Arguments
Recent Comments
Prev 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 Next
Comments 129201 to 129250:
-
chris at 09:27 AM on 21 July 2009Climate time lag
"Phenomena do not typically have long-term with one another when there is not some causal connection" But we've already seen that this simply isn't true for the very phenomenon we've been discussing. A large set of analyses described in my post #71 indicates that any correlation between CRF and climate-related influences (low level clouds) is NOT causal, and is an artefact of the correlation of the CRF with the solar cycle, components of which DO correlate with the effect. That could hardly be plainer. We don't choose the "simplest theory possible" if the theory is incompatible with the evidence. We know that the CRF generally varies in line with solar outputs (whether or not there is a strict linear relationship) and in very many studies is used as a proxy for solar output variation. We can hardly assert that changes in solar irradiance are insufficient to account for the phenomenon observed if we don't (a) have a measure of the solar irradiance contemporaneous with the phenomenon of interest and (b) have a good handle on the magnitude of solar irradiance required to influence the phenomenon. I don't see any point in introducing "catch all fill-in-the-blanks type mechanisms" as pseudo-explanations (CRF) when the evidence doesn't support these. What we do have is abundant evidence that ocean/atmosphere circulation changes are associated with much of the variation in high Northern latitude climate variation through the Holocene. We can accept that (heat transfer variations) as a fundamental proximate cause of temperature proxies observed since the evidence is very strong. We don't have to postulate global scale phenomena since the evidence doesn't support this. We don't understand the ultimate causes of the circulation changes very well- these do seem to have a solar component for Bond cycles observed in the Northern latitudes. The evidence indicates that this isn't due to the CRF component of the solar influence. Where we do have some evidence (MWP/LIA) this is likely solar irradiance/volcanic sea surface temperature influences (see Trouet et al, 2009 cited above, for example). I'm happy to leave it there until evidence accrues that allows us to make more detailed causal interpretations of Holocene N. hemisphere climate variability. I have no problem with accepting uncertainty where this exists - what we certainly don't do is to introduce Kirkby-style "catch all fill-in-the-blanks type mechanisms" to "fill in" uncertainty, particularly when the causality associated with the mechanism is increasingly found to be suspect. -
shawnhet at 08:50 AM on 21 July 2009Climate time lag
Chris: "That's a self-contradictory assertion. It contradicts the essential basis of scientific understanding namely . We've already seen that there is abundant evidence for THC contributions (Lund et al, 2006; Denton and Broecker, 2008; Trouet et al, 2009; see Thornalley et al 2009 below) to the events we've been discussing; we could cite much more of this. You reject it without giving any evidence." My point is that saying that THC changes are responsible for something when we don't know what causes the THC to change is simply begging the question. I think THC is a symptom of climate "fundamentals", not properly the cause of them. For you to simply accept that the THC causes climate change without understanding what causes the THC is not "supporting fundamental interpretations". ""I don't know enough about the Bond effects to consider causality in detail, but I'd be very interested to see what scientific analysis informs your views on this. In the meantime, I'm prepared to accept Bond's interpretation of solar forcing with some potenial THC amplification. Since we don't know the magnitude of solar irradiance contemporaneous with these events we can hardly assert that this was not sufficient to mediate these phenomena. Your either this/either that binary choice is non-scientific, since it pre-selects for interpretations that are not necessarily consistent with the evidence. For example, it's quite possible that the Bond events report changes in heat transport through variations in thermohaline circulation that predominantly affect the high Northern latitudes. That's consistent with much of the science I've already cited (including Bond et al 2001) as well as additional recent evidence for Holocene oscillations in North Atlantic heat and salinity driven by variations in the THC [*], and observations that the events observed in the High Northern latitudes (Bond events, MWP; LIA) generally don't have deep Southern Hemisphere correlates [**] " First off, if THC is the result of an amplification of some sort then THC-forcing is simply an indirect solar forcing. Secondly, the large climate events correlate to CRF, so if the magnitude of CRF doesn't correlate with the magnitude of irradiance, then that is good evidence that CRF *on its own* has climate impact. You call this either-or science, I call it simple logic. Phenomena do not typically have long-term with one another when there is not some causal connection. I think it is always preferable to have the simplest theory possible. Cheers, :) -
chris at 08:26 AM on 21 July 2009Climate time lag
whoops, I left out a word: My first two sentences should read: That's a self-contradictory assertion. It contradicts the essential basis of scientific understanding evidence. -
chris at 08:22 AM on 21 July 2009Climate time lag
"I don't really want to get into the reasons why THC based explanations aren't very good IMO. That is a whole other line of argument. I don't really have a fundamental problem with them as *response* to long-term solar heating, I suppose. It is simply with them as a catch all fill-in-the-blanks type mechanism, I object to." That's a self-contradictory assertion. It contradicts the essential basis of scientific understanding namely -
shawnhet at 06:05 AM on 21 July 2009Climate time lag
What Bond et al. are rather clear on is the correlation btw solar events and climate ones and the magnitudes thereof. They don't mention CRF, of course, (and I never said they did), but they do say such things as "Our correlations are evidence, therefore, that over the last 12,000 years virtually every centennial time scale increase in drift ice documented in our North Atlantic records was tied to a distinct interval of variable and, overall, reduced solar output." They provide various possible amplifiers for solar input, because solar input alone doesn't work. Obviously, CRF climate interactions are one possible solar amplifier. "Think about it. Your assertion requires that you know the magnitiude of the irradiance changes contemporaneous with the events. We've been talking about contributions from irradiance changes (0.2 oC's worth) during a period where there's a reliable reconstruction (Lean et al back to the Maunder Minimum). Do you know what the irradiance values were further back in the Holocene? I don't think so…" There are two options here. Either the magnitude of solar irradiance has a (more or less) constant relationship to the level of CRF fluctuations or it does not. If the first case is true, then the pattern of climate fluctuations to the solar proxies implies that there is an amplifying agent, which is why Bond et al. proposes some. If, OTOH, the magnitude of solar changes is not constant wrt CRF changes then there is no reason why the correlations that Bond et al find should exist at all. IAC, perhaps we are making headway here - do you agree with Bond et al. that some sort of solar amplification is likely? I don't think we have enough evidence to tell what the nature of the solar amplification is, but we do IMO have enough to tell us that one does exist. I don't really want to get into the reasons why THC based explanations aren't very good IMO. That is a whole other line of argument. I don't really have a fundamental problem with them as *response* to long-term solar heating, I suppose. It is simply with them as a catch all fill-in-the-blanks type mechanism, I object to. Cheers, :) -
chris at 04:56 AM on 21 July 2009Climate time lag
I've read Bond et al shawnet. I was referring to some research published in the intervening period based on research that isn't nearly 10 years old. Your idea that research fields can be fully defined by recourse to single papers or dodgy reviews is not going to give you much insight into these difficult subjects! Note that you've mis-interpreted Bond et al who are rather consistent with the evidence from the pukka science that I've been discussing, and makes no mention of any CRF effects. In fact Bond et al interpret their data in terms of solar irradiance changes, amplified by thermohaline circulation effects:"Each of those episodes also corresponds to paired intervals of reduced solar irradiance and increases in North Atlantic ice drift in our records" and: "Results of recent atmospheric general circulation (GCM) modeling, however, have shown that a decrease of only ~0.1% in solar activity over the 11-year sunspot cycle could produce a change in surface climate through the atmosphere's dynamic response to changes in stratospheric ozone and temperature"
Whereas you consider the thermohaline circulation "pretty speculative" (even 'though I provided papers referring directly to evidence for this for the periods specified), Bond et al certainly don't consider it to be speculative:The Arctic-Nordic Seas thus may have been a key region where solar-induced atmospheric changes were amplified and transmitted globally through their impact on sea ice and North Atlantic thermohaline overturning. Reduced northward heat transport, moreover, could have further altered North Atlantic latitudinal temperature and hydrologic gradients, potentially enhancing the climate response in low-latitude climates [e.g., (39)].
This assertion of yours is illogical: "Do you know of a minor change that would cause a 2C change in the Atlantic ocean. Certainly, it couldn't be solar which can only change irradiance by about 0.2C or so". Think about it. Your assertion requires that you know the magnitiude of the irradiance changes contemporaneous with the events. We've been talking about contributions from irradiance changes (0.2 oC's worth) during a period where there's a reliable reconstruction (Lean et al back to the Maunder Minimum). Do you know what the irradiance values were further back in the Holocene? I don't think so… -
Thumb at 04:26 AM on 21 July 2009Climate time lag
#130 - "Now that the oceans T appear to be flattening and cooling since early 2000s " How many cubic miles of land ice are running into the oceans as ice-cold water in recent years? Has this number been increasing? Wouldn't this have some effect on ocean temps in the same way adding ice to your drink will cool your drink? -
shawnhet at 04:17 AM on 21 July 2009Climate time lag
Chris:"That's not to say that there isn't also a lot of evidence over very long periods for N. hemisphere – S. hemisphere "see-saw" with compensating temperature rises and falls, or at least hemispherically-dominant phenomena. That's partly the theme of the Denton/Broecker paper in my post #116. For example the Dansgaard-Oeschger events that indicate large periodic temperature fluctuations in the Greenland cores are barely represented in Antarctic cores, and these are also interpreted in terms of exactly the same ocean/atmosphere heat transfer varaibility that likely underlie much of the MWP/LIA temperature variation. It's just that the D/O events entailed far more dramatic heat transfer changes possibly involving complete shutdown and later on rapid resumption of the thermohaline circulation in the N Atlantic." The thermohaline explanation is pretty speculative frankly, but IAC, the point is that the see-saw doesn't operate symmetrically on both sides of the equator. The Northern side fluctuates much more than the Southern side(and the Southern side doesn't really go up, when the Northern side goes down). ""I'm not going to comment on Bond events (other than in relation to D/O events for which Bond events might be a Holocene-scale minor continuation). I don't know enough about these and haven't got time to do much hunting in the scientific literature (last Thurs to Sat I was ill at home and found lots of time to do this – as well as watching the Open, the Ashes and the Tour de France!). If you know of any scientific literature that provides a good account of these phenomena as well as a discussion of potential causality I'd be more than happy to read these…" Bond events aren't minor. Do you know of a minor change that would cause a 2C change in the Atlantic ocean. Certainly, it couldn't be solar which can only change irradiance by about 0.2C or so. In that context, the correlation btw such changes and CRF makes no sense. IAC, good luck with your search. Let me know what you find out when you have explored other avenues of evidence. Here is a pretty good place to start IMO - Bond, G.C., B. Kromer, J. Beer, R. Muscheler, M.N. Evans, W. Showers, S. Hoffmann, R. Lotti- Bond, I. Hajdas and G. Bonani, Persistent solar influence on North Atlantic climate during the Holocene, Science 294, 2130–2136 (2001). Cheers, :) -
chris at 02:52 AM on 21 July 2009Climate time lag
re #131 shawnet, we've already seen that there is some uncertainty in the analysis of temperature changes during the time of the MWP/LIA, in solar irradiance reconstruction and so on. So whether the solar irradiance contribution is 0.14 oC or 0.2 oC is pretty immaterial; either of these is entirely consistent with the scientific evidence and it's hair-splitting to suggest that one or other (0.06 oC over hundreds of years!) is more correct. The point is that the currently best evidence for solar irradiance changes indicates that they are significant, and these, plus our understanding of likely greenhouse gas contributions to temperature change over this period, plus the evidence for ocean/atmosphere circulation contributions (see my post #123), allows a pretty self-consistent interpretation of (N. hemisphere) temperature variation over the period we've been discussing. Sadly, Kirkby gives a completely false picture of the science on this subject since he resolutely pretends that there has been no role for CO2 changes in paleotemperature variation, and completely misrepresents current science on solar contributions (let alone the other contributions we've discussed). There isn't any evidence for a CRF contribution during these periods whereas Kirkby insinuates that it's almost entirely CRF driven. That's not to say that there wasn't a small CRF, or other non-irradiance contribution…there just isn't any evidence for it, nor is there a requirement for it in order to understand the phenomena. I don't understand your point about "variance in Northern-Southern hemisphere temperature changes". The point I'm making based on the analysis of the Trouet paper in my post #123 (and quite a wealth of other work this subject, none of which is referred to by Kirkby who seems reluctant to give his readers a reliable account of research on this subject)….is that changes in N. hemisphere temperatures during the MWP/LIA periods likely have contributions from variations in heat trasfer from the equator to the high Northern latitudes. That doesn't imply that the S.H. had "….a larger climate response in any period, than the Northern one did." Far from it. In fact we expect that the climate response to be significantly less in the S.H. during changes in heat transfer to the high Northern latitudes for exactly the reason you suggest – there is a lot more ocean in the S.H. Again that's consistent with the evidence that the MWP/LIA were largely N. hemisphere phenomena and were likely fairly insignificant in terms of global scale warming/cooling. That's not to say that there isn't also a lot of evidence over very long periods for N. hemisphere – S. hemisphere "see-saw" with compensating temperature rises and falls, or at least hemispherically-dominant phenomena. That's partly the theme of the Denton/Broecker paper in my post #116. For example the Dansgaard-Oeschger events that indicate large periodic temperature fluctuations in the Greenland cores are barely represented in Antarctic cores, and these are also interpreted in terms of exactly the same ocean/atmosphere heat transfer varaibility that likely underlie much of the MWP/LIA temperature variation. It's just that the D/O events entailed far more dramatic heat transfer changes possibly involving complete shutdown and later on rapid resumption of the thermohaline circulation in the N Atlantic. Not sure what you mean by "current climate changes". If you truly mean "current" (i.e. contemporary) then these have essentially zero evidence for a casual CRF connection (we've discussed this at great length here!). Notice that the ITCZ changes are understandable in terms of the ocean/atmosphere heat transfer changes of the sort that Trouet et al provide additional strong evidence for (my post #123). As they suggest the trigger for these may be ocean surface heat changes arising from solar irradiance and volcanic forcing. It's unnecessary to attempt to sneak in spurious CRF contributions when these have been shown likely to be insignificant. Kirkby's own analysis indicates that these can't have made significant contributions to the MWP phenomenon, and they're certainly not required for the LIA as we've discussed. I'm not going to comment on Bond events (other than in relation to D/O events for which Bond events might be a Holocene-scale minor continuation). I don't know enough about these and haven't got time to do much hunting in the scientific literature (last Thurs to Sat I was ill at home and found lots of time to do this – as well as watching the Open, the Ashes and the Tour de France!). If you know of any scientific literature that provides a good account of these phenomena as well as a discussion of potential causality I'd be more than happy to read these….. -
shawnhet at 01:48 AM on 21 July 2009Climate time lag
Chris; "[FOUR] Note that the ~ 1 W/m^2 of Wang et al. (2005) is a general interpretation from two analyses using slightly different models that Wang et al made. One analysis gives a TSI cycle-averaged TSI change at the Maunder Minimum of 1.0 W/m^2; the other (containing a secular varying ephemeral region background) gives a change of 1.4 W/m^2. 1.4 W/m^2 gives almost exactly 0.2 oC temperature contribution to reduced surface temperature at the Maunder Minimum from irradiance variation using our parameters." So, IOW, if you take the highest value for TSI variation in the last few hundred years, you can account for the solar induced temperature change. However, if your reconstruction is on the high side, there will still be room for a solar amplification of some sort. Further, none of this really explains the close long term correlations btw precipitation and cosmic rays(as, for instance, with changes in the ITCZ and there relationship to Bond events). If cosmic rays had no effect on cloudiness, you would not expect this correlation to be present(and Bond events are much larger in magnitude than can be produced by TSI changes alone). As I keep saying, current climate changes are but one line of evidence for the CRF climate connection. "[FIVE] Again there are several uncertainties. We've already seen that the MWP and the LIA are predominantly defined in the N. hemisphere and we've used the paleoreconstruction having the largest variation (Moberg et al. (2005)). The atmospheric/ocean current changes that seem to be involved in MWP/LIA N hemisphere temperaturevariation (see my post just above) likely involve large changes in heat transfer to the high Northern latitudes, and the volcanic and solar influences on these might be amplified somewhat by albedo effects from slow Arctic sea ice regression/expansion over the long time scales involved. So the climate sensitivity might be a tad larger than the 0.8 W/m^2 over the very long timescales encompassing MWP/LIA temperature variation.." Just for the record, I don't buy these explanations for the variance in Northern-Southern hemisphere temp cahnges. I don't think anyone can find any evidence that the Southern Hemisphere has ever had a larger climate response in any period, than the Northern one did. There is a very simple reason for this IMO, the Northern hemisphere has more land than the Southern one, and land is more sensitive than water to changes in forcing. One only needs to look at maps of the ice extent in the N & S hemispheres during the last ice age to see what I mean. Cheers, :) -
thingadonta at 19:07 PM on 20 July 2009Climate time lag
The so called 'energy imbalance', ie the warming oceans over the last ~50 years, simply confirms the solar heat lag effect. (eg like air warming between 1 and 3 pm on any normal day). There is no 'energy imbalance' (eg like air warming between 1 and 3 pm on any normal day). Now that the oceans T appear to be flattening and cooling since early 2000s (ie like after 3pm on any normal day-already invalidating Hansen's prediction of "record-breaking T" in the 3 or 4 years after 2005- "the climate system is now being pushed so hard that I have suggested that we can say with confidence that 2005 will have a warmth comparable to that of 1998, and the remarkable 1998 global temperature record will soon be broken, if not this year than within the next several years.)," (http://junkscience.com/Greenhouse/imbalance_release.pdf) Another failed prediction of Hansen...thus, because the 'energy imbalance' is simple a heat lag efect from the sun, the air T will not rise much further,there is no 'imbalance', and oceans will probably cool further. This solar heat lag is really so simple, yet it is not investigated either here, or by Hansen. I he had of bothered to model solar heat lag into his imbalance he would have found it fitted nicely with the energy that has gone into the ocean from the solar peak in the 20th century, with heat lag. How the oceans are cooling, in line with the subsiding heat lag effect and subsiding sun. Too simple for 'global warmists by humans' to even bother investigating. -
Robbo the Yobbo at 15:22 PM on 20 July 2009Climate time lag
All the Spencer link form 1997 says is that a more complex vertical temperature structure is evident in the satellite data than is evident in the land based observations. Spencer still does this work for NASA. 'Analysis of the satellite record that began in 1979 indicates that global temperatures are increasing in the mid-troposphere, but the magnitude of the trend differs based on the analysis methods used in adjusting for factors such as orbital decay and inter-satellite differences. Mid-tropospheric and lower stratospheric temperature data are collected by NOAA's TIROS-N polar-orbiting satellites and adjusted for time-dependent biases by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been preformed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004)**. Not sure what the problem is? Let's see if I have got the Swanson paper right. There was a 1976/77 climate shift and one that occured in 2000/2001. Ignoring the end points as climate shifts - gives an underlying warming trend - between 1977 and 1997 of 0.1 degrees centigrade per decade. Not enough to be a serious concern. The current warming hiatus is likely to last 20 to 30 years. Yes I think that's everything. -
thingadonta at 13:05 PM on 20 July 2009Does ocean cooling disprove global warming?
The ocean T is flattening/cooling because there is no energy imbalance, and solar heat lag effects are now subsiding. Human c02 is having very little effect on surface or ocean T, with the sun and its heat lag on the oceans now waning. -
NewYorkJ at 09:18 AM on 20 July 2009Climate time lag
Re: #115 Robbo: "Spencer has done an ernormous amount in satellite sensing at temperature. He still works for NASA. " He even won an award for this work in the mid-90's. That was before a series of very large and embarassing errors were discovered, some by others, in the UAH data product. The errors have been numerous, of great magnitude on the global trend, and with corrections going almost all in the same upward direction. http://www.nsstc.uah.edu/data/msu/t2lt/readme.18Jul2009 Robbo: "Dr Roy Spencer has always been measured and rasonable." Hardly. When his data showed a per decade cooling trend, he uncritically accepted that it was entirely correct, all other data was wrong, and GCMs were mainly bunk - displaying the opposite characteristics of a good measured and reasonable skeptic. Article: Spencer and co-author Dr. William Braswell of Nichols Research Corporation have great confidence in the quality of their satellite data. "We've concluded there isn't a problem with the measurements," http://science.nasa.gov/newhome/headlines/essd5feb97_1.htm This is one reason why it's odd that he's still the go-to-reference for some. What's a bit more strange is I still see the 1997 NASA link above being cited by skeptics on occasion. -
chris at 03:03 AM on 20 July 2009Climate time lag
re #124 shawnet, Kirkby simply isn't a good guide for reliable understanding of these issue as we've seen already. I used the reconstruction of Judith Lean: Y.-M. Wang, J. L. Lean and N. R. Sheeley, Jr. Modeling the Sun's Magnetic Field and Irradiance since 1713 Astrophysical J. 625 522-538 Lean, J. L., and D. H. Rind (2008), How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006, Geophys. Res. Lett., 35, L18701 Here's the sentence on page 6 of Kirkby which you have used to make your calculation: "The increase in irradiance amounts to less than 0.5 W/m^2, which corresponds to about 0.08 W/m^2 at the top of the atmosphere, globally averaged (Fig. 5). Assuming a climate sensitivity of 0.7 K/W/m^2, this would contribute less than 0.06C of the estimated 0.6 C mean global warming between the Maunder Minimum and the middle of last century, before significant anthropogenic contributions could be involved." Those two sentences are packed with inaccuracies: [ONE] the data in his "Fig 5" shows two reconstructions of Lean (1995 and 2002). However the reference to the Lean 2002 data refers to a paper (his ref 6) in which Lean only analyzes the solar irradiance back to 1840. [TWO] the data in his Figure 5 assigned to Lean 2002, looks more like a solar irradiance reconstruction that Lean published a few years later in 2005 in which she and her collaborators explicitly considered irradiance changes since the Maunder Minimum (it's the one I used): Y.-M. Wang, J. L. Lean and N. R. Sheeley, Jr. Modeling the Sun's Magnetic Field and Irradiance since 1713 Astrophysical J. 625 522-538 Lean's analysis gives a cycle-average reduction in the total solar irradiance at the time of the Maunder Minimum of ~ 1 W/m^2 (rather than Kirkby's "…less than 0.5 W/m^2). 1 W/m^2 gives a temperature change of 1 * 0.25 (geometry)* 0.7 (albedo)* 0.8 (sensitivity) or 0.14 oC. (see point [FOUR] for a bit more on this analysis). [THREE] We've already seen that Kirkby's statement about "…. the middle of last century, before significant anthropogenic contributions could be involved." is entirely bogus. The anthropogenic contribution to surface temperature results from a pre-"middle of last century" change in atmospheric CO2 from 280 ppm (pre-industrial) to 310 ppm (in 1940). This gives near 0.44 oC of warming at equilibrium within a climate sensitivity of 3 oC. [FOUR] Note that the ~ 1 W/m^2 of Wang et al. (2005) is a general interpretation from two analyses using slightly different models that Wang et al made. One analysis gives a TSI cycle-averaged TSI change at the Maunder Minimum of 1.0 W/m^2; the other (containing a secular varying ephemeral region background) gives a change of 1.4 W/m^2. 1.4 W/m^2 gives almost exactly 0.2 oC temperature contribution to reduced surface temperature at the Maunder Minimum from irradiance variation using our parameters.. [FIVE] Again there are several uncertainties. We've already seen that the MWP and the LIA are predominantly defined in the N. hemisphere and we've used the paleoreconstruction having the largest variation (Moberg et al. (2005)). The atmospheric/ocean current changes that seem to be involved in MWP/LIA N hemisphere temperaturevariation (see my post just above) likely involve large changes in heat transfer to the high Northern latitudes, and the volcanic and solar influences on these might be amplified somewhat by albedo effects from slow Arctic sea ice regression/expansion over the long time scales involved. So the climate sensitivity might be a tad larger than the 0.8 W/m^2 over the very long timescales encompassing MWP/LIA temperature variation.. -
thingadonta at 21:12 PM on 19 July 2009Climate time lag
response to response to 106: "The energy imbalance has been directly observed, independent of models, theories or predictions" This is patently false, and you know it. The 'energy imbalance' has been derived and modelled from all the usual suspects, ie -greenhouse gases, aerosols, and such like. Reference: climate-science.org/PDF/Earth.EnergyImbalance.pdf. You have lost credibility. The energy imbalance of Hansen 2005 is modelled, it is not an "observation", and is certainly not "independant of models, theories and predictions". The model, (even Hansen and co use the word) assumes strong c02 forcing, to arrive at the figure. Solar heat lags are not mentioned or investigated. With a solar heat lag the ocean would indeed warm, but the derived imbalance is actually based on assumed c02 forcing, and then 'checked' by model runs, also assuming c02 forcing. Oceans warming is probably correct, the imbalance estimate is a model. So much for your argument, and ability to properly investigate assumptions, the above is just a re-iteration of the creed of c02, nothing more. -
shawnhet at 03:59 AM on 19 July 2009Climate time lag
Oops, I misread the last bit of your post. Please ignore the last paragraph of my previous post. SOrry. -
shawnhet at 03:57 AM on 19 July 2009Climate time lag
Chris, perhaps I have misunderstood you somewhere, so a point of clarification here. You say that 0.2C was caused by solar changes, so working backwards, this implies approximately 1.5W/m2 increase in TSI by my back of the envelope calculation(1.5W/m2 translates into about a 0.24W/m2 forcing at the top of the atmosphere(globally averaged), which in turn translates into ~.17 deg C. at 0.7Wm2/deg C. I confess I didn't look too closely at every reference you provided, so I may have missed the TSI reconstruction you are using. My understanding is that long-term TSI variations(no matter which one) are currently expected to be much less than that. The source for my conclusions is based on Kirkby's position that TSI varies (in recent times) by about 0.5W/m2. There is clearly a contradiction btw *that number* and the claim that solar influences led to a 0.2C temperature difference. If the 0.5W/m2 number is accurate, then a long-term correlation btw solar and climate influences needs some sort of amplification. BTW, the point about ascribing climate changes to changes in the ocean was that it is begging the question. Clearly, ocean temperature fluctuations have a major impact on the climate, but what causes the ocean's behavior to change? There is no contradiction btw saying that NAO was consistently positive in the MWP and saying that MWP was warmer because of a solar influence. Cheers, :) -
chris at 23:50 PM on 18 July 2009Climate time lag
a bit of a formatting error in my post just above - hope this works better!Chris, you've just spent the last few posts arguing that solar contributions to climate change are negligible. For the LIA, the increase is due to CO2 from land use changes(ignoring the fact that those same land use changes also cool the climate) and for MWP the cause is the TH circulation......
Please don't misrepresent straightforward posts shawnet. What are you hoping to achieve by distortion? Nowhere did I say that solar contributions to climate change are negligible. I have already stated that one cannot understand the paleotemperature/greenhouse relationships over the long earth history without taking into account the steady long term increase in solar output during earth history. I've pointed out the research of solar scientists that the evidence supports a solar contribution of around 0.1 oC to 20th century warming and that the solar contribution to the around 0.6 oC of warming from the Maunder minimum to the mid 20th century was likely around 0.2 oC. As far as the evidence goes, the reduction in N. hemisphere temperature from the baseline -0.35/-0.4 equilibrium temperature to a value near -0.6 oC was likely largely a solar effect as was its recovery back to the equilibrium level near -0.35/-0.4 oC. I didn't say that "For the LIA, the increase is due to CO2 from land use changes" did I shawnet. I pointed out that the well characterised anthropogenic rise in atmospheric from the start of the 19th century to the mid 20th century, the early sources of which were from land use changes, is expected to give a temperature rise approaching 0.5 oC at equilibrium, perhaps giving around 0.35 oC by 1950 with the rest "in the pipeline" to be realized post-1950. I pointed out the likely solar contribution (see previous paragraph) and a volcanic contribution, and cited some empirical evidence for a ocean/atmospnhere heat transfer (Gulf stream) reduction which may have contributed to high N hemisphere cooling during the LIA. I even said in relation to the MWP/LIA: "We don't have to consider a role for CO2 (there was a little contribution but not much) other than the very well-characterised and quite large contribution to the long term temperature rise from around 1800 to the mid 20th century base period." And yet you paraphrase my comments on this subject to infer that I stated that "For the LIA, the increase is due to CO2 from land use changes…Go figure! You did ask a relevant question about about the possible contributions of changes in ocean circulation that could have given rise to the around 0.2-0.25 oC rise in high N. hemisphere temperature and the 0.2-0.25 oC drop in high N. hemisphere during the LIA, according to the Moberg reconstruction. This has been addressed in a recent detailed analysis of ocean and atmospheric circulation in the North Atlantic during the MWP and the LIA: Valérie Trouet et al. (2009) Persistent Positive North Atlantic Oscillation Mode Dominated the Medieval Climate Anomaly Science 324, 787-80 http://www.sciencemag.org/cgi/content/abstract/324/5923/78 (abstract below) What might be the origin of these circulation changes? The authors conclude:"The persistent positive phase reconstructed for the MCA appears to be associated with prevailing La Niña–like conditions possibly initiated by enhanced solar irradiance and/or reduced volcanic activity (21) (Fig. 4D) and amplified and prolonged by enhanced AMOC."
(AMOC being "Atlantic meridional overturning circulation") Solar irradiance and volcanic activity. Again no need to postulate a role for the unsubstantiated CRF hypothesis ------------------------------------------------------- abstract: The Medieval Climate Anomaly (MCA) was the most recent pre-industrial era warm interval of European climate, yet its driving mechanisms remain uncertain. We present here a 947-year-long multidecadal North Atlantic Oscillation (NAO) reconstruction and find a persistent positive NAO during the MCA. Supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker NAO conditions into the Little Ice Age (LIA). Globally distributed proxy data suggest that this NAO shift is one aspect of a global MCA-LIA climate transition that probably was coupled to prevailing La Niña–like conditions amplified by an intensified Atlantic meridional overturning circulation during the MCA. -
chris at 23:42 PM on 18 July 2009Climate time lag
Chris, you've just spent the last few posts arguing that solar contributions to climate change are negligible. For the LIA, the increase is due to CO2 from land use changes(ignoring the fact that those same land use changes also cool the climate) and for MWP the cause is the TH circulation......
Please don't misrepresent straightforward posts shawnet. What are you hoping to achieve by distortion? Nowhere did I say that solar contributions to climate change are negligible. I have already stated that one cannot understand the paleotemperature/greenhouse relationships over the long earth history without taking into account the steady long term increase in solar output during earth history. I've pointed out the research of solar scientists that the evidence supports a solar contribution of around 0.1 oC to 20th century warming and that the solar contribution to the around 0.6 oC of warming from the Maunder minimum to the mid 20th century was likely around 0.2 oC. As far as the evidence goes, the reduction in N. hemisphere temperature from the baseline -0.35/-0.4 equilibrium temperature to a value near -0.6 oC was likely largely a solar effect as was its recovery back to the equilibrium level near -0.35/-0.4 oC. I didn't say that "For the LIA, the increase is due to CO2 from land use changes" did I shawnet. I pointed out that the well characterised anthropogenic rise in atmospheric from the start of the 19th century to the mid 20th century, the early sources of which were from land use changes, is expected to give a temperature rise approaching 0.5 oC at equilibrium, perhaps giving around 0.35 oC by 1950 with the rest "in the pipeline" to be realized post-1950. I pointed out the likely solar contribution (see previous paragraph) and a volcanic contribution, and cited some empirical evidence for a ocean/atmospnhere heat transfer (Gulf stream) reduction which may have contributed to high N hemisphere cooling during the LIA. I even said in relation to the MWP/LIA "We don't have to consider a role for CO2 (there was a little contribution but not much) other than the very well-characterised and quite large contribution to the long term temperature rise from around 1800 to the mid 20th century base period." And yet you paraphrase my comments on this subject to infer that I stated that "For the LIA, the increase is due to CO2 from land use changes…Go figure! You did ask a relevant question about about the possible contributions of changes in ocean circulation that could have given rise to the around 0.2-0.25 oC rise in high N. hemisphere temperature and the 0.2-0.25 oC drop in high N. hemisphere during the LIA, according to the Moberg reconstruction. This has been addressed in a recent detailed analysis of ocean and atmospheric circulation in the North Atlantic during the MWP and the LIA: Valérie Trouet et al. (2009) Persistent Positive North Atlantic Oscillation Mode Dominated the Medieval Climate Anomaly Science 324, 787-80 http://www.sciencemag.org/cgi/content/abstract/324/5923/78 (abstract below) What might be the origin of these circulation changes? The authors conclude:"The persistent positive phase reconstructed for the MCA appears to be associated with prevailing La Niña–like conditions possibly initiated by enhanced solar irradiance and/or reduced volcanic activity (21) (Fig. 4D) and amplified and prolonged by enhanced AMOC."
(AMOC being "Atlantic meridional overturning circulation") Solar irradiance and volcanic activity. Again no need to postulate a role for the unsubstantiated CRF hypothesis ------------------------------------------------------- abstract: The Medieval Climate Anomaly (MCA) was the most recent pre-industrial era warm interval of European climate, yet its driving mechanisms remain uncertain. We present here a 947-year-long multidecadal North Atlantic Oscillation (NAO) reconstruction and find a persistent positive NAO during the MCA. Supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker NAO conditions into the Little Ice Age (LIA). Globally distributed proxy data suggest that this NAO shift is one aspect of a global MCA-LIA climate transition that probably was coupled to prevailing La Niña–like conditions amplified by an intensified Atlantic meridional overturning circulation during the MCA. -
thingadonta at 21:27 PM on 18 July 2009Climate time lag
Sorry for the capital letters in the last post, I just wanted to differentiate my words from others. I wont do it anymore. -
thingadonta at 20:31 PM on 18 July 2009Climate time lag
re: response to 107: I did read the whole Hansen 2005 paper, and Wong 2005,and I'm not at all convinced that so-called energy imbalances are 'measured' and not modelled-in fact I think Hansen 2005 is actually saying that he does 'model' the imbalance, both current and predicted. Hansen 2005 states that he derives 'predicted' energy imbalance from greenhouse gas models. "First, the predicted energy imbalance DUE TO INCREASING GREENHOUSE GASES has grown to 0.85 ± 0.15 W/m2". (Hansen 2005) (although he also conveniently often fuses the 2-'calculated' and 'predicted'). However, you state the energy imbalance of the climate is "measured" independant of theories, models and predictions: "The energy imbalance has been directly observed, independent of models, theories or predictions". (THIS IS WRONG, IT IS "CALCULATED", USING A MODELLED RELATIONSHIP BETWEEN OCEAN HEAT, ATMOSPHERE T, AND OUTGOING AND INCOMING SOLAR ENERGY.MOREOVOER, this modelling of Hansen 2005 does not take into account solar changes and heat lags in 20th century, it is solely MODELLED using strong c02 forcings of the 20th century. Contrary to what you state, there is NO way this relationship between ocean heat, climate T, and incoming-outgoing heat can be 'measured', outside of modelling, and assumptions. Moreover, the predictions or Hansen 2005 of future energy imbalances are based on greenhouse gas models, further IMPOSED on this exisitn modelling. It is an exquisite case of modelling on modelling on modelling. THERE IS NO INVESTIGATION, OR INPUT FROM SOLAR EFECTS IN THE 20TH CENTURY IN THE HANSEN 2005 PAPER-NOT EVEN MENTIONED. Your points: 1."We predict there will be an energy imbalance due to increasing CO2". (THIS IS A MODEL, AS YOU SAY, BASED ON MODELLED GREENHOUSE -T RELATIONSHIPS IN THE 20TH CENTURY-WITHOUT TAKING INTO AFFECT THE SUN-AS ALSO DOES HANSEN 2005) 2."Empirical observations of increasing ocean heat confirm there is an energy imbalance". (THIS 'IMBALANCE' IS DERIVED FROM GREENHOUSE GAS MODELS IN THE 20TH CENTURY-THERE IS NO "CONFIRMATION" UNLESS ONE FIRST ASSUMES THAT THE SUN HAS HAD LITTLE/NO EFFECT, WITH NO SOLAR HEAT LAGS-WHICH CNACEL THE IMBALANCE) 3."The energy imbalance, calculated from ocean heat measurements, is steadily growing and is currently at 0.85 W/m2" (A MEANINGLESS FIGURE BASED ON MODELS BETWEEN CLIMATE'S CURRENT T AND OCEAN HEAT-AS DERIVED FROM MODELLED PAST RELATIONSHIPS OF SUN-OCEAN RELATIONSHIPS-WONG 2005) "In terms of the sun/heat lag issue, all we need to know is direct observations tell us the planet's energy imbalance has been gradually increasing over the past 40 years". (NO, OCEANS HAVE BEEN HEATING IN LINE WITH SOLAR ACTIVITY AND HEAT LAG-THIS IS NOT INVESTIGATED IN HANSEN 2005 PAPER, IT IS ONLY ASSUMED TO BE DUE TO C02). "Therefore, recent global warming cannot be a case of lagged solar warming which would show the energy imbalance approaching equilibrium (in fact, should've reached equilibrium approximately 20 years ago)". IT IS ONLY ASSUMED TO BE NOT BE APPROACHING EQUILIBRIUM IF ONE FIRST ASSUMES T IS BEING DRIVEN BY C02 EFFECTS, WHICH THEN PRODUCES THE "IMBALANCE", THEN IS NO INVESTIGATION MADE OF SOALR ACTIVITY, SOLAR LAGS, AND EFFECTS ON THIS ON OCEAN HEAT IN 20TH CENTURY. Heat solar lag effects would produce increasing ocean heat content, which would level off, as it has done since the early 2000s in the ocean-land T. There is no 'imbalance', unless one models the ocean-atmosphere-solar system as being driven by c02 - the paper by Hansen 2005 does NOT address solar heat lag, solar effects, it only assumes that there is a long climate heat lag from c02 (not the sun), and then assumes an imbalance from this effect, then predicts a long term lag from this current, modelled imbalance, ALL BASED ON GREENHOUSE GAS MODELLING. Circular, and willfully ignorant. Hansen 2005 paper does not refute solar heat lag, because Hansen himself does not address it in the paper. He states that he uses greenhosue gas modelling. "First, the predicted energy imbalance DUE TO INCREASING GREENHOUSE GASES has grown to 0.85 ± 0.15 W/m2". In other words he assumes that past century T rise is by greenhouse gases first, which has therefore created a "predicted energy imbalance", by "increasing greenhouse gases". If we assume an energy imbalanace, then we get an energy imbalance. Mindbloggingly circular and stupid. There is no evidence to conclude, as he does, that the there is an energy imbalance at present, unless one assumes that T is rising by C02 in the first place, as he states above, that he does. This is not proof, is is circular reasoning. If we assume an energy imbalanace, then we get an energy imbalance. He uses the same argument further down to get a figure of 0.6 degrees C still 'in the pipeline' ie from ocean heat content, ie imbalanced with c02 forcing. NOWHERE does he discuss or address or acknowldedge the fundamental assumptions of the models he bases this figure on, ie that he ASSUMES T rise is being driven by c02, and not the sun. I am not convinved that, both the paper of WONG 2005 and Hansen 2005- that they don't model an "imbalance" based on greenhouse gas modelling, and also neither address solar effects and heat lags. Climate is approaching equilibrium, T has levelled off since the early 2000s, in both land and ocean, and this so-called large climate 'imbalance' is only in the heads of the human-induced global warmists, getting bigger every day as they attempt to explain why the earth is no longer heating sicne the early 2000s.There may be some ocean heat lag leftfrom solar actvity in 20h century, particularly in the southern hemisphere, but c02 is playing very little effect, as can be seen over the last decade as T from the sun levels off-co2 has been trying to heat the earth sicne this time, but it is just way too small to have any effect. There is no large current energy imbalance, this is a conclusion based on assumed strong c02 forcing, conceptually 'stealing' the real climate heat lag discovered from the sun, and which 'model' does not even bother investigating solar activity and solar heat lags (Hansen 2005 Wong 2005). -
shawnhet at 05:46 AM on 18 July 2009Climate time lag
Just a couple of quick points here. Whether or not thermohaline circulation is implicated rather begs the point. What causes the circulation to vary this massively? If it's not solar, then what? "shawnet, since the CRF correlates with the other solar parameters (outwith Forbush events and perhaps some other events) one cannot assume that any historical correlations in 10Be and 14C isotopes with local climate proxies signify causal CRF-climate relationships. They could be irradiance-climate correlations. We've already seen that during the periods when we can actually assess this specific point in great detail, that the original CRF-cloud-temperature hypothesis is found to be wanting (see my post #71)." Chris, you've just spent the last few posts arguing that solar contributions to climate change are negligible. For the LIA, the increase is due to CO2 from land use changes(ignoring the fact that those same land use changes also cool the climate) and for MWP the cause is the TH circulation. Are we then supposed to believe that for other previous correlations solar proxies actually have a causative effect? This would, of course, imply that the that the relationship btw CRF and solar irradiance was different in the past, than it is now. I don't think so. IAC, as I have said before, this particular line of argument is but **one** piece of the CRF picture. Sure you can ignore the CRF-climate correlation of the last 1000 years and treat them as coincidental to other effects(land use changes or some other phenomenon), but to have a chance of having an accurate theory you have to explain all the other correlations that Kirkby mentions. I submit that were you to attempt this, your final theory would be a massive kludge. Cheers, :) -
Philippe Chantreau at 04:50 AM on 18 July 2009Climate time lag
There is no CO2 snow falling on Earth at Vostok, or anywhere else, even in infinitesimal amounts. If you want to argue that it is physically possible on this planet to have atmospheric CO2 naturally snow, go right ahead. Spencer has done indeed some work and the serious work he has done is a far cry from the stuff he allows himself to post on the internet. Check the link and look at his demonstration if you don't believe me. "CO2 has a direct ocean link." Obviously. What are you trying to say? The oceans are the largest net carbon sink on the planet. Spencer has tried to argue that they are instead a source of atmospheric CO2, against all evidence and all known physical processes. Your interpretation of the RC post is more a reflection of your ideology and bias than of the actual content of the post. -
chris at 04:42 AM on 18 July 2009Climate time lag
re #113The issues here are so complex and involved that it would take all year to go through them. For me, it is enough to point out the *multiple* studies show a match btw the phase and magnitude of climate changes and CRF. If you have a dispute with parts of this, (say for instance of the relationship btw cosmic rays and the intertropical convergence zone), that is your responsibility.
shawnet, since the CRF correlates with the other solar parameters (outwith Forbush events and perhaps some other events) one cannot assume that any historical correlations in 10Be and 14C isotopes with local climate proxies signify causal CRF-climate relationships. They could be irradiance-climate correlations. We've already seen that during the periods when we can actually assess this specific point in great detail, that the original CRF-cloud-temperature hypothesis is found to be wanting (see my post #71). As for my "responsibility", I'm just pointing out what I consider the scientific evidence shows! Nobody has any particular responsibility here (I think it's useful to be honest, clear and to provide supporting evidence for anything I say). Perhaps if you can take anything from my posts, you might consider that I'm demonstrating why, despite some extraordinary self-publicising by a couple of its advocates, that rigorous scientific analysis of climate contributions doesn't include this ill-characterised and unquantitated hypothesis. -
chris at 04:26 AM on 18 July 2009Climate time lag
re #114 That's not really logical shawnet – you seem to be following Jasper Kirkby's fallacy which is to assume that everything has a single cause! Far better to consider all of the factors known to contribute to these phenomena. Let's consider this in the light of the (N. hemispheric) paleoreconstruction that gives the largest temperature variation, even if this may well be an over-interpretation of the true variability. This is Moberg et al (2005) [*]. You can look at part of this in Jasper Kirkby's figure 2. All temperature anomalies are relative to the mid 20th century anomaly of 0 oC 1. The MWP. Jasper Kirkby truncates Moberg's reconstruction, but inspection of the original paper shows that (as far as the reconstruction indicates), the N. hemispheric temperature trundled along near an anomaly around -0.35 for hundreds of years, but then rises very slowly from around 700 AD to a value almost reaching 0 oC for a while centred around 1100 AD. 2. During the subsequent couple of hundred years the temperatures drifted back to the pre-MWP value (around -0.35 oC). 3. The LIA. From around 1400 to around 1550 the temperatures drifted down towards the value associated with the LIA (around -0.6 - -0.65 oC) where the temperature stayed for 100-150 years before starting to drift back up from around 1700. Causality: 4. First off we don't know for sure. Two other sources of uncertainty: (i) We've chosen the most extreme paleoreconstruction; the real temperature variation might not be so large as Moberg determines. (ii) The MWP and LIA seem likely to be predominantly N. hemisphere phenomena (see point 6 and 7 below). Therefore we don't know how much we need to explain these phenomena in terms of forcings involving global scale temperatures. Let's press on anyway: 5. The MWP. It's not clear whether there was a solar contribution. The sunspot record only starts around 1600. We can inspect Kirkby's Figure 2 again and see that the CRF proxy bears little relation to the MWP. The MWP temperature max was achieved well before 1100 when the CRF proxy started rising (I'm using Kirkby's inversion of the CRF where "rise" corresponds to "warming"). Much of the MWP warmth was dissipated before the CRF proxy started falling around 1250-1300. 6. A plausible explanation for the very slow and rather small temperature rise to the MWP was a small change in the Gulf Stream component of the thermohaline circulation [**, ***]. If the Gulf stream intensity increases more heat is drawn to the high Northern latitudes and vice versa. This doesn't require much, if any, global scale temperature variation, but is mostly a redistribution of heat. There's quite a bit of evidence for this contribution to late Holocene temperature, particulalry for reduced Gulf Stream flow during the LIA [***]. 7. So we can understand the MWP (if we wanted to) in terms of a slow, slow rise of the Gulf Stream intensity, and its slow return to the pre-MWP equilibrium. That only leaves an explanation for the LIA which is essentially a drift of the (N. hemisphere) temperature from the equilibrium near -0.35/-0.4 value to a value around -0.6/-0.65. We've already seen that the very anomalous solar changes might have given a reduced irraidiance contribution of up to -0.2 oC globally. There is also the evidence for a small reduction of Gulf Stream intensity [***]. The low volcanic acivity of thre MWP gave way to high and persistent volcanic activity during the LIA. We only need to "find" 0.2 – 0.25 oC of cooling. 8. So we don't need to conjure up any "magical " contributions. We don't have to consider a role for CO2 (there was a little contribution but not much) other than the very well-characterised and quite large contribution to the long term temperature rise from around 1800 to the mid 20th century base period. We could assume that the "recovery" of the LIA would take the N. hemisphere temperature back to the -0.35/-0.4 oC level. However the growing anthropogenic forcing made this overshoot to the mid 20th century 0 oC value. [*] Moberg, A et al. (2005) Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data Nature 433, 613–618 (2005) [**] Lund DC et al. (2006) Gulf Stream density structure and transport during the past millennium, Nature 444, 601-604 [***] Denton GH and Broecker WS (2008) Wobbly ocean conveyor circulation during the Holocene? Quart. Sci. Rev. 27, 1939-1950. -
Robbo the Yobbo at 04:10 AM on 18 July 2009Climate time lag
I was talking about minute amounts of CO2 snow in mid winter in Vostok. Spencer has done an ernormous amount in satellite sensing at temperature. He still works for NASA. Likewise, CO2 has a direct ocean link. Meanwhile (LOL) our mates at realclimate - confirmed this week that the planet wasn't cooling. Just not warming for 20 or 30 years from 2000/2001. -
Philippe Chantreau at 02:48 AM on 18 July 2009Climate time lag
I don't think it was even going that far David, although I wouldn't be surprised if it did. Not sure how exactly the all thing developped, I followed a link from another site. What's really funny is that a number of posters who pontificate on a regular basis at WUWT were arguing very seriously about the idea. That included Watts himself and some dude (Steven Goddard) who apparently is the go-to guy over there on matters of meteorology, although he is obviously not too good with phase diagrams. Eventually Watts got some sense hammered into his head by posters who knew better. All that happened on the science blog of the year, I kid you not. Yet, as idiotic as WUWT stuff can be, some of his regulars were suggesting that one of Spencer's more off-the-deep-end ideas about the carbon cycle should be removed from the site. That says someting about the ideas that Spencer puts on the intertubes. His published works are far less, if at all, challenging to the consensus model of Earth climate. He had a really funny one at Watts, on which he makes a complete hash of statistical analysis, trying to argue that the Oceans are actually the source of the increased atmospheric CO2. His fuzzy maths were addressed by Tamino on this post: http://tamino.wordpress.com/2009/01/19/a-bag-of-hammers/ It's kind of funny since Spencer is himself the go-to guy for many "skeptics" seeking appeal to authority. I believe that the post was subsequently removed, as often happens on wuwt. -
shawnhet at 01:59 AM on 18 July 2009Climate time lag
Chris, that might work(if you ignore land use's cooling effects) except that now you can't explain the MWP. There are no anomalous processes that took about 40 ppm of CO2 out of the atmosphere to cool the MWP temp to the ones recorded in the LIA. As such, you are left with a solar forcing for this change and if the variation of SI doesn't change much(and the relationship to its variation wrt CRF is constant), then you're theory is in trouble. "You dont "see the point..(re Kirkby's presentations)....of talking about each one in detail". But isn't that what we should do if we're trying to establish (i) the veracity of a presentation with respect to scientific understanding...and (ii) use logic, empirical and theoretical analysis to understand causal relationships in the natural world?" The issues here are so complex and involved that it would take all year to go through them. For me, it is enough to point out the *multiple* studies show a match btw the phase and magnitude of climate changes and CRF. If you have a dispute with parts of this, (say for instance of the relationship btw cosmic rays and the intertropical convergence zone), that is your responsibility. Cheers, :) -
shawnhet at 01:29 AM on 18 July 2009Climate time lag
Chris, that might work(if you ignore land use's cooling effects) except that now you can't explain the MWP. There are no anomalous processes that took about 40 ppm of CO2 out of the atmosphere to cool the MWP temp to the ones recorded in the LIA. As such, you are left with a solar forcing for this change and if the variation of SI doesn't change much(and the relationship to its variation wrt CRF is constant), then you're theory is in trouble. "You dont "see the point..(re Kirkby's presentations)....of talking about each one in detail". But isn't that what we should do if we're trying to establish (i) the veracity of a presentation with respect to scientific understanding...and (ii) use logic, empirical and theoretical analysis to understand causal relationships in the natural world?" The issues here are so complex and involved that it would take all year to go through them. For me, it is enough to point out the *multiple* studies show a match btw the phase and magnitude of climate changes and CRF. If you have a dispute with parts of this, (say for instance of the relationship btw cosmic rays and the intertropical convergence zone), that is your responsibility. Cheers, :) -
thingsbreak at 00:57 AM on 18 July 2009The CO2/Temperature correlation over the 20th Century
John, This paper might be of interest: http://www.cccma.ec.gc.ca/papers/ngillett/PDFS/nature08047.pdf It also illustrates that although the empirical relationship between CO2 and temp is logarithmic, on shorter timescales and due to other climatic factors, it can be represented linearly. See also: http://moregrumbinescience.blogspot.com/2009/03/does-co2-correlate-with-temperature.html Great work! -
David Horton at 19:59 PM on 17 July 2009Climate time lag
Philippe, I'm often baffled by the stuff these guys come up with to avoid recognising the reality of greenhouse gas global warming. What was the point of "CO2 snow"? Did they think that all the excess CO2 was going to come tumbling out of the sky in the polar regions and so, even though CO2 wasn't causing any problem ("we call it plant food"), it certainly couldn't cause any problem as the CO2 snow flakes drifted down in the ultimate negative forcing. I mean, I know this sounds silly, but is that what they were saying? -
chris at 19:47 PM on 17 July 2009Climate time lag
re #105 Yes that's right shawnet. So of the 0.5 oC of anthropogenic warming contribution expected from the change in atmospheric CO2 in the long period between the Maunder minimum and 1940, we might expect to have realized 0.35 oC by 1950, with 0.1 - 0.15 "in the pipeline" to be realized sometime after 1950. Something like that. The solar contribution was around 0.2 oC....0.1 oC of the warming might be attributed to the release of negative forcing from the reduction of the large volcanic activity... So it's straightforward to obtain 0.6 oC of warming from our understanding of known forcings and their magnitudes. Of course the numbers are unlikely to have been exactly as I defined! But analyzing the data in line with empirical evidence and theoretical understanding (the known levels of greenhouse gases, the well-characterised estimates of radiative forcings, the current best estimates of solar irradiance changes and their forcings and so on)....gives us a value of warming that corresponds to pretty much the largest estimate of temperature change for the MM to 1950 period(Moberg's reconstruction - see my post # 88). We don't have to propose as yet uncharacterized contributions for which recent evidence suggest are less than likely to exist. You dont "see the point..(re Kirkby's presentations)....of talking about each one in detail". But isn't that what we should do if we're trying to establish (i) the veracity of a presentation with respect to scientific understanding...and (ii) use logic, empirical and theoretical analysis to understand causal relationships in the natural world? -
Robbo the Yobbo at 18:31 PM on 17 July 2009Climate time lag
Mr Yobbo to you too Phillipe. OK...I did say broadly from a couple of numbers on Wikepedia. Do you know it's cold in Vostok? Cheers Robbo -
Philippe Chantreau at 18:16 PM on 17 July 2009Climate time lag
Furthermore, we're looking at a pressure near or below 1 atmosphere. Carbonic snow on Earth? Only the so-called "skeptics" come up with that kind of stuff. -
Philippe Chantreau at 18:06 PM on 17 July 2009Climate time lag
Robbo, it's very simple. CO2 exists in the atmosphere at 387 ppm. We're not talking about freezing 100% CO2 in gas form. -
thingadonta at 13:43 PM on 17 July 2009Climate time lag
Can some 'global warmists by humans' care to explain this revealing sentence from Hansen 2005, claiming we have an energy imbalance in the atmosphere, and still have 0.6 degrees in the pipeline?? "First, the predicted energy imbalance due to increasing greenhouse gases has grown to 0.85 ± 0.15 W/m2". I'll clarify: How many circular assumptions kiddies are in this statment?? I count 3. 1. "predicted energy imbalance"..ie based on their being an energy imbalnace due to c02 driving T. 2."due to increasing greenhouse gases"-which assumes that they are driving T. No mention of the sun in the article, or heat lag from such. 3.Has grown-ie if you assume the first 2 you get the last-"has grown". Hansens 2005 paper is NOT a refute to the heat-lag sun dominant-driver argument, it is just a re-iteration of the creed of c02 driving warming. IE 'We know that the heat lag from the sun isnt approaching ewquilibrium because c02 is driving warming, which means there must be a 'predicted' energy imbalance'. A perfectly circular argument. Sounds like 'bankspeak' to me, I wouldn't invest my money in it. Nor should any country.Response: You're misreading what Hansen is saying. If you read the whole paper so you have the full context, you'll see that Hansen 2005 is saying that:- We predict there will be an energy imbalance due to increasing CO2.
- Empirical observations of increasing ocean heat confirm there is an energy imbalance.
- The energy imbalance, calculated from ocean heat measurements, is steadily growing and is currently at 0.85 W/m2
-
Robbo the Yobbo at 12:58 PM on 17 July 2009Climate time lag
Mr. Yobbo to you Chris - I don’t really think you have had time to read the Alaskan paper I referenced last. Nice link to the global SST. I am sure you recognise that the Nino 3.4 area is in the central Pacific Ocean. The graph is comparing global anomalies to central Pacific sea surface anomalies. It shows the dominance of changes in Pacific Ocean processes in the global mean. Here’s a good link to a number of relevant indices. http://ioc3.unesco.org/oopc/state_of_the_ocean/all/ I have a web site with some information of the relevance of these indices and a description of the physical processes involved in the Pacific dominance. Something I occasionally update as my interests develop. www.earthandocean.robertellison.com.au I think your graph illustrates the Pacific dominance well - and I will certainly go back to it. But we know that atmospheric temperature and total ocean heat content has plateaued on perhaps a thousand year high. Yep – it’s warm alright (except in Vostok). All that I am saying is that there is a very obvious 50 year cycle superimposed on background warming. The Nino 3.4 data clearly shows the difference between the 1946 to 1975 state and the 1976 to 1998 state. This can be more clearly seen in the Multivariate ENSO index of Wolter Claus (http://www.cdc.noaa.gov/people/klaus.wolter/MEI/ ) – or the related PDO index (http://jisao.washington.edu/pdo/PDO.latest ). Here’s a great paper on the interactions of ENSO and the PDO. A cool mode PDO is associated with more frequent and intense La Niña and, conversely, a warm mode is associated with more frequent and intense El Niño. Verdon, D. and Franks, S. (2006), Long-term behaviour of ENSO: Interactions with the PDO over the past 400 years inferred from paleoclimate records, Geophysical Research Letters 33: 10.1029/2005GL025052. Statistically, a weak El Niño or neutral conditions is more likely than a return to strong El Niño. The current Nino 3.4 anomaly is at 0.63 °C for the week ending July 11. The definition of an El Niño is sustained sea surface anomaly of greater than 0. 5°C for five months. Look at your Nino 3.4 graph at the bottom. The recent La Niña was not exceptional at all and we have barely scratched the surface an El Niño yet people are jumping on the bandwagon – and hoping like hell things will turn around. The PDO and ENSO states have been mixed since 1998. Swanson et al – uses a global sea surface temperature synchronisation technique to posit shifts in climate state. They were very pleased with themselves for using an objective technique rather than eyeballing it in. I think the terminology is useful and the methodology promising. http://www.uwm.edu/~kswanson/publications/2008GL037022_all.pdf http://www.realclimate.org/index.php/archives/2009/07/warminginterrupted-much-ado-about-natural-variability/and Dodgy sources I know – but what can you do? NASA nominated a switch to a cool PDO since 2008. The anchovy index indicates a shift in post 1998 - http://news.bio-medicine.org/biology-news-2/From-sardines-to-anchovies-and-back-in-50-years-5939-2/ Now I’m just being provocative – I’ll get the missus to spank me. Try instead: http://alexeylyubushin.narod.ru/Climate_Changes_and_Fish_Productivity.pdf You are very out of your depth here Chris Cheers Robbo -
shawnhet at 10:56 AM on 17 July 2009Climate time lag
Chris, the 0.5C number is an equilibrium number(after albedo etc...). Your "simple" calculation doesn't take that into account. Yes, the CO2 effect might *in equilibrium* cause a temperature increase of about 0.5C. Since most of that Also, in re:land use changes, while they may release more CO2, they have cumulativelty also changed albedo resulting in a cooling of around 1/2 the warming due to CO2 you are talking about(if memory serves). see for instance Brovkin et al. (1999) IAC, the reasons for suspecting a CRF climate-link was explored in many, many papers on Kirby, I don't see the point of talking about each one in detail. Fact is, you asked for reasons to suspect that there is something about CRF specifically that influences climate, I provided it. I don't have any desire to eliminate all doubt in your mind. Cheers, :) -
chris at 09:50 AM on 17 July 2009Climate time lag
re #99 Robbo, your odd and unsupported assertions seem strangly divorced from reality. What are you think of? There isn't any non-arbitrary evidence that the climate has shifted post 1998. 1998 was just an anomalously warm year on a rising trend. If one considers the 10 record warm years (NASA Giss) all of the 2000's years are greater than all of the 1990's years except for 1998 and 1997: 2005 1998 2002 2003 2006 2007 2004 2001 2008 1997 2008, despite the large La Nina and the sun sitting stubbornly at the bottom of the solar cycle, is the 9th warmest year on record. 2009 will almost certainly be warmer than 2008 and so only the highly anomalous year of 1998 will be in the top ten. Despite your assertion of a climate shift and an extended cool period (none of which has any basis in non-arbitrary assesment), we seem to be entering the early stages of an El Nino. The El Nino/La Nina pattern doesn't seem to be different pre-1998 vs post-1998 [see *]. The sea surface temperature in June was the second warmest month on record [*]. [*]http://data.giss.nasa.gov/gistemp/graphs/SST.glob+Nino3.4.pdf Now of course one should be careful in drawing conclusions from short periods. But it's difficult to relate your assertions of cooling with the observation that despite the fact that we've just come through a strong La Nina, and the sun is right at the bottom of its solar cycle (I thought you guys were arguing for a very strong solar contribution to climate???) and seems to be sitting there in a rather protracted manner, that the global sea surface temperature is almost as high as in the very anomalous 1998. -
Robbo the Yobbo at 09:20 AM on 17 July 2009Climate time lag
Chris - Even the IPCC concentrates on the past 50 years. I think your being to precise with paleo graphicic data. I eyeballed in the Vostok data. Multi- decadal climate shift seem especially significant in the Arctic and North America as a whole. The graph of Arctic temperature is a goo d place to start. The following contains a more detailed discussion. The Significance of the 1976 Pacific Climate Shift in the Climatology of Alaska Brian Hartmann and Gerd Wendler http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2FJCLI3532.1 -
chris at 08:56 AM on 17 July 2009Climate time lag
whoops that table didn't format terribly well!1006.0000 279.4000
means that the year is 1006 AD and the [CO2] atmospheric is 279.4 ppm2001.0000 373.0000 1.6000
means that the year is 2001 AD, the [CO2] atmospheric is 373 ppm, and the increment for that year (2001) is 1.6 ppm. -
chris at 08:52 AM on 17 July 2009Climate time lag
Robbo, this is an oddly false assertions...what were you thinking of?: "Temperature rise to 1945 was largely natural – in that CO2 concentrations of 300 ppmv is par for the course for an interglacial. Please note that the IPCC talks about the last 50 years. CO2 levels started rising after the mid 1940’s – and temperatures declined for 30 years." No. The natural interglacial concentration is 270-280 ppm. We can assess this in great detail for the present interglacial [*]. The preindustrial concentrations were very close to around 277 +/- ~ 5 ppm since around 1000 AD to the preindustrial period. Significant anthropogenic contributions to atmospheric CO2 started around the start of the 19th century (land use changes largely at that point) and CO2 concentrations had reached around 310 ppm by around 1940. That CO2 rise is expected to give a contribution to the earth's global temperature of around 0.5 oC at equilibrium (using the median value of the climate sensitivity of 3 oC). So the pre-1945 temperature rise was very unlikely to be natural. Quite a large chunk is almost certainly anthropogenic. Note that the rather rapid increases in anthropogenic CO2 only started after post-war industrialisation especially from the early 1960's ([CO2] levels were still only 320 ppm in 1962). They really started to race upwards from around that time (see data below). Of course the IPCC doesn't just "talk(s) about" the last 50 years. Why not try reading some of the IPCC reports rather than just making up stuff? 1006.0000 279.4000 1046.0000 280.3000 1096.0000 282.4000 1146.0000 283.8000 1196.0000 283.9000 1246.0000 281.7000 1327.0000 283.4000 1446.0000 281.7000 1499.0000 282.4000 1547.0000 282.8000 1589.0000 278.7000 1604.0000 274.3000 1647.0000 277.2000 1679.0000 275.9000 1720.0000 277.5000 1760.0000 276.7000 1796.0000 283.7000 1825.0000 285.1000 1845.0000 286.1000 1861.0000 286.6000 1877.0000 288.8000 1882.0000 291.7000 1891.0000 294.7000 1899.0000 296.5000 1905.0000 299.0000 1912.0000 300.7000 1926.0000 305.0000 1936.0000 307.9000 1948.0000 311.4000 1954.0000 314.7000 1959.0000 315.7000 1959.0000 318.2000 0.9400 1960.0000 319.2000 0.5000 1961.0000 319.7000 0.9600 1962.0000 320.7000 0.6500 1963.0000 321.3000 0.7400 1964.0000 322.0000 0.3000 1965.0000 322.4000 1.0700 1966.0000 323.4000 1.2600 1967.0000 324.7000 0.6800 1968.0000 325.4000 1.0400 1969.0000 326.4000 1.3700 1970.0000 327.8000 1.0000 1971.0000 328.8000 0.7800 1972.0000 329.6000 1.7900 1973.0000 331.4000 1.1800 1974.0000 332.5000 0.7600 1975.0000 333.0000 1.0900 1976.0000 334.0000 0.9000 1977.0000 335.3000 2.0700 1978.0000 337.4000 1.3400 1979.0000 338.7000 1.6400 1980.0000 340.0000 1.8400 1981.0000 342.0000 1.4400 1982.0000 343.6000 0.7100 1983.0000 344.0000 2.1600 1984.0000 346.4000 1.3500 1985.0000 347.8000 1.2200 1986.0000 349.0000 1.5100 1987.0000 350.0000 2.3500 1988.0000 352.8000 2.1100 1989.0000 355.0000 1.2800 1990.0000 356.2000 1.3100 1991.0000 357.6000 0.9900 1992.0000 358.5000 0.4500 1993.0000 359.0000 1.3100 1994.0000 360.3000 1.8900 1995.0000 362.2000 2.0100 1996.0000 364.2000 1.1900 1997.0000 365.4000 1.9800 1998.0000 367.4000 2.9500 1999.0000 370.0000 0.9100 2000.0000 371.2000 1.7800 2001.0000 373.0000 1.6000 2002.0000 374.6000 2.5500 2003.0000 377.1600 2.3100 2004.0000 379.5000 1.5400 2005.0000 382.0000 2.53 2006.0000 384.0000 2.00 D ata are from: D. M. Etheridge et al (1996) "Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn J. Geophys Res. 101, 4115 -4128, and direct measurement from the Mauna Loa station from 1959 Column 1 is the year, column 2 is the [CO2] in parts per million, and column 3 is the yearly increment in the period from 1959. Ice core data from Etheridge (up to 1959) from a series of Antarctic (Law Dome) cores. -
chris at 08:23 AM on 17 July 2009Climate time lag
I did read that in Kirkby's review, shawnet. This specific point that you cut and pasted doesn't accord with the evidence for two reasons. (i) Kirkby has very oddly attempted to treat every last bit of paleoclimatology in terms of the CRF. It leads to some ludicrous interpretations which we could discuss. He completely discounts any possible contribution from greenhouse gas variations stating in a footnote at the outset, this rather audacious illogic falsehood: "Greenhouse gases are not included since, prior to the twentieth century, short-term changes of greenhouse gases, such as occurred during glacial-interglacial transitions, are found to be a feedback of the climate system and not a primary forcing agent [11]." Perhaps you didn't read my post above (#88), but it's very straightforward to assess the CO2 concentrations through the last 1000 years from a number of Antarctic cores drilled at Law Dome. The pre-industrial CO2 concentration was near 280 ppm (reduced to around 276 at the Maunder minimum) and was around 310 ppm by 1940. Within a climate sensitivity of 3 oC, it's also straightforward to calculate the temperature rise at equilbrium resulting from a 276-310 increase in atmospheric CO2. It's near 0.5 oC. So Kirkby's assertion that you cut and pasted is bogus as is his astonishing footnote. We expect that the temperature rise from the CO2 change (virtually all of which is anthropogenic), to be very significant indeed (something approaching 0.5 oC) between the Maunder minimum and the mid-20th century. (ii) Kirkby comes up with a tiny value for the solar irradiance contribution to warming from the Maunder minimum to the mid 20th century. He's right that the value is not very large. However, the solar scientists that actually determine the solar irradiance reconstructions consider that the irradiance contribution is somewhat larger than that. Lean calculates a solar irradiance contribution near 0.9 oC between 1890 and the present with almost all of this before the mid 20th century. The Maunder minimum to mid 20th century contribution is likely near 0.2 oC (see reference in my post #88 – her 2008 paper). So Kirkby's argument just doesn't accord with the evidence. There is a well-characterised source for a large contribution to to the temperature rise between the Maunder minimum and the mid-20th century. Kirkby also ignores the volcanic contribution to the Little Ice Age cold [*; see Figure 7]. But then his review rather astonishingly ignores anything that can't be interpreted in terms of the CRF…. [*] P.D. Jones and M.E. Mann (2004) Climate over Past Millenia (2004) Reviews of Geophysics, 42, RG2002. -
Robbo the Yobbo at 07:17 AM on 17 July 2009Climate time lag
idiocy, stupidity, abnormal psychology, aggressive – is there a pattern emerging here? But the mildest reply and my feelings are hurt? Phillipe –what part of Vostok minus 89 degrees – freezing point of CO2 minus 57 – don’t you understand? To continue with irrelevancies is silly. If I got the numbers wrong from my quick internet search – please tell me. Otherwise it is simply another straw man. I have no problem with technology, efficiency and innovation. Efficient and cost effective technology needs no assistance from government – except perhaps i in providing R&D funding of which not nearly enough is happening. People like Bjorn Lomberg consistently argue for more R&D and an economically rational transition. Nothing to do with giving any game away – increasing costs for energy in the third world is guaranteed to have a price in human lives. Temperature rise to 1945 was largely natural – in that CO2 concentrations of 300 ppmv is par for the course for an interglacial. Please note that the IPCC talks about the last 50 years. CO2 levels started rising after the mid 1940’s – and temperatures declined for 30 years. The usual explanation was that sulphur dioxide caused the dip. But the IPCC net forcing was always positive in the period. Climate shifted suddenly in the mid 1970’s to a period of more frequent and intense El Niño and rising temperature and has shifted again post 1998 – as in the Swanson et al paper and Real Climate blog I have already referenced. But the literature on PDO, AMO, ENSO multidecadal variation and decadal fisheries and ecological productivity is extensive. This is a 50 year climate cycle. Global temperature has declined and ocean heat content is at most steady since 1998. As in the Swanson paper shows – the underling trend of post war warming (across a full cycle of multi-decadal variation) that might be attributed to CO2 is 0.08 degrees centigrade per decade and the planet is cooling for another decade or two. -
shawnhet at 06:51 AM on 17 July 2009Climate time lag
Chris, I think you would be well served by reading the Kirkby review here/ From p.5-6 2.1.3 Solar and cosmic ray changes since the Little Ice Age The cold climate of the Little Ice Age appears to have been caused by an extended period of low solar activity. Few sunspots implies low magnetic activity and a corresponding elevated GCR flux. But could the observed warming since the Little Ice Age be explained by changes of solar irradiance rather than introducing the possibility of GCR-climate forcing? Recent results on Sun-like stars, combined with advances in the understanding of solar magnetohydrodynamics [8] have revised earlier estimates of the long-term variation of solar irradiance [5] downwards by as much as a factor of five (Fig. 5) [6, 7]. Apart from the irradiance changes due to sunspot darkening and facula brightening, no mechanism has been identified for solar luminosity variations on centennial or millennial time scales [8]. Current estimates of the secular increase of irradiance since 1700 are therefore based only on the variation in mean sunspot number. The increase in irradiance amounts to less than 0.5 Wm2, which corresponds to about 0.08 Wm2 at the top of the atmosphere, globally averaged (Fig. 5). Assuming a climate sensitivity of 0.7 K/Wm2, ***this would contribute less than 0.06C of the estimated 0.6C*** mean global warming between the Maunder Minimum and the middle of last century, before significant anthropogenic contributions could be involved. On the other hand, there is clear evidence of a substantial increase in solar magnetic activity since the Little Ice Age (Fig. 6) [55, 3]. http://arxiv.org/PS_cache/arxiv/pdf/0804/0804.1938v1.pdf "4. The fact that the CRF might vary more than solar irradiance (I assume you mean in terms of % variation around some mean), doesn't necessarily say anything about the relative contributions of the CRF changes and irradiance changes. After all, if CRF changes don't have a significant climate effect it doesn't matter how much these change." It does when the solar irradiance only has a slight ability to affect the climate(as per above for one of many examples), when the actual changes to the climate are much more extensive. If the magnitude of changes to climate and CRF are both large, then it follows that CRF is a better candidate than irradiance for the climate driver. If the magnitude of changes solar irradiance were of the same size as the changes in climate(or CRF), it would be simpler to assume irradiance was the culprit, but the magnitude is much too small. Cheers, :) -
chris at 05:30 AM on 17 July 2009Climate time lag
The problem with this line of argument is that total irradiance doesn't vary nearly as much as the climate has. Kirkby's 2007 review states that "...more recent estimates suggest that long-term irradiance changes are probably negligible". As such, since the total irradiance doesn't change much and the CRF does, the fact that CRF varies in tandem with climate changes, is good evidence that the CRF itself influences climate somehow.
That doesn't seem logical to me Shawnet. It begs rather a lot of questions. 1. The climate transitions since the Maunder minimum are understandable in terms of known contributions from solar, volcanic and greenhouse contributions (points 4,5 and 6 of my post #88). That doesn't mean that my breakdown of contributions is exactly correct! However one doesn't need to postulate any as yet uncharacterised forcings (solar or otherwise) to understand this variation. 2. That may or may not apply to the previous few centuries, e.g. involving the MWP. The climate variation during this period isn't so well characterised, and some of the climate variation may be regional and due to changes in ocean/atmospheric heat transport (my point 3 in post #88). Of course that begs the question of whether these heat transport variations are internal modulations of the climate system or are externally forced. 3. Previous to that there isn't a very good understanding of global Holocene climate variability I believe (I haven't seen serious Holocene global paleoproxy reconstructions other than these: Holocene_Temperature_Variations.png There are various bits of highly localized proxies (stalagmites; glacial ice etc.) which correlate solar proxies with climate proxies, but whether these are representative of global scale changes isn't very clear I think. So I'm not sure we can say that the total irradiance hasn't varied as much as the climate has, since we haven't got much evidence for the climate variability and solar irradiance variability during periods of the Holocene before a couple of millenia ago. Note that some of the early Holocene climate variability (around 8000-6000 years ago, I think) is a Milankovitch effect). 4. The fact that the CRF might vary more than solar irradiance (I assume you mean in terms of % variation around some mean), doesn't necessarily say anything about the relative contributions of the CRF changes and irradiance changes. After all, if CRF changes don't have a significant climate effect it doesn't matter how much these change. 5. Obviously climate has changed considerably in the past. But this is largely understandable in terms of earth orbital variations (Milankovitch cycles) with greenhouse gas and albedo feedbacks (last couple of million years), and further into the deep past through changes in greenhouse gas concentrations (rising CO2 concentrations from tectonic processes; reducing greenhouse gas concentrations from weathering processes), the progressively decreasing solar constant as we go back in time (Kirkby must surely know this, 'though perhaps by "long-term" he doesn't mean millions of years time scale), and tectonic activity. 6. So I'm not sure that we need to postulate any solar contributions outside irradiance changes. That's not to say that these don't exist (the evidence for the direct CRF-climate contribution is weak in my understanding of the science - e.g. see my post #71); it's just that they haven't been identified (to my knowledge), and aren't necessarily required to explain anything.... ...what do you think? Is there some serious evidence that some non-irradiance solar contributions are rwquired to explain particular climate transitions/variations? -
PeterPan at 05:15 AM on 17 July 2009Climate time lag
I've been trying to understand RC's post on a simple model in the light of this article and, if possible, I would like to understand the reason for a difference. According to RC's post: σTs4 = S /(1 - 0,5λ) Where S = (1-a)TSI/4 λ = emissivity (0,769) However, as I understand it, according to this article, that would rather be: σT4 = S/λ Using RC's notation: λ = ε (emissivity) S = what in this article is S(1-A)/4 Are my numbers wrong? Are the two approaches based on different simplifications? Thanks! RC's post Formulas better displayed here -
shawnhet at 04:22 AM on 17 July 2009Climate time lag
"Similar arguments apply even more strongly in the past. Changes in 10Be in ice cores and 14C in tree rings is a measure of varying solar outputs represented by the CRF. But just as with the very detailed contemporary analyses (see my post #71), there is no good a priori reason for assuming that any climate-related consequences of solar variation are causally related to the putative CRF component of the solar variation. In fact recent evidence suggests that this a priori assumption is a very weakly supported one." The problem with this line of argument is that total irradiance doesn't vary nearly as much as the climate has. Kirkby's 2007 review states that "...more recent estimates suggest that long-term irradiance changes are probably negligible". As such, since the total irradiance doesn't change much and the CRF does, the fact that CRF varies in tandem with climate changes, is good evidence that the CRF itself influences climate somehow. It is possible that some other solar-related property varies much more closely than CRF to the observed climate changes, but clearly irradiance changes themselves don't explain what we see happening. Cheers, :) -
Thumb at 02:25 AM on 17 July 2009Climate time lag
"Honestly - I link and quote a Stanford University website on what is a widely accepted understanding of space-time and a foolish little person insists on compounding their idiocy. Time would be better spent in expanding both their education and their imagination." Methinks someone's feelings were hurt. "'To make groupthink testable, Irving Janis devised eight symptoms indicative of groupthink (1977)." Now you're projecting. You gave your game away with this line: "...is not sufficient to warrant restricting the economic aspirations of billions of people." Your entire ongoing argument is based on finding anything, however small, that supports what I would argue is a false premise; that addressing our continued contribution to greenhouse gases would somehow have an adverse economic affect on "billions of people." In the real world in which I work converting to high efficiency and alternative energy sources creates jobs and holds an easily calculable payback when measured against current systems and fossil fuels, which, BTW, simply can't go on forever. Reducing greenhouse gases might be a driving force for some, but the real selling point for moving the global economy into green energy technologies is their potential to expand and enhance the economic aspirations of billions of people.
Prev 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 Next
