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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)

Over the last 35 years the sun has shown a cooling trend. However global temperatures continue to increase. If the sun's energy is decreasing while the Earth is warming, then the sun can't be the main control of the temperature.

Figure 1 shows the trend in global temperature compared to changes in the amount of solar energy that hits the Earth. The sun's energy fluctuates on a cycle that's about 11 years long. The energy changes by about 0.1% on each cycle. If the Earth's temperature was controlled mainly by the sun, then it should have cooled between 2000 and 2008. 

TSI vs. T
Figure 1: 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 solar fluctuations since 1870 have contributed a maximum of 0.1 °C to temperature changes. In recent times the biggest solar fluctuation happened around 1960. But the fastest global warming started in 1980.

Figure 2 shows how much different factors have contributed recent warming. It compares the contributions from the sun, volcanoes, El Niño and greenhouse gases. The sun adds 0.02 to 0.1 °C. Volcanoes cool the Earth by 0.1-0.2 °C. Natural variability (like El Niño) heats or cools by about 0.1-0.2 °C. Greenhouse gases have heated the climate by over 0.8 °C.

Contribution to T, AR5 FigFAQ5.1

Figure 2 Global surface temperature anomalies from 1870 to 2010, and the natural (solar, volcanic, and internal) and anthropogenic factors that influence them. (a) Global surface temperature record (1870–2010) relative to the average global surface temperature for 1961–1990 (black line). A model of global surface temperature change (a: red line) produced using the sum of the impacts on temperature of natural (b, c, d) and anthropogenic factors (e). (b) Estimated temperature response to solar forcing. (c) Estimated temperature response to volcanic eruptions. (d) Estimated temperature variability due to internal variability, here related to the El Niño-Southern Oscillation. (e) Estimated temperature response to anthropogenic forcing, consisting of a warming component from greenhouse gases, and a cooling component from most aerosols. (IPCC AR5, Chap 5)

Some people try to blame the sun for the current rise in temperatures by cherry picking the data. They only show data from periods when sun and climate data track together. They draw a false conclusion by ignoring the last few decades when the data shows the opposite result.

 

Basic rebuttal written by Larry M, updated by Sarah


Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial

 

This rebuttal was updated by Kyle Pressler in 2021 to replace broken links. The updates are a result of our call for help published in May 2021.

Last updated on 2 April 2017 by Sarah. 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.

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Comments 626 to 650 out of 1288:

  1. John Cook - Perhaps a statistical analysis thread would be helpful? I'm afraid I'm not the person to write it, unfortunately...
  2. KR #625 I quite like to recommend this book to people who want to get started with statistics. Although a lot of applied statistics is a bit of a black art that comes from experience of analysing your own data. I'm open to the idea of writing a piece on statistical basics when time permits, but what would be nice would be a statistical naïve to collaborate with :)
  3. kdkd - I'll take a look at your recommended book; if it's as good as their one on genetics, which I've given or pointed out to a number of people, it should be excellent. I can certainly supply some naive if you'd like!
  4. KR #623 kdkd #624 There is no way that the above chart could allow Solar forcing to be dominant in the first half of the 20th century as concluded mostly correctly by kdkd. By setting the Solar forcing to zero in AD1880, when all other forcings except the volcanic aerosol (mainly from Krakatoa) are in fact zero or negligible in order to measure 'differences' ignores the fact that the actual value of the Solar forcing is in the range of 0.3 - 0.5W/sq.m and ongoing since about AD1700. See: http://www.ncdc.noaa.gov/paleo/pubs/ipcc2007/fig613.png There is a major dip in Solar and huge Volcanic cooling around AD1815 coinciding with Tambora, but the Solar forcing curve is positive and increasing in the 0.3 - 0.5W/sq.m range up to the present. If you agree that the areas under the curves represents the energy attributable to each forcing, then there is positive area under the Solar forcing curve since AD1700.
  5. Ken writes: the actual value of the Solar forcing is in the range of 0.3 - 0.5W/sq.m and ongoing since about AD1700. "Since about 1700"? Ken, on the IPCC graph you link to, the black line is well below 0.3 until the 1930s. It never rises as high as 0.5. It also turns downward after 1975. Looking at the period since 1750 to the late 20th century, solar forcing goes from about 0.15 to 0.45. Over the same time period, GHGs go from 0 to over 2.5. So yes, solar irradiance does account for a large part of the warming from 1750 to 1900, and a smaller part of the warming from 1900 to 1940. It accounts for very little of the warming post 1940. Both KR's graph and the IPCC one you link to show this.
  6. Ken - Thank you for that chart, it's very interesting: It also clearly shows my point. Given that the chart I linked from GISS shows deltas from 1880 (not 1750), and in agreement with your chart indicates a TSI delta over that time of ~+0.4W/m^2, while the "All other forcings" in both charts from GHG's sum to ~2W/m^w at the current time, I fail to see any disagreement in our data. The slight rise in TSI seems to be important ('tho not overwhelmingly so) in the early part of this century, warming was damped by high aerosols mid-century, and in the 70's (accompanied by the Clean Air acts and aerosol reduction) GHG forcing became the very dominant factor. Now, as regards to ...setting the Solar forcing to zero in AD1880"", Ken, you still appear to be suffering from some misapprehensions regarding what delta (anomaly) baselines are used for. The chart I linked from the CO2 is not the only driver of climate looks at deltas since 1880, while the one you linked from NOAA/IPCC (here's the article link backing that chart) looks at deltas since ~900AD. Was the climate at equilibrium in 900AD? No. Was it in equilibrium in 1880? In 1750? No and no. But we can certainly look at changes in forcings versus changes in climate, and determine from magnitude and correlation which forcing changes are the dominant drivers of the current temperatures. And, given that information, it's clear that it's not the sun driving late 20th century temperature rises. Nor, for that matter, is it a badly mis-measured TSI at the start of any of these time periods, integrated over the period, as that would show up as a monotonic temperature change over the period of mis-measure, a difference in slope between TSI and temperature. That simply isn't present; there is no unmeasured offset.
  7. Even more interesting in that NOAA/IPPC article you referred to, Ken, 2007 Intergovernmental Panel on Climate Change Working Group I: The Physical Science Basis of Climate Change, Chapter 6 Paleoclimate, is this graph: What's illustrated here are the various forcings on climate, temperature reconstructions (gray bands covering uncertainty ranges on lower graph), and multiple climate model runs with and without anthropogenic forcings. Looking at the lower right of the bottom graph you can see matched color traces with/without GHG additions. It's clear that without the GHG forcings (but with the solar forcing) none of the models can match the current temperature trend. They all predict temperatures going back to levels of the early 1800's. Add the GHG forcings back in, and voila - all the models track measured temperatures fairly closely. It's not the sun.
  8. One side note - the previous posting included a graph that only runs to 2000, not up through 2010.
  9. Ken #629: "By setting the Solar forcing to zero in AD1880, when all other forcings except the volcanic aerosol (mainly from Krakatoa) are in fact zero or negligible in order to measure 'differences' ignores the fact that the actual value of the Solar forcing is in the range of 0.3 - 0.5W/sq.m and ongoing since about AD1700." As has been explained to you before, a 'forcing' is a CHANGE from the baseline value. If 1880 is the baseline then BY DEFINITION the forcing in 1880 is zero. Has to be. That's what the words MEAN.
  10. Well my model was derived empirically from IPCC data. It was pretty naïve statistically speaking, and the model wasn't without its violations of assumptions. On the other hand as the magnitude of CO2 versus solar forcing was roughly consistent with my regression model, I don't see how Ken reaches his conclusion that "is no way that the above chart could allow Solar forcing to be dominant in the first half of the 20th century" (it would be nice if Ken referred to which chart). I think he's got to get over the confirmation bias.
  11. Ned #630 How about we agree on 0.2-0.5W/sq.m for the range of Solar forcing since AD1725. Gridding a very small scale graph I get AD1725 for when the Solar forcing crosses above the 'zero' axis which is pretty close to the end of the Maunder minimum around AD1715. KR #631 "Was the climate at equilibrium in 900AD? No. Was it in equilibrium in 1880? In 1750? No and no. But we can certainly look at changes in forcings versus changes in climate, and determine from magnitude and correlation which forcing changes are the dominant drivers of the current temperatures." Well you tell me KR. How do you know it was NO and NO? Prima facie, the zero axis on the graph implies that positive Solar forcings will add energy and warm the Earth and negative forcings will lose energy and cool the Earth. Is the 'zero' axis not the zero Solar forcing and equilibrium TSI where the Earth neither warms nor cools due to Solar?? If not what else could it be?? If you look at the areas under both Solar and 'All other Forcings' curves in Fig 613 back to the start of the current warming ARO AD1725 they both represent the energy added to the Earth system and they both add together. I don't have an electronic way of doing this but could scan this with an ACAD planimeter and get an estimate on a reasonably scaled graph. kdkd could probably do this with the raw data. Using some crude geometry I have calculated the area under the Solar curve at 9300E20 Joules and the 'All Other Forcings' curve at 10600E20 Joules. I assume that 'all other' means every forcing on your chart at #623 netted into one curve. This gives a roughly 45/55% ratio Solar/All Other for not just the first half of the 20th century - but the whole period 1725 up to 2000. My point which brought on this debate is that if the 'zero' axis on any of the forcings (but Solar is most important due to its constant presence) was shifted down or up by a small amount - a large extra slice of area is added or subtracted from the area under the curve. eg 0.05W/sq.m shift over 250 years is over 2000E20 Joules in added or lost energy. I assume you are also not including the climate response forcings (IR cooling and WV feedbacks) in this analysis which net currently is -0.7 W/sq.m and would give a significant energy loss area under its curve to add to the Solar and All Other above. We are assuming here that Volcanic evens itself out over time which curve seems to be roughly equal in area above and below its 'zero' axis. When you talk of modelling temperatures and forcings - I assume you mean land and ocean temperatures - the response of which would have a thermal lag, as 90%+ of the calculated energy imbalance should reside in the oceans which have huge thermal mass. What would be the models' general assumptions regarding thermal lags in that composite temperature?
  12. Ken Lambert - You ask "How do you know it was NO and NO?"; how do I know that the climate wasn't in equilibrium in 900, 1750, 1880? Very simple, Ken. The slope of temperature change entering into those years, as shown by instrumental and proxy records, was not at or even close to zero. If the world was at equilibrium, you would see only seasonal changes in temperature. But given the time constants for ocean energy change, variations in forcings, etc., it would take a fairly significant time period for equilibrium to settle. [Side note - the fact that the various models track the paleoclimate record using historic forcings indicates that they are doing a reasonable job of dealing with thermal lags] 1750 has perhaps the best (not perfect) chance of being at equilibrium of those three dates - 900 temps have a steady downward trend, part of the Little Ice Age, I suspect, while 1880 is in early industrialization with numerous forcing changes from early CO2. But as the various forcings move around, the climate can only follow, only hitting equilibrium if (a) forcings don't change for a period long enough for the oceans to catch up, or (b) forcings reverse and pass climate change going the other way. I believe (IMO) that you are stuck on the "baseline" definition here, Ken. A proper analysis starting from a baseline includes not only changes after the baseline (forcing deltas, in this case), but the original trajectory of the system prior to the baseline, which includes all forcings at that date. Given those you can measure magnitude and correlation of trajectory changes relative to forcing changes. Failing to incorporate the baseline trajectory, the history, would be a massive error - but as far as I can see nobody has made that particular mistake. Only you, if you insist that existent forcings at the baseline are not included in the original temperature trajectories. Your "large extra slice of area" is part and parcel of the non-equilibrium trajectory at the baseline date; part of the history. I really don't know what else I can say, Ken. It's really that simple.
  13. Ken Lambert writes: How about we agree on 0.2-0.5W/sq.m for the range of Solar forcing since AD1725. How about we don't try to maximize confusion by blurring the distinction between time periods? You claimed that a graph showed that "the actual value of the Solar forcing is in the range of 0.3 - 0.5W/sq.m and ongoing since about AD1700" That was a highly misleading statement, since the actual graph showed it not even rising up to 0.3 -- the bottom end of your claimed range for the past three centuries -- until the 1930s. Ken continues: Is the 'zero' axis not the zero Solar forcing and equilibrium TSI where the Earth neither warms nor cools due to Solar?? If not what else could it be?? Ken, there is no unique "equilibrium TSI where the Earth neither warms nor cools due to Solar". No such number exists! There are infinitely many possible values of TSI which would produce neither warming nor cooling of the Earth. I keep making this point and you keep ignoring it. Assume that TSI is currently X. Now, assume that it increases to X+0.25 W/m2. The additional irradiance causes the planet to heat up, and feedbacks in the climate system amplify that warming slightly. As the planet warms, outgoing longwave radiation increases per Stefan-Bolzmann, until the planet reaches a new equilibrium where all of the following are true: (1) TSI is X+0.25 (2) Outgoing longwave radiation has risen to balance that increase in TSI (3) The temperature is stabilized at a new, higher level, and the planet is neither being warmed nor cooled. You keep assuming that any departure from some imaginary equilibrium TSI would lead to perpetually increasing or decreasing temperature. That is just plain wrong -- fortunately, because if you were right there would probably be no life on this planet! Ken continues: Using some crude geometry I have calculated [...] This gives a roughly 45/55% ratio Solar/All Other for not just the first half of the 20th century - but the whole period 1725 up to 2000. You are once again lumping together different periods of time. I assume you're just inadvertently deceiving yourself rather than deliberately trying to deceive others. Before the early 20th century, solar forcing is much larger than GHG forcing. By the mid 20th century, GHGs are catching up and passing solar. In the late 20th century, GHG forcing is very large and solar is not merely smaller in relative terms, it's actually decreasing post 1975.
  14. Gah - writing too fast. In my previous post I should have said "1750 was part of the end of the LIA", not "900".
  15. "You claimed that a graph showed that "the actual value of the Solar forcing is in the range of 0.3 - 0.5W/sq.m and ongoing since about AD1700" That was a highly misleading statement, since the actual graph showed it not even rising up to 0.3 -- the bottom end of your claimed range for the past three centuries -- until the 1930s." You are exaggerating and splitting hairs Ned. Some of the proxies are higher than the black line average and some naturally below. The highest is about 0.4W/sq.m circe AD1750. I can dig up the actual numbers from the site and check it - but for now 0.2 - 0.5 is good enough. My point about the area under the curve being the total energy is the critical one. "Ken, there is no unique "equilibrium TSI where the Earth neither warms nor cools due to Solar". No such number exists! There are infinitely many possible values of TSI which would produce neither warming nor cooling of the Earth. I keep making this point and you keep ignoring it." Again - such a number MUST exist for the pre-industrial (unforced by AG forcings) Earth. Conservation of mass would indicate that the Earth has a constant amount of dirt, water (in ice of liquid form) air etc etc. There would be an overall function which takes into account the specific heats, latest heats etc of the whole Earth system subject to warming by external forcings. "I assume you are also not including the climate response forcings (IR cooling and WV feedbacks) in this analysis which net currently is -0.7 W/sq.m and would give a significant energy loss area under its curve to add to the Solar and All Other above." I have already mentioned S-B IR cooling plus feedbacks as being added to the other forcings which will bring the system toward equilibrium. S-B cooling is currently -2.8W/sq.m and proportional to T^4 so will rise rapidly with actual temperature increase - closing the forcing gap (unless WV and ice feedbacks rise faster) The S-B IR + WV response curves should be included in these 'AG Radiative Forcing' charts with Solar so the viewers can get the real picture of the overall warming curve for the planet. Try harder next time Ned.
  16. Has anyone a comment on this report of variations in solar output during 2004-2007? "The amount of visible radiation entering the lower atmosphere was increasing, which implies warming at the surface," says atmospheric physicist Joanna Haigh of Imperial College London, who led the research, published in Nature on October 7. But the change from 2004 to 2007 in the sun's output of visible light, and the attendant warming at Earth's surface of 0.1 watt per square meter, is roughly equivalent to the overall forcing of the sun on the climate over the past 25 years—estimated by the U.N. IPCC to be an additional 0.12 watt per square meter. That suggests scientists may have overestimated the sun's role in climate change. Regardless, the solar change is dwarfed by the impact from the extra heat trapped by CO2 alone since 1750: an additional 1.66 watts per square meter, an effect that other greenhouse gases, such as methane, strengthen further. In other words, whereas the new satellite measurements call into question computer models of solar output, it does not change the fundamental physics of human-induced global warming.
  17. RC have a post up on it - which is basically "wait and see, we think it is instrument error".
  18. Ken Lambert - You haven't responded to my latest post. Do you understand that the 'baseline' is the starting point for forcing deltas, and that the incoming trajectory for temperature incorporates the forcings existing at the baseline timepoint? The offset you are so concerned about?
  19. *Including* the offset you are so concerned about?
  20. Ken writes: Try harder next time Ned. Not going to happen. After the fiasco of the Waste Heat thread, I'm no longer willing to expend indefinitely large efforts on repeatedly explaining the same points over and over again without any evidence of benefit. Yes, you do mention the OLR negative feedback that leads all forcings to decay towards 0 over time, as the planet's outgoing radiation increases or decreases. But you are still blindly ignoring this when you talk about your imaginary "equilibrium TSI". In fact, there is a continuous range of TSI values, any one of which can be balanced by a corresponding OLR value, leading to some particular stable temperature. There is no reason why one particular TSI value can or should be artificially promoted as the uniquely special equilibrium TSI that the Earth wants to be in balance with. If you still don't get this, someone else can take over, because I'm done.
  21. muoncounter #641: Yes, I saw that report too. The bit about the magnitude of any solar change being "dwarfed" by the increase in CO2 forcing makes it somewhat of a minor issue AND the researchers note that the results need further verification... but it is certainly an interesting new wrinkle. Unfortunately, if validated it would essentially mean that we can't be sure about precise solar forcings prior to this kind of detailed spectral analysis. Is a solar minimum ALWAYS accompanied by higher output of VISIBLE light or was that the case for this particular minimum but not all? Are solar maximums characterized by DECREASED visible light or exceptionally increased levels? However, again... the possible range of variation here is more than an order of magnitude less than GHG forcings. The report also shows that while the solar forcing for 2004-2007 may have been greater than would have been suggested by looking at total solar irradiance (rather than a specific wavelength analysis)... it was still less than the IPCC projected for this time period.
  22. KL #various Your "area under the curve" stuff is (from a statistical perspective) just a calculus-centric view of talking about regression models. We've done that to death elsewhere, and it doesn't confirm your over-complex, often illogical, statistically illiterate and difficult to ascertain argument. Come up with something new and I'll be happy to assess your arguments on its merits. This particular dead horse however is well and truely flogged.
  23. CBD, "the possible range of variation here is more than an order of magnitude less than GHG forcings. ... solar forcing for 2004-2007 ... was still less than the IPCC projected for this time period. " I thought those were the salient take-aways, especially in the context of 'its the sun' and 'its only the sun'. Funny how order of magnitude seems to get lost when discussing the role of various deltas.
  24. Ned #645 Clearly the waste heat thread went pear-shaped after I left. Ned: "Yes, you do mention the OLR negative feedback that leads all forcings to decay towards 0 over time, as the planet's outgoing radiation increases or decreases. But you are still blindly ignoring this when you talk about your imaginary "equilibrium TSI". In fact, there is a continuous range of TSI values, any one of which can be balanced by a corresponding OLR value, leading to some particular stable temperature. There is no reason why one particular TSI value can or should be artificially promoted as the uniquely special equilibrium TSI that the Earth wants to be in balance with. If you still don't get this, someone else can take over, because I'm done." Ned, you have just confirmed exactly my contention about a 'unique' TSI corresponding to a particular 'Equilibrium' temperature. Let's repeat what you say above: "In fact, there is a continuous range of TSI values, any one of which can be balanced by a corresponding OLR value, leading to some particular stable temperature." Question: And can you guess what that particular temperature of interest is? Answer: The Earth's temperature in AD1750 which according to you and the AGW community is 0.8 degC COOLER than today's temperature. And what follows from that is that we have a TSI AD1750 corresponding to Temp AD1750. Pray tell me then Ned what is the value of TSI AD1750? And after you have done that you should than be able to advise what particular TSI value corresponds to an Earth temperature 0.8 degrees higher than that of AD1750.
  25. Ken Lambert - I would agree, there is one TSI for one equilibrium temperature of the Earth, with all other variables held constant. Of course, if you change (for example) CO2 levels, the equilibrium temperature for a particular TSI will change, as the radiative efficiency of the Earth will change. But all other variables are not held constant. The other radiative influence changes are much much larger over the last 150 years. This is a multi-variate issue, and you're only looking at TSI vs. Temperature!!! So: - You insist upon equilibriums, when it's obvious from the temperature record that temps were not at equilibrium in 1750 (cooling slightly), - You don't recognize that existing forcings at any baseline date are incorporated in the temperature trajectory entering that baseline (your offset concerns), - You're going on about equilibrium TSI, when the TSI deltas are an order of magnitude less than the other forcing changes, - And most importantly, you're not (in any of the recent comments here, here, or elsewhere) including the CO2 or aerosol radiative deltas in your 'equilibrium' considerations. This horse has been flogged to death, Ken - you are hunting for a solar cause, you are not considering the relative magnitudes and importance of the radiative factors, and have ceased to add content to the discussion some time ago. I'm out of here...

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