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Do solar cycles cause global warming?

What the science says...

A full reading of Tung 2008 finds a distinct 11 year solar signal in the global temperature record. However, this 11 year cycle is superimposed over the long term global warming trend. In fact, the authors go on to estimate climate sensitivity from their findings, calculate a value between 2.3 to 4.1°C. This confirms the IPCC estimate of climate sensitivity.

Climate Myth...

Solar cycles cause global warming

A new peer-reviewed study on Surface Warming and the Solar Cycle found that times of high solar activity are on average 0.2°C warmer than times of low solar activity, and that there is a polar amplification of the warming. This result is the first to document a statistically significant globally coherent temperature response to the solar cycle, the authors note (source: Mark Morano).

The study is Surface warming by the solar cycle as revealed by the composite mean difference projection by Charles D. Camp and Ka Kit Tung. They find a global warming signal of 0.18°C attributable to the 11-year solar cycle. Eg - from solar minimum to solar maximum, global temperatures increase 0.18°C due to an increase in Total Solar Irradiance (TSI). To find the solar signal, they detrended the temperature data by removing the global warming trend. They found the detrended temperature correlated well with the solar cycle.

TSI including 11 year solar cycle vs detrended surface temperature
Figure 1: Detrended temperature (solid) compared to TSI (dotted) (Camp 2007)

However, a fair degree of climate variability contaminated the signal. Volcanic eruptions in 1982 and 1991 coincided with solar maximums. Similarly, the El Nino peak of 1998 occured during low solar activity. Tung and Camp filtered out the noise using various statistical techniques and found an even higher correlation with the solar cycle.

They concluded that from solar minimum to maximum (eg - from 1996 to 2001), the forcing from the sun increases global temperatures by 0.18°C. Conversely, from solar maximum to minimum (eg - from 2001 to 2007), the reduced forcing from the sun cools global temperatures by 0.18°C. This 11 year cycle is superimposed over the long term global warming trend.

Climate Sensitivity

Camp and Tung explore the ramifications further in a follow-up paper Solar-Cycle Warming at the Earth’s Surface and an Observational Determination of Climate Sensitivity. Independently of models, they calculate a climate sensitivity between 2.3 to 4.1°C. Eg - if CO2 levels are doubled, global temperatures will increase around 3.2°C. This confirms the IPCC estimate of climate sensitivity. In Tung's own words, "The finding adds to the evidence that mainstream climate models are right about the likely extent of future human-generated warming. It also effectively rules out some lower estimates in those models."

The other significant finding is that solar forcing will add another 0.18°C warming on top of greenhouse warming between 2007 (we're currently at solar minimum) to the solar maximum around 2012. In other words, solar forcing will double the amount of global warming over the next five to six years.

Last updated on 9 July 2010 by John Cook.

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Comments 26 to 50 out of 65:

  1. Falkenherz, even if we assumed your discovered "serios and intentional miscommunication from IPCC" were true, your following statements are non sequiturs (logical fallacy): - past temperature increases are not extrapolated forward by the climate models; the models are based on atmospheric physics not statistics - because some relationships existed in the past (increasing CO2 being a feedback) does not mean that it has to be like that now (CO2 being a forcing agent) - correlation is not equal to causation As the responses to your comments above and the IPCC report you studied explain, the increase in TSI can possibly explain early 20th century warming, but not late 20th (and current) century warming. Current warming has not yet reflected the observed CO2 increase, aka we are in equilibrium yet. Your hint towards "it has not warmed since 1998" is a myth dealt with on another thread. If you find a way to get your hand on TSI data covering the glaciations, and a way to show that it was rather TSI not Milankovitch cycles driving them, make sure you publish that. (sorry for the satire, but your comments have drifted into trolling)
  2. gws, let's not start with polemics, I am seriously interested in AGW, what I just do is trying to link things together. These here are some factors I don't understand. I think I understand now the way GHG work, but TSI still is a topic I have to learn about. So sorry when I confuse TSI with Milankovitch cycles, I just assumed TSI is what arrives from the sun as measurable on earth, whether it comes from sunspots or from a shifted orbit or axis. I also understand that oceans still have warmed since 1998, and the total is still a warming. But at the same time it is also a fact that the atmosphere has not warmed any further since 1998, right? But that was not my point in my above post. I just wanted to say that it makes sense that a dropping TSI could lead to a non-warming up atmosphere because it is the fastest feedback, compared to the ocean. My point in my last comment was, that I always understood and read about 0,8 Degree/last100years attributed to AGW. But, based on what I read here and in the IPCC report, that is not really true. Can you confirm that at least that? The essay linked by DSL says in its conlusions: "At the same time greenhouse gases total radiative forcing has shown a strong Granger causal link with temperature since the 1940s up to the present day." So, they also do not start at 1890, but at 1940 (again a different date, instead of 1960). But, bottomline, that only that is my point, we should rather look at and communicate the historical amount of GW that can really be attributed to aGHG. This seems to be less than 0,8 Degrees so far, even though I know we are not in equilibrum yet. I still need to understand which factors make the models match the facts that ~0,2 Degree in the past 50 years leads to a possible new equilibrum at +3-6 Degrees for a CO2-doubling. Models might not extrapolate historical data, that would indeed be too simple, but all models advertise that they match up with historical data. So first let's clarify the observable historical data.
  3. Falkenherz, I cannot answer in detail all your questions as that would be equivalent to reciting much of the AR4 and associated literature. But I shall make an attempt at some of your inquiries. - TSI is the measured "output" from the sun; it changes on geological time scales based on the nuclear reaction cycle in our star, which is and has been very stable; as you can see from the y-axis in your own link, its relative change (sun spots cycle, impacting radiation arriving at Earth on "short" time scales) is small - no, the atmosphere has further warmed since 1998, check, e.g., here - the IPCC has not attributed all observed warming ("0.8 deg C") to increased GHG alone - you are making the mistake of wanting to assign a single measure to a single cause; observed warming is a combination (sum) though between different forcings, and while the GHG forcing is currently the largest one, it is counteracted by an also anthropogenically caused increase in atmospheric aerosols; some people use the term "masked" to characterize the apparent lack of more warming caused by aerosols vs GHG only - these facts enter the IPCC graphs you see above to create the "match" between model and observations, and the lack of such when ignoring GHG forcing - aerosol levels are not expected to continue increasing much further (that will be reevaluated in light of rapid FF development lacking particle filters in Asia), while GHG levels are
  4. Falkneherz, you seem to expect a linear response from changes in GHG forcing. I suggest doing a little more research on transient climate response and equilibrium climate response. What the article I linked to was pointing out, as gws notes, is that solar was the dominant forcing in the early 20th century, and GHG forcing was dominant in the last half of the century. GHG forcing became detectable during the 1940s, but it didn't overwhelm solar variation until the early 1960s. That also doesn't mean that the solar signal has no effect on the trend. That's why studies like Foster & Rahmstorf (2011) are so important. F&R removes the signals of solar, aerosols, and ENSO from the last 30 years of the major surface/lower trop temperature analysis ensemble. If no AGW exists, F&R should have found a slightly bumpy flat line or an insignificant trend. Instead, they found a trend of about .17C per decade over the period.
  5. 27, Falkenherz, Some points of reference for you to research: 1) Milankovitch cycles overall only fractionally change the amount of energy received by the Earth. What changes, rather, is the distribution of that energy over the globe in space and time (i.e. how much at what latitudes during what season). Look here. 2) The atmosphere has warmed since 1998. And both 1998 and the end of 2011 are cherry picks, because 1998 was the strongest El Niño in memory, while 2011 was a La Niña. It's like comparing your income on the day you work two jobs to the day you sleep in. It says nothing about how much you are likely to make in a year. Look here. And here. And here. 3) "I still need to understand which factors make the models..." Yes. Look here. And here. And here. 4) "...but all models advertise that they match up with historical data." Yes. Look here. [And I wouldn't put too much weight behind what Pielke Sr. (or Jr.) posts on the subject.]
  6. Falkenherz, your central argument seems to be that because there are other factors in play it is incorrect to attribute all of the 0.8 C observed warming to GHGs. The problem with this is that research indicates that the net effect of all those other factors has been cooling... such that without them the impact of GHGs alone would have been greater than 0.8 C. Milankovitch cycles involve a lot of factors, but the primary glacial/interglacial trigger corresponds to an orbital tilt. Basically, when the tilt of the planet causes the northern hemisphere to be angled closer to the sun the net absorption of sunlight increases (because there is more land in the northern hemisphere than in the southern) even though the total amount of sunlight reaching the surface hasn't changed (the SH gets just as much less as the NH does more). The 'no warming since 1998' bit is an outdated statistical fallacy even when properly constrained to the surface atmospheric temperature. It was derived by taking the anomalously high temperature in 1998 as a starting point and then pretending that because the trend of increasing temperatures after that point had not gone on long enough to reach 95% statistical significance yet (i.e. passed a mathematical test to indicate that the observed trend was likely 'real' rather than caused by random 'noise' in the data) that there 'was no warming'. That was nonsense to begin with... but it is now outdated nonsense. The increasing temperature trend since 1998 now does pass a 95% statistical significance test. Try 'no statistically significant warming of the surface atmosphere since 2005'... the next really hot year in the record which is still too recent to pass 95% statistical significance. It'll still be deceptive nonsense, but not outright false like the 1998 claim you were repeating.
  7. Falkenherz - ...we are basically not talking about a GHG-attributed warming of 0,8 Degree increase in 100 Years, but about a 0,2 Degree increase in 50 Years. Where are you getting that? The 1901-2005 land global temperature trends in that table are 0.84, 0.68, 0.69, and 0.69 C, with ocean global temperatures increasing over that period at 0.67 C. Over the more recent 25 year period of 1979-2005 the numbers are much higher: ~0.31 C per decade land, ~0.134 C per decade ocean - certainly not 0.2 C. I believe you have misread something; and claiming miscommunication from the IPCC based upon misreading a table is quite inappropriate. Actually, without human activity, based on the natural forcings, we should have seen roughly a 0.2 C decrease in temperature over the last 100 years, or a difference from current temperatures of ~0.8 C. --- I really hate to say this, but you seem to be hunting for any 'sticky' skeptic point possible - and in the process not fully reading the references, or looking at the data. If you consider the full set of data, you will not (IMO) find any significant support for the 'skeptic' arguments; the data, the evidence points all but a tiny minority of climate researchers towards AGW.
  8. Hey, thanks for the explanations and links. IPCC should really ready the next report and be a bit more clear about this part. They filed 0,76 Degree under "Direct Observations of Recent Climate Change", so yeah, they did not directly attribute it to AGW, but neither they did to other factors, and the whole report is about AGW, isn't it. Also, in the passage I quoted, the IPCC speaks of a linear warming trend of 0,13 Degree per Decade over the last 50 years, which in sum would be 0,65 Degree for 50 years. So, putting numbers together as IPCC placed them, not more than 0,09 Degree (0,65+0,09+0,74) was caused by TSI before GHG became a dominant factor from 50 years ago. That again seems to be too much the other way around, and this result is also in conflict with the temperatures shown in the graphs by KR here, at 06:15 AM on 15 September, 2012. And if I put that together in an incorrect way (because you probably cannot add up trend figures to an absolute total?), this shows for me that the data was presented in an incorrect context. I think, all the explanations are fine and sound kind of logic, but the data needs to be presented in a clear and coherent way, first. Again, thanks a lot for the explanations.
  9. KR, yes I hunt for any stick, because I want to be able to reply to any sceptic argument. So I am assuming the role of one, here. You can be sure I do the opposite on a sceptic website. So let me summarize so I can use this in discussions: - global temp increase from 1850 to 2005 is about 0,76 Degree - TSI factors into this figure, but latest since 1965 cannot explain the increase by the observed amounts ... aaaand I am back to what puzzled me and why I started commenting here: How much of those 0,76 Degree is TSI and what is GHG (before/after 1960)??? It is just, as KR pointed out, I don't really seem to understand how to put this decadal trend figures into context. At least roughly speaking, there should ne some connection between absolute rise between absolute increas and the the calculated decadal trend figures? How? Why do IPCC and others throw them together without making at least a distincion?
  10. "the whole report is about AGW, isn't it." well actually, no, it discusses both natural and anthropogenic climate change. The Technical Summary makes it very clear that both natural and anthropogenic forcings are necessary to adequately explain the observed patterns of climate change.
  11. Uhm... I think I lead myself astray from the original question. I came here because of the WP graph, which shows a continuous upwards trend of TSI, as does also the graph "historical TSI reconstruction" on So... the answer to the original is, the TSI should not got upward during the last few years, but even it it may still be upward on a longer time axis, it still cannot explain the increasing decadal trend of rising global temperature???
  12. .... aaand my english becomes more and more horrible, sorry for that, this kind of shows my confusion. Let me restate with some corrections: "So... the answer to my original question is; ACCORDING TO CURRENT DATA, the TSI should not GO upward during the last few years, but even IF THERE WOULD still be AN upward TREND on a longer time axis, THIS ALSO cannot explain the increasing decadal trend of rising global temperature???" [I hope that is a slightly less horrible english] I stop posting now, but am grateful for all answers.
  13. Falkenherz, Just for reference... the IPCC does nothing more than accumulate and report on the state of the science. When you say "the IPCC says..." what you really mean is "back in 2007, based on the state of the science at that time, the IPCC reported that..." The main takeways are: 1) The IPCC is merely reporting the primary belief of scientists in the field at the time, based on published and un-refuted papers. 2) The science and the world keep advancing. There have been a large number of studies since 2007 that affect both the value (0.76) and how that value is interpreted (e.g. Huber and Knutti 2011, Foster and Rahmstorf 2011). Any time anyone takes the approach "The IPCC says..." that should immediately give you pause. Quoting an IPCC statement on the state of the science 5 years ago, as if time is frozen and the IPCC are themselves experts declaring truth, is just wrong.
  14. Has anybody found more details on the source of the TSI data in the graph of the Washington Times, which is named "University of California-Berkeley Earth-Surface Temperature Project"?
  15. Dear co-commenters, my main question has not been answered, instead I received a lot of corrections on some of my (admittedly wrong) conclusions, and some nitpicking on words. But, on the basic questions, I am still unclear what to think. 1. The graph in the Washington Times (Source: "University of California-Berkeley Earth-Surface Temperature Project" -> so it IS based on scientific work?) shows a continuous upwards trend of TSI, as does also the graph "historical TSI reconstruction" on I am asking about the long-term observations on TSI, not only since 1960. There are people like Leif Svalgaard on WUWT who deny any TSI increase since 1800 (if I understood his ppt presentation which he linked there correctly). 2. If people say that TSI since 1960 is not raising anymore and that is why GHG have to be the dominant driver: Did people think about possible lags to TSI forcings in our climate system? Couldn't it be that global temperature is still rising because of the TSI forcings from before 1960? 3. If we nevertheless assume (or have evidence?) that the TSI is not high enough to further raise global temperature, how come that I always encounter the claim that there is a rise of +0.76°C since 1850, and "most" of it was caused by AGW? I hold my claim that this is a miscommunication, and I am asking of how much is exactly attributed to GHG after removing the TSI forcing. When I look for answers, I am suddenly confronted with decadal trends, which in fact does not answer my question. I read the one essay from Pasini et al. (2012) which is trying to answer this (link provided by DSL further up). But if I understand that essay correctly, their only evidence is a so called Granger causality. Looking this mathematical contruct up on wikipedia, I think this can hardly be treated as sound evidence, rather as an indication that there could be evidence.
  16. Falkenherz@40 "Couldn't it be that global temperature is still rising because of the TSI forcings from before 1960?" I have a hard time understanding this point. The problem AFAIK is that up until this timepoint the TSI/temperature has been coupled directly without any delay. Now you propose that there is a delayed mechanism hidden somewhere that continues to heat up the atmosphere (and apparently upper 2000m of the sea). Furthermore the mechanism is at least as strong as the apparent TSI-effect was. So the question is: Why hasn't this mechanism revealed itself earlier and where was the heat hidden?
  17. To my question 3, I think I got it; from "it's the sun", nicely explained there, thanks. According to figure 8 over there, for the last 100-150 years, there is very roughly about 22% of solar contribution to global warming. Translating this into the kind of answer I was looking for in question 3, roughly about 0,6 Degrees of the 0,76 Degrees raisal of global temperature in the last centuries cannot be attributed to TSI and must be due to GHG. I hope this is roughly correct. Now I just need to understand what TSI data is correctly used and how they translate TSI into temperature... on to more articles to read! I anybody could still bring some light (or links) into questions 1 and 2, please.
  18. Lanfear, if this is true, then my question is answered. But how do we know that global temperature and TSI were coupled directly? If I see curves (like in figure 15 here, especially the one from "Lean 2000", then there might as well be a lag, since TSI seemed to go upward already a long time, roughly since 1700, by a total of roughly 2,5 W/m2 since then.
  19. Falkenherz With regard to lags, if you look at the chart from the Washington Times article, clearly TSI appears to be lagging behind USA temperatures, not the other way round (until 1960 ish). Temps start rising in about 1860, but TSI falls until about 1890, temps fall from 1940, but TSI falls from about 1950. This would suggest changes in USA temperatures cause changes in TSI prior to 1960. However, the real point regarding lags is that there needs to be a reasonable physical explanation to explain why there should be a lag, rather than a mere statistical phenomenon. It is hard to see a physical mechanism that would explain why TSI changes have a lagged, rather than an instantaneous effect.
  20. Marsupial, my question Nr. 2 was not linked to the graph in the Washington Times. My question Nr. 2 was rather assuming that that graph was wrong and TSI acutally did not increase since 1960, as this seems to be in line with the theory which this website believes to be correct. So, what I meant with a lag is that the increase of TSI until 1960 probably did not directly relate to temperature, but only shows its effect after 1960. The rise of temperature between 1900 and 1960 would then have a cause in rising TSI from before 1900. Long term graphs always seem to show a long term raise of TSI. So basically, the question is, why can we exclude a TSI induced raise of global temperature which lags behind, say, roughly 50 or even 100 years?
  21. @Falkenherz As I said in the second paragraph of my previous post, there needs to be a plausible physical mechanism to explain why there should be a lag. Essentially the laws of physics are the reason why temperature doesn't lag 100 years behind TSI. Correlation is not cuasation, and a good way of avoiding falling into the trap of making an incorrect association is to require a plausible physical mechanism. Given the nature of noisy time series, there will often be an apparent corellation in time series if you adjust enough parameters of the anlysis (e.g. start/end points, lags etc.) purely by random chance. As the old statistical maxim goes "if you torture the data enough, eventually they will always confess".
  22. Falkenherz@43 "TSI seemed to go upward already a long time, roughly since 1700, by a total of roughly 2,5 W/m2 since then." Hmmm... where did you get that figure? The study you refer to states: "The cycle-averaged increase in TSI since the Maunder minimum is estimated to be ~1 W/m2." This is also supported by fig 14 (using the eye-chronometer). Regarding your point 2: There still remains the question of where that heat from the slightly positive TSI-trend is hidden? I think the only possible answer here would be the deep sea (>2000m). But then again, it seems to be working on a too slow pace for this case, if one is to believe the validity this claim: "Scientists estimate that it takes one section of the belt 1,000 years to complete one full circuit of the globe." In that case it would mean that we would be seeing the heat energy coming up from the MWA and not the latest TSI positive trend. As Dikran said in 44 (and repeated later, your're writing too fast :-), you need to come up with a more physical explanation, otherwise this is only (IMHO) a exercise in hiding the god.
  23. Falkenherz, when TSI started increasing way back when, the Earth heated and therefore started radiating more on its way to thermal equilibrium between the new, higher level of energy coming in, and the energy going out. It could not reach equilibrium, because the incoming radiation (from TSI) kept increasing. When TSI plateaued around 1960, the Earth still was working toward equilibrium by continuing to increase its outgoing radiation. But because the incoming radiation now was constant, the Earth should have crept closer to equilibrium. That closing of the energy imbalance between energy coming in and energy going out should have been reflected in the in-out gap decreasing. Instead, the in-out gap has continued to increase despite the constancy (or slight decline) of the incoming radiation. So there must be some factor reducing the energy going out. What could that be, do you suppose? See John's post on climate lag.
  24. Falkenherz wrote: "1. The graph in the Washington Times (Source: "University of California-Berkeley Earth-Surface Temperature Project" -> so it IS based on scientific work?)" Yes, that label would mean that the graph was part of a scientific study... if the label itself weren't fiction. The Berkeley Earth Surface Temperature (BEST) project concluded that past temperature studies were accurate (in contradiction of their initial assumptions) and that the observed warming was almost entirely due to humans. Their findings on solar influence can be summed up with the statement, "Solar variation does not seem to impact the temperature trend." So the question becomes, how did Soon and Briggs get a graph (which appears nowhere in the BEST studies) showing a 'strong correlation' between temperatures and solar variation from a study that concluded there was no correlation between temperatures and solar variation? The likely answer is that they took temperature data from BEST, TSI data from some other source, put them together on a graph, and falsely labelled the result as coming from the BEST study. The 'US daytime high temperature' values shown on the WT graph appear to match up with the 10 year moving average of such on this page from BEST. So far as I know the source of their TSI 'data' remains a mystery.
  25. Heh, now that I look more closely I note that while the 'shape' of the temperature line on the WT graph matches that on the BEST graph... the scales are different. WT shows all values ~2.5 C higher than the BEST graph. The X axis also appears to be off with various peaks being shown in slightly different years between the two graphs. This would seem to confirm skywatcher's earlier suggestion that the WT chart was produced by some method other than direct graphing of the data.

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