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Comments 129451 to 129500:

129451. Ian Forrester at 01:21 AM on 24 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129452. Mizimi at 19:42 PM on 23 June 2009
        CO2 lags temperature
        MattJ: It has been demonstrated empirically that plants do indeed flourish if CO2 levels are higher than the present 380ppm or so, all other things being equal. Many horticultural industries use CO2 augmentation to grow bigger plants, faster. (Levels of around 1000ppm which is still low enough not to have a deleterous effect on animal health). Coupled with the knowledge that in the deep past the plants we now burn as coal grew in a climate with far higher CO2 levels ( and were adapted to such) and by locking up that CO2 reduced levels to around 200ppm...at which point they had 'starved' themselves..some species to extinction. About 8Mya, the grasses appeared - well adapted to thriving with low CO2 levels ( and are arguably the most successful plants we know). So there is no valid counter-argument. Climate is a highly complex interactive system and responds to changes in the physics and chemistry of the sun and this planet ( including those produced by life itself) and so it is necessary to look at ALL factors and how they interact, not focuss on a single mechanism. In that regard this site actually does quite a good job.
129453. thingadonta at 10:30 AM on 23 June 2009
        This just in - the sun affects climate
        The earths magnetic field has been declining for several hundred years, and some are worried that it might actually flip soon (we will see compass's needles pointing south, instead of north-this is common in geological time, and has been used to correlate, in time, magnetic-bearing rock sequences which show identical flip patterns over time. I think, from memory, magnetic flips occur roughly every several hundred thousand years, (but don't quote me on this) and,to use a bad cliche, "we are due"). Anyway, I read in some internet sites that a lower magnetic field suggests an increased solar effect, it is mentioned in eg the meeting between Minister Wong and Fielding and Co. scientists, but I dont have any papers per say, on hand. Try the NIPCC 'climate reconsidered' report which is a good overview of alternative theories, also Plimers recent book may contain reference footnotes on it.
129454. thingadonta at 10:10 AM on 23 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129455. XPLAlN at 07:52 AM on 23 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129456. canbanjo at 06:40 AM on 23 June 2009
        The CO2/Temperature correlation over the 20th Century
        chris, thanks for taking the time to respond. much appreciated. cbj
129457. Steve L at 05:29 AM on 23 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129458. thingadonta at 00:11 AM on 23 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129459. chris at 22:43 PM on 22 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129460. chris at 22:35 PM on 22 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129461. thingadonta at 19:20 PM on 22 June 2009
        The CO2/Temperature correlation over the 20th Century
        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).
129462. Adlai Gavins at 20:59 PM on 21 June 2009
        The CO2/Temperature correlation over the 20th Century
        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!
        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...
129463. canbanjo at 19:07 PM on 21 June 2009
        The CO2/Temperature correlation over the 20th Century
        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
129464. chris at 02:39 AM on 21 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129465. chris at 02:36 AM on 21 June 2009
        The CO2/Temperature correlation over the 20th Century
        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
129466. Steve L at 02:28 AM on 21 June 2009
        This just in - the sun affects climate
        Thingadonta, you seem to think you have a model of climate with which you can attribute portions of temperature change to specific causes. And you think that yours is better than models used for such purposes by "all the PhDs" who contribute to climate science via research articles used by the IPCC. Rather than making an anonymous assertion that can't be scrutinized by others, please show us the model. "It is one of the biggest arguemnts of skepics [#6]" -- perhaps the model is already published? If not, then maybe you can convince a skeptic luminary to help you formalize it? That would be excellent, because then the model could be used to make predictions. I gather from what you've written that you expect temperature to decrease into the future. How much future warming will be inconsistent with your model? PS. Can you cite a peer-reviewed scientific publication describing the effect of Earth's magnetic field on average surface temperatures?
129467. Steve L at 02:09 AM on 21 June 2009
        The correlation between CO2 and temperature
        For Andrew K, I think you've ignored what John Cross wrote about the length of time that volcanoes have a strong effect on temperatures. But for me there is a statistical point that is more important -- you can't perform a frequentist statistical analysis every time you get a little more data. Doing so invalidates the accepted Type I error. If you flip a coin 100 times and THEN look to find out whether you have rejected the null hypothesis' expectation of 50:50, that is a valid test at some arbitrarily accepted Type I error rate (typically 5%, or 1 out of 20). If you decide to flip a coin up to 100 times and perform the same test after each flip with the intent of stopping and reporting a significant value when you reach it, you are inflating the Type I error because you are making no correction for the number of tests you are performing: "one out of 20" is no longer fair because you have increased the number of tests.
129468. canbanjo at 21:59 PM on 19 June 2009
        The CO2/Temperature correlation over the 20th Century
        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
129469. MattJ at 17:48 PM on 19 June 2009
        CO2 lags temperature
        An argument I was hoping to find the refutation for here is: "CO2 has been much higher than now in teh past, and species flourished; why wouldn't they do the same now?" My understanding has been that because of greatre climate sensitivity to ocean current changes, a little CO2 now has a much bigger change on the climate than back in the days (for example), of Pangaea, when having only one continent created very different ocean currents. But I was unable to confirm the correctness of my understanding from this skeptical science site.
129470. thingadonta at 10:52 AM on 19 June 2009
        The CO2/Temperature correlation over the 20th Century
        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).
129471. canbanjo at 06:56 AM on 19 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
        Response: Can you clarify where you see the 40 year lag periods? Usoskin 2005 has the correlation peaking at a 10 year lag:
        
        
129472. chris at 03:08 AM on 19 June 2009
        The correlation between CO2 and temperature
        re #19 Unsupported assertions on dodgy web sites are rarely helpful HS and you've again dumped several on this thread. The author of the web page you linked to is hugely misinformed about several things, including this in reference to the lifetime of enhanced atmospheric CO2 levels:

        "Instantly on a climatological scale would be a few years or decades at most. It would depend on the half-life of CO2 in the atmosphere, which is a disputed topic. Many processes, including photosynthesis and dissolution into bodies of water, act to reduce CO2."

        However the evidence is pretty clear on the expectation that greatly raised atmospheric CO2 levels remain raised by a very long time indeed (100’s to 1000’s of years, with a long tail lasting 10’s of 1000’s of years and more). Some of the evidence for this is given below. It’s worth pointing out that the odd notion that “photosynthesis” will “act to reduce CO2” is a meaningless statement, especially without consideration of timescales and mechanisms. In the real world photosynthesis has very little effect on nett atmospheric CO2 levels since draw down of atmospheric CO2 by photosynthesis is largely balanced by oxidative organic decay and the return of CO2 to the atmosphere. There is only so much scope for enhanced nett primary production of flora (and the sequestration of CO2 by plant fossilation only occurs on the hundreds of thousands to million years timescale). Unfortunately the situation is worsened in our current world with rainforest degradation and the expectation that primary production (nett plant growth) will decrease in a warming world. Some of these points are discussed here http://www.skepticalscience.com/Is-Antarctic-ice-melting-or-growing.html (see posts #13/14). Likewise the rate at which oceans sequester enhanced levels of atmospheric CO2 is slow (100’s of years timescale) [1]. Additionally the ability of the oceans to absorb is reduced as enhanced atmospheric CO2 “drives” CO2 into the oceans, and already the evidence indicates that the expected tendency for the upper oceans to saturate with respect to CO2 uptake is already occurring [2,3]. A review of some of the evidence that informs our understanding of the lifetime of enhanced atmospheric CO2 was published late last year [1], and indicates that sequestering of CO2 occurs on multiple timescales, the most rapid of which (ocean uptake) takes many hundreds of years, with very long tails of recovery lasting 1000’s and 10’s of 1000’s of years. This is consistent with evidence from analysis of carbonates in sediments that are used to determine CO2 levels in the deep past, that indicate that the massive increases in atmospheric CO2 associated with extinctions at the Triassic-Jurassic boundary [4,6] or the Paleo-Eocene Thermal Maximum [5,6] (for example) take many 10’s of 1000’s of years to return to pre-extinction event levels. I haven’t spent very much time looking up this stuff, and no doubt one could come up with more and better examples of the evidence that informs our understanding of the lifetimes of greatly enhanced CO2 levels. [1] Archer D and Brovkin V (2008) The millennial atmospheric lifetime of anthropogenic CO2 Climatic Change 90, 283-297 Abstract: The notion is pervasive in the climate science community and in the public at large that the climate impacts of fossil fuel CO2 release will only persist for a few centuries. This conclusion has no basis in theory or models of the atmosphere/ocean carbon cycle, which we review here. The largest fraction of the CO2 recovery will take place on time scales of centuries, as CO2 invades the ocean, but a significant fraction of the fossil fuel CO2, ranging in published models in the literature from 20-60%, remains airborne for a thousand years or longer. Ultimate recovery takes place on time scales of hundreds of thousands of years, a geologic longevity typically associated in public perceptions with nuclear waste. The glacial/interglacial climate cycles demonstrate that ice sheets and sea level respond dramatically to millennial-timescale changes in climate forcing. There are also potential positive feedbacks in the carbon cycle, including methane hydrates in the ocean, and peat frozen in permafrost, that are most sensitive to the long tail of the fossil fuel CO2 in the atmosphere. [2] Le Quere C et al (2007) "Saturation of the Southern Ocean CO2 sink due to recent climate change" Science 316, 1735-1738. [3] Schuster U et al (2007) “A variable and decreasing sink for atmospheric CO2 in the North Atlantic” J. Geophys. Res. Oceans 112, art # C11006 [4] B. van de Schootbrugge et al (2008) Carbon cycle perturbation and stabilization in the wake of the Triassic-Jurassic boundary mass-extinction event Geochem. Geophys. Geosys. 9 Q04028 [5] G. R. Dickens et al. (1997) A blast of gas in the latest Paleocene: Simulating first-order effects of massive dissociation of oceanic methane hydrate Geology 25, 259-262. [6] A. S. Cohen et al. (2007) The Late Palaeocene–Early Eocene and Toarcian (Early Jurassic) carbon isotope excursions: a comparison of their time scales, associated environmental changes, causes and consequences J. Geological Soc.164, 1093-1108
129473. Alexandre at 00:24 AM on 19 June 2009
        The CO2/Temperature correlation over the 20th Century
        Great post, John. You´re website is a great source to finding AGW-related scientific references.
129474. Stig Mikalsen at 19:52 PM on 18 June 2009
        The CO2/Temperature correlation over the 20th Century
        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.
129475. thingadonta at 17:59 PM on 18 June 2009
        The CO2/Temperature correlation over the 20th Century
        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
        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.
129476. thingadonta at 10:17 AM on 18 June 2009
        This just in - the sun affects climate
        You haven't addressed lag-time effects with your sun-temperature disconnect theory from about 1980. 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 2002. 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 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 2002. 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.
        Response: The issue of climate time lag is addressed in the post coincidentally titled Climate Time Lag.
129477. HealthySkeptic at 12:43 PM on 17 June 2009
        The correlation between CO2 and temperature
        re #16 >> I assume that when he says that if we stop emitting CO2 the level would "instantly return to pre-industrial levels." it is just a typo and was not what he intended to say. John, I queried the author personally on this and this is his response'- "Instantly on a climatological scale would be a few years or decades at most. It would depend on the half-life of CO2 in the atmosphere, which is a disputed topic. Many processes, including photosynthesis and dissolution into bodies of water, act to reduce CO2." HS.
129478. HealthySkeptic at 14:28 PM on 16 June 2009
        The correlation between CO2 and temperature
        re #16 John, With regard to saturation of the CO2 bands, do we know what percentage of energy, in the wavelengths that CO2 can absorb, is already being absorbed? I have seen figures as high as 99%. Some have even quoted that satellites equipped with infrared spectrometers have confirmed that there is already little or no infrared energy from the earth's surface escaping the earth's atmosphere in the CO2 absorption bands. Do any of these claims have any substance? If not, do we know at what atmospheric CO2 concentration the CO2 bands WILL become completely saturated? Regards, HS.
129479. Andrew K at 11:14 AM on 15 June 2009
        The correlation between CO2 and temperature
        John Cross -- I suppose my point is purely emperical. The current non-warming is explained away as the result of recent weather noise masking the long term warming trend, but a statistical test using for example the d* method of Santer (which using data up to the end of 2007 proved the above explaination) now shows that the lack or warming is more than expected from known (ie previously observed) weather noise. To counter this statistical failure it has been pointed out that there have been decade or so long non-warming (or even cooling) periods within the long term warming trend as shown in Figure 2 above, but previous non-warming (or cooling) periods have followed large volcanoes whilst the current period doesn't. In summary the current period cannot be explained away either as statistical noise or as a simple occurance of known natural events that will soon reverse. So what is causing the non-warming when 'all the consesus science' says there should be (note: some are now claiming it is the sun although a few years ago we were told that solar changes and effects were all known and included in the models)? Either the measurements are wrong or there is a problem with 'the consesus science'
129480. gruntled at 13:58 PM on 14 June 2009
        CO2 measurements are suspect
        I was looking for some information on the reliability of ice cores. A common argument I'm hearing lately is that chemical effect in ice cores breaks down CO2, making them unreliable proxies.
129481. Patrick 027 at 11:21 AM on 11 June 2009
        Arctic sea ice melt - natural or man-made?
        "This is why this is a political hot potato and needs to be approached with unassailable science that everyone can accept, and they can not do that. " There is no such thing - unassailable science that everyone can accept. In recent weeks I've witnessed a case of a person who cannot accept simple arithmetic. We need good science. We already have a lot. We shouldn't stop trying to get more, but we needn't wait to use what we have in appropriate ways. However good the science is, there will be people who cannot accept it. I don't really care anymore what they think - I hope those of us living in reality are a strong enough majority, and those who stubbornly bury their heads in the sand while feigning self-righteous protest - they will just have to live with the decisions the rest of us make. Should I be so optimistic as to expect a room of adults to agree that the sun is a star?
129482. John Cross at 22:39 PM on 10 June 2009
        The correlation between CO2 and temperature
        HealthySkeptic: Thanks for the link. I will note that the article (I don't believe it is a paper) is interesting but misses a couple of important points. As simple physics shows, even if the CO2 bands were totally saturated, adding more would still cause an increase in temperature. In addition, when the author calculates his projection he assumes that all warming takes place instantaneously. This is of course not true - warming takes place over numerous time scales. I assume that when he says that if we stop emitting CO2 the level would "instantly return to pre-industrial levels." it is just a typo and was not what he intended to say. So, by all means read it, but as with everything, read it with a skeptic's eye. Regards, John
129483. Gord at 16:47 PM on 10 June 2009
        It's the sun
        Patrick - Re: your Post #511 You remind me of "Baghdad Ali". Although, your logic may be just a tad inferior to his. Don't understand?...It's OK....everybody else will.
129484. HealthySkeptic at 14:06 PM on 10 June 2009
        The correlation between CO2 and temperature
        JWC, This paper may answer some of your questions regarding the relative effect of increasing CO2 concentrations on global temperatures. http://brneurosci.org/co2.html
129485. HealthySkeptic at 12:34 PM on 10 June 2009
        The correlation between CO2 and temperature
        Now, if we can just get that sunscreen up into the upper atmosphere....
129486. Patrick 027 at 04:35 AM on 10 June 2009
        It's the sun
        sure, Gord, and why is anybody talking about the graviational pull of the moon and sun when the tides can be so easily explained by waves and currents? Your posts are UTTERLY STUPID. But I hope most people reading this do not need me to point it out.
129487. Craig Allen at 03:40 AM on 10 June 2009
        The correlation between CO2 and temperature
        JWC: This analogy may help - The mass of the sunscreen that you need to smeer on your arm to stop almost all the UV light getting through is tiny compared to the mass of the atmosphere sitting above you which failed to stop it (there are about ten metric tons of atmosphere per square meter of surface I think). A trace amount of a substance can have a big effect if that substance is very effective at what it does. The amount of cyanide that it would take to kill you vs. the total volume of air that you breath is another example.
129488. John Cross at 00:14 AM on 10 June 2009
        The correlation between CO2 and temperature
        JWC: just because something is trace does not mean that it has a small effect. The lethal dose of botulism is about 5 parts per billion. Now, if you are asking about the actual physics of the interaction of longwave radiation with the CO2 molecule, that is a different question - but one I am sure we could look at if you wish. Regards, John
129489. JWC at 22:06 PM on 9 June 2009
        The correlation between CO2 and temperature
        If CO2 is such a trace gas, currently 380 PPM of the atmosphere, someone needs to tell me, an inquiring layperson, how an incremental increase in that amount can possibly have much affect on temperature increase. It doesn't make much sense, to me, and, though I've asked numerous times elsewhere, no one seems to be able to explain it to me. I was referred to this website by someone I was disagreeing with about AGW. A site to debunk the debunkers? Those skeptics must certainly be gaining some ground. Many AGW "alarmists" seem to think "the debate is over." Seems to me, it would be very hard to do further unbiased research if that's the attitude taken by these (I believe misguided) followers of King Albert of Gore. Sorry; I just call it like I see it.
129490. Gord at 21:24 PM on 9 June 2009
        It's the sun
        The STUPIDITY of AGW. ---- Trenberth's Energy Budget Incoming Solar Radiation = 342 w/m^2 Solar Radiation Absorbed by atmosphere = 67 w/m^2 ------------------- (342 - 67) Leaves 275 w/m^2 available. Reflected by Clouds etc. = 77 w/m^2 Reflected by Surface = 30 w/m^2 Total due to reflection = 107 w/m^2 The percentage of reflected energy is 107/275 = 0.389 or 38.9%. Leaves 168 w/m^2 absorbed by the Surface of the Earth. 168 w/m^2 and an emissivity of 1, gives a temperature of 233.31K or -39.69 deg C. -------------------- Now what happens if the reflected energy was decreased by 1% to 37.9%? 0.379 X 275 = 104.23 w/m^2 so an additional (107 - 104.23 = 2.77 w/m^2) is available to heat the Earth. 168 + 2.77 = 170.77 w/m^2 is now absorbed by the Surface of the Earth. 170.77 w/m^2 and an emissivity of 1, gives a temperature of 234.26K or -38.74 deg C. -------------- The Earth just warmed by (39.69 - 38.74) 0.95 deg C !! That's just due to a ONE PERCENT change in reflected energy!! ----------------- Why the Hell is anybody talking about CO2, positive feed-back loops, carbon taxes etc. to explain something so easily explained? Especially since the AGW'ers admit that their "computer models" can't and don't handle CLOUDS well and the SUN is the ONLY ENERGY SOURCE! ----------------- AGW is UTTER STUPIDITY no matter how you look at it!
129491. HealthySkeptic at 14:09 PM on 9 June 2009
        This just in - the sun affects climate
        Then, there's this... New Paper Demonstrates Anthropogenic Contribution to Global Warming Overestimated, Solar Contribution Underestimated A new paper has been published in GRL by Scafetta and Willson entitled: ‘ACRIM-gap and TSI trend issue resolved using a surface magnetic flux TSI proxy model’ The Abstract states: “The ACRIM-gap (1989.5-1991.75) continuity dilemma for satellite TSI observations is resolved by bridging the satellite TSI monitoring gap between ACRIM1 and ACRIM2 results with TSI derived from Krivova et al.’s (2007) proxy model based on variations of the surface distribution of solar magnetic flux. ‘Mixed’ versions of ACRIM and PMOD TSI composites are constructed with their composites’ original values except for the ACRIM gap, where Krivova modeled TSI is used to connect ACRIM1 and ACRIM2 results. Both ‘mixed’ composites demonstrate a significant TSI increase of 0.033%/decade between the solar activity minima of 1986 and 1996, comparable to the 0.037% found in the ACRIM composite. The finding supports the contention of Willson (1997) that the ERBS/ERBE results are flawed by uncorrected degradation during the ACRIM gap and refutes the Nimbus7/ERB ACRIM gap adjustment Fröhlich and Lean (1998) employed in constructing the PMOD.” The authors state in their conclusions that: “This finding has evident repercussions for climate change and solar physics. Increasing TSI between 1980 and 2000 could have contributed significantly to global warming during the last three decades [Scafetta and West, 2007, 2008]. Current climate models [Intergovernmental Panel on Climate Change, 2007] have assumed that the TSI did not vary significantly during the last 30 years and have therefore underestimated the solar contribution and overestimated the anthropogenic contribution to global warming.” Scafetta N., R. C. Willson (2009), ACRIM-gap and TSI trend issue resolved using a surface magnetic flux TSI proxy model, Geophys. Res. Lett., 36, L05701, doi:10.1029/2008GL036307.
        Response:

        The ACRIM vs PMOD debate is a question over which composite of satellite TSI data is more accurate. ACRIM shows a slight warming trend. PMOD shows a slight cooling trend. Even using the ACRIM data, the warming trend is so slight, it is insufficient to explain the steep warming over the past 35 years. However, various independent measurements of solar activity all show closer agreement to the PMOD reconstruction which indicates the sun has been showing a cooling trend over the last few decades. This is explained in detail at Determining the long term solar trend.
        
        UPDATE: I read the Scafetta paper which claims the ACRIM data (which shows slight warming) is more accurate than the PMOD data (slight cooling) because it shows closer agreement with the TSI reconstruction by Krivova and Solanki. I found this curious as Krivova 2007 itself compares its results to PMOD and finds close agreement. So I contacted Sami Solanki, one of the authors of the Krivova model. He replied (very promptly, a very approachable scientist) that they had actually written a paper responding to Scafetta's claims that is currently awaiting publication. I will keep everyone posted when the paper is published.
        
        Incidentally, Krivova's TSI reconstruction is the data I use in Figure 1 above.

        UPDATE 2 Nov 2009: The response from Solanki and Krivova has been published. I summarise it's findings in ACRIM vs PMOD, the rematch.

129492. Patrick 027 at 10:10 AM on 9 June 2009
        It's the sun
        "I think that type of reflecting surface has inverted square pyramids" ... Oh, maybe that's just bicycle reflectors - but you get the idea. -------------- And now the moment very few people have been waiting for: What is the spectral (monochromatic) Ibb? For N = 1: Where the blackbody flux per unit area = π*Ibb = sigma * T^4 where sigma (also known as BC above) =2 * π^5 * k^4 /(15 * c^2 * h^3) and Where c, h, and k, and sigma are: (Where there are two values, the second value is from a physics textbook (or calculated from physics textbook values), and the first value is from Wikipedia ( http://en.wikipedia.org/wiki/Boltzmann's_constant , http://en.wikipedia.org/wiki/Avogadro_constant , http://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_constant ): c = 2.99792458 E+8 m/s h = 6.62606896 E-34 J*s h = 6.626075 E-34 J*s k = 1.3806504 E-23 J/K k = 1.380658 E-23 J/K sigma = 5.670400 E-8 W/(m2 K4) sigma = 5.670511 E-8 W/(m2 K4) Ibb(T,L) = |d[Ibb(T)]/dL| = ( 2*h*c^2 / L^5 ) / ( exp[h*c/(L*k*T)] - 1 ) Ibb(T,v) = |d[Ibb(T)]/dv| = ( 2*h*v^3 / c^2 ) / ( exp[h*v/(k*T)] - 1 ) where: c = L * v v = c/L |dv| = c / L^2 * |dL| L is the wavelength in a vacuum, v is the frequency. The L of maximum Ibb(T,L) is equal to (2897 microns/K )/ T (Wien's displacement law, from class notes but can be found elsewhere.) The L of maximum Ibb(T,L) is 10 microns at T = 289.7 K.
129493. Patrick 027 at 10:10 AM on 9 June 2009
        It's the sun
        "I think that type of reflecting surface has inverted square pyramids" ... Oh, maybe that's just bicycle reflectors - but you get the idea. -------------- And now the moment very few people have been waiting for: What is the spectral (monochromatic) Ibb? For N = 1: Where the blackbody flux per unit area = π*Ibb = sigma * T^4 where sigma (also known as BC above) =2 * π^5 * k^4 /(15 * c^2 * h^3) and Where c, h, and k, and sigma are: (Where there are two values, the second value is from a physics textbook (or calculated from physics textbook values), and the first value is from Wikipedia ( http://en.wikipedia.org/wiki/Boltzmann's_constant , http://en.wikipedia.org/wiki/Avogadro_constant , http://en.wikipedia.org/wiki/Stefan%E2%80%93Boltzmann_constant ): c = 2.99792458 E+8 m/s h = 6.62606896 E-34 J*s h = 6.626075 E-34 J*s k = 1.3806504 E-23 J/K k = 1.380658 E-23 J/K sigma = 5.670400 E-8 W/(m2 K4) sigma = 5.670511 E-8 W/(m2 K4) Ibb(T,L) = |d[Ibb(T)]/dL| = ( 2*h*c^2 / L^5 ) / ( exp[h*c/(L*k*T)] - 1 ) Ibb(T,v) = |d[Ibb(T)]/dv| = ( 2*h*v^3 / c^2 ) / ( exp[h*v/(k*T)] - 1 ) where: c = L * v v = c/L |dv| = c / L^2 * |dL| L is the wavelength in a vacuum, v is the frequency. The L of maximum Ibb(T,L) is equal to (2897 microns/K )/ T (Wien's displacement law, from class notes but can be found elsewhere.) The L of maximum Ibb(T,L) is 10 microns at T = 289.7 K.
129494. Patrick 027 at 04:42 AM on 9 June 2009
        It's the sun
        LW radiation: "If this is specular reflection (As might be expected for relatively calm water), then, except in an inversion with sufficient opacity, the reflected radiation will be absorbed over a shorter distance in the air" ... as opposed to Lambertian reflection.
129495. Patrick 027 at 04:41 AM on 9 June 2009
        It's the sun
        "I have actually noticed in lawn grass in sunny conditions that the grass appears brighter just around the shadow of my head - this means that there is a concentration of reflected radiation going back near the direction from which it came - similar to the reflecting surfaces used for traffic signs. I noticed a similar phenomenon in gravel." But the process that produces this effect is different for the traffic signs (and the effect itself will probably be a little different). I think that type of reflecting surface has inverted square pyramids, where each flat triangular surface is at a 45 deg angle to the plane of the larger surface, and each flat triangular surface has specular reflection. In contrast, what may be happening with the grass and the gravel is that the individual surfaces have nearly Lambertian reflection - they will look at bright from any direction - but the surfaces themselves are angled differently and thus have more or less sunlight per unit area to reflect. When looking toward the shadow of one's own head, one would see more of the surfaces that are nearly normal to the direct solar rays. ---- Sometimes the brightest and deepest colors can be seen when looking at the diffuse transmission through leaves and petals. Highly recommended viewing.
129496. Patrick 027 at 04:27 AM on 9 June 2009
        It's the sun
        Additional notes and observations of scattering of solar radiation: When there is a hole through which direct solar rays pass, scattering along the path of the beam allows the beam to glow with scattered radiation - it can be seen from outside itself. This can be observed in a dusty room with sunlight coming through a window. A shadow cast through the air can also be seen from outside itself by the same mechanism. Variations in direct solar ray intensity can be seen to the extent that they have optical thickness along the line of sight and there is not too much optical thickness along the line of sight between the viewer and variation being observed. These variations are called crepescular rays and can be seen when the direct sun is blocked by a layer of clouds with holes, or there are patches of clouds casting shadows, or when the sun is behind a cloud with an irregular edge. One particularly interesting case is the shadow cast be a long thin straight contrail (the cloud left by a jet when conditions allow). Such a contrail casts a shadow that is a thin planar slice through the air; along lines of sight nearly parallel to this shadow, a dark streak can be seen through the sky; it will be darkest to viewers within the shadow. But the shadow will not be observed along lines of sight in most other directions because the shadow is thin in those directions. Clear air atmospheric scattering is generally stronger for shorter wavelengths. This is of course why the midday clear sky is generally blue (it can be white near the horizon - possible contributors to that: less blue light reaches to air near the surface, while there is nonzero scattering of other wavelengths, and lines of sight near the horizon pass through a greater thickness of lower-level air as well as the total atmosphere; some aerosols with different scattering properties may also be abundant in the lowest level air). White objects near the horizon may appear slightly red because blue light is scattered out of the line of sight. However, some blue light is scattered into the line of sight from an overhead sun and/or overhead thin clouds. Thick clouds overhead can reduce this effect, so that distant clouds lit by the sun will appear more red. Of course, the extinction of blue light and the nonzero scattering of other wavelengths explain the colors of sunset and sunrise. The overhead clear sky still appears blue, and the sky near the horizon can appear blue after sunset and before sunrise - this is because of the curvature of the Earth; the solid/liquid Earth casts a shadow on it's own atmosphere, but the edge of the shadow is at some finite height within the atmosphere at dawn and dusk, and when reaching the Earth nearly horizontally, sunlight travels through a smaller mass of air when it goes by higher above the ground, so there is plenty of blue light to scatter. --------- Specular reflection (as in a mirror) can be observed for some smooth surfaces, such as calm water. Wavy water still has locally specular reflection but images will break up and be distorted. Diffuse reflection takes an incident beam of light and reflects it over a range of directions. It is a form of scattering. Lambertian reflection is diffuse reflection in which the reflected radiation is isotropic. Reflected radiation can be a mix of Lambertian and specular or nearly specular (images would appear fuzzy), or more complex. I have actually noticed in lawn grass in sunny conditions that the grass appears brighter just around the shadow of my head - this means that there is a concentration of reflected radiation going back near the direction from which it came - similar to the reflecting surfaces used for traffic signs. I noticed a similar phenomenon in gravel. Have you ever noticed crepescular rays when looking down into murky water? When the surface has a high albedo, the sky can appear brighter than otherwise because it can scatter back to the surface some of the radiation reflected from the surface. I have seen a picture of a blue light on the base of clouds over a patch of shallower water (which appears bright blue because there is less absorption of sunlight through the thinner water layer and there is reflection from the underlying surface) - perhaps an atoll. (Clear) water is generally blue because, while nearly transparent (to visible wavelengths) in thin layers, it does absorb light, and more strongly at longer visible wavelengths than for blue light. Of course, looking near the horizon, one sees less into the water and more the reflection of the sky off the water. When there are waves, one can see into the water best on the side of the wave closest to normal to the line of sight, while mainly a reflection of the sky will be seen from the other side of the wave or where the line of sight just grazes the water surface. PS for LW radiation: Then nonzero LW albedo of the surface: If this is specular reflection (As might be expected for relatively calm water), then, except in an inversion with sufficient opacity, the reflected radiation will be absorbed over a shorter distance in the air because a greater portion of it will come from angles near the horizon where the LW glow fo the air will (except for a low level inversion with sufficient opacity) generally appear brightest near the horizon.
129497. Patrick 027 at 03:46 AM on 9 June 2009
        It's the sun
        A condition where the phase of the wave could matter (?) is when there is significant nonlinearity - In nonlinear optics, passage of very high amplitude electromagnetic waves through a medium can alter the optical properties of the medium, allowing photon-photon interaction. When evaluting I# at specific values of P, the P at one location is not necessarily the same P everywhere, and when finding the emission distribution, there could be multiple P values at the same location corresponding to different paths that photons took between locations and the different changes to P along the way. P is obviously relative to the orientation of processes that depend on P. ---------- For radiative energy transfer in the atmosphere, there are some useful approximations (for at least Earthly conditions): 1. Assume local thermodynamic equilibrium, at least below some height level (that is at least above the tropopause). Ignore non-thermal emission. Assume emission cross section = absorption cross section. 2. For wavelengths shorter than about 4 microns (SW radiation), assume the only emission is from the sun. 3. For wavelengths longer than about 4 microns (LW radiation), assume there is no solar contribution (a bit less accurate than assumption 2, but still a good approximation). 4. Aside from absorption and emission, assume N = 1 within the atmosphere on a macroscopic scale (larger than scattering mechanism scales), and ignore gravitational lensing, so that radiation propagates in straight lines within the atmosphere and space, except for scattering and reflection. 5. Also ignore gravitational redshift, and the blueshifting and redshifting of solar energy at sunrise and sunset, etc. 6. Below some level that is above the vast majority of atmospheric emission and absorption at most wavelengths, ignore the curvature of the Earth and atmosphere, so that radiation propagating in straight lines is assumed to have a constant angle relative to the local vertical, and the total horizontal area around the globe at any height can be assumed constant over vertical distance. 7. Except at the land and ocean surface, assume zero scattering and zero reflection for LW radiation within the atmsophere. (Note that even when there is some significant single-scatter albedo, the multiple scatterings required (when that is the case) for radiation to scatter back from, for example, a cloud, can result in very low albedo due to absorption between each scattering.) 8. For some purposes, scattering and reflection at the surface can also be neglected for LW radiation.
129498. Patrick 027 at 03:17 AM on 9 June 2009
        It's the sun
        In so far as the differential equation following a path locally in the direction x over distance dx, for I# in the direction x: At specific v and P, per unit spectrum and polarization dv and dP (P could have more than one dimension, actually): d(I#) = IL#(G) * Lcsv * dx + Ibb#(T) * ecsv * dx - I# * (acsv+scsv) * dx + Is# * scsv * dx - I# * R + Ir# * R The terms on the right hand side (if this were written out in one line) 1. non-thermal emission into the path (such as fluorescence), where Lcsv is a cross section density for that process and IL#(G) is a function of the the energy available for such a process and the nature of such a process. 2. thermal emission into the path, where ecsv is the emission cross section density and Ibb#(T) is the blackbody intensity. 3. absorption and scattering out of the path, where acsv and scsv are the absorption and scattering cross section densities, which sum to give the extinction cross section density. acsv = ecsv at local thermodynamic equilibrium (it could be possible to define them as equal even when not at local thermodynamic equilibrium since a non-thermal emission term is also included). 4. scattering into the path, where scsv is the same scattering cross section density, but Is# depends on I# in all directions at that location (including backwards along the same path) and the type of scattering. 5. specular reflection out of the path, where R is the reflectivity of any interface encountered within dx. 6. specular reflection into the path, where Ir# depends on the I# going backward along the path taken by reflection out of the path. Inclusion of reflection at a discontinous interface (relative to the scale of the wavelength) in the differential equation works so long as dx is small enough that the other terms are very small.
129499. NewYorkJ at 01:46 AM on 9 June 2009
        This just in - the sun affects climate
        Contrarians have a tendency to not only recylce old arguments, but in this case to recycle old arguments and then distort them to support a political agenda. This is related to the same strawman that claims climate scientists think only CO2 affects climate. In NASA's 2007 temperature summary, Hansen notes: "This cyclic solar variability yields a climate forcing change of about 0.3 W/m2 between solar maxima and solar minima. (Although solar irradiance of an area perpendicular to the solar beam is about 1366 W/m2, the absorption of solar energy averaged over day and night and the Earth's surface is about 240 W/m2.) Several analyses have extracted empirical global temperature variations of amplitude about 0.1°C associated with the 10-11 year solar cycle, a magnitude consistent with climate model simulations, but this signal is difficult to disentangle from other causes of global temperature change, including unforced chaotic fluctuations. " http://data.giss.nasa.gov/gistemp/2007/
129500. Dan Pangburn at 01:29 AM on 9 June 2009
        Models are unreliable
        Climate Scientists have adopted the word 'feedback' but apply it completely differently from the way engineers had already successfully used it for decades. Correct use of 'feedback' combined with paleo temperature data proves that added atmospheric carbon dioxide has no significant effect on average global temperature. Any activity to curtail the atmospheric carbon dioxide level puts freedom and prosperity at risk.

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