second is cherry-picked TSI estimate is from yet another tiny graphic (Fig 5b of Egorova et al 2018) in turn the trace being based on Muscheler et at (2016) which employs proxy data to create estimates of TSI, so not a precise method you would want to put much faith in.

    The numpties offer no comment on such an obvious problem with their grand thesis, that it has such a narrow and less-than-reliable basis for the singularly important calculation within their account. Such an omission is a sign that you have strayed from reasonable analysis and entered the lunatic asylum.

  3. krit242 at @1298
    As Bob Loblaw pointed out in @1300, the total energy emitted by the Sun at shorter wavelengths is very limited. The Sun isn’t a perfect blackbody, but it’s reasonably close, so I used the Blackbody Calculator at spectralcalc.com to find the energy emitted at those shorter wavelengths as a percentage of the Sun’s total energy output. This was the result when the temperature was set to 5772 K:

    UV-A (315-400 nm):    8.03 %
    UV-B (280-315 nm):    2.05 %
    UV-C (200 -280 nm):   1.95 %
    F-UV (122-200 nm):     0.15 %
    0-122 nm:                    0.0002 %

  4. HK @ 1303:

    Those numbers are consistent with other sources.

    Note that the shorter wavelengths do not reach the earth's surface. They are absorbed in the upper atmosphere - e.g., by ozone in the stratosphere. Absorption of radiation is what heats the stratosphere, as seen in this image I linked to in another thread last week (from Manabe and Weatherald, 1967):

    Manabe and Weherald 1967 figure 16

    This page, from highly-respected radiation instrumentation company Kipp and Zonen, gives a breakdown of atmospheric transmission of various wavelengths.

    https://www.kippzonen.com/Knowledge-Center/Theoretical-info/Solar-Radiation

    The shorter UV-B and UV-C wavelegnths are either mostly or completely absorbed before reaching the surface. A table from that page:

    Kipp and Zonen atmospheric transmission table

     

    The low amounts of energy in those short wavelengths - plus the low amounts that penetrate past the stratosphere - are the main reason that climate "skeptics" look for indirect effects, such as cloud formation, cosmic rays, etc. (They are still looking...)

  5. What about the admission by 6th IPCC assessment about uncertainty in solar related data?

    Look at

    https://www.youtube.com/watch?v=9Q2YHGIlUDk

    Response:

    [BL] Three points:

    1. The web software here does not automatically create links. You can do this when posting a comment by selecting the "insert" tab, selecting the text you want to use for the link, and clicking on the icon that looks like a chain link. Add the URL in the dialog box.
    2. The Comments Policy specifically states "Any link or picture should be accompanied by text summarizing both the content of the link or picture, and showing how it is relevant to the topic of discussion. Failure to do both of these things will result in the comment being considered off topic." As Rob Honeycutt states, just providing a link without much context is just sending people off on a wild goose chase, and is considered bad form.
    3. The link does work for me, but the first two names that I see are Judtih Curry, and Jordan Peterson. Neither are particularly reliable. Details on Judith Curry are available here and here. She has a reputation for beating the Uncertainty Drum as if it was a rented mule. Jordan Peterson has no background in any sort of atmospheric science, let alone climate science. You can read more about him here.

    If you wish to continue this line of thought, you are going to have to provide some sort of coherent discussion and argument.

     

  6. panhuang... How about you explain what you think the IPCC is claiming rather than sending people off on a wild goose chase?

  7. Panhuang @1305,

    my computer says your video is no longer available.  Error at my end or at your end ?

    Either way, please have the courtesy to explain the video contents.

    If the IPCC is wrong on global warming, then the World needs to know!  And there might be a reporter's Pulitzer Prize in it for you . . . and just possibly your share in a Nobel Prize for Physics.

    On the other hand, you may be misunderstanding the basics.  Likely?

  8. Moderator @1305    [note: 3 additional scroll & clicks were required to reach Page 53 of Comments in this thread]

    Thank you Bob, it likely my VPN "blocks" the video.  But the VPN is not worth circumventing, if that video is by Curry and/or Peterson.  As you say, both Dr Curry and Dr Peterson have poor track records.

    (Personally, I have never seen either of them put forward an argument which invalidates the scientific evidence found in IPCC reports.   Panhuang @1305 has a great deal of explaining to do. )

  9. Yes, the links in the "Recent Comments" page still do the wrong page number. On the list to fix.

    This gets you to your comment properly:

    https://skepticalscience.com/argument.php?a=18&p=53#140262

    This is the borked link on the Recent Comments page.

    https://skepticalscience.com/argument.php?a=18&p=27#140265

    The trick is knowing whether 2x27 will be 53 or 54... Whichever one you guess, it will probably be the other one.

    I did not watch the video. I just saw the names in the text description below it. That was enough, until panhuang tells us more. (I won't hold my breath.)

  10. The link given @1305 leads me to a bunch of YouTube adverts but if you specify a time with the link, the Curry/Peterson nonsense appears. Thus:
    https://www.youtube.com/watch?v=9Q2YHGIlUDk&t=60s
    Below the video there is a box that can be expanded with a 'show more' tab and that shows a list of a couple of dozen parts to the video (called Chapters) and one of these does mention things solar (which was what panhuag @1306 was asking about) 'The Challenger explosion, how the sun affects climate'. This provides the following from Curry:-

    "Once you get into the sun, it's even crazier. The IPCC has pretty-much dismissed the role of the sun in the last 150 years but the interesting AR6.6 finally acknowledged the great uncertainty in the amount of solar forcing in the late 20th century and this arises from ... a gap in the satellites measuring the sun's output that occurred at the time of the Challenger shuttle disaster... So one solar sensor was running out and they were supposed to launch another one but all the launchers were put off for a number of years until they sorted out... (the launchers). So there's a so-called gap which depending on what was happening in that gap, you can tune the solar variability to high variability or low variability. So all the climate models are being run with low solar variability forcing.
    For the first time in AR6.2 (2.2.1), the observational chapter acknowledges this issue, that there are huge amounts of variability.
    And this doesn't even factor in the solar indirect effects.... It's not just the heat from the sun. There's a lot of issues related to UV and stratosphere and cosmic rays and magnetic fields and all these otehr things that really aren't being factored in. They're at the forefront of research but they're certainly not factored into the climate models so there are so many uncertainties out there that affect certainly the projections of what might happen in the 21st century but also our interpretation of what's been going on with the climate for the last 100 years and exactly what's been causing what.

    A quick look at AR6.2.2.1 shows Curry is doing particularly well ast spouting nonsense here.

  11. MA Rodger @1310 , thank you for extracting some classic Curry.

    I particularly liked :- "... huge amounts of [solar] variability ... a lot of issues related to UV and stratosphere and cosmic rays and magnetic fields and ... things that really aren't  being factored in [to models] ..."

    A quote so typical of Dr Curry.  A bit of smoke & mirrors, vague handwaving, followed by more sciencey-sounding vagueness, plus the magic word Uncertainties uttered thrice.   And at this point, every Denialist is nodding in agreement, with all critical abilities set in the OFF position.   Her style is unique.

    If Dr Curry were pressed on some of that nonsense, she would walk it back ~ by retreatiing into more vagueness.  She outclasses Dr Peterson in that way ~ he at least can look slightly embarrassed when he is caught out in some of his own nonsenses (and he does, when caught, walk his mistakes back . . . temporarily).

    Dr Curry's style of discourse reminds me somewhat of another speaker, but she has never actually suggested fixing solar problems by injecting bleach into the sun.

  12. MAR, is this an allusion to the ACRIM gap or the old ACRIM vs PMOD debate? If it is, both of these horses have already been flogged to death as far as I recall.

  13. Philippe Chantreau @1312,

    While Curry is evidently referring to the ACRIM gap of 1989-91 when she talks of "a gap in the satellites measuring the sun's output that occurred at the time of the Challenger shuttle disaster" of 1986, mainly because there is no other "gap". But her reference to AR6.6 'Short-lived climate forcers' as giving discussion of some "great uncertainty in the amount of solar forcing in the late 20th century" that "arises" from the ACRIM gap is deluded nonsense. AR6.6 concerns aerosol forcing and thus the solar aspects of this and nowhere considers any gaps in TSI data.

    As you say, the ACRIM gap was an issue of long ago although I think it remains an issue when used in historical proxy TSI reconstructions and whether the Maunder Minimum TSI was 1Wm^-2 or 2Wm^-2 lower than today. But this is not apparently what was Curry attempting to describe in her deluded rant. (The graphics below are from an Andy May discussion of TSI dated 2018.)

    TSI satellites

    TSI proxy reconstructions

  14. As blind chance etc. would have it I currently find myself engaging with Judith Curry's denizens under her article about the recent joint venture with Jordan Peterson.

    This is presumably the cause of some or all of the "it's the sun, stupid!" nonsense currently being promulgated in the Twittodenialosphere?

    As a consequence my Arctic alter ego felt compelled to bring the following NASA article to the attention of one such Dunning-Kruger sufferer:

    https://climate.nasa.gov/ask-nasa-climate/2949/why-milankovitch-orbital-cycles-cant-explain-earths-current-warming/

    Elon's new thought police helpfully suggested that I might want to reconsider my attempted violation of Twitter's community guidelines:


    The allegedly "offensive language" was merely echoing that of the DK sufferer in question.

    What a "Brave New World" we currently inhabit!
      

  15. Jim Hunt @1314,

    The reference to "Brave New World" is noted. But it can be understood to be the "Same Harmful Old World".

    There is currently a resurgence of people demanding the promotion and protection of harmful misunderstandings that excuse understandably harmful developed aspects of the Status Quo. Many people dislike learning that excuses of harm done are misunderstandings. They resist learning evidence-based evaluations done in pursuit of limiting harm done and developing sustainable improvements.

    What is seen to be happening regarding Twitter and other media, and clearly dominant in politics, can be well explained as follows:
    • People who want to prolong harmful misunderstandings demand that presentations of harmful misunderstanding must be 'protected freedom of thought and expression'
    • Those same people declare that it is unacceptable to ridicule people who present understandably ridiculous beliefs. They have a ridiculous belief about community-building. They believe that community-building requires acceptance of harmful people who want to promote and prolong harmful misunderstanding. Ridiculing people who persist in resisting learning to change their mind about harmful misunderstandings is deemed to be 'harmfully divisive'.

    The future of humanity requires this cyclical resurgence of harmful selfishness to fail. Ultimately what is required is social transformation that limits the harm of attempted resurgence of harmful selfishness. But, unfortunately, as the climate science case proves, the current system is substantially compromised by harmful selfishness. It allows a lot of harm to be done by the promotion and prolonging of harmful misunderstandings. And climate science is not the only matter where more harm is being done due to the ‘ridiculous freedom of harmful selfish people to believe and do whatever they desire and resist being restricted and corrected by Others’.

  16. Jim Hunt @1314 ,

    Judith Curry's denizens are, as you well know, much uninclined to engage with you in any true sense.  They tend to operate by deflections and faux misunderstandings.  (Commenters Joshua, Willard, and David Appell are very much the exceptions ~ but they appear rarely.)

    The Curry-ites are somewhat more upper class than the WUWT-ites, on the whole.  But you may have noticed that many of them have a sort of Schroedinger Feline brain ~ you cannot be certain whether inside the cranium is something which is brain-dead or brain-alive.  Or a brain which is both at the same time, or is rapidly alternating.  This might explain how so many of them know that you [Jim Hunt] are correct in what you have (so often) said to them in the past . . . and yet they usually seem ignorant of that information (and are not wishing to know it).

    BTW Jim, with my newest VPN version, I do not get to access your website GreatWhiteCon.info   ~  stuff comes up like "cannot access this site"  or  "this site does not support https".   Presumably the fault is mine as a computer ingenu . . . but would you mind checking your https status ?  Thanks.  [No need to reply]

  17. Please note: the basic version of this rebuttal has been updated on Feb 14, 2023 and now includes an "at a glance“ section at the top. To learn more about these updates and how you can help with evaluating their effectiveness, please check out the accompanying blog post @
    https://sks.to/at-a-glance

    Thanks - the Skeptical Science Team.

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