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Comments 127601 to 127650:

127601. Steve L at 07:14 AM on 25 September 2009
        Measuring Earth's energy imbalance
        Manuel #26, let's put it another way -- if you were a stock broker and you said you weren't very certain about a bunch of stocks, but one you were very certain of should increase in value from 60% to 240% over the next five years, would you have any takers? [I'm not arguing that this is a good analogy. But I think it's just as good as yours.]
127602. chris at 06:46 AM on 25 September 2009
        Measuring Earth's energy imbalance
        re #26

        A strong "quantitative" correlation between two variables can serve as an indication to try and find a relation between them. It does not prove a relation indeed exists. I am sure you agree with me.

        Yes that's fine as a general philosophy Manuel. However we often have independent evidence of causality (I'm using "causality" in place of your "relation"). For example (despite the efforts of a separate set of scientific misrepresenters!), we know that the statistical correlation between lung cancer and ciggie smoking indicates a causality since we can examine the lung cells of smokers and determine the carcinogen-induced DNA damage that leads to loss of cellular control of unconstrained proliferation. A similar case may be made for the correlation between hugely enhanced atmospheric CO2 level and enhanced surface temperature. Simply put, the correlation is pretty much what we expect from the known properties of CO2 as a greenhouse gas, our understanding of the greenhouse effect and a rather large amount of evidence form empirical analysis of paleodata on the relationships between atmospheric CO2 levels and earth surface temperature. So while the observed correlation doesn't prove causality, it is highly consistent with the expectation of causality, and clearly one should not leave out pre-existing empirical and theoretical understanding from the analysis of correlations when addresing causality.

        With respect to the degrees of uncertainty involved in the issues we are discussing: It is huge. As an example, the last IPCC report says that total anthropogenic radiative forcing has a 90% confidence of being between 0.6 to 2.4 (with a central value of 1.6). That's a 4x factor between the lowest and highest values, and nearly 3x between the lowest and medium.

        That's not quite right. Remember that the likelihood of the "correctness" of a particular value in a normal (Gaussian) distribution falls as one moves away (in either direction) from the most likely value. So while the central value has (by virtue of the mathematics of Gaussian distributions) a probability near 0.7, the 90% confidence level values in the wings of the distribution have a probability near 0.1 or less. And of course uncertainty works in both directions. So while one might feel relieved by the possibility that a rather low anthropogenic radiative forcing might apply in reality (with very low probability), we have to accept the same probability that an anthropogenic radiative forcing on the high wing of the distribution is equally likely. In fact the high end of the distribution of anthropogenic radiative forcing is considerably less poorly constrained, and in fact recent evidence indicates that the probabilities of anthropogenic radiative forcings on the low side are less likely than considered to be the case in the rather conservative IPCC assessment reports of 2007. Of course talking about normal distributions is unsatisfactory without actually looking at them! A recent paper analysing the reduction in uncertainty in anthropogenic radiative forcing is cited below. Figure 1 of this paper illustrates the Gaussian distribution defining the probabilities of values of anthropogenic radiative forcing, and gives a much better idea of what the error range actually means with respect to the likelihoods of particular values of the anthropogenic radiative forcing. Unfortunately I haven't been able to find a freely downloadable version. J Haywood and M. Schulz (2007) Causes of the reduction in uncertainty in the anthropogenic radiative forcing of climate between IPCC (2001) and IPCC (2007). Geophys. Res. Lett. 34, L20701, doi:10.1029/2007GL030749 Abstract: Mechanisms that drive climate change are quantified by the radiative forcing which is the perturbation to the global energy balance of the Earth/atmosphere system. These mechanisms may be of anthropogenic or natural origins and each has an associated level of scientific uncertainty. Until recently, even the sign of the anthropogenic radiative forcing has been in doubt because strong, poorly quantified negative radiative forcings such as those from aerosols act to oppose the strong, well quantified positive radiative forcings from well mixed greenhouse gases. We present an analysis of the probability distribution function of the anthropogenic radiative forcing for the individual forcing mechanisms identified by IPCC (2001) and IPCC (2007). We conclude that significant progress in reducing the uncertainty of the anthropogenic radiative forcing has been made since IPCC (2001). The single most important contributor to this conclusion appears to be the reduction in the uncertainty associated with the aerosol direct effect, followed by the provision of a best estimate for the aerosol cloud albedo indirect effect.
127603. chris at 06:15 AM on 25 September 2009
        Measuring Earth's energy imbalance
        Re #13 and #17 Manuel, your interpretation of the linearization of the relationship between temperature change and radiative forcing as used by Murphy et al (2009) (their equation 1 that you reproduced in your post #13) isn't correct. Thus the concern you raise in your post #17 is misplaced in this instance. Your suggestion that the increase in radiation is proportional the the fourth power of the increase in temperature (Stefan-Boltzmann law) is fine, but not relevant to what Murphy et al (2009) are investigating. The Stefan-Boltzmann law relates the radiation emitted from the surface of a body at a defined temperature and does indeed have a fourth power relationship. However Murphy et al (2009) are estimating the radiative forcing F which is essentially the net radiation once the energy balance is "accounted" (i.e. top of the atmosphere radiation in minus radiation out). It turns out that this net radiation does have a generally linear relationship with the change in the earth's surface temperature (more sensibly, the earth's surface temperature change is roughly proportional to the radiative forcing). This could be investigated further by reading the following paper: Gregory JM and Forster PM (2008) Transient climate response estimated from radiative forcing and observed temperature change. J. Geophys. Res. 113, D23105 Abstract (my highlights): Observations and simulations (using the HadCM3 AOGCM) of time-dependent twentieth-century climate change indicate a linear relationship F = rho Delta T between radiative forcing F and global mean surface air temperature change Delta T. The same is a good description of Delta T from CMIP3 AOGCMs integrated with CO2 increasing at 1% per year compounded. The constant "climate resistance'' rho is related to the transient climate response (TCR, Delta DT at the time of doubled CO2 under the 1% CO2 scenario). Disregarding any trend caused by natural forcing (volcanic and solar), which is small compared with the trend in anthropogenic forcing, we estimate that the real-world TCR is 1.3-2.3 K (5-95% uncertainty range) from the data of 1970-2006, allowing for the effect of unforced variability on longer timescales. The climate response to episodic volcanic forcing cannot be described by the same relationship and merits further investigation; this constitutes a systematic uncertainty of the method. The method is quite insensitive to the anthropogenic aerosol forcing, which probably did not vary much during 1970-2006 and therefore did not affect the trend in Delta T. Our range is very similar to the range of recent AOGCM results for the TCR. Consequently projections for warming during the twenty-first century under the SRES A1B emissions scenario made using the simple empirical relationship F = rho Delta T agree with the range of AOGCM results for that scenario. Our TCR range is also similar to those from observationally constrained model-based methods.
127604. Manuel at 18:25 PM on 24 September 2009
        Measuring Earth's energy imbalance
        Chris, "That seems a very strange (and false) emotionalization of a quantitative analysis!" I was just trying to characterize the two most extreme factions of the AGW debate I have met. On the one hand those that say "It's [only] the sun" on the other side the most exaggerate proponents of AGW that say "CO2 is gonna kill us [we have no time left to act]". My personal view, as I have already expressed is that both extreme views are probably wrong, and I am sorry if my phrase sounded like an insult to you. With respect to correlations: A strong "quantitative" correlation between two variables can serve as an indication to try and find a relation between them. It does not prove a relation indeed exists. I am sure you agree with me. A weak "qualitative" correlation is just the expression of the desires of the person that makes the graph. This reminds me of what a coworker told me many years ago. His first employment, as an intern in an investment bank, was mainly to try and find the specific kind of deals for which his bank was the market leader. He succeeded quarter after quarter. (And, yes, the "bank" was a small local operation, more a financial boutique than a real bank) With respect to the degrees of uncertainty involved in the issues we are discussing: It is huge. As an example, the last IPCC report says that total anthropogenic radiative forcing has a 90% confidence of being between 0.6 to 2.4 (with a central value of 1.6). That's a 4x factor between the lowest and highest values, and nearly 3x between the lowest and medium. I used to make my living selling companies. If I had told my clients that their businesses were valued something between 1 and 4, most probably around 3 ... I wouldn't have had many clients, would I?
127605. canbanjo at 16:54 PM on 24 September 2009
        Measuring Earth's energy imbalance
        Tom, thanks again but wouldn't a more accurate analogy be at equilibrium - the water being added is equal to that which is leaving through a hole. AGW equivalent - the hole is decreasing in size, but the water being added stays the same. So the bucket starts to fill up. The speed of water through the hole increases but it is not enough to compensate. ?
127606. Tom Dayton at 08:48 AM on 24 September 2009
        Measuring Earth's energy imbalance
        A flaw in my metaphor of water-bucket for energy-Earth is that there are no laws of physics compelling the bucket system to reach equilibrium. The hole's size and position, the bucket's size and shape, the rate of water input, would have to all be exactly the right combination for the system to stabilize at some high enough rate of water spurting out the hole, to prevent the bucket from overflowing. It can happen, but it's unlikely. In contrast, objects are constrained by laws of physics to radiate more the hotter they are, until they put out as much as they get in.
127607. Tom Dayton at 08:23 AM on 24 September 2009
        Measuring Earth's energy imbalance
        Re: #22 canbanjo Poke a small hole in the bottom of a bucket. Put a water hose in the bucket. Turn on the water so the amount of water going into the bucket is slightly more than can leave through the hole. Over time, the amount of water in the bucket will increase, which will increase the weight of the water, which will increase the pressure of the water at the bottom of the bucket. The higher pressure will push a larger quantity per second of water through the hole. Result: The input is constant, but the amount of water in the bucket increases at the same time the amount of water escaping from the bucket increases. The extra water going out of the bucket is a fraction of the water that is accumulating in the bucket.
127608. canbanjo at 07:34 AM on 24 September 2009
        Measuring Earth's energy imbalance
        Tom, thank you for trying to explain. Unfortunately I come back to the fact that the earth is heating up, that energy is coming from outside, so overall there is more energy coming in than is going out. the energy coming in is not increasing, so the energy going out cannot be increasing. there must be something else to this that is not being explained.
127609. Tom Dayton at 03:22 AM on 24 September 2009
        Measuring Earth's energy imbalance
        Re: #20, canbanjo Greenhouse gases don't trap all the outgoing radiation. They trap some, which causes the temperature to increase, which causes the Earth to "try" to radiate more energy. Only some of that increased radiation is trapped by greenhouse gases; the rest escapes. Of course, the portion of that increased radiation that is trapped, raises the temperature even more, which in turn causes the Earth to "try" to radiate more, and so on. But that process does not run away; the increases in attempted radiation and in trapping are only fractional, so their absolute amounts become progressively smaller until they become effectively zero; that's equilibrium. But equilibrium lasts only if the amount of greenhouse gas stops increasing. Since greenhouse gases keep increasing, equilibrium is a moving target.
127610. canbanjo at 02:54 AM on 24 September 2009
        Measuring Earth's energy imbalance
        I still don't get the idea of increased radiation into space due to to the earth becoming hotter. If the earth is getting hotter due to greenhouse gases trapping outgoing longwave radiation, then there must be a decrease in outgoing radiation not an increase. The relative increase would only occurr once the system is returning to equilibrium.
127611. Mizimi at 00:11 AM on 24 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        Analysed another random cell (6x6 degrees)in central USA using 4 rural stations. The ten-year trend varied from 0.08/0.03/-0.027/0 (zero) giving a mean value of 0.021C. Nowhere near the 0.2C per decade expected. Again a lack of correlation within the grid which seems to counter the argument that the trend is well correlated at great distances. Or maybe I just struck lucky.
127612. Mizimi at 23:54 PM on 23 September 2009
        The growing divide between climate scientists and public opinion
        Have a look at "Battle of the Jaywalk - May 2005 2/2" on You-tube. This is the FINAL of a general knowledge test in the USA. Is this the kind of ordinary 'Joe Public' person asked to give their opinion as to whether human activities contribute significantly to climate chamge? Heaven help us if it is. Shawnhet, your post hits the nail firmly on the head. It seems to be getting towards the stage where if you challenge the degree of the effect ( not the effect itself) you are a 'denier'.
127613. Mizimi at 22:54 PM on 23 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        #33.."But no, the loss of data from Russia, China etc doesn't necessarily affect the answers we get...what makes you think it does?" So let's pretend I own 60 supermarkets ( I wish) and each store downloads sales information on a weekly basis so that I can track sales of each item for re-ordering purposes ( central buying) and also so I can construct a profit/loss account. The computers at 20 stores go down and I don't replace them. How do I know what to order and how much? How can I construct a P/L account for the company? Answers...I cannot do either with the accuracy I used to have. I will over/under order and cannot determine the current financial state of the group. If you multiply the stores up to 1000 and I lose data from 500 ( roughly equivalent to the reduction in weather stations) the result is the same and I am left with only guesswork.
127614. Mizimi at 21:15 PM on 23 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        On 1200km cells..........went back to GIStemp and took annual mean temp data from 6 stations within a 1200km grid. Calculated the temp anomaly for each station over a time period of 10 years (1980-1989). 3 stations had an anomaly of 0.14- 0.15 C, the other 3 had anomalies of 0.03/0.08/0.10C The average anomaly within the grid using just these stations is thus 0.106C which is half of what is expected. So I don't see correlation within a grid, let alone between grids. But I will do some more checking.............
127615. chris at 20:51 PM on 23 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        No you're pursuing a non-sequiter Mizimi. Yes, insufficient data and poor coverage affects the end result. That is obvious. But no, the loss of data from Russia, China etc doesn't necessarily affect the answers we get...what makes you think it does? You certainly can't draw that conclusion from your simplistic perusal of 16 stations. These issues have to be analyzed properly. Raising theoretical issues based on simplistic analysis and then concluding that these issues apply without showing evidence that they do is false argumentation. In fact it's quite apposite in the context of this thread, since that selfsame false logic is the fundamental flaw of Mr Watt's misanalysis (or non-analysis) of the US surface temperature record.
127616. chris at 20:40 PM on 23 September 2009
        Measuring Earth's energy imbalance
        Manuel, it's worth going back to your explanation 2 since that's what you're disputing (it seems you raised it just to knock it down!) Explanation 2:

        200 of actual heat increase = 100 coming from the increase in solar radiation + 1,600 from greenhouse gases effects – 300 from stratospheric aerosol effects – 350 from outgoing radiation that really isn’t going anywhere because of the greenhouse gases – 950 from mostly unknown (or not yet quantified) causes.

        Two things that might help: i. The "350 from outgoing radiation" really is going somewhere. It's escaping from the atmosphere into space. I'm pretty sure this does not refer to long wave IR emitted from the earth's surface, but to the enhanced emission of IR to space as the climate system tends towards equilibrium with the enhanced (greenhouse) forcing (see my post #7). I welcome input on whether I've interpreted that correctly. ii. The 950 isn't mostly unknown nor "not yet quantified". It's largely aerosol direct and indirect effects, and these have been quantitated (see e.g. [***]). Of course there is signifcant uncertainty in these analyses. [***] V. Ramanathan & G. Carmichael (2008)Global and regional climate changes due to black carbon, Nature Geoscience 1, 221 - 227 (2008) Ramanathan's analysis can be read in a similar form from this Senate committee hearing document here: http://www-ramanathan.ucsd.edu/testimonials/BlackCarbonHearing-testimony.pdf
127617. Mizimi at 20:27 PM on 23 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        No Chris, I am not trying to calculate the anomaly from 20 stations, I am showing that insufficient data and poor coverage affects the end result. A pretty obvious thing I would have thought. So that the loss of data from Russia, China at al affects the the answers we get. Defining the US anomaly with 70 stations is rather unhelpful in defining the GLOBAL anomaly if we do not have data from stations on a GLOBAL scale.
127618. chris at 19:50 PM on 23 September 2009
        Measuring Earth's energy imbalance
        Manuel, Of your two explanations, your explanation 1 is clearly incorrect (see mine and Tom’s explanation)…you agree with this. Explanation 2 is simply and unequivocably correct in the context of the paper. After all, these forcings are independent and thus an unbiased summation is the correct means of coming to a conclusion about the residual forcing and its contributions. Obviously there is uncertainty over the magnitudes of these, but that doesn’t negate the fact that an unbiased overall summation is appropriate. I’m curious about your extrapolation from the fact that the evidence very strongly supports a strong enhanced greenhouse forcing (which is very obviously much stronger than the solar forcing as indicated by a substantial evidence base), to an interpretation that explanation 2 corresponds to a "CO2 is gonna kill us" hypothesis” . That seems a very strange (and false) emotionalization of a quantitative analysis! “Qualitative correlations”. This is an interesting point. One of the difficulties with establishing attribution of forcing contributions to 20th century and contemporary warming is that the sort of “correlation” that you desire (presumably something like a mathematical/statistical linearized relationship between variables) isn’t appropriate for assessing attribution of 20th century warming to its contributing forcings. However we would be in a very sorry position if were to conclude that attribution was therefore not accessible nor robust. We can assess attribution via modelling based on known/estimated magnitudes of the forcings coupled with knowledge of climate responses and their time constants, and reintroduce a quantitative (‘though non-linear) element into the relationships. Notice that we can assess climate responses (earth temperature) and greenhouse gas concentrations with quantitative correlations of the sort you desire via analysis of paleoproxy data (e.g. as compiled, for example, here [***]) where the relationship between temperature and CO2 concentrations can be linearized since the temperature can be reasonably assumed to have come to equilibrium with the forcing in these analyses. Incidentally, although this is a semantic point, the use of the word “ correlation” certainly doesn’t imply that the correlation between variables is quantitative. Here’s a dictionary definition of the term “correlation”, and I suspect that the term is used in that sense in the page I linked to on this site in my post just above. However, as I indicated above, a quantitative analysis via mathematical modelling can be used to extract attributions of 20th century warming (rather in the manner of the quantitative analysis in the Murphy paper we’re discussing). correlation n. A causal, complementary, parallel, or reciprocal relationship, especially a structural, functional, or qualitative correspondence. [***]Royer, D. L. CO2-forced climate thresholds during the Phanerozoic. Geochim. Cosmochim. Acta 70, 5665–5675 (2006).
127619. Manuel at 19:05 PM on 23 September 2009
        Measuring Earth's energy imbalance
        John, Thank you very much for your reply. Re. correlation. As per my previous post, my main point is that correlations have to be taken with great care as they provide very poor basis to prove or disprove anything. Re. linear modelization. Yes, I am looking at the following formula which, as you say, refers to net radiation: N = F - lambda x Delta T + epsilon One of the concerns I have when I look at climate papers is how linear relationships are being used for phenomena which don't seem to be linear. By the way, that's also why I find suspicious linear correlations to begin with.
127620. Manuel at 18:35 PM on 23 September 2009
        Measuring Earth's energy imbalance
        Thank you very much for your detailed answers. I agree with Tom that Explanation 1 (corresponding to the "it’s the Sun" hypothesis) is too simplistic to be correct. But I have to disagree with Chris and maintain that Explanation 2 (the "CO2 is gonna kill us" hypothesis) is also almost surely to be incorrect, if only because of the degree of uncertainty with which the different components of radiative forcings, positive or negative, are being "estimated" or "asumed". I have to maintain "estimated" or "assumed" because few things in Climate can be really "measured" and the paper itself recognizes that the big white chunk of figure 3 is a result, not a calculation. My personal impression (which I understand has little or no value) is that radiative forcings of greenhouse gases have been overestimated. Leaving a much more manageable situation on the right side of the equation once they are adjusted to their true value (less unknown effects to be accounted for). Furthermore, many of the claims made by both sides of the debate seem to me to be too opportunistic and self-contradictory, like rising temperatures prove CO2 warming, but when they apparently stop rising, other factors should be acknowledged for, even though they weren’t considered before. By the way, I am happy to concede that on the other side it is also easy to spot bogus arguments, if only because the skeptics’ front is less organized. I am sorry Chris, but "qualitative" correlations have little or no value for me at this point. They hardly prove or disprove anything, or rather they can "prove" anything you like them to "prove". That’s why I think that the only "correct" explanation at this point is that we still don’t know enough and everybody is free to make her own bets, but please let's try to be at least consistent with the implications of our hypothesis.
127621. chris at 05:54 AM on 23 September 2009
        Global warming and the El Niño Southern Oscillation
        A rather more rigorous analysis of the contribution of generalised ocean circulation effects to 20th century temperature variation has just been published [***]: K.L. Swanson et al. (2009) Long term natural variability and 20th century climate change Proc. Natl. Acad. Sci. USA 106, 16120-16130 This analysis indicates that natural contributions (largely ocean circulation variability) have had a significant effect on 20th century temperature variability. However the nett contribution to overall 20th century warming is close to zero. Essentially ocean circulation variability made a positive contribution to early (1900-1940) 20th century warming, a negative contribution to mid 20th century warming and a positive contribution to late 20th century warming. Once the natural variability is removed the externally forced (greenhouse) contribution is manifest as a continuous accelerating warming. [***] http://www.pnas.org/content/early/2009/09/09/0908699106.abstract abstract: Global mean temperature at the Earth's surface responds both to externally imposed forcings, such as those arising from anthropogenic greenhouse gases, as well as to natural modes of variability internal to the climate system. Variability associated with these latter processes, generally referred to as natural long-term climate variability, arises primarily from changes in oceanic circulation. Here we present a technique that objectively identifies the component of inter-decadal global mean surface temperature attributable to natural long-term climate variability. Removal of that hidden variability from the actual observed global mean surface temperature record delineates the externally forced climate signal, which is monotonic, accelerating warming during the 20th century.
127622. Tom Dayton at 02:46 AM on 23 September 2009
        Measuring Earth's energy imbalance
        Re: #13 by Manuel: Manuel, your Explanation 1 is incorrect, because all those non-solar positive and negative forcings you say the author "assumed," instead are real, concrete, physical, measured phenomena that must be accounted for just as much as the solar forcing and the resulting temperature must be accounted for. Even if the global temperature was not increasing, the exact same analysis would be done using empirical facts for all those forcings, and in that non-warming case the accounts would have to balance. Your misunderstanding is understandable, because the popular media and especially the denialist ones try to create the impression that climatologists noticed that the temperature increased and in response started guessing at what might be causing it, without any empirical evidence. It's like your home budget. Receipts for spending, and paychecks, all are empirical facts that must be accounted for in the overall balance. Yes, there is uncertainty about some of your spending, and maybe about some of your income if you didn't keep good records of your garage sale. But you can't ignore the actual receipts and paychecks.
127623. chris at 02:20 AM on 23 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        Well yes Mizimi....it's obvious that you can't determine the global temperature anomaly trend from 16 sites. I don't really understand your point. In post #25 you stated that you "would not consider 100 stations since 2001 as being significant" in the context of the US Climate Reference Network that I described in posts #22 and #29. However now you're attempting to determine the global anomaly from 16 sites which is a surface density of around 0.3% of the USCRN. So how can an analysis of 16 sites be sufficient in your post #30, when you consider a density equivalent to ~6500 sites worldwide to be insignificant for determining a temperature anomaly trend? Clearly there is a requisite number of sites for adequate determination of a global temperature anomaly with acceptable statistical uncertainty. It's obviously greater than 16. The fact that the US temperature anomaly trend can be defined pretty well with 70 sites (see Figure 2 in the top article), suggests that a number well below 6500 is enough. Making any further conclusions requires consideration of the vast multitude of data and analyses in the published science where these issues have already been addressed at length (see links in my post #28).
127624. chris at 01:43 AM on 23 September 2009
        Measuring Earth's energy imbalance
        Manuel, your "explanation 2" has to be the correct one in the context of the study. The negative forcings (note these are not "negative feedbacks" as you describe them), are individual components of forcings, the summation of which gives the total forcing (that yields the cumulative 200 x 10^21 J). The total greenhouse gas-induced forcing is obviously much larger than the solar one, and any negative forcing acts to counter all of the positive forcings – one can't single out a single forcing (solar) and consider that its contribution is somehow left "unopposed" by negative forcings. (incidentally, and rather in line with the annoyingly vague descriptions in the paper, there is no reference to the source of the solar forcing contribution. The published data indicate that solar contributions have not only been very small since the 1950's, but have been in a cooling direction for around the last 20 years. However Murphy's data [Fig 2 above], indicates a (admittedly small) solar contribution that continues to increase during the 15-20 years up to 2004. The authors refer to global dimming effects, and I wonder whether these (i.e. recovery from "dimming") is included in the solar contribution…the authors give us no insight on this!). On you specific question #1: Firstly we should be careful how we're using the term "correlation". It's not a mathematical/statistical correlation, and one shouldn't be expected in the CO2/surface temperature relationship. At best we can say that in line with the rather slow early 20th century increase in greenhouse gas, the surface temperature rose slowly, and following the very rapid rate of increase in CO2 emissions from around the mid 60's the temperature increase has been faster. But the effects of CO2 on surface temperature are mixed in with the effects of all the other forcings [***], and are further "discorrelated" by lags in the response times of the various elements of the climate system (atmosphere, land, ocean surface, ocean depths), and so strict "correlations" in the statistical sense aren't expected. That there is a qualitative "correlation" as described by John Cook here….. http://www.skepticalscience.com/The-correlation-between-CO2-and-temperature.html ….is due to the fact that increasing the greenhouse effect does cause the Earth's surface to warm, and there haven't been any truly humungous events (massive changes in solar outputs or truly dramatic volcanic events etc.), that have overcome the dominant greenhouse contribution. In any case even 'though the tiny atmosphere/surface ("tiny white sector of figure 3") is indeed tiny with respect to the CO2 effect ("big gray sector on figure 2"), the ocean effect does clearly "correlate" with the CO2 effect, and we expect the land surface effect to "correlate" with the ocean effect since the latter has a strong influence on the former. So I don't think the "correlation" (using the term broadly!) is unexpected. [***] a very interesting paper on this is just published in PNAS – it's very apposite: http://www.pnas.org/content/early/2009/09/09/0908699106.abstract
        Response: I queried the author re where his solar data comes from, it comes from Gregory and Forster (2008). Re the PNAS paper you link to, I just received a copy about a week ago and plan to do a post on it shortly.
127625. Manuel at 21:34 PM on 22 September 2009
        Measuring Earth's energy imbalance
        Looking again at figures 1, 2 and 3, I have a couple of observations to make: 1) If the average of the curve depicted in figure 1 were 4x10^21 J/yr, which looks like it could be, the total imbalance during the 50 year period would be 200x10^21 J which is the observed increase in the heat contents of the system (the line blue on figure 3). The blue line also seems to follow the shape of figure 1. BTW, this is what one would expect, wouldn't it? Heat increase = Cumm. radiation in - Cumm. radiation out 2) On figure 2, we see that about half of that increase (100x10^21 J) can be explained by an increase in solar input. Note that I am just reading what the figures say. That leaves the other half to explain (100x10^21 J). Rather, the author prefers to assume that in fact the cumm. effect of radiative forcings is of the order of 1,600x10^21 J, but there exist many negative feedbacks that counteract the effect of greenhouse gases. In other words: Explanation 1) 200 of actual heat increase = 100 coming from the increase in solar radiation + 100 coming from unknown sources and measurement errors. Explanation 2) 200 of actual heat increase = 100 coming from the increase in solar radiation + 1,600 from greenhouse gases effects – 300 from stratospheric aerosol effects – 350 from outgoing radiation that really isn’t going anywhere because of the greenhouse gases – 950 from mostly unknown (or not yet quantified) causes. [Note that the above figures have uncertainties that in some cases are of the order of 25% or more of the calculated value. And the real figure is totally unknown in the case of the 950 sundry effects figure and in fact is the result of the other calculations added to match] Which one do you prefer? I have two specific question for John. 1) I have read with interest your recent comments about the correlation between CO2 and atmospheric temperature. I agree with you that trying to disprove the AGW theory based on the fact that during the last 10 years there is no correlation. On the other hand you present a correlation during 100+ years. Looking at figures 2 and 3, don’t you think that any correlation between the tiny white sector of figure 3 (representing the variation of atmospheric, land and ice heat) and the big gray sector on figure 2 (representing the effect of the increase in CO2) is in fact meaningless? 2) I understand from the text of the paper, that it uses a linear method to compute the now famous "outgoing radiation". But the increase in radiation is not linear but rather proportional to the the fourth power of the increase in temperature. What do you think are the consequences of this "simplification"?
        Response: Good questions. In fact, upon reflection, this post on energy imbalance gives a richer perspective on the two previous posts on short term CO2 correlations and long term CO2 correlations.
        
        Question 1. The correlation between CO2 and temperature is not meaningless. It's not a mathematical abstraction but grounded in physical reality. The earth radiates infrared (or longwave) energy back out to space. Atmospheric CO2 absorbs the longwave radiation, some is turned into heat and some of the longwave radiation is radiated back down towards earth. So this will have a direct effect on atmospheric temperatures hence the correlation.
        
        I'm not trying to downplay surface temperature record, just put it in it's proper context. It's important to realise that atmosphere is just one small piece of the climate puzzle. Much of that longwave radiation that gets radiated back down to earth is absorbed by the ocean. Figure 3 reminds us that the ocean has a much great heat capacity than the atmosphere. Then you have internal variation from phenomena like El Nino where the ocean exchanges heat with the atmosphere. This internal variation is superimposed on the long term warming trend caused by the energy imbalance. Internal variation doesn't add any extra energy to the planet - it just moves the energy around. This is the point I make in my post on short term CO2 correlations.
        
        In my post on long term CO2 correlations, I make the point that CO2 is not the only forcing that affects climate. You have solar variations, stratospheric aerosols (from volcanoes), methane, ozone, etc. Figures 2 and 3 are good reminders of this, even breaking down the various components based on empirical measurements.
        
        Question 2. Not sure about this, still wrapping my head around that part of the paper but in the part of the paper I think you're looking at (Section 3. Surface temperature and radiation), I don't think he's talking about outgoing radiation but net radiation balance. I could ask the author about it but I've nagged him enough asking questions and requesting data (to be used in an upcoming post), I don't want to push the friendship! Feel free to follow up with the author yourself :-)
127626. jshore at 13:08 PM on 22 September 2009
        There's no tropospheric hot spot
        It is also worth noting that the claims that "hot spot" is a signature of AGW is not correct, at least in the sense of it being a distinguishing characteristic for that particular warming mechanism. As Gavin Schmidt has shown here, the same sort of signature would be expected if the warming were due to an increase in solar irradiance: http://www.realclimate.org/index.php/archives/2007/12/tropical-troposphere-trends/ [Where the two mechanisms (greenhouse gases vs solar) are distinguishable is in the stratosphere where solar should cause warming and greenhouse gases should cause cooling. There, the satellite and radiosonde data unambiguously show cooling.] In fact, this amplification of trends as you go up in the tropical troposphere is predicated on a very basic piece of physics, what is called "moist adiabatic lapse rate theory"...And, it is expected to hold not only for the multidecadal trends but also for the temperature fluctuations over shorter intervals (say on the order of months to a year or so) due to things like El Nino oscillations. And, the satellite and radiosonde data confirm this amplification for the fluctuations (see Santer et al., 2005: http://www.sciencemag.org/cgi/content/abstract/sci;309/5740/1551 ). Where the satellite data and radiosonde data do not necessarily confirm the amplification is for the multidecadal trends...but both the satellite data and radiosondes are known to have problems that can easily produce spurious secular trends over these long time periods. So, in other words, the data only deviates from the theoretical expectations where the data is least reliable (and whether it deviates significantly depends on whose satellite analysis or radiosonde analysis or re-analysis you believe). This whole thing reminds me of the "God of the Gaps" argument. Originally, the UAH analysis of the satellite data showed the troposphere to be cooling globally...in contradiction to the surface record...and this was a major "skeptic" talking point. Then, a longer record and corrections for problems in the analysis (like the neglect of orbital decay of the satellites) turned the global cooling trend into a global warming trend, but it wasn't as strong as at the surface...and this was still a major "skeptic" talking point. Now that a still longer record and further corrections (along with a completely independent analysis of the satellite record by the RSS group) show that the trend found by satellites matches the trend found at the surface globally within error bars, the "skeptic" talking point has become the trend in the tropics. And, no doubt, when that is resolved, they will find something else to point to! No matter how little the "gaps" are, there is always room to say, "The evidence disproves AGW!"
127627. thingadonta at 10:26 AM on 22 September 2009
        Measuring Earth's energy imbalance
        Figures 2 and 3 don't have any low level cloud data, which are reduced during a warmer earth, as well as during greater sunspot activity (eg 20th century), especially in temperate climes, where most surface warming has occurred. Reduced levels of low cloud cover enhances any warming trends (approx 2.5 times the solar irradiance during sunspot cycles), as well as allowing more heat to be absorbed into the oceans and thus enhancing any radiative imbalance, but note all cloud data is conveniently absent, alomg with any discussion, in Figures 2 and 3. There are plenty of papers and research to attest to the reduced levels of low level clouds during eg the 11 year sunspot cycles (enhancing the sunspot cycles approx 2.5 times what would be expected from the irradiance alone-where is this in Figure 2?? -and where is the asscoiated 20th century climate forcing from increased sunspot acivity if they have increased markedly over ~hundred years from ~1800s, along with associated longer term effects on clouds and the radiative imbalance, known to be roughly 2.5 times solar irradiance effects throughout the 20th century??) (And before someone says sunspot effects are way too small, we KNOW the effects from sunspot cycles on earth are enhanced ~2.5 the solar irradiance alone (eg due to less low level clouds), this therefore is a longer term forcing agent that is absent in Figure 2.
127628. Manuel at 01:37 AM on 22 September 2009
        Measuring Earth's energy imbalance
        John, Thank you for sending me the paper. I think that I understand better what are different the components of the three figures, including the somewhat misnamed "outgoing radiation". My impression is that the paper deals with two unrelated issues. On the one hand, an analysis of the warming that has occurred in the last half of the 20th Century. It seems reasonable and the results consistent with other sources I have seen. On the other hand, a very interesting way of presenting the implications of the radiative forcings of different greenhouse components as estimated by sources like the IPCC reports. It shows that the effect of greenhouse gases is much bigger than the observed warming. Therefore, either their true radiative forcings are smaller or there exist other factors that are “masking” their effect. Unfortunately, the paper does not present any evidence to support either case. But, as I said, it provides indeed an interesting approach. As an aside, I agree with you that analogies have to be used with great care.
127629. Steve L at 01:12 AM on 22 September 2009
        Measuring Earth's energy imbalance
        Re Canbanjo @8: John, I agree that we should be wary of analogies, but explaining why an analogy doesn't apply should enhance understanding. Unfortunately, I thought Canbanjo had it right -- nothing is keeping the radiator at the same temperature but the outside energy input is the same. If the Earth received constant solar energy, this would be analogous. Maybe the problem is use of the word "heat"? Incoming solar energy per second equals that which leaves (at equilibrium), but in a warmer Earth rather than so much visible light being reflected straight back (not as heat), it is converted to infra-red which is trapped and can only leave as heat. But that can't be the whole problem. I guess I'm also having a problem with "cumulative" and who knows how many other concepts. I'll read the paper!
127630. XPLAlN at 23:23 PM on 21 September 2009
        Measuring Earth's energy imbalance
        canbanjo: were you thinking of a balanced heating system or TRVs fitted? John: thank you for another good article. I guess the point is that here is further evidence (as if it were needed) consistent with the Earth currently heating up. And it's empirical so it can't be blamed on 'unproven computer models'. Okay, so this isn't proof that CO2 is the cause of the imbalance; so what, plenty of other evidence exists for that. Nor does it say anything about the hypothesis that cosmic rays enhance cloud formation. But it is another nail in the coffin of the 'urban heat island' myth along with the 'it's the Sun' myth. And probably some other myths as well....
127631. canbanjo at 16:41 PM on 21 September 2009
        Measuring Earth's energy imbalance
        ah, morning, so if you have a domestic wall 'radiator' and it is on a constant temperature and you keep adding blankets to it, surely it will keep reaching a new equilibrium as the heat is trapped inside until it is hot enough to compensate for the blanket being there, but it will never 'radiate' more heat than it did to start with. so i don't understand yet.
        Response: And thus we see the dangers of using analogies - eventually the comparison breaks down and they confuse more than clarify. The earth is not like a domestic radiator because its not on a constant temperature. It gets hotter as it accumulates heat. And as it gets hotter, it radiates more heat. This is why I prefer to explain the science straight.
127632. shawnhet at 10:44 AM on 21 September 2009
        The growing divide between climate scientists and public opinion
        Chris, even if my post is off topic(and I don't think it is) that doesn't mean it is a denialist fantasy or whatever pejorative you want to use. It was a simple restatement of the scientific method and what it means for competing hypotheses. Fact is, the whole thread is contingent on what the various groups think is "significant warming", and isnce the two groups most likely don't have the same understanding of what that means, comparison is silly( so I didn't bother discussing it). Two people can agree on the exact extent of human caused warming(in degrees C) and answer the question differently. Thusly, comparison of the two polls is meaningless IMO. Do you think the respondents to the Gallup poll had the same understanding of what significant warming was as the scientists? I don't. ""Do you think human activity is a significant contributing factor in changing mean global temperatures?". The evidence is strongly on the side of a response in the affirmative, wouldn't you say?" In the scientific context, yes. In the context of the mainstream media where significant warming mean more or less two steps away from Armegeddon, then no, I wouldn't. Are you **denying** that most of the respondents get their information on GW from the media? BTW, alternative theories to the GCM centred view of climate(with strong positive feedback) are, in simple terms, negative feedback and no net or zero feedback. I would've thought that they were obvious, I don't think I need to give specific examples here. "Denialism is largely based on the presumption of ignorance and relies on a withdrawl of sufficient information from the debate that a self-serving interpretation can be induced using specious "arguments". Unwittingly or not, that’s what you’ve done. You've taken a specific and well-defined question and its responses, withdrawn all the specifics from this and substituted an information-free notion of imaginary "hypotheses" within a logical construct that forces the conclusion that you've built into it. Interesting! " And one good way to deal with any inconvenient objections is to ignore their substance entirely, call them "denialist" and never think about them again. Here is an **interesting** exercise for you: Ignore the fact that my orginal response **may** have been off-topic and re-read it on its own merits. I think you'll see that I didn't actually *deny* anything. It's pretty hard to be a "denialist" if you don't deny anything IMO. However, perhaps I am mistaken, perhaps anyone who even **questions** a scientific "consensus" is automatically a "denialist". Maybe we should come up with a term for people who call others "denialists" when they really mean "off-topici-sts" LOL
127633. chris at 09:35 AM on 21 September 2009
        Measuring Earth's energy imbalance
        I'm also a little confused by the cumulative increase in "outgoing radiation". I have an idea what it might but it isn't very clear: 1. Even though the Earth warms up, the outgoing radiation at equilibrium must equal the incoming radiation. In an enhanced-greenhouse warmer world at equilibrium, even 'though the Earth's surface is warmer and thus emits a higher radiative flux to the atmosphere, the IR radiative flux emitted to space will not increase, since it is essentially emitted at the same temperature as previously (i.e before the enhanced greenhouse), but at a higher altitude on average that corresponds to the same temperature as before. Whenever equilibrium is reached the incoming and outgoing radiation must be equal whatever the Earth's surface temperature and size of the greenhouse effect. 2. However, after a step increase in greenhouse gas concentration (as in John Cook's response to post #1), there will be a reduction in outgoing radiation, until the Earth warms up sufficiently to "force" the emission of IR back to the level that balances the incoming solar radiation.... ....so does the cumulative increase in "outgoing radiation" correspond to an increase relative to the temporarily suppressed outgoing radiation that results from the enhanced greenhouse gas concentration? In other words the "outgoing radiation" is increasing due to the recovery of the radiative imbalance as the climate system tends towards re-equilibrium. In other, other words some of the radiative imbalance is "leaking away" (as it must do) due to the tendency to progress towards a new equilibrium... ...that's how I see it...not sure 'though if it's a correct interpretation of the paper. Expressing these forcings as "cumulative forcings" is conceptually difficult to me.
127634. canbanjo at 07:56 AM on 21 September 2009
        Measuring Earth's energy imbalance
        further to 5. the cabin won't keep heating up forever but it will keep heating up as long as the insulation keeps increasing. although normally with insulation you think of turning on the central heating, so the air warms up, then the building fabric, and if it is well insulated, then it takes a long time to reach equilibrium, by which time you have probably turned the heating down. Not sure where I am going with this, but presumably the increase in greenhouse gases is slow and so on average around the planet the heating is roughly constant and the insulation is gradually increasing so there is no time lag waiting for the fabric to heat up, oh except there is, its the sea - maybe like having a big sculpture made of lead in your front room, by the heater, except the lead is fluid and transfers heat around the room and makes things really hot and steamy in some places. I'm gong to bed.
127635. Mizimi at 07:44 AM on 21 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        #23...a nice demonstration Chris of how x+ 0.2 - x =0.2 but are they real figures? I doubt it. So just for some indication I went to GISS dataset and abstracted annual mean temps for 20 stations picked at random across the globe from 1980 - 1990. Of those 20, four stopped sending data in 1990/1991 (Madrid, Riga,Fugin, Minqin). Constructed a simple mean 'global' T series from the data, then did it again dropping out those 4 stations. The result? With all stations included the ten year 'trend was 0.2C...not too far from established results. But the trend when they were removed fell to 0.12C. Not conclusive in absolute terms but enough I would say to demonstrate that both the number of stations and the area covered are vital to getting the trend right.
127636. Steve L at 02:07 AM on 21 September 2009
        Measuring Earth's energy imbalance
        Manuel, see if this thought experiment helps: Say you have a stove in a very leaky one room cabin with broken windows and the door off the hinges. The stove always puts out the same amount of heat (the energy going into the stove is always equal). It's cold, with the heat energy quickly escaping from the cabin, so you nail boards over the windows and fix the door. At first the heat from the stove escapes less quickly, and the cabin starts to warm ... but it doesn't warm forever. Eventually a new equilibrium is reached. Again, the added heat from the stove is balanced by the heat escaping the cabin, but because of the extra time spent by the heat in the cabin, you're more comfortable there. If you continue to improve the insulation, then the equilibrium temperature in the cabin will continue to increase. There is a slow down in the heat leaving the cabin with each increase in insulation, but that only lasts until the temperature inside has increased. Eventually the rate of heat production by the stove is still equal to the rate of heat emitted by the cabin. I hope this analogy is more helpful than harmful.
127637. Manuel at 19:40 PM on 20 September 2009
        Measuring Earth's energy imbalance
        John, Thank you very much for your clarification. I think I can follow the idea of energy imbalance and why it requires a higher equilibrium temperature, or more specifically, a combination of higher local temperatures that make the radiation going out equal to the radiation getting in. I say combination of temperatures and not global temperature, because it is still very hard for me to understand the physical meaning of an average temperature. I still don't understand the term "outgoing radiation" on figure 3. On your reply to my comment you say: "What is happening is the energy coming in is relatively constant but the energy radiating back out into space is being partially trapped by increasing greenhouse gases. Hence less energy going back out = energy imbalance." What is then, the "outgoing radiation" shown on figure 3? I hope this clarifies my previous question. And, in any event, I am going to take advantage of your offer to get the full paper.
        Response: The outgoing radiation in figure 3 and the outgoing radiation that gets trapped by greenhouse gases are one and the same. The earth radiates longwave radiation. As the earth gets hotter, it radiates greater amounts of longwave radiation. Greenhouse gases partially trap the longwave radiation on the way out to space.
127638. thingadonta at 12:21 PM on 20 September 2009
        Measuring Earth's energy imbalance
        A couple of points: 1) If the earth has been heating since the 1970s due to other factors than greenhouse gases (eg less low level clouds due to eg long term solar magnetic trends, delayed tipping points/feedback loops from longer term solar lag effects etc), the apparent 'energy imbalance' (ie the factors used to calculate it) would still be there(Figure 1). E.g. less clouds- warmer earth/ oceans/atmosphere= 'apparently' more energy in than out. If the oceans warmed due to less clouds, this would absorb heat coming in, without it going out, but greenhouse gases would not be producing the warming. 2) The warmer oceans from 1950s for example could be eg either 1) a lag effect from long term temperature trends, or 2) a result of less low level cloud cover. Figures 1,2,3 are models/interpretations, not data. Figure 4 appears to be data. 3)One would have to check the papers and data in more detail etc, but one suspicion is, is that ocean/land heat/atmoshpere content etc has been measured correctly, but modelled using assumptions about greenhouse gas forcing and not other possible factors, to create an apparent 'imbalance' that is not there. (The also the attached Murphy 2009 paper requires subscription).
        Response: To answer your points:
        
        1. I intentionally don't go into much detail on what's causing the energy imbalance (apart from touching on it briefly in Figure 2). That's a topic for a future post or two (or more). I'm taking baby steps here - just to accept that there's an energy imbalance is a big step for some :-)
        
        2a. The increasing energy imbalance since the 1950's cannot be a lag effect. In my response to Comment #1 and the climate time lag post, we see that if there's a change to the planet's energy imbalance (eg - increase in solar activity, increase in greenhouse gases), the planet will gradually approach equilibrium. This is not the case here - we're seeing the energy imbalance actually increasing in time since the 1950's.
        
        2b. Figure 1 is based on direct empirical observations of heat content. Narry a model is seen or used. Figure 2 is based on radiative line-by-line calculations, not climate models - nevertheless I only touch on this in passing as my main point is the overall energy imbalance, not the individual contributors. The various factors of Figure 3 are all calculated from empirical observations apart from stratospheric aerosol forcing which again is calculated from radiative line-by-line calculations. Nevertheless, my main point from Figure 3 is to compare the heat capacity of ocean to atmosphere which is hardly a controversial point to make.
        
        3a. Ocean/land/atmosphere heat content is based on empirical measurements. Modelling or greenhouse gas assumptions are completely irrelevant. We're talking about direct observations here. With all due respect, thingadonta, you need to switch off the cognitive dissonance here.
        
        3b. Sorry, I've been unable to find a link to the paper online yet, it was emailed to me. If anyone would like to read the full paper, contact me and I'll email it to you.
127639. Steve L at 11:01 AM on 20 September 2009
        Measuring Earth's energy imbalance
        Hi John, I also had a bit of a hard time following everything, but for a different reason than Manuel. For me the steady increase in cumulative forcing from solar and from ozone are problematic. In addition I'm surprised that most important negative forcing ("aerosol direct + indirect + other forcings") doesn't get a fuller description. Is the paper explicit about these things?
        Response: The stratospheric and tropospheric ozone forcing is taken from NASA GISS data - there's a page on the NASA website going into details on how this is calculated. Re "aerosol direct + indirect + other forcings", this is actually one of the major points of the paper - I chose to concentrate on the simpler issue of energy imbalance (the reasons become evident if you read comment #3).
        
        Aerosol forcings are one of the major areas of uncertainty with climate models. So what this paper does is place empirical constraints on aerosol forcing by working out the total energy imbalance, then pruning away other forcings that we know with greater certainty. What is left is "aerosol direct + indirect + other forcings".
        
        If you'd like the full paper, contact me and I'll email it to you.
127640. Manuel at 07:40 AM on 20 September 2009
        Measuring Earth's energy imbalance
        Hi John, I don't follow completely the reasoning behind this paper (or maybe that of your excellent summary). You start your post saying: "When the Earth is in energy imbalance, with more energy coming in than radiating back out into space, we experience global warming." But then, you say: "Note that outgoing radiation is on the increase - another indication that the planet is indeed warming and consequently radiating more energy back into space." But if Earth is both warming and also radiating more energy out, it means that the energy coming in is also increasing. Where does this extra energy come from?
        Response: Very good questions and apologies for the confusion. There is a lot more to the paper than what I outlined above - I focused on just a few of the main points of the paper in an effort to be concise and accessible - perhaps not successfully!
        
        No, the energy coming in isn't increasing. In fact, that's another important point to make. We have satellite measurements of incoming solar radiation and it shows little to no long trend over the past 50 years. What is happening is the energy coming in is relatively constant but the energy radiating back out into space is being partially trapped by increasing greenhouse gases. Hence less energy going back out = energy imbalance.
        
        In fact, the paper explains some of the basics of this process by imagining what would happen to global temperatures if there was a sudden increase in greenhouse gases (a hypothetical simplified situation for the purpose of understanding the physics involved):
        
        
        
        If greenhouse gases suddenly increased to a new level, the planet would suddenly be in energy imbalance. The energy out would be less than the energy in and the planet would start accumulating heat. Hotter objects radiate more energy. Therefore, as the planet gets hotter, it radiates more energy so the energy imbalance lessens. Eventually the planet will have accumulated enough energy so that the energy out approaches the energy in. Eg - the system approaches equilibrium.
        
        This is why we talk about there being 'warming in the pipeline'. Even if we completely stopped all our CO2 emissions right this moment, we would still be left with a significant energy imbalance. It would take several decades of warming before the planet reached equilibrium. And that's a best case scenario. Of course we're not going to immediately stop CO2 emissions so the energy imbalance will only increase in the years to come.
        
        I tried explaining this process in the Climate Time Lag post but people seemed confused there too - I might have to rework my explanation of the whole process :-)
127641. BKsea at 06:37 AM on 19 September 2009
        The growing divide between climate scientists and public opinion
        One of the overlooked aspects of this discussion is what the question means: "Do you think human activity is a significant contributing factor in changing mean global temperatures?" To a scientist, this may mean "Is there a correlation between human CO2 release and global temeperature change that exhibits a p-value less than 0.05?" To a non-scientist, it might be interpreted as "Is human activity directly impacting my life through changing temperatures?" I think this is part of the big challenge for scientists. We communicate and interpret through our scientific filters. But those filters may be distorting the message received outside the scientific community or our interpretation of the messages coming in.
127642. chris at 20:41 PM on 18 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        re #26 Not really WA. I don't think you've made an effort to investigate the US Climate Reference Network (USCRN). One can learn about the history of the development of this network here: http://www.ncdc.noaa.gov/crn/ and more specifically, here, for example: http://www1.ncdc.noaa.gov/pub/data/uscrn/publications/annual_reports/FY08_USCRN_Annual_Report.pdf In a nutshell, the USCRN was set up following a recognition starting in the mid-90's that it would be very useful to set up a network of US climate monitoring stations that would give a very long term (50-100 year) uninterrupted data set for high quality US climate analysis into the future. The network is part of the continuing role of the NOAA, enshrined by legislature to do climate monitoring. In other words it's a major role of the NOAA to continually assess its products and consider improvements/updates, much like any organization with a defined role. The essential nature of the USCRN was defined in a consultative period which came up with a set of principles by around 1999. There then began the process of planning, site acquisition, testing, quality control etc., with the first stations going "live" around 2001. There are now around 130 of these. Now that's all very well documented. The network was a response to careful analysis and planning and didn't have much to do with people "making a fuss".....nor did it have anything to do with "tooth fairys".
127643. chris at 20:38 PM on 18 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        re #25 You're not really addressing the data Mizimi, and what you "think" isn't a good basis for addressing science. That's a theological position (see WA message above). After all you "think" that that web site you linked to is useful when it's demonstrably rubbish (see my post #23). So if you don't "think" that 100 stations is enough to determine the temperature anomaly "over a 1200km sq cell" you should give some evidence why. In fact you've misunderstood the 1200 km correlation point. The fact is (this can be ascertained by examining station data output [*]) that the temperature anomaly is well correlated between stations even if these are separated by quite large distances (up to 1200 km in middle to high latitudes). That means that data from stations separated by medium and even large distances can be combined to give high spatial coverage with apparently sparse sampling to determine the gridded anomaly. Obviously this wouldn't work if we were interested in some spurious notional "average temperature" since the absolute temperature varies markedly on the small spatial scale. But we don't pretend to be interested in that (whatever dodgy web sites say!); we're interested in the referenced spatially-averaged temperature change (the anomaly). If you don't understand this fundamental point you're simply not going to be in a position to comment meaningfully on the data. Do we have scientific evidence that this is valid? Yes. We can calculate the profile of temperature anomalies using sub-sets of the total data. This has been done numerous times. An example is given in Figure 2 of John Cook's top post in which the temporal temperature anomaly profile for the contiguous US is calculated using a subset of the 70 best stations. It's very similar to the profile determined from the full record. That's not surprising since while absolute temperatures are highly non-correlated on the local scale, the temperature anomaly is rather well correlated. So we don't need a vast number of stations to determine the temperature anomaly. In another theological argument you say you don't consider 100 stations since 2001 as being significant". In fact the US Climate Reference Network has constructed around 130 stations in the new network covering the entire US since 2001. If a representative anomaly can be reconstructed from a subset of 70 temperature stations (see John Cook's Figure 2 above), I wonder what lends you to consider that 130 optimally sited stations with carefully optimised spatial coverage isn't even "significant". Note that 130 sites covering the US (2% of Earth surface) is equivalent to 6500 sites averaged over the earth’s surface. That’s a good coverage. In fact the real difficulty in obtaining full spatial coverage in the past has been the large areas of ocean that were poorly represented. However with the advent of satellite sea surface temperature measures, and improved networks of in situ sea surface measures….that situation has changed and there is now good ocean coverage. Re your comment: “obviously NOAA concedes there is a problem …”, that also needs some qualification. There is a continual drive to improve methodologies and analysis (e.g. see [***] for the most recent improvements in NOAA surface temperature analysis). That’s an on-going process in science. The existing met station network and other records has produced useable data since the late 19th century and the methodology for analysis and quality control has been continually improved as described in many dozens of papers over the past 20 years. If the advent of satellite sea surface temperature measurements can improve SST coverage then why not include this vast resource into the surface temperature analysis…improved in situ sea surface measurements from buoys and disposable instruments has been made – why not include those? If we can construct an improved network of met stations in the contiguous USA, then great. None of this means that pre-existing networks and analyses were not adequate. But given decent funding and scientific inventiveness, we can always make things better, and that’s done in climate-related science as in any scientific endeavour. If you’ve got some substantive criticism of these methods then address them specifically. Referring us to dismal websites that are rather obviously designed to mislead the poorly informed isn’t “skepticism”. [*] see papers describing NASA Giss methodologies here: http://data.giss.nasa.gov/gistemp/ [**] papers describing Hadley Hadcrut methodologies here: http://www.cru.uea.ac.uk/cru/data/temperature/#sciref [***] see this paper for example, for recent improvements in the NOAA surface temperature record: Smith TM, Reynolds RW, Peterson TC et al (2008) Improvements to NOAA's historical merged land-ocean surface temperature analysis (1880-2006). Journal of Climate: 21, 2283-2296. http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F2007JCLI2100.1
127644. chris at 20:30 PM on 18 September 2009
        The growing divide between climate scientists and public opinion
        Shawnhet, your post doesn't address the subject of this thread, but instead is about a sort of made up denialist fantasy. John Cook's top article and the paper under discussion addresses two quite specific things, the most general being the disconnect between informed opinion and public opinion in the US , and more specifically the response to two straightforward questions about (i) whether the global temperatures have risen since the late 19th century, and (ii) whether human activity is a significant contributing factor in changing mean global temperatures. There is nothing in these questions or analyses that have anything to do with GCM's and one wonders why you wish to attempt to introduce a denialist "stalking horse" where it doesn't belong. The evidence that the global temperature has risen (point i) has nothing to do with GCM's (it's the result of direct observation of land, sea and tropospheric temperatures, mountain glaciers, high latitude ice sheets, sea levels, seasonal climate effects, trends in the biosphere etc.). The evidence for the contribution of human activities (point ii) also has little to do with GCM's (it's the result of basic empirical and theoretical knowledge of the greenhouse effect and greenhouse gases, understanding of natural contributions to temperature change, and empirical knowledge of the variation of greenhouse gas concentrations and of natural factors). So your curious notion that the top article lends us to consider a "choice" between GCM's and some "alternative hypothesis", is doubly bogus in the context of the top article and the paper being discussed. (I wonder what your unstated "alternative hypothesis" might be!). Your last sentence/paragraph is a contrived "forced sequitur", where you've chosen to drift from the clear and explicit (points i and ii) to the vague and undefined. Specifically, the question addressed in the survey that both scientists and public responded to is "Do you think human activity is a significant contributing factor in changing mean global temperatures?". The evidence is strongly on the side of a response in the affirmative, wouldn't you say? However you've chosen to elide from the specific to the vague ("hypotheses A and B" which you say are "equally likely to be true"!). Which hypotheses might these be?! Obviously if you postulate two imaginary undefined hypotheses of which you've made up a notion that they are "equally likely to be true", then obviously we might question whether expert opinion can reliably distinguish these. But, of course, that's not what the thread, the top article or the paper under discussion is about, which is something quite specific. Denialism is largely based on the presumption of ignorance and relies on a withdrawl of sufficient information from the debate that a self-serving interpretation can be induced using specious "arguments". Unwittingly or not, that’s what you’ve done. You've taken a specific and well-defined question and its responses, withdrawn all the specifics from this and substituted an information-free notion of imaginary "hypotheses" within a logical construct that forces the conclusion that you've built into it. Interesting!
127645. georgebailey2 at 07:13 AM on 18 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        First post, please don't attack. Some thoughts crossed my mind as I read this and the various responses and I hope I can make those thoughts clear. With regard to the temperature anomaly, I understand the concept and that the change is important in trying to determine directional temperature trends. There was a point I think that thingadonta was trying to make in #5 with regard to Tom Dayton that Former Skeptic tried to counter in #7. If the absolute temperature error is constant, and the dynamics of that particular station are constant, then there is no effect on the anomaly. First, let\'s leave the dynamics of a particular station alone. If, in a perfect measurement, the station should read 32.0 degrees F, but it reads 32.2 degrees then for the anomaly to be unaffected, on a 95 degree day, the station should read 95.2 degrees. I would hazard to guess that the differential goes up in correlation with the increase in temperature above some certain level (e.g. the initial .2 degree difference may be unchanged until the real temperature reaches 50 degrees then begins to increase slightly thereafter due to external radiative influences). My question is whether there are similar influences that could make it go the other way, such as ice/snow on a 40 degree day and, even so, would that extend to temperatures below freezing? Also, I don\'t know if I should read anything into the fact that Figure 2 is in Fahrenheit while the NCDC ratings for range of error are in Celcius. Just thoughts about this topic and this topic only.
127646. TOP at 04:06 AM on 18 September 2009
        Water vapor is the most powerful greenhouse gas
        Something to consider. The global dew point has been rising faster than global temperature. At the same time the pan evaporation rate has been dropping with an increase in global temperature.
127647. Former Skeptic at 02:04 AM on 18 September 2009
        It's Urban Heat Island effect
        Paravantis: So, from your econometric training, are you saying that UHI is NOT affected by wind?
127648. Cryptonomicon at 00:30 AM on 18 September 2009
        The correlation between CO2 and temperature
        I can see your argument about the dips being about a trend but I still have several concerns with the data. As you mentioned you can not look at just a small piece. The same argument also holds for the pro global warming argument. You can't just look at the last century. You need to put the current temperature profile into the context of the whole of the Quaternary. Believe me doing so is non trivial. The issue I have is the unusual "flat spot" if you want to call it that of the last 10,000 years. Historically as you would know the Holocene we are in is an extremely unusual interglacial in the middle of the Quaternary glacial period. The argument is that the reason humans were able to develop civilization in the first place is because of this unusual warm flat temperature range. Simply put we got lucky. We evolved for far tougher conditions and the nice comfortable range of the current interglacial meant that humans were able to spend less time just surviving and more time thinking. The crux of my problem is that the flat range is unusual. It was due to end thousands of years ago based on the periodicity of the data - which btw simply screams Fourier Series. So how do you demonstrate absolute causal dependency between CO2 and temperature and disprove the possibility of a bigger problem - the end of the Holocene - or worse the end of the Quaternary period driven by massive effects that we have no hope of controlling. Remember temporal dependency does not imply causal dependency. Just because things occur at the same time does not imply one causes the other. If it did you could correlate your temperature rise to the amount of music played on the planet - which also increased over the 20th century. Why are you so convinced that the correct response is to try and fight change rather than adapt to it? Why would global warming be bad? Think of the consequences of a reduction in human population versus an increase? It seems a rather arrogant echo of King Canute to think that man can make the Holocene last forever simply by commanding it so
127649. shawnhet at 02:02 AM on 17 September 2009
        The growing divide between climate scientists and public opinion
        Am I the only one here who thinks that polling scientists to find out their *opinions* is silly. Science is about making *predictions* about things that we haven't observed yet IMO. Regardless of what the opinion of scientists working with them, they only get to claim superiority of their *hypotheses* when they are able to demonstrate some valid *risky* predictions of the phenomena they consider. While the GCMs haven't been falsified yet (at least IMO), that doesn't mean that they have enough evidence to allow us to choose them over one of the alternative hypotheses. If hypotheses A & B are equally likely to be true(based on the evidence), then the fact that most scientists believe A to be valid and most plumbers believe B to be valid, doesn't mean that we should take the *beliefs* of scientists to be more likely true. Cheers, :)
127650. Wondering Aloud at 01:24 AM on 16 September 2009
        Is the U.S. Surface Temperature Record Reliable?
        Sub set etc... does a different subset have different results? I espect so but it doesn't even matter the point is that the uncertainty is much larger than people pretend and indeed larger than the entire signal. I am still hopeful for significant warming but belief... As to fixing the stations... Do you think that would have gotten funded if no one had made a fuss about the problem? If so do you also believe in the tooth fairy? We were doing corrections with a "algorythym based on low resolution satellite photos.

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