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The CO2/Temperature correlation over the 20th Century

Posted on 18 June 2009 by John Cook

Previously, we looked at the correlation between CO2 and temperature over the past 40 years. However, as I'm always saying, you need to look at the broader view, not just a single piece of the puzzle. The 40 year period was chosen to demonstrate that even during a period of long term warming, internal variability causes periods of short term cooling. What if we look at a longer time series? Over the past century, are there any periods of long term cooling and if so, what is the significance?


Figure 1: CO2 green line derived from ice cores obtained at Law Dome, East Antarctica (CDIAC). CO2 blue line measured at Mauna Loa (NOAA). Global temperature anomaly (GISS)

Figure 1 compares CO2 to global temperatures over the past century. The first thing to clarify is that the relationship between CO2 and global temperature is not linear. As more CO2 is added, the warming effect has a diminishing return. Hence, the relationship between CO2 and temperature is logarithmic, not linear. A more appropriate comparison with CO2 is radiative forcing.

Radiative forcing is loosely described as the change in net energy flux at the top of the Earth's atmosphere. Eg - the change in how much energy the planet is accumulating or losing. The relationship between global temperature anomaly and radiative forcing is linear. Figure 2 compares greenhouse gas forcing (which is predominantly due to CO2 but includes smaller contributions from CH4, N2O and CFC) to global temperature anomaly.


Figure 1: Greenhouse gas forcing (GISS) and global temperature anomaly (GISS).

In truth, Figure 1 and Figure 2 both paint a similar picture. While CO2 is rising from 1940 to 1970, global temperatures show a cooling trend. This is a 30 year period, longer than can be explained by internal variability from ENSO and solar cycles. If CO2 causes warming, why isn't global temperature rising over this period?

The broader picture in this scenario is to recognise that CO2 is not the only factor that influences climate. There are a number of forcings which affect the net energy flux into our climate. Stratospheric aerosols (eg - from volcanic eruptions) reflect sunlight back into space, causing net cooling. When solar activity increases, the net energy flux increases. Figure 3 shows a composite of the various radiative forcings that affect climate.


Figure 2: Separate global climate forcings relative to their 1880 values (image courtesy NASA GISS).

When all the forcings are combined, the net forcing shows good correlation to global temperature. There is still internal variability superimposed on the temperature record due to short term cycles like ENSO. The main discrepancy is a decade centered around 1940. This is thought to be due to a warming bias introduced by US ships measuring engine intake temperature.


Figure 3: Net forcing (Blue - NASA GISS) versus global land ocean temperature anomaly (Red - GISS Temp).

So we see that climate isn't controlled by a single factor - there are a number of influences that can change the planet's radiative balance. However, for the last 35 years, the dominant forcing has been CO2.

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Comments 1 to 50 out of 79:

  1. You pick and choose where you want to apply CO2 effects,and where you want to intergrate other effects. It's circular reasoning. What about lag time effects with regard to the solar irradiance?. No mention at all.

    You haven't addressed lag-time effects with your sun-temperature disconnect theory from about 1980 (eg in other posts). Tying in effects on clouds, or the earths magnetic field (which has been declining naturally for the last few hundred years-which would amplify any warming-an important point), and you could explain a global emperature peak around the 2000s. For example:

    -When is the hottest part of the day?-around 3 hours AFTER the sun reaches its peak (~30% of the entire day-warming trend).
    -Which is the hottest part of the year?-about 6 weeks AFTER the longest day of the year (~25% of the annual warming trend).

    If one increases temperature to a pot on a stove, and then flattens or decreases the temperature, the potwill show a small lag time effect, then will CONTINUE to heat for a period afterwards, and then slowly decline. How long does it take the earth system to absorb lag time heat, 1 year? 5 years?, 20 years?, 50 years 100 years?, Does anybody know?? You claim that in the last 35 years C02 has been dominant, but you do not discuss lag time heat effects from the sun, which you say has disconnected since 1980, without discussing lag time effects.

    If 25-30% heat lag effects are a guide, then adding 25-30% of lag time to the suns warming trend, from a peak around 1980 fits perfectly with a peak around 2000s.

    To pre-empt a reply based on the lag time only, don't forget, there may be OTHER factors that enhance lag time, such as the very slow lag-time heating of the ocean, the earth's magnetic field reduction, and clouds etc etc.

    Please address? It is one of the biggest arguemnts of skepics, but I don find your site addressing it much anywhere
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    Response: I recommend you read Usoskin 2005 which looks at both the correlation between solar activity and climate and the time lag between long term changes in solar activity and global temperature. They compare solar and climate data and find the correlation is highest when there's a 10 year lag. It also finds the correlation breaks down when the modern global warming trend begins in the mid-70's. I also look at Usoskin 2005 on the "It's the Sun" page and touch on the time lag issue at the bottom of the page.
  2. John, thanks for the post. I just want to add a point about the "mid-century-cooling".

    In this post by Tamino, John Mashey perhaps has a useful comment (dated May 24) about global sulfur dioxide emissions. The data can be found here:

    These emissions approximately tripled between 1945 - 1975, and then fell back with the Clean Air Acts. Mashey finds it plausible "that a 52Mt increase in yearly emissions could generate a ~ .4C NH dip from ~1945-1975", and thereby helped "masking" the effect of CO2 in this period. I don't know whether NASAs model of 2002/2004 accurately reflects this or not. Just a thought.

    Or perhaps the "mid-century-cooling" correlated also with natural changes in some of the longer ocean circulations... (PDO?)

    To thingadonta, I would guess that your lag time effect of 20-30 years for solar irradiance should be visible in the later historic record, which I believe it isn't.
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  3. Great post, John. You´re website is a great source to finding AGW-related scientific references.
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  4. Re point 1 and the Usoskin 2005, I understand there is greatest correlation between temperature and solar when the temp lags solar by ten years. But the graph also shows 40 year lag periods, albeit with a weaker correlation. Could you please explain why this rules out solar activity accounting for the last 30 years temperature rises? I am just an interested layman btw. Many thanks.
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    Response: Can you clarify where you see the 40 year lag periods? Usoskin 2005 has the correlation peaking at a 10 year lag:

  5. I have read Usoskin 2005 and various others you refer to, and your 'Its the sun' page, and very few of the papers refer to longer term lag effects-most 'look' for a mechanism-over the last 35 years or so, and rarely consider lag effects after a SUSTAINED peak.

    Also, your graph at the bottom of 'Its the sun' page uses T with respect to the mean from 1960-1990? on its Y axis,-which would be EXPECTED to show anomalies/a rise to the mean, after ~1980, if there was a lag effect. So the 'anomalous T' axis you use is irrelevant to this argument, and is misleading with respect to lag effects, if anything- it supports it!.

    Have another look at your summaries of papers on 'its the sun page'-very few of these address lag effects. Most look for a 'mechanism' to sustain a recent warming trend, which they wont easily find if the warming is largely a longer-term, lag effect (or if tipping points in solar effects exist-the favourite of human-warmists). I have looked through a few of these papers, but not all (some wont open in the links);there is little proper investigation of lag effects from a sustained high peak in Solanki 2004,Solanki 2003, Usoskin 2005. HOWEVER Haigh 2003 does look at longer term time lags with respect to sustained peaks,and actually partially supports my sustained high peak argument, to quote: "chemical and dynamical processes in the middle atmosphere may act to amplify the solar impact", even though she doesnt think solar variables can explain recent warming since 1980.

    Usoskin 2005 simly states, 'we didn't look at it', and 'it must have another cause'. Thus the paper does not address lag time effects ONCE A SUSTAINED HIGH PEAK HAS BEEN REACHED.

    The 10 year time lag referred to by Usoskin 2005 only refers to short period peaks and troughs, and doesnt negate the last 30-40 years of warming, since other peaks in the past were not sustained at these high levels.

    Also, how does one know that a 'tipping point' (the darling of global warmists), hasnt been reached with regard to the sustained solar peak since about ~1970-80, where reduced magnetic field effects and cosmic rays really only become influential once the sun has reached a certain sustained level of activity?? (If this argument is weak, note that it is one of the KEY concepts often used by human-warmists with regard to C02).

    All the papers you refer to do not disprove the key argument, that the sustained high level of solar activity can't have time-lagged a T rise since 1980, especially if you use raw troposphere temperature (which has shown little rise since 1979), rather than anomalies to the 1960-1990 mean, which distorts the effects of time-lags(eg your graph at the bottom of the page on 'Its the sun' page).

    Also, the paper of Usokin 2005 does pick up trends on longer time scales, but says they are weak: ie 'centennial' and 'intracentennial'.

    So, I'm afraid you have still not properly addressed lag effects after a sustained high peak, (and NOT in relation to the 1960-1990 mean, which would be EXPECTED to show a marked rise in 'anomalous T' if there was lag effects after 1980).
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  6. Re 4.
    The 40 year lag on the graph corresponds to a correlation coefficient of about 0.3, compared to about 0.55 at 10 years.
    (maybe 5. is a more detailed version of this query?)
    Appreciated if you could explain.
    Thanks
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  7. Re #5

    thingadonta, it’s clear to me how you infer that Haigh (2003) looks at longer time lags with respect to the earth’s surface temperature response to solar variation. The only reference to time lags in Haigh’s paper is the phase lag of 1-2 years in the response of the sea surface temperature to changes in solar cycle variations in irradiance reported by White et al (1997). Judith Lean, who has also (amongst others) studied the earth’s temperature response to solar cycle variation, finds small lags (a month) between solar irradiance variation through the solar cycle and the surface temperature response [***].

    How about time lags in the earth’s temperature response to persistent changes in solar activity? If we want to consider this with respect to late 20th century warming (last 35 years), we should consider (i) what we mean by “lag” and (ii) the magnitude of potential contribution of changes in solar activity.

    (i) There should be very little lag in the onset of the response of the surface temperature to a change in forcing. Of course the full response that occurs when the climate system has fully re-equilibrated with the enhanced forcing will take some time to occur. And so one expects to see a lag between the change in forcing and the maximum response. But there’s certainly no physical basis for a long lag, where nothing happens, between the forcing and the response. That’s what you are asserting for the large late 20th century warming, and it doesn’t seem physically feasible.

    So if one examines the relationship between surface temperature and solar variation during the 20th century, the temperature followed the small increase in solar irradiance [*] (or sun spot numbers [**]) with little lag, and the solar output maxed by the 1950’s. The earth’s temperature more or less followed the increase in solar activity through this period (a small lag), but then was pretty flat until the early-mid 70’s. The question is: if the earth’s surface temperature response hasn’t yet reached equilibrium with the new (1950’s) level of solar output, how can the earth’s temperature become unresponsive to the maximum in solar output for a period of 20 years or more and then suddenly start to rise rapidly with no secular change in solar output?

    [*]http://www.skepticalscience.com/solar-activity-sunspots-global-warming.htm

    [**] http://en.wikipedia.org/wiki/Sunspot

    (ii) lag or no lag, have the changes in solar output been sufficiently strong to produce temperature changes of the magnitude we’ve seen? Not really. If we go back to the Haigh (2003) paper you referred to, Haigh analyses the empirical data to conclude that the solar contribution to the earth’s surface temperature change has been around 0.35 oC since the Maunder minimum (i.e. early 18th century; see [**] again). Since it’s likely that the earth’s temperature has risen by over 1 oC since then, the solar contribution to warming during this entire period is at most 35%, with essentially all of this occurring before the mid 20th century. Likewise Lean and Rind [***], determine from an analysis of monthly solar irradiances from 1889 that the solar contribution to the surface temperature has been around 0.1 oC during the entire period (and largely in the period 1900-1950). Lean and Rind conclude that changes in solar output have contributed around 10% of the warming in the period 1906-1996.

    So lag or no lag, the changes in solar output are simply not large enough to have made much of a contribution to 20th century warming as a whole, let alone the very marked warming of the last 35 years.

    [***]J. L. Lean and D. H. Rind (2008) How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006 Geophys. Res. Lett, 35, L18701
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  8. canbanjo, those are very low correlation coefficients And if one is going to attest a 40 year time lag based on a correlation coefficient of 0.3, one may as well attest a time lag of -20 years which is also represented by a correlation coefficient of 0.3.

    More likely the null hypothesis applies, namely that there isn’t a significant relationship between solar variations and a 40 year-lagged (or -20 year-lagged for that matter!) earth’s surface temperature response.
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  9. thanks chris
    i have since looked up correlation coefficients on wikipedia and realise it is complicated but am i right in thinking the graph gives the 'average' correlations over the period studied. But then analysing the actual period in question, we can see that particular factors (as you explain in 7.) demonstrate that the average 40 year lag correlation does not fit, so we can confidently say that in this 40 year period the correlation would be much closer to 0, rather than 0.3.
    does that make sense?
    thanks
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  10. John Cook,

    I'm not a scientist but a layman. Can you please explain to me how they derived past global temperature anomolies from the based period of 1951-1980?

    Thanks.

    P/s: excellent site. I'm glad that I've stumbled onto here. Cheers!
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    Response: The NASA GISS temperature record displayed above is constructed from weather station measurements over land and ship measurements over the ocean. The 1951 to 1980 base period is arbitrary - if you change it to a different period, the trend is exactly the same, it's just the Y-axis that shifts.. More info here...
  11. Chris some points:

    1) The issue, as you say, is persistent/sustained solar activity, which in my opinion allows a longer time lag (eg 35 years) to be viable with regard to solar-induced earth warming. The 10 year lag recognised by Usoskin 2005, and the shorter lags recognised by Haigh 2003, are not related to sustained periods of solar activity.

    The sun's sustained activity in the last ~60+ years implies a longer thermodynamic time lag to the short peaks and troughs analysed by Usoskin and Haigh. This is a pretty simple calculation, relating to the total area under the curve of sustained activity.In simple terms: longer sustained peaks create longer lag effects.

    This is exactly the same reason that on an average day, highest T is reached well after the sun reaches a peak (ie from the total area unde the curve throughout the time from dawn to noon), whilst shorter term lags occur throughout the day from shorter-term peaks, such as from cloud cover etc etc.

    2) I don't agree with your statement:

    "But there’s certainly no physical basis for a long lag, where nothing happens, between the forcing and the response".

    This sort of argument is contradicted by eg thermodynamics, eg heat effects on partly 'buffered' systems (eg an example being water boiling), and also past earth climate changes/lags. 35 years is nothing with regard to earth time-lags to heat.

    An important issue is thermodynamic response by the earth's climate to prolonged-sustained solar activity, rather than a short-term peak. If one eg heats water to close to 100 degree C, is doesnt boil unless significant more energy is applied. In other words 'tipping points', are a typical feature of sustained heating on multi variable complex systemssuchas the earths climate, as much as in other complex fields. We shouldn't expect a linear response, from the earth system, to sustained solar actinity, in whcih case a flat-lining for 20 years is not unusual or unexpected. It is only after heat energy is sustained for a longer period that the T, as we have observed in the latter 20th Century, will start to rise again, probably due to negative-feedbacks and oceanic heat lags. This is not unusual, either in earth history, or in thermodynamic systems.

    3) the question of changes in the sun being 'enough' to warm earth ~1 degree C since 17th century is supported by similar changes in the past climate, which were due undoubtedly due to the sun, (as there were no changes in eg C02). In other words, I contend that solar forcings are vastly under-estimated, whilst c02 forcings are vastly inflated, to support various bias/agendas.

    You repeat the conclusions and estimates of those who attribute low solar forcings to climate change. I could also just as easily quote those who conclude the opposite-that there are only low c02 forcings. Which is correct? Earth's past climate is one guide, and it doesn't look good for those who support high forcings for C02, and low sun forcings.

    The only thing one can conclude from examining climate history, is that humans learn nothing from climate history.

    I suggest, that thermodynamic, non -linear effects are sufficient to explain heat lag effects from the sun on earth T inhte 20th century, and flat line periods (such as is occuring in the last decade).
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  12. re #9

    Yes I think that's right canbanjo. The situation is complicated by the fact that the solar output goes up and down somewhat on fixed (solar cycle) and variable time scales, as can be seen by looking at the sunspot numbers as a proxy for solar outputs:

    http://en.wikipedia.org/wiki/Sunspot

    So while the climate response to a change in solar output is certainly going to be "lagged" (but note that this "lag" refers to the maximum response rather than a lag in the onset of the response!), the variability will result in a range of response times, and so as you say, the graph in Usoskin will have some relationship to "averaged" lags.

    Again I think you're right in suggesting that just as one can assess causality via an analysis of correlations between a number of events (e.g changes in solar output) and their responses (surface temperature changes), we can also examine individual specific examples (e.g. late 20th century warming) in mechanistic detail. An analogy might be assessing the statisical relationship between ciggie smoking and lung cancer via analysis of large populations of smokers and non-smokers. In addition to this statistical analysis, we could look at a single individual and observe, for example, carcinogen-induced DNA damage in the lung cells of a smoker to assess the mechanism that underlies the statistical correlation observed in populations.

    So if we do this for late 20th century warming, we find that the mechanism (warming response to change in solar output) is incompatible with the evidence and what we know of the physics of radiative forcing and the climate response, at least to the extent that I outlined in my post #7.
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  13. re #11

    1) O.K. thingadonta, but above you asserted that Haigh (2003) “looked at longer term time lags with respect to sustained peaks”. One only needs to read her paper to see that she does nothing of the sort. If we are going to make assertions we should back them up with reliable evidence (since this is about science and not politics or propaganda or something else!).

    2) Your “thermodynamic” arguments seem suspect. I agree with you completely that the response to an enhanced forcing (e.g. enhanced and persistent solar forcing) should result in a warming response, the maximum extent of which will be delayed as the climate system comes to a new equilibrium with respect to the forcing. However there won’t be a “lag” before the warming starts (unless an opposing forcing occurs for a while; see below), and in fact the maximum rate of warming should occur early in response to a change in forcing. That applies to the climate response, just as it applies to any simple experiments with water in a pan on a cooker (why not try it?!) or the response to enhanced insolation during the day or as a result of seasonal variations. So your notions are incompatible with the record of temperature variation throughout the 20th century. The surface temperature rose somewhat in line with a small increase in solar forcing from the early 20th century to the mid 1940’s but then went pretty flat for around 30 years (see Figures in John Cook’s top article above). The solar output maxed in the 1950’s. So what can have caused the long lag before any warming occurred in response to the maximum in solar output in the 1950’s?

    The explanation for the temperature stasis in the mid-20th century is the effects of atmospheric aerosols which produced a negative forcing (see Figure 2 in John Cook's top article). Can that be used as an explanation for a lagged solar contribution? No not really. That would only work if the negative aerosolic forcing was suddenly reduced around the early 1970’s so that the aerosolic suppression of the effects of enhanced solar forcing disappeared. However that doesn’t work, since all the evidence indicates that the negative aerosolic forcing has increased since the 1950’s, largely due to continuing industrialisation and “dirty fuel” use in the developing world (see Figure 2 in John Cook’s top article; see also

    http://www-ramanathan.ucsd.edu/publications/Ram-&-Feng-ae43-37_2009.pdf )

    What warming forcing has increased since the 1970’s that can have “overpowered” the cooling effects of atmospheric aerosols? Not the sun. We know categorically that its small excess forcing maxed in the 1950’s. The greenhouse gas forcing has increased markedly especially from the mid-late 1960’s (see Figure 2 in John Cook’s top article). The temperature rise has followed that increased forcing pretty much as we might expect (no lag!), even if internal variations in the climate system has overlaid the temperature rise with noise.

    3) With respect to the large amount of quantitative information on the rather small effects of solar forcing to 20th century warming (a couple of examples I gave in my post #7), you suggest that you could “just as easily quote those who conclude the opposite”. Fine, then why not do so? So far you are arguing by assertion, and the one paper you cite in support of your assertions (Haigh, 2003), doesn’t actually say what you says it does. Since these are scientific issues we should be interested in the properly published evidence and not unsupported assertions.
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  14. re:13

    1) My reference to Haigh 2003 was that she implies the potential for solar forcings after a sustained period......"chemical and dynamical processes in the middle atmosphere may act to amplify the solar impact". 'Amplify' means that a time-lag component is implied, you cant 'amplify' something without a time lag, but I did think she addressed longer lags by the flavour of her paper.

    I don't have the rest of her paper now, but very few of the others i have perused on tnis site even bother recognising that a time differential/lag is even possible after sustained solar activity, or that 'dynamical processes' can 'act to amplify solar impact'-this stark lack of address of such a simple concept as time lag after a sustained peak activity, should give pause for thought. It is entirely reasonable, thermodynamically.

    2) "So what can have caused the long lag before any warming occurred in response to the maximum in solar output in the 1950’s?"

    Note that earth T went flat at roughly the same time as ths sun did (1950s). So far so good. Now sustained solar activity bombards the earth for 20 years. It is entirely reasonable thermodynamically, for a complex system to parallel and absorb this sustained flat activity until a saturation point is reached, before T starts rising again (although there would hve to be some kind of buffering/inhibitor, similar to H bonds in water with boiling-I dont know what this is, only that it is theoretically reasonable); another possibility is a slow reduction in clouds in response to lower influx of cosmic rays and sustained solar wind. Another possibility is UV changes. The possibilities are numerous, but the main point is, that the concept of delayed effects following a sustained peak of activity is NOT unusual in thermodynamics.

    (EG I once opened the microwave after heating a mug of coffee too long, with no observable effect on the long-bombarded mug of coffee-no boiling was visible, but with the slightest disturbance to the surface of the water-the water literally exploded out of the cup-the heat energy was absorbed by the water for some time without any boiling, a critical threshhold was reached, and a strong time-delayed effect followed. This is relatively common in themodynamics).

    Overall cloud reduction by an increase in cosmic rays, if such indeed occurs, does not have to happen 'immediately'; the relationship betweeen cosmic rays and cloud cover etc may build up over ~20 years of sustained solar activity 1950-1970, before a critically low level of cloud formation mechanisms are reached, with subsequent rising temperatures. ???

    I dont think aerosols have much/anything to do with T in the 20th century, primarily because aerosols have NOT declined since 1980, if anything the high rate of industrialisation in unregulated 3rd world industries in the latter 20 century suggests that aerosols have increased. Also, aerosol reductions are just a cop-out/ego trophy for greenies.

    As for predictions, i guess T shouldn't rise over the next 20 years (?), as the sun and T have now flattened (the flattening T supports the long-lag effect of the sun, whiuch has also flattened). It is difficult to imagine a double-delay T lag, or a climbing ladder- lag T effect in the earth system (even though these ALSO exist in thermodynamics, beleive it or not).

    3) As for low c02forcings, the NIPCC report contains plenty of references to peer-reviewed papers advocating such. I dont have time to review them now. But I'm pretty sure they are there, I know for a fact there are plenty which advocate significantly enhanced solar forcings.

    I enjoy your responses, but I still think the sun is the driving force in climate change. Check again in 2030, T shouldnt (?) have risen/much if the sun is the main force in all this.
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  15. Thingadonta: just because you can imagine a thing doesn't make it true; nor does it make it the most likely. The trick is converting what seems fanciful to most people (I imagine) into something convincing.
    PS. Your coffee was superheated, meaning that the temperature continued to rise above the boiling point. It's not as though the energy disappeared and then re-appeared.
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  16. chris, thanks for taking the time to respond. much appreciated.
    cbj
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  17. Thingadonta:

    "If one increases temperature to a pot on a stove, and then flattens or decreases the temperature, the potwill show a small lag time effect, then will CONTINUE to heat for a period afterwards, and then slowly decline."

    If what you're saying - and it's not that clear - is that the water in a pot will continue to warm for a bit after you turn off the hob then sure.

    If you were trying to determine if the hob was still on by only measuring the water temperature then you would obviously have to wait a bit before the actual status of the hob became clear.

    OTOH, if you were monitoring the hob directly you would know as soon as it was switched off. And note here that we are monitoring the sun's output directly with satellites.

    Now, from what you say, you strike me as the kind of guy who'd switch off his stove but not believe it until he'd checked the water temperature was actually on the decline. It's good to check. Of course, if the water in the pot actually went on getting warmer for the next 40 years it WOULD be perplexing. It might be that you'd actually turned off the wrong hob. Or, of course, it could be the sun.
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  18. re:17

    "Of course, if the water in the pot actually went on getting warmer for the next 40 years it WOULD be perplexing".

    This is a ridiculous and dishonest statement. The pot is an analogy, the time period of heating of the pot (minutes), has nothing to do with the time period of heating of the earth from the sun (years); the parallel is in the principle of a heat lag afer a sustained peak. You must be an incrediby dishonest researcher to falsely equate the RAW time periods of the two, yet not recognise the parallel in concept.

    The point is, is that time lag of heating anything relates to the area under the curve of total warming, not short term peaks/troughs. This indicates that a SUSTAINED solar peak from the mid 20th century, starting from a rise in the 17-18th century, can account for warming in the latter 20th century.
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  19. Thingadonta, your analogy is false for the following reason.

    The heating element is much hotter than either the pot or the water (check it, it glows red!). When you turn off the the power the element has to cool to a lower temperature than the pot and water before cooling of the water starts. There is a lot of heat energy in the red hot element that has to be dissipated before cooling of the water starts.

    If you remove the pot from the element rather than turning off the poweer cooling will start immediately (the pot may be a little warmer than the water) but total heat energy will start dropping right away.

    Non scientists should think through their analogies carefully before drawing wrong conclusions.
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  20. I think what thingadonta is saying (to paraphrase) is that a persistent increase in solar energy in the last couple of centuries would increase the equilibrium temperature of the Earth. However, before the temperature will reach that equilibrium, the oceans will first have to warm. As the oceans slowly warm, they will continue to pull up the temperature of the Earth, even though the solar energy may have plateaued already.

    As analogy, if my burner is set to a temperature of 90 deg C and the water in the pot is 25 deg. C, the temperature of the burner does not have to keep increasing in order for the temperature of the water to keep increasing. There is no inherent contradiction btw saying the sun's energy has remained constant over the last X years and saying that the sun's energy has caused the Earth's temperature to continue rising throughout(for example) that period.

    Cheers, :)
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  21. re: 19

    This sort of argument of your shows how people don't understand much about thermodynamics. Will chemists and physicists please contribue to the debate on global warming, so self-ordained stove specialists dont end up running run the worlds economy?

    If this sort of argument is any guide, I dont have any faith in the ability of global warmists to properly assess the affect of the sun on rising earth temperature, with lag effects. The question is one of lag effects following a sustained peak of T (not turning off an element, as if one could turn off the sun). The rather simple point is, T will continue to rise after heat has reached a sustained peak, roughly equivelent to the total area under the curve of the T graph, from the start of heating. It's really very simple, the same as a days highest T occurs about 2-3 hours after the sun has reached a peak overhead.

    PS: I am a scientist. I hope you don't intend to cook anything with your pot-understanding.
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  22. You asked for a scientist to respond to your crazy pot boiling. Well I am a scientist, BSc in chemistry and PhD in Biochemistry and your pot boiling is a load of nonsense.

    If you knew anything about thermodynamics you should know that energy is neither created nor destroyed. The energy in the pot cannot increase after you remove the source of heat. Thus its temperature cannot increase after removing the source of heat. It is that simple. Go and read some texts on thermodynamics.

    I am glad that you seem to be only a "blog scientist" and your ideas are confined to the blogsphere and not the real world.
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  23. Ian is right. The total energy of the system CAN NOT increase after the heat source is removed. If the heat source is removed and the energy proxy (i.e.water temperature) shows an increase, it means that an element of the system acted as a heat storage and is now releasing that heat faster than the decrease due to removing the source AND in a way that can be reflected by the proxy. So the kettle analogy is rather poor. Shawnhet's description is probably better.

    Furthermore, if Thinga wants to make the argument that there is an unknown storage element that releases heat exactly at 40 years, the necessity for a physical mechanism becomes imperious, lest the heat storage idea become nothing but a fudge factor.

    As a layman, I am unconvinced because it does not seem to add up. TSI variation are very small. If the climate can react that wildly to such small forcings, then we might be in for some serious sweating with just the CO2 released so far, even witout all the feedbacks.
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  24. Thinga, don't talk down people with "as if you could turn off the Sun." You're the one who chose the analogy and the terms going with it.
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  25. re: 22, 23, 24.

    The heat source is not removed. A heat lag on earth follows a peak of solar activity- Usoskin 2005 agrees, and concludes this heat lag averages ~10 years over the last thousand years or so, in an analysis of peaks and troughs of T relating to solar activity.

    A sustained peak since the mid 20th century implies a longer time lag, although one issue is why the earths T flattened from the 1950s-1970s. But the concept of a heat lag is really not that difficult. Annual T peaks every year about 6 weeks after the summer solstice (in Feb in the southern hemisphere), and day temperatures peak about 2-3 hours after the highest point of the sun overhead (about 3pm). In both cases, the heat is not 'removed', there is simply a lag effect, note that overall heat supplied does not increase, new heat is not 'created', but actually decreases in both cases, yet the earth continues to warm. Tough one eh!

    So, back to cooking classes.
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  26. I think there is a bit of confusion with what Thinga is trying to say.



    Continuing the pot on the stove analogy, lets assume:

    The pot has been on the stove at a setting of 5 and achieved equilibrium temp of 80C and setting 6 would give 85C, setting 7 90C, etc.

    I believe what Thinga is trying to get across (going back to post #11, correct me if I am wrong, Thinga) is that if you change the setting to 7 for one minute and the temp goes up to 83C, at this point even if you turn it down to 6 the temp will continue to rise.

    In this analogy the papers described above would be the equilivant of measuring the AC current flowing through the element and trying to correlate it to the changes in temperature of the water in the pot (though frequency and the equilibrium time are much further apart that that of the sun and Thinga's 40 year mark)

    As this is my first post, I would like to take the opportunity to commend John (and the majority of those whho post here) on an excellent site.
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  27. Sorry for the double post.

    While I have no idea if such a mechanism exists with regard to the sun and the ocean, or that there would be any way to measure this in the presence of all the other forcings, it does seem like a fair comment that any significant 'lag' would result from the total energy (integral over time) of the sun's output rather that a directly proportional response. This is something I found quite confusing in Usoskin 2005 and that time lag graph.
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  28. RE 20: Shawnhet, thanks for that.
    re 28: Niten77, I think you've got the general idea.

    I dont know why a heat lag is so difficult to understand, its really quite simple, average daytime T peaks around 2-3pm, but the suns incoming energy peaks around noon (a 20-30% heat lag of the total time of warming since dawn). There is a LAG effect; there is no 'immediate' response to the reduction in solar input from noon; crudely applying this 20-30% general lag to the sun's overall warming trend from the 17th century to the mid 20th century, means you can get a peak around the early 2000s.

    This model doesnt necessarily explain everything (eg why was T flat from 1950-70?), and may be invalid in terms of length/degree/solar forcing etc, but the concept of a heat lag itself, following a peak, IS entirely invalid, and more so if the peak is sustained over several decades, which implies an even longer heat lag effect (eg from ?warming the oceans over several decades?).

    Too simple for some to understand.
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  29. It's easy to understand until you come up with a bad analogy. Of course the heat source is not removed, that's why your initial analogy was poor. I understand everything you say, it's really not complicated.

    It's just not very convincing. Your condescending tone does not make it more so.
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  30. There is no lag time from the sun. Just check what happens immediately after volcanic eruptions. The earth cools immediately.

    Check what happened in the middle East when the oil fires were started. The area down wind cooled immediately.

    Check what happened to US temperatures after 9/11, can you tell me what happened? I doubt it.
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  31. Planes were grounded so there were no contrails so temperatures immediately went up, and came back down as soon as planes started flying. but isn't that a local effect? like northerly winds? i thought thingies point was that there had been hundreds of years (or whatever it was) of gradual increased solar output before ending last century, and therefore lag effects are relevant. Although (i might be wrong) i'm not sure thingy has explained what kind of earth science processes would create a lag that would flatten first and then rocket upwards later (and if he has a theory whether this can be tested with measurements)?
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  32. if anyone is interested in another pot analogy, please see realclimate: http://www.realclimate.org/index.php/archives/2009/06/a-warning-from-copenhagen/langswitch_lang/sp#more-690
    this one i think concerns a different kettle of fish.
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  33. re: 31, and re:13:

    One possible reason that earth T flattened following the solar max in the mid 20th century is one often used by global warmists-the ocean intially absorbed the heat for around 20 years from 1950-70, then the lag kicked in from 1980-2000s.

    A predition of this model would be that T in the norhtern hemisphere between 1980-2000s should have gone up more than the southern hemisphere, since there is more ocean in the southern hemisphere to absorb the suns warmth.

    This IS in fact what is observed, T has only increased slightly in the southern hemisphere since around 1980.

    Moreover, if one looks at satellite trophosphere T, rather than surface T, (which is suspect), T hasnt gone up that much since 1980 in any case.

    Another prediction from this model is a flattening of T since ~2000, especially in the northern hemisphere, as the lag effect wanes.

    Predictions based on this model: The sun has now waned slightly.

    -T in the southern hemisphere might to continue to rise slightly over the next 20 years, as the large area of ocean which has absorbed the solar max since ~1950 continues to slightly warm the atmosphere,
    -however T in the northern hemipshere should flatten or slightly decline (with less ocean heat which has pobalby already reached equilibrium).
    -Overall the earth as a whole should not warm much over the next 20 years (well below IPCC forecasts), based on a dominant solar model driving climate change.

    I'll check back in in 20 years.
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  34. Thingy, I would have thought the next ten years would be enough to show whether you are right or not? The argument about the apparent flattening out, or even falling over the last ten years is that it is not a long enough period to read any trend into it. But surely the last ten plus the next ten is?
    But I hope you are right. I have a 1 year old daughter who could therefore live to see 2100. Scary.
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  35. "However, for the last 35 years, the dominant forcing has been CO2."
    I have to disagree..the dominant forcing agent is water in its various phases, particularly as vapour. Unfortunately measuring WV variation globally to include within models is next to impossible and so estimates are used.
    We do know that our use of water, both industrial and agricultural, has increased enormously over the same period that 'global warming' has occurred with consequent increase in atmospheric wv.
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  36. mizi, have you read:
    http://www.skepticalscience.com/water-vapor-greenhouse-gas.htm
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  37. #36: yes, Chris and I had quite a civilised discussion in that thread concerning the role of WV.
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  38. hmm i had a look but didn't notice any contribution from yourself. ;)
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  39. The strange thing about the thingadonta contributions is that there is no indication of why she/he thinks that the sun warms up the ocean and then that heat is released a long time later. Hence the odd debate about turning off a hot plate and a pot continuing to boil (well, yes, it does, but its temperature begins to drop immediately). I don't mean why does thingadonta WANT there to be some mechanism for absorbing energy from the sun that doesn't show up until much later, the answer is obvious. He/she believes the sun is causing global warming, and since it isn't, now, there must be, must be, a mechanism for a time lag. Because the unthinkable alternative is what the science says - the cause of rising temperature is increasing CO2. Quite why this is unthinkable is what makes all of us in the reality-based universe throw up our hands in despair. But I repeat, what on Earth makes thingadonta think that there is a mechanism in practice as distinct from wish fulfillment? What measurements, what observations, make him/her think the Earth is actually behaving like this?
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  40. : 39.
    A strange post indeed. Some comments.

    Methinks that solar variables, especially over the long term, have not been investigated enough to be dismissed as having only a minor effect on recent earth climate change.

    Note, once more, as I have said many times, THE HOT PLATE (IN THIS CASE THE SUN) IS NOT TURNED OFF, NOR IS IT REMOVED, RATHER, A SUSTAINED PEAK OF SOLAR ACTIVITY IS MAINTAINED (SINCE ~1950-2000s), WHICH CAUSES THE T of the earth to continue rising, as it has not yet reached equilipbrium.

    A heat lag effect occurs, following the rise from solar activity from about 1750-1950, which, by analogy, also occurs eveyday for daily T, with about a 20-25% time lag from the noon peak to between 2-3pm. Correlating this 20-25% time lag to the rise in solar activity from 1750-1950, gives a time lag of ~40-60 years, gives a peak in the early 2000s, which is also what is observed. It is a model that has not been properly investigated in various time lag analyses of solar activity from 1750-1950 (eg Usoskin 2005, Haigh 2003), which look at short term peaks and troughs, not total warming end-point trends.

    The question of flattened T 1950-1970 may be explained by ocean absorption, or even the 'aerosols' of the global alarmists. If this is wishful thinking, then it is also wishful thinking on the part of the human-induced global warmists, who invoke exactly the same mechanisms.

    I also note that the current global warmists also invoke a 'wishful thinking' mechanism to explain why the earth is not heating in the last decade, using eg oceans absorbing heat. So its ok when they do it, but is wishful thinking when someone else does it? My model of long term heat lag effects actually predicts a flattening in T in the last decade, as heat lags effects of 20-25% of total warming time from 1750-1950 subside, global warmists have to actually invoke your 'wishful thinking' to expalain why the earht is not heating in the last decade. Is there a double standard in your thinking? Who is doing the wishful thinking?

    As for what makes me think the earth is reacting to changes in the sun, have a look at what happens every day the sun comes up? Is this so unreasonable, to look closely at earth-sun relationships?

    Methinks, the overthrow of c02 as a dominant mechanism driving climate change will ultimately come from ordinary people and ordinary scientists, who can see with their own eyes how the sun is dominant over all other forcings, but it won't come easily from the inbred, vested interests of bureaucratic, anti-capitalist science.
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  41. Thingadonta: your analogy does not reflect the real world. Better to imagine a lamp shining on the SURFACE of a bowl of water. The bottom layers of the water will stay (relatively) cool due to stratification so absorbed heat is restricted to the uppermost layer. This what happens in the ocean. Whilst there will be a thermal inertia effect it will be much shorter than you suggest.
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  42. #40 "vested interests of bureaucratic, anti-capitalist science" - and so we get down to the ideology. Always do, in the end.
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  43. Ideology and name calling as well. Inbred? Ordinary scientists, as opposed to what, extraordinary? Whatever.

    Methinks the aforementioned relationship has been investigated rather well and is actively investigated as we speak.

    Since you have a "model" and you're a scientist, by all means you should publish. You'll be an instant hero to everyone sharing in your ideology. Considering that even garbage as pathetic as Gernisch and Tscheuchnauer can make it in respectable publications, for the sake of presenting "the other side", your high quality work should be a breeze to get out there. And there is always Energy and Environment.
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  44. thingadonta: A heat lag effect occurs, following the rise from solar activity from about 1750-1950, which, by analogy, also occurs eveyday for daily T, with about a 20-25% time lag from the noon peak to between 2-3pm. Correlating this 20-25% time lag to the rise in solar activity from 1750-1950, gives a time lag of ~40-60 years, gives a peak in the early 2000s, which is also what is observed. It is a model that has not been properly investigated in various time lag analyses of solar activity from 1750-1950 (eg Usoskin 2005, Haigh 2003), which look at short term peaks and troughs, not total warming end-point trends.

    I think your claim that the long term peak is 20-25% of the the cycle after the long-term cycle stops increasing follows from the fact that the daily peak is 20-25% of the day after it stops increasing. Presumably, the location of the long-term cycle's peak follows from the length of time it takes for the ocean to reach its new equilibrium(however long that takes).

    Personally, I think you may well be right that the long-term increase in solar activity hasn't been adequately addressed, but that doesn't mean that the answer is anything like you've proposed here.

    Mizimi: your analogy does not reflect the real world. Better to imagine a lamp shining on the SURFACE of a bowl of water. The bottom layers of the water will stay (relatively) cool due to stratification so absorbed heat is restricted to the uppermost layer. This what happens in the ocean. Whilst there will be a thermal inertia effect it will be much shorter than you suggest.

    The bottom layers may stay *relatively* cooler(to the surface water), but they will be warmer than they would've been if the lamp had never been turned on.

    Cheers, :)
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  45. My first paragraph above to thingadonta was mistakenly worded. Sorry. I had meant to say that I *don't* support the idea that because the daily max is 20-25% of a day after the max in solar heating, we can determine when the peak of a long-term cycle is(ie 20-25% of that cycle after the maximum). The determination of the long-term max will be a function of how long it takes the ocean to reach its equilibrium, which AFAIK the daily max's timing is a completely separate issue.
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  46. Thingadonta... do you accept that the earth is warming or not?

    If not why not?

    If so and caused by lagging solar activity, where is your historical data to support your model?

    Your opening comment about the selective use of CO2 data to support global warming also appears to apply to your own use of solar-lag. Show me the data.

    My own position... we are warming... too much consistent data to ignore. Why are we warming... I dont know and am finding simplistic models supported by rhetoric or worse... poor science... confusing.... Thinga... if your argument is valid (and it may be) please support it with data and models we can test and and draw our own supporting conclusions from, rather than listen to unhelpful shallow guesses.
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  47. :50 Some points:

    Yes the earth is warming- about 1C+- over the last few hundred years.
    You can link to many many websites which show solar vaiables which have increased since about 1700, peaking in the mid-late 20th century. This website also agrees with as much.

    eg http://commons.wikimedia.org/wiki/File:Solar_Activity_Proxies.png

    -With such things as oceans taking time to absorb heat, ice melting slowly in the Arctic causing slowly decreasing albedo, and well-known properties of thermodynamics itself, you get heat lags. Its too simple for 'global warmists by humans' to undertand. These heat lags can be susbstantial eg 20-25% of the total warming trend in daily T from dawn, and annual peak T 20-25% after the summer solstice. (check any meteorological record). This 20-25% would explain heat time lags after peak solar activity in the 20th century, if the model correlation is valid, but even if it isnt directly applicable (global climate is complicated and may not be directly proportional to eg daily T), the concept of a heat lag itself IS valid.Its a question of how much heat lag.

    Also note, that raw satellite troposphere data doesn't show much of a warming since 1979 in any case; and I don't trust bureaucratic 'corrections' to this data, which amplifies recent warming since ~1980. But it is clear that T has increased +-1C since about 1700+-. The sun could explain all of this heating, in my opinion, without needing to invoke C02.

    Those who don't like the sun causing this much change, since solar variables seem to be too weak, have to also explain why the sun caused similar-scale T changes in the past, associated with similar 'weak' solar changes. They also dont like the stepwise trend in T when placed against solar trends, but they have to deal with this with C02 as well.

    In other words, it is quite possible that solar forcings are under-estimated by the IPCC etc, one piece of evidence being changes in T being caused by similar small changes in solar variables in the past.

    A similar sort of problem occurs with those who want to invoke eg mammoth extinction to climate change, mammoth surived similar many similar changes to climate before humans came around, so if humans didnt cause their extinction, hwo does one explain their non-extinction in simialr climate changes in the past?? Similarly, how does one explain similar T changes in the past, without any changes in c02, if solar forcings arent stronger than assumed by eg the IPCC??

    To answer your request about models and data etc properly, I would have to be involved with full time research, which I am not. I don't have time to write a 'paper', but you can get solar reconstructions from various places, eg the NIPCC report is a good reference. If I was a government-funded researcher I might be able to give you much more, not enough time now.
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  48. "The sun could explain all of this heating, in my opinion, without needing to invoke C02" - and your opinion is good enough for me, mr thingadonta. But it is a great pity that you "don't have time to write a 'paper'", what a loss to science that is, surely some 'government-funded researcher" could take you on and let you achieve greatness?

    Correct me if I am wrong, but let me see if I have understood your "e=mc2" moment. The hottest part of EVERY day (leaving aside variables like cloud cover) is an hour or so after mid-day. The hottest part of EVERY year is usually a bit later than summer solstice in whichever hemisphere you live. So, drum roll, the effects of the increase in sun activity some 50 years ago are only just being felt now, by analogy. But the analogy is false, I'm afraid, so you better stick to your day job. Every part of the earth does warm up and cool down considerably, alternately, each day, every part of the earth does warm up and cool down considerably, alternately, each year. What makes you think that there is a long term delay as a result of tiny fluctuations in sun's activity? Let alone in proportion to the delay on a daily basis. This sort of nonsense just keeps on coming while, leaving aside temperature measurements and regression analysis, the world is responding, unmistakably - plants, animals, glaciers, deserts - to a warming planet.
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  49. I dont need 'greatness', since I dont think like boring, pompous academics. And yes, the earth is responding to warming-natural warming, (except none in the last decade or so, whilst c02 just keeps on rising-no evident connection).

    Lag effects are well known by most academics anyway, except perhaps your great self. EG:

    -C02 rise lags earth T rise in orbital variations, by ~400-1000 years. This is a pretty long lag.
    -The onset and end of ice ages have long offsets/lags, from orbital variations. There is T 'resistance' to both onset and the end of ice ages, but more resistance to an end, where T subsequently rises rapidly, possibly after ice sheets thin out, have mostly melted and albedo effects become (suddenly) greatly diminished. ?
    -It is recognised there is a statistical 10 year time lag between solar activity and earth T (Usoskin 2005). My question is whether or not they have looked at longer term trends (ie from the very beginning of a climate shift, such as the 1500 year sun cycle, rather than short term peaks and troughs) and also sustained solar peaks, in this 2005 analysis, and others. I suspect that they haven't. The 1500 year solar cycle may be important in this respect. So far (~1750-2000s), the earth is responding as it should to this solar variation- about +-1 degree in the first ~250 years or the solar warming cycle, we have about another 250 years and ~1 more degree of warming to go to ~2250, in the 1500 year solar cycle trend. This warming is well in line with previous 1500 year solar cycle warmings. (I just got the new book of the 1500 year solar cycle by Singer, so more later). Have you read it?

    The issue of variations in solar activity on the earth as a whole between day/night and between seasons and hemispheres is irrelevant, it doesn't change net affect over time. The same applies to C02, it traps incoming heat by day, keeping the heat in by night, but the net effect over time includes both day and night. Solar activity is no different. Summer (eg in the S hemisphere)still warms between December and February, despite their being 'nights', with no local solar activity, the net effect is positive, with a heat lag of 20-25% of the total warming trend since the winter solstice. Whether or not the 20-25% heat lag correlation is valid is another matter, but heat lag effects themselves, even multi-decadal ones, are well known.

    There is nothing extraordinay, or 'e=mc2' in my ideas, they are quite simple, I find that most 'global warmists by humans' are pretty naive and uniformed about even simple, contrary views or ideas to their mantra/mission/religion/ideology etc. Most haven't even got a clue that the sun drove climate change in the past, and could therefore be doing so now also- with similar-scale T changes to similar-scale solar variations.
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  50. Hmmm. "It's the sun what done it". "Um, no, variation in sun activity too small, and in any case has been decreasing in recent times while temperatures rise". Pause. "It's the sun what done it, but it is a delayed reaction, just like it is warmer after lunch".

    This sort of stuff is faith in action. Denialists know the truth - ie that no environmental concern must ever get in the way of, hell, must never even pause, neoconservative laissez faire unregulated capitalism for the very rich - and therefore no fact can ever demonstrate the failure of their ideology. All facts can be explained away, individually, no matter how far fetched each explanation is, and no matter what the combination of all data tells you about the real world.

    Now, where else have I seen that mind set in action?
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