Arguments
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. |
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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.
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."
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.
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
Perhaps we are asking the wrong questions, or looking for a simple correlation?
The nexus may not be a direct link nor logarithmic progression. It may be that a number of factors must align, or a threshhold be reached, before the effect of sunspot activity, volcanic activity or other factors have more than a negligable effect on the weather - this would perhaps be best demonstrated by research into unusual tornado events in winter, in the US. It was suspected the link related to El Nino/La Nina events. This, and swings in the jet stream related to it, were eventually established once the right question was found. This is not a simple correlation but rather that a cluster of severe torandoes must be identified, rather than simply that a tornado occured, before the effect is identified (movement of the jetstream, spinning up the severe tornados, related to the El Nino/La Nina winds changes), and a correlation established.
This information was there for all to see but not found until the right question was asked.
Those who cite unusual weather events as proof are puting the cart before the horse, and ignoring the fact that weather prediction is an evolving science without absolutes.
Those who cite CO2 as the only culprit in weather change are again ignoring the fact that our models to date have failed to predict temperature and weather movements with a reasonable degree of accuracy.
Chris wrote: "Those who cite CO2 as the only culprit in weather change..."
No such people exist. As should be clear from the original article, the Sun does have a major impact on weather and climate. It just demonstrably is not responsible for the current unprecedented warming. Volcanoes, ENSO fluctuations, greenhouse gases other than CO2, aerosols, clouds, and many other factors which influence climate are discussed in detail in various posts on this site.
However, the factor currently undergoing the biggest change is clearly the atmospheric CO2 level. We can look at every other factor and see that it has changed by a few percent at most... atmospheric CO2 is up by more than 40% in the past ~150 years. That's a profound change at a rate vastly greater than anything we have ever seen in nature. Ditto the corresponding increase in temperature. We've got two shockingly fast global increases occuring in tandem and basic physics tells us that increasing CO2 must cause increasing temperatures... yet somehow people keep insisting that we ignore the obvious primary issue and concentrate on anything and everything else.
Why is that?
Chris, your idea of "reasonable degree of accuracy" obviously expects models to predict science says they cannot. They are designed to predict climate not weather and have shown considerable skill. Please see "Models are unreliable" and feel free to comment if you still dispute this after reading the article.
Please note to that strawmen arguments are easy - disputing a claim that the science has never made - but doing that here will win you no points.
Chris:
There is a fundamental problem with your argument, as indeed with any argument which tries to exonerate the enormous - and extraordinarily rapid - rise in atmospheric CO2 as the principal cause of the recent, also extraordinarily rapid, changes in the Earth climate system. This fundamental problem is that it flies in the face of extremely well-validated radiative physics.
Chris: "Those who cite CO2 as the only culprit in weather change are again ignoring the fact that our models to date have failed to predict temperature and weather movements with a reasonable degree of accuracy."
Ironically, it's fake skeptics who pull this sort of maneuver by claiming "natural cycles" or solar or GCRs and refusing to account for the rather well-established greenhouse effect and its recent enhancement.
I have recently had a conversation with a 'sceptic' friend who believes 'it's the sun' . Showed him figure 1 to which he appeared slightly aggitated and suggested that whoever produced the chart was being misleading as it is based on the 11 year average, and this is not as reliable as the 'smooth' average. Apparantly the smooth average shows much less of a divegency between solar avtivity in temps from 1980 onwards. Can anyone enlighten me as to what he is on about? Thanks.
Ho hum. Call me wrong. I really thought the ocean cycles would have to flip to get the cooling thing going, but it seems the solar backing down is doing it all on it's own. I said it once and I'll say it again. When the solar output drops below 1365.7, and it has, the warming stops. If it drops into area below 1365 get ready for major cooling. It looks to be going there.
cruzn246... Yes, you are clearly wrong on this one. My suggestion would be for you to read all three levels of the scientific response to the myth you're presenting. The relative forcing you're presenting is small compared to GHG forcing.
[DB] Please note that cruzn246 has an extensive history of sloganeering and trolling in this venue.
Cruzn, that's a really wierd argument. You're implying that solar is responsible for the fifty year trend, yet the 11-year cycle is not well-represented in the GMST trend. For a forcing to be that dominant, one would expect the trend of that forcing to be writ large in the long-term trend. It's not. The long-term trend is rather steady in its advance. Surely you're not arguing from the long-term solar trend--clearly flat or falling since 1960. We just had the deepest 11-year cycle minimum in the instrumental period (trough bottomed out through 2009-2010). That trough spent a year below the minima of previous cycles. The 12-month period between mid 2009 and mid 2010 was the warmest 12-month period in the instrumental record.
If you were truly basing your theory on solid evidence, you'd have absolutely no need or motivation for the bitter tone and reluctance to share your math. Your past history smells like troll. Is that the extent of your contribution?
The whole point is about the solar forcing value ,versus the CO2 forcing
Unless a big volcanic event come to mess things up
we should observe the consequences ( or not ) of the very weak solar cycle 24 ,
it has now just passed its maximum with a very curious double peak .
solar cycle 25 has everyone guessing,the consensus is a long inter cycle minimum with a record low maximum .
Should this be the case we will be able to observe and compute the solar forcing
I think we are starting to see the effect of a weak cycle 24 with the unusually cold winter in the eastern U.S., and the strong rebound in the Arctic sea ice extent, escpecially the 3-4+ year ice.
Perhaps you can explain why a weak sun doesnt make everywhere colder? The immediate reason for the cold eastern US winter (and the very warm winter weather elsewhere) is the pertubations on the jet stream. How does the sun slipping just below peak cause this?
Science works like this: you put forward your hypothesis. Assuming the hypothesis is true what observations would I expect to see. Check observations against predictions. Your hypothesis would seem to fail against such tests while the alternative hypothesis (reduction in pole/equator temperature difference affecting jet stream) seems to be holding well.
Over here Klapper postulated a link to climate from AA index.
Klapper, lets see if I have understood this:
You are postulating a climate effect from geomagnetic activity (or other) for which the AA index is a proxy. Furthermore, you are implying that variation in this phenomena is more effective climatically than variations in radiative energy from the sun (ie TSI, measured directly from satellites since 1979). As a corollary, you are also postulating an undiscovered negative feedback or process that stops the extra longwave irradiation due to enhanced greenhouse effect from warming the earth.
Your lag proposal postulates a process where the response can increase after the driving force has decreased.
Frankly, call me skeptical. What is missing from your arguments is evidence for plausable physical processes. Rather it seems further evidence that you have uninformed a priori position on AGW and looking for supporting arguments while ignoring the overwhelming support for a better model.
WUWT web site (purportedly "The world's most viewed site on global warming and climate change", ahem) claims the following paper suggests it really IS the Sun and solar cycles and so forth. Has anyone read it? I think it's in Chinese. Yet it does amuse me that much of the solar science purporting to refute AGW is from this part of the world, or Russia.
ZHAO X H, FENG X S. Periodicities of solar activity and the surface temperature variation of the Earth and their correlations (in Chinese). Chin Sci Bull (Chin Ver), 2014, 59: 1284, doi: 10.1360/972013-1089
knaugle - As was pointed out (repeatedly) on that 2-month old WUWT thread by Leif Svalgaard, a solar expert who is a frequent visitor there, there has been no recent 'Modern Grand Maximum'. Their paper fails on that alone.
Add to that issues such as equating postulated 64.3-year (oddly specific) temperature cycles to 50-year solar cycles (bzzzt), making claims based on low correlations, requiring a climate response far beyond the changes in solar forcings (implying a very high climate sensitivity), and the general avoidance of other forcings such as GHGs, aerosols, land use, etc., and the paper appears to be an exercise in bad curve-fitting.
Non-linear changes in various climate forcings (see here for data and links to published work on those) cause non-linear temperature changes - and if you ignore those factors you might think that there were significant long-term cyclical oscillations. But you have to ignore a great deal of the physics to do so.
knaugle:
I only read the abstract and list of references. The references include Friis-Christensen and Lassen, Singer, and Svensmark. Not exactly awe-inspiring.
Zhao and Feng have now published their paper in Journal of Atmospheric and Solar-Terrestrial Physics: Correlation between solar activity and the local temperature of Antarctica during the past 11,000 years
Would be great to get som updated comments since this is making the denier blog round
The scaling of the graphs is disguising the true facts. ‘Oh really’ I hear you say! Yes really I say to you.
The key to the truth is a characteristic of the temperature graph, which can be seen in any temperature record from around the world, and that is the falling temperature from the late 40’s to the early 80’s, which, according to the IPCC, was due to post WW” industrial pollution pumping tons of aerosols into the atmosphere, probably augmented by the hundreds of atmospheric tests of nuclear devices carried out during the same period. This pollution was reduced by changes in global legislation in the early 1980’s.
Now, according to the reconstructions of Total Solar Irradiance (TSI), solar irradiance began to increase in the late 1980’s and using Central England Annual Mean Temperature (CEAMT) data available from the Met Office, it can be seen that temperature began increasing at the same time. Both parameters continued to the late 1940’s when TSI continued to increase but CEAMT began to fall.
TSI stabilised in the mid to late 50’s and began oscillating in the 11 year Schwabe cycles, so when the atmospheric pollution was reduced during the 80’s, CEAMT began to rapidly rise playing ‘catch up’ with TSI, a rapid rise which caused so much concern and was the birth of Global Warming. However, had the ‘man made’ period of falling temperatures not occurred CEAMT would most likely to have continued rising until the 60’s when it would of levelled out and stabilised with TSI.
Further connection with the sun can be achieved by not only comparing the CEAMT data with TSI but from 1929, with England Annual Hours of Sunshine (Sunshine being when a minimum of 120W/m2 can be measured on the surface.) where you will find a very unexpected level of correlation.
All this data is freely available from the Net and the Met office and can easily be graphed in Excel – give it a try.
Good luck. TonyMo
@ TonyMo
What part of "the CEAMT is not a global record" is not understood by you?
TonyMo. Your description of TSI reconstruction doesnt match the graph above nor more recent reconstructions (more). "began oscillating"?? Solar physics and sunspot observation would suggest the 11 yr oscillation has persisted much much longer than that. Perhaps you should provide a link to the graph that you are looking at?
TonyMo, at the top of this page, click the "Intermediate" tab. After you read that tabbed pane, click the "Advanced" tab and read that tabbed pane.
Several researchers have tried different durations of lag between solar input to Earth and Earth's temperature, and they all have found nothing like what you claim.
In addition, there are other aspects of warming that are incompatible with your assertion. For example, in the Advanced tabbed pane, read the sections "Inability to Explain Empirical Observations" and "Conservation of Energy."
TonyMo @1093 says:
Sorry to be so stupid, but can anyone tell me how to insert graphs or pictures int a comment? Many thanks T
[RH] Look at the comments text box. On top there are three tabs. One says "insert." You click the image icon and paste in a link to the image. Note that your image has to be hosted somewhere. You can't paste in images from your computer. That's just a limitation to our current systems.
Ah, I see, nothing easy in this life! So next stupid question - where and how do I host my images to do this? Thanks' very much for you reply. T
[RH] Try tinypic.com
Postimage is quite usable, also free. Imgur is another option for image hosting.