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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 576 to 600 out of 1300:

  1. GnDoty - you can't ignore volcanic sources of CO2 over the (very) long haul. Temperatures are related to both CO2 and solar input, as described on CO2 was higher in the past. The difficulty now is that we're adding CO2 at an extremely high rate by geologic standards, and the geological weathering feedback and other CO2 sinks are too slow to keep up. We're entering a new domain, as described on On temperature and CO2 in the past. I'm not looking forward to the temperature catching up with current CO2 and solar levels...
  2. I'd be interested in data on current CO2 output caused by fossil fuels versus the CO2 output of an active volcanic period. Both rapidly increase CO2 levels. Would everyone agree that if the output was similar, the earth and life would simply adapt as it has before? This is assuming we as a species will advance technologically to the point of becoming far less dependent on fossil fuels. In my opinion, we can't come to any realistic conclusion when too many variables such as solar influence are not fully understood. This leads a person with an open mind like me to wonder why such drastic measures are being proposed when the situation is still not factually conclusive.
    Response: Here is a comparison of CO2 levels and volcanic activity. The 3 largest volcanic eruptions over the past 50 years had an almost negligible effect on CO2 levels:

  3. GnDoty, if a tree falls in the forest and nobody is there, nobody can be crushed by the tree. We've no experience with having 7+ billion people on the Earth during (for instance) the Deccan flood basalt events, which in any case took far longer to mutate the climate than what we're doing. I'm a firm believer that we're not going to go extinct any more than are cockroaches, but by ignoring what we're doing we're going to end up living a little bit more like cockroaches. Why would we want to do that? Folks raising their hands "aye" to enjoying our present living standard should pay heed. Just ask President Medvedev of Russia. He's got a fresh perspective on "adaptation."
  4. GnDoty - read Do volcanoes emit more CO2 than humans for some info on relative CO2 rates. Volcanoes emit at a time averaged ~1% of current human rates - they aren't similar. As to solar influence - that's really pretty well understood. It's been decreasing since the 1970's, but over geologic/cosmic time it's been brightening, as per its life cycle. Stellar evolution is considered to be very well understood - we've got, after all, billions of examples to look at. There's a nice image of the solar life-cycle on Wikipedia.
  5. I have been reading many of the posts here and must admit I am a layman in terms of climatology, however, has anyone looked into comparing the density of atmospheric gasses/atmosphere/atmospheric ceiling over time?. As I understand it, Low earth orbit debris has been increasing due to a lower atmospheric ceiling, and if it is due to a lower ceiling/upper atmosphere density has the atmosphere increased in pressure or been absorbed somwhere else? (co2 into the ocean possibly? methane reacting with UV?). Now if the aforementioned where true, would it not be a similar scenario to how a refrigerator functions in that the denser gas acts as an insulator retaining the heat then as it is decompressed/expands it cools by realising the heat energy (like an aerosol can)?.. as i have previously stated I am a complete novice and apologise for not being able to submit any sources, this comment is intended more as food for thought than anything else and will most likely barking up the wrong tree altogether!
  6. What I am trying to articulate (badly) is the overall constitution of atmospheric gas density and thermal retention - is there a correlation there?
  7. Eg. atmospheric density affecting solar absorbtion rates
  8. Apologies for spamming the forums! heres one source that discusses the low earth orbit/atmospheric friction/ solar activity
  9. sun tzu @ 580 No harm in being a layman in anything. All of us were at one time. Remember the atmosphere is layered, like an onion. Forces that act on one layer may, or may not, act upon an adjacent one. Increasing CO2 exerts its main influence in the upper troposphere, the lowest layer, causing it to warm. Lack of energy being transmitted upward from the troposphere to the stratosphere means the stratosphere cools (which is measured by satellites). When layers cool, they can compress, thinning somewhat. Recent UV output from the sun has been declining, causing the thermosphere, one of the outer layers of the Earth's atmosphere, to compress downward, to a record low thickness. The net effect of this compression is less atmospheric drag on our communication & research satellites in low Earth orbit (which extends their service lifetime - bonus!). Note that changing energy levels of the various layers of the atmosphere or their thicknesses has no effect on the mass of the column of air above any point on the Earth (which is what determines the local air pressure). Atmospheric physics is a complex area of study. Even experts in it get confused sometimes (or tripped by the D-K Effect). For an introductory starting point, try start here first, then go here, then go here to figure out where to go next. Wiki, surprisingly, is a good source as well. Once you know what to type in, anyway (Catch-22: you have to know enough to search for what to learn about next, but how do you search if you're a complete beginner?). Hope this helps, The Yooper
  10. Thanks for the reply, actually the above question stemmed from reading a book by Sir Patrick Moore called 'Astronomy' where he briefly covered solar activity and the effects on the thermosphere (I am currently starting to study Astronomy and astrophysics as a past time and found it to be a great starting point!). The reason I considered the atmospheric effect is we have been undergoing a mild period of cooling over the last couple of years whilst the upper atmospheric altitude is apparently reduced. It occured to me that another effect of this is, if the atmosphere has a smaller diameter then is it logical that the planets solar foot print is also smaller meaning more solar energy just keeps on going through space rather than getting absorbed by atmospheric gasses?.. Another area I dont think I have seen mentioned on here is the question of why are the planet Mars Ice caps also receeding? is this in some way linked to our own warming or is it simply a matter of Mars orbit in realtion to the sun? has anyone been able to reference Martian Polar recession with our own warming cycles in relation to its proximity to the sun?... Im not 100% in favour of 'The sun did it' as there are many many other areas that affect global climate, Deforestation of the rain forests, Methane, CO2 Emissions, Atmospheric particulates, Atomic Testing infact a whole load of variables.. however, it does occur to me that perhaps CO2 is more an effect than a cause? eg CO2 release due to polar ice decay, Deforestation etc... I would hate to describe myself as a 'tree hugger' but from what I can tell perhaps everyone in both camps might be right here increased carbon gasses and solar activity may both have a role to play in global warming, amongst many many other variables!... another thought as well is the icecaps are receeding then doesnt that put alot more cold water at the bottom of the oceans too? and im guessing that might in someway cause for carbon release? Anyhow, looks like i have a few years worth of reading, experimenting and computer modelling to go lol... All I can say is Im half between 'Tax on Co2' being a government attempt to charge more for less resources (charge more for fuel and electricity whilst not having to invest in infrastructure for the ever growing global population,peak oil etc, after all Climategate has done the scientific community no favours at all either way) and a very serious genuine problem that needs to be addressed urgently yet is being cashed in on by unscupulous politicians and glory seeking scare mongerers!..anyhow, thanks for the excellent reply and will get thinking, researching and trying to test some ideas out!
  11. Another thought in a devils advocate kind of way is perhaps there are just too many people? is there a correlation between warming and population both in the more technologically advanced/dependent societies and some of the less industrialised nations? could sewerage/carbon cycling of crops be a major factor? eg. biomass stores co2 and would traditionally store it, however its now being consumed with some of the co2/methane being released prematurely? could crops also affect the heat absorbing properties of the earths surface?..anyhow.. the questions are endless lol..
  12. sun tzu wrote : "...we have been undergoing a mild period of cooling over the last couple of years..." Have we ? Having seen this year so far break most global temperature records, it would be interesting to see how you came up with that particular statement. Where did you get it from ? Or is it something you worked out yourself ? If so, what information did you use ? Here are some other threads on this site, to do with other matters you have included in your post : Mars is not warming globally Land use CO2 coming from the ocean CO2 is the main driver of climate change It's the sun Climategate 'conspiracy'
  13. thanks Jim, its more looking for answers to some personal observations (theres so much conflicting information on temperature statistics and other environmental information its difficult to choose which ones are genuine and statistically stable or otherwise!)and I do not profess to be an expert at all.. I'll have a read of those threads Thanks again
  14. Actually, got another question, Jim asked where did I get my data from which lead me to ask, where does everyone else get their data from? is there an unbiased neutral source of climate data available with reference to Earths average temperature? Ive had a good look around the internet (must be accurate!) and theres alot of conflicting information out there all cited by 'credible' sources!
  15. just for the record I am not denying or admitting that I consider global warming or regional warming/cooling (altering the global statistics) to be occuring, The question is how much of it is man made? how much of it is a natural cycle, and if either is the case is one accelerating the other? and does nature have a counter balance? however for every argument I have read there are an equal number of counter arguments which usually end up in slanging matches with lots of opposing data being thrown around. It occurs to me that there are far too many motives both commercially, governmental, or in terms of attention seeking scare mongering in order to secure funding and the whole subject of research into climate change is completely polluted with its own hot air. Basically from what I have read between it all is CO2 and other gasses are being released at a greater rate than at any other time in recorded history and the averages of global temperature over a given period show a relatively rapid increase in warming. The bit that gets me is that every time I try to find out atmospheric concentrations of CO2 or global average temperatures (its a starting point, some places seem get colder others hotter seasonally) im confronted by a whole array of wildly differing information! the overal summary as a layman is 'we jsut dont know the answer to why the place is getting warmer but its highly likely to be related to the increase in certain atmospheric gasses as a result of mans activity, however not every one agrees on this!' I might be wrong or right and I am not a scientist, but from someone trying to casually research the subject I find that I am continually going around in circles with out any clear answers!
  16. suntzu, you could start with WIKIPEDIA, which will give you all the available sources of temperature readings, where you will see how all of them agree on an upward trend : Instrumental temperature record Why not look further from there, or from another thread on this site : Are surface temperature records reliable? There are three versions to look at in the above, depending on how much detail you are looking for. You still haven't said where you got your information concerning the "mild period of cooling over the last couple of years". Can you reveal all, to me or Jim...
  17. sun tzu, stick to the science and the peer-reviewed literature, rather than opinion on blogs. There is plenty of information on this site : Start Here There is also plenty of information (and many sources) here : IPCC Summary for Policymakers Why aren't you more forthcoming as to the sources of your information ? Provide a few examples of where contrary information is being given that you believe is as believable as any of the information you find on this site.
  18. they are not scientific sources although they do cite them selves as such, however given the massive number of variables at play in the overal arena of 'warming' or 'cooling' whos to say they are any more accurate than anyone elses opinions? im sure next week will be another startling media discovery or discreditation to do with climate anomolies... from where Im sitting with the information presented to me via these forums, the internet as a whole not to mention having lived in many locations around the globe and witnessed first hand from real people discussing the way in which their environments have changed, eg lack of snow on peaks, reservoir depletion and also the opposite too, snow storms, floods etc all of which where loclalised events but none the less at each place I have been to every one seemed to agree that one way or another something is changing percevably with the climate. anyhow, I could fire up a supercomputer and feed lots of stats in and see what the results tell me, but even so, if I miss so much as one variable or miscalculate or use inaccurate results im going to be back at square one with 'im not sure'... however theres a good chance its this...
  19. ps. that was just a small cross section of some of the media reports etc, im not quoting any of them specifically
  20. more to the point, without citing other people stats or research, what do you think is the cause behind climate fluctuations and why?
  21. my personal unaided view is chopping down the amazon, solar activity and increased agruculture have alot to answer for!
  22. "more to the point, without citing other people stats or research, what do you think is the cause behind climate fluctuations and why?" If you discount stats and research (ie, science), you're pretty much left with anecdotal data. Why, in this day and age, anyone would think that anecdotal data has any real standing in science amazes me. Looking for science information in the media also seems suspect to me. I'm not a climatologist, but I am a scientist, and the number of times that the media has gotten things wrong in areas I do know about are depressing.
  23. sun tzu, I see where you are being side-tracked now. From your links : The BBC one is a blog post from a year ago; The Canada Free Post one is an Opinion piece from 6 years ago; The Telegraph article (by an Environmental reporter) is about a report, published in Wiley Interdisciplinary Reviews Climate Change, which confirms what you could find by sticking to the actual science; The Yahoo Answers link is not worth the paper it's not printed on ! Don't rely on blogs, opinion or the mass media. Try the links I gave above, plus : Scientific American The Discovery of Global Warming Science Science News Science Daily Physics World New Scientist Nature National Academies, and here Knight Science Journalism Tracker Climate Central Climate Data
  24. sun tzu - MORE to the point - why should any consideration be given to uninformed opinion? What affecting climate... well without moving the earth's plates around you have four ways to influence climate. 1 solar - amount and distribution. Stable or dropping 2 aerosol - stable 3 albedo - actually replacing forest by agriculture increases albedo and so a net cooling affect. 4 GHG - increasing and unsurprisingly, so is temperature.
  25. thanks, after reading up on it and starting to understand the basics im pretty much sold on the CO2 and greenhouse gas as the prime candidates.. only problem is, it seems so many people want to blame it on something that wont hit their profit margins, not to mention all the media and blog sensationalism pushing the general consensun to the point of denial. Anyhow, thank you very much for taking the time to reply to my posts. I also found this link to be a source of great information : However I cant help but feel that a very real problem is being used as an excuse to keep energy company shareholders happy - charge more for less - after all... its saving the world lol

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