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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 51001 to 51050:

  1. Doug Hutcheson at 10:36 AM on 5 December 2012
    Climate's changed before
    skywatcher @ 335 You said
    Real-world geophysical events are not controlled by the Moon, but by much larger forces - motions, stresses and sources of heat within the Earth.
    I seem to remember reading that the tidal stress of the moon's gravity acting on our rocky planet generates some of the heat in our core, so some earthly geophysical effects may be contributed to by this influence. Certainly not by the phases of the moon, but could lunar perigee/apogee gravitational differences be enough to have an effect on Terra? I doubt it.
  2. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    Tom Curtis@22: The pink line in Figure 3 terminates outside what is probably the "ensemble envelope" (the green shade). Your reasoning is that La Nina's are responsible but these events don't count in the longer term. I'm not so sure that is true. I think the major oscillations advance temperature (or not) by changing the ratio/frequency of El Ninos to La Ninas. If I am wrong then there is no need to compensate for ENSO since there will be no secular trend in it after you get past 15 years of trend length or so. As for volcanic influence there is none significant in the last 17 years or so. As for solar, 2013 will be getting into the peak of cycle 24, although it is a weak cycle. All this leads into a prediction for 2013 which Dana has made (GISS = +0.76). I'm not sure if he's going to update that based on the most recent ENSO prediction, but I don't believe 2013 will be that warm. It would be a record by quite a lot. Either way it will be a test of the hypothesis the real warming trend is being suppressed by ENSO/TSI.
  3. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    Klapper @20... You didn't answer my question. Would it change the conclusion of the graph? If not, why does it matter?
  4. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    Klapper @18&20, the most recent years data is not shown in figure 5 for the simple reason that it was prepared in Oct 2011, and only used data to that date. Preparing these graphs is time consuming, unfortunately, slanders to the effect that SkS authors are paid for their efforts are in fact false. Dana's herculean efforts are unpaid, and he must find the time for them between the hours spent in paid employment and independent (peer reviewed) academic research. Consequently graphics are not updated with every reuse, nor with every update of the data source. As it happens, if you do prepare a graph of Gistemp with a 12 month running mean, the result is effectively the same as the pink line in figure 3 above. The decline in temperature is so slight that all of the denier predictions other than Akasofu's are still falsified by the data, and Akasofu's prediction is running on the edge of falsification. If you account for volcanic, ENSO and solar influences (as in the red line in figure 3), it is clear that the temperature increase has been accurately predicted by the IPCC TAR and AR4, and not accurately predicted by any denier. In the meantime, I am left wondering, how often will it be necessary to state the obvious: La Nina events are not the same as the onset of the next ice age. That is so obvious a point that you would think that just once deniers would extract the ENSO signal before discussing whether temperatures have increased or not.
  5. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    Rob, This gets so tiring. Is there anything that is not construed by certain types -- let's call them D'ers -- as part of some vast conspiracy?
  6. Philippe Chantreau at 09:01 AM on 5 December 2012
    The Greenhouse Gas Effect All-Star Fan Club
    Seems Aaron gives a pass to the 2nd law but not the 1st...
  7. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    Rob Honeycutt @19: Why not show the downturn then? Who's going to to offer up the reason the temperature graph was terminated on a high point (2010), while the forecasts continued to 2011?
  8. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    Klapper @18... Do you believe that would change the overall conclusion of what the graph is presenting?
  9. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    [snip] The GISS SAT record in red appears to end in 2010. I realize it is a centred running average, however the trace could have been extended to 2011, assuming the smoothing was less than 18 months or so. The record should turn sharply down after 2010 but this part of the trace is ommitted.
    Moderator Response: [RH] Snipped per policy.
  10. 2012 SkS Bi-Weekly News Roundup #3
    Agreed, shoyemore, and for the future, this jetting around the globe to faraway destinations for talks about climate change is, IMNSHO, anathema to the raison d'etre of the COPs: Seems to me that the vast majority, if not all the business at hand could be done using teleconferencing, or at least at the same central location, year to year. That's going to have to be part of 'walking the walk,' for JSP (Joe Six Pack) to even come close to buying what the science is saying.
  11. It's El Niño
    It will be interesting to see if Bob returns to answer the questions he's yet to answer: however, in the meantime, he's back at W**T, galloping along with the same tired, rebutted points that he wouldn't answer here. I was looking forward to his answers.
  12. The Greenhouse Gas Effect All-Star Fan Club
    Another resource: I found this paper to be very well written, interesting and useful. Ray Pierrehumbert in "Physics Today" on Infrared Radiation and Planetary Temperature
  13. The Greenhouse Gas Effect All-Star Fan Club
    Aaron Edwards@8: it's said that for every problem, there is a simple elegant answer...which is also wrong. Your supposition, "CO2 by comparison, is inconsequential in moving heat into the atmosphere." is one of those wrong ones. Further discussion of ENSO should be taken here. http://skepticalscience.com/argument.php?p=1&t=153&&a=57
  14. The Greenhouse Gas Effect All-Star Fan Club
    Aaron, I do hope you'll go on to post your concerns with the science, and do so on the appropriate threads. For example, maybe you can help Bob Tisdale figure out a physical mechanism for his claim that ENSO is a forcing. Also, a question: what's worse -- a democracy that thinks that climate sensitivity is perhaps half of the mainstream mean, or a democracy that thinks the greenhouse effect is a fraud designed to squeeze the taxpayer? Which question deserves more attention on a site that is trying to A) communicate the published science to the general public, and B) de-bunk the accountability-free claims of the merchants of doubt?
  15. The Greenhouse Gas Effect All-Star Fan Club
    The Duncan Stewart demonstration is probably the best demonstration of the CO2 Greenhouse Effect on the web. Apparently, in some other video demonstrations, there may be other influences or contamination. Beware of smartasses who may point that out!:) Eli Rabett's Puzzle Right Results, Wrong Physics Quote: "Classroom experiments that purport to demonstrate the role of carbon dioxide’s far-infrared absorption in global climate change are more subtle than is commonly appreciated"
  16. CO2 effect is saturated
    curiousd @178, I recently created a radiative model of the atmosphere on a spreadsheet to analyze related questions. The result is that essentially all Outgoing Longwave Radiation (OLR) has its last point of emission before being radiated to space in the lower 30 km of the atmosphere, ie, from the surface, troposphere or stratosphere. Above the stratosphere, atmospheric density is so low that emissions from those altitudes are negligible. My model was too simple to include additional factors (pressure broadening of emission bands; declining CO2 content of the atmosphere above the tropopause) that would reinforce the result. Consequently any satellite, and even sufficiently high flying aircraft, will show essentially the same spectrum. You can experiment with the effect of altitude (up to 70 km) using the modtran model placed in the net by David Archer. Just compare different Iout values for different look down altitudes without changing other settings. With default settings, I obtained the following results: 70 km - 287.844 W/m^2 35 km - 287.027 W/m^2 20 km - 287.593 W/m^2 15 km - 291.863 W/m^2 10 km - 306.433 W/m^2 5 km - 348.54 W/m^2 2 km - 387.79 W/m^2
  17. The Greenhouse Gas Effect All-Star Fan Club
    Great to see a plug for Science of Doom (SoD) here. If you're keen to build your understanding of the fundamentals of this topic in a fully comprehensive and methodical way, you'll find SoD's explanations a real treat.
  18. The Greenhouse Gas Effect All-Star Fan Club
    Aaron @ 8... I believe the point is that there's a very noisy faction of climate change deniers who reject very fundamental and well understood science. If you spend any time reading the comments on WUWT, Jo Nova or Judith Curry's blogs you find that there is a sizable percentage of their most vocal following who subscribe to the "there is no greenhouse effect" theory. Those (quite honestly) insane viewpoints tend to get allowed on their blogs because they merely hold the same anti-AGW position.
  19. The Greenhouse Gas Effect All-Star Fan Club
    Aaron Edwards @8, the "ignorant small minority" represents a sizable fraction of AGW deniers on the internet including many regular readers of, and even guest commentators at AGW denial sites such as WUWT. Apart from the few rare statements such as those collected above, the opinion leaders in AGW denial largely ignore the unscientific clap trap from those who deny even the atmospheric greenhouse effect. IMO, the blind eye they turn to pseudo-scientific poppycock is motivated by their political ends. They do not debate climate science because they are interested in the truth about climate science, but because they desire a political stalemate on action to combat AGW. A political stalemate based on misinformation and pseudo-science is as useful to them as one based on valid criticisms. Indeed, in the end it is all they have to offer. Consequently they turn a blind eye the pseudo science offered by others because, politically, it is as useful as the pseudo science they themselves offer. Only when their reputation started to become tarnished by the association did they speak up - and then having made the appropriate declarations, went back to largely ignoring or egging on of the claptrap they claim is false. It is because of this lack of intellectual integrity by the leading opinion makers among AGW deniers that we must waste time rebutting nonsense such as the denial of the atmospheric greenhouse effect; or other tacit rejections of the laws of thermodynamics such as the claim that the Pacific Ocean (which is warming) has caused the atmospheric warming by loss of heat.
  20. CO2 effect is saturated
    There's a very useful description of the theory, design and operational principles of the AIRS instrumentation at JPL, curiousd. How AIRS Works I'm certainly no expert but it appears the height of the instruments in this context is insignificant in the same way the distance to a star is not important when obtaining information via spectroscopy.
  21. Sheffield vs. Dai on Drought Changes
    A good source of data, viz. drought. USA Drought Information portal.
  22. The Greenhouse Gas Effect All-Star Fan Club
    I am a newcomer to your blog and just read the article claiming that persons who are not convinced of catastrophic global warming believe that the greenhouse effect of atmospheric water vapor and other trace gases does not exist. You then list experts in the field who believe as I do (that there is no looming global warming catastrophe that will destroy mankind) who plainly state the greenhouse effect does exist. I am confused as to the point of the article. What ignorant small minority believes that there is no greenhouse effect and why do you address them? What does a reference to these inconsequential people have to do with the work of highly qualified individuals asking legitimate scientific questions about the data and the science behind the claims of the climate alarmists? I am also surprised by your statement, “Of more general interest, the history of climate science is largely the history of what we've learned about CO2.” A more accurate statement would be, “Of more general interest, the history of climate science is largely the history of what we have learned about the chaotic behavior of the ENSO and the redistribution of Pacific Ocean heat into the atmosphere.” CO2 by comparison, is inconsequential in moving heat into the atmosphere.
  23. The Greenhouse Gas Effect All-Star Fan Club
    Son of Krypton@6, *please* keep me informed of your pseudoskeptic's responses! harwig57 at gmail dot com.
  24. Son of Krypton at 02:52 AM on 5 December 2012
    The Greenhouse Gas Effect All-Star Fan Club
    @John, reading your post at work was a rather terrible idea. Trying to stifle the resulting laughs took far more effort than this cold morning warrants. This post is definitely a gem, and it will be put to good use. I've been in an online fued of sorts with a pseudoskeptic in online debates for more than a year now who often claims there is no evidence for the greenhouse effect and that CO2 is such a small trace gas that increasing amounts have negligable effects. Given that Spencer, Christy, Lindzen and Singer are his favourite sources, this should be a real treat to see
  25. 2012 SkS Weekly Digest #48
    Vrooomie: Looks like an interesting read (I just ordered it from the library). Since I'm relatively new to wrestling with the discourse and I come from a family of climate change deniers, I'm pretty sure I'm the target audience. I am still struck by the incongruity of using a mythical behavior to depict the opposing camp when the opposing camp seems to obfuscate the conversation with myth. But since I can't come up with a better image (a walrus covering it's eyes? do walruses do that?), perhaps the "useful metaphor" is appropriate.
  26. The Greenhouse Gas Effect All-Star Fan Club
    Well played, John Brookes. Well played.
  27. CO2 effect is saturated
    Question here from a physicist educator. I have looked at these satellite comparisons between time frames. I particularly like the last in the series by Chen, et al. They look at the difference between spectra taken in two different satellites between, 1970 and 2006. But, if one were to look at outgoing IR as a function of height, does not the degree of saturation and therefore the details of the spectrum depend on the height you are measuring from? Do we care how precisely these two satellites are at the same height, here? Or perhaps all satellites are so high that the effect I am concerned about is not an issue? This is my first effort to try to understand one of these satellite papers in detail. Therefore I realize my question is probably naive to the expert.
  28. The Latest Pre-Bunked Denialist Letter in Lieu of Real Science
    As soon as you see "no significant warming since xxxx", you know you are dealing with the undead.
  29. The Greenhouse Gas Effect All-Star Fan Club
    I'm sorry, but just because you've got a lot of people agreeing, that doesn't make them right. I remain absolutely convinced that there is no greenhouse effect because it contravenes the 2nd law of thermodynamics. Now I don't really know what the 2nd law of thermodynamics is, but I've hung my hat on it, and there it will stay. You can't convince me I'm wrong, because I have no idea why I'm right. So don't even try, or I'll create this great big fog of words, so that no one can see what my position is at all. And more than that, I'll get indignant and abusive. So there!
  30. The Greenhouse Gas Effect All-Star Fan Club
    Definitely a keeper ;) Will use this one ;) I don't think the "skeptics" will ever give up, they will deny and deny, somewhere in 2025 we will still be discussing with some "skeptic" that there has been no statistical significant global warming since 2018
  31. The Greenhouse Gas Effect All-Star Fan Club
    Of course we hate to make predictions, but based on this emerging trend of concessions about the greenhouse effect surveyed here, I'd like to predict that the grand philosophical tradition of 'Climate Change Skepticism' will melt away at the same rate as the multi-year Arctic ice, and be all gone by the end of this decade. I can't wait to hear them denying their denial.
  32. 2012 SkS Weekly Digest #48
    AML, to fully understand the power of the term "an ostrich with its head in the sand," which is indeed a myth, but a useful metaphor, I *highly* recommend an obscure book; titled "The Standardization Of Error," By Vilhjalmur Stefansson. The term's mythic nature in no way detracts from its usefulness as a tool to describe, in simple and unambiguous terms a concept virtually all literate adults can understand. It would only be ironic is it were used as if it were employed as a fact: it is not.
  33. The Greenhouse Gas Effect All-Star Fan Club
    Amazing how the non-scientists among that august gang, can't *quite* bring themselves to unequivocally state the greenhouse effect actually exists: Monckton's "concedo" is one of the more stilted ones, reflecting his inability to just speak in plain language, ditto Jo Nova. Funny how Monckton "concedes" that the past 150+ years of research actually *might* be right! Thanks, Daniel, for a excellent, well-organized post.
  34. President Obama's Statement on Climate Change
    @vrooomie : “Had the vehicle-miles remained static”… but they don’t ! That is exactly the point I am trying to make: scientists are used to do experiments in which 1 parameter varies, while all other parameters remain fixed. It doesn’t work like that in the real world. According to the economic law of supply and demand: if the price of a product goes down (in this case the price of a vehicle-mile) then the consumption of this product increases. So consumed vehicle-miles go up as a direct consequence of improving the fuel efficiency. There is a relationship, and it must be taken into account.
  35. 2012 SkS Weekly Digest #48
    AML, in the minds of the target audience (those who do not have the time, energy, training, and or means to engage the entire body of research, but still desire to ask questions, learn, and wrestle the discourse), the myth is more likely more of a reality than the reality. In other words, it's an effective metaphor, no matter what ostriches do when they get spooked.
  36. It's El Niño
    Kevin C. Kudos for taking the time to tease apart some of the artifactual conclusions in Bob Tisdale's approach. Perhaps if he had been careful to consider and to address the fundamental questions repeatedly put to him, he might have been able to rise above his biases and see the bigger picture, and the factors that impinge on it... assuming that he does not already do so in private. I'm looking forward with interest to the validation post. Between you and Tom Curtis' patient work, perhaps Tisdale will realise that he's holding the wrong end of the stick (again, assuming that he does not already do so in private). And if he cares to refute your work and Tom's perhaps finally he'll do so with some recognition and explicit incorporation and description of the breadth of underlying physical influences.
  37. 2012 SkS Weekly Digest #48
    I just stumbled on SkS and it promises to be a great resource. Thanks for all the info! I think it's strange that the cover of the book "Climate Change Denial: Heads in the Sand" and the cartoon above both depict an ostrich with it's head in the sand. I've heard from multiple sources that this is a myth. It seems strange to appeal to the mythical effect when seeking to expose the myth promulgated by Climate Change deniers. Is it meant to be ironic?
  38. It's El Niño
    So far I’ve constructed a plausible model which the statistics say is more informative concerning the rest-of-the-world SST data. The next steps are as follows: 1. Dismantle the model to find out how it works. That’s helpful in trying to relate the model to mechanism, which is after all what we are after. 2. Validate the model: Test whether the model is robust to the choice of data and whether it has predictive power. I’ve been working on the first of these. So far I’ve highlighted how the use of two lags improves the fit to the data, as well as reducing the impact of the two anomalous features Bob identified. Whether that reduction is justified we’ll come to in the validation step. However once I started breaking down the model, it became obvious that the two-lag effect, while it makes a difference, is not the principle effect in reducing the two anomalies. The most significant causes are much simpler: The volcanic term, the trend and the scale. These are strongly interlinked in ways which are counterintuitive. Initially it seems implausible that the volcanic term should contribute to the anomalies, because they do not overlap in the time series. However, the interaction of the unmodeled volcanic term and the detrending of the SST data have exactly that effect. The reason is shown in the following animation, which shows the removal of a trend and offset from the volcanic term: Because the volcanoes are negative, detrending them shifts the whole series upwards. Because they are offset towards the start of the frame, the beginning is shifted up more. This creates a positive bias for the non-volcano influenced periods. Add a noise signal and negative excursions become ‘normal termperatures’ while positive excursions become ‘anomalies’. Now the SST signal contains the volcanic term, so detrending the SST data without removing the volcanic term introduces exactly this kind of bias. And the bias is significant in the two regions where the two anomalies occur. We would have detected this straight away had we looked at the data on a longer time frame. The interplay of all these factors in the model is moderately complex. In the following animation I’ve rolled the volcanic term into the Nino data and scaled it from zero to full scale during the animation. That takes us from the simplest Nino34-only model to a single-lag+volcano model. The model is regressed against the data with trend and offset. R2 is shown top right. The other point of note is the scale of the model. At the start the fit is very poor owing to the omission of the volcanic term from the model. The scale of the model curve is also very small - it looks too small. In fact this is the expected behaviour. The explanation is non-trivial, but is consistent with determining the ‘best’ (most probable and/or least noisy) model under the assumptions of least squares. The result can be understood from a perspective of likelihood, or least squares, or random walk statistics, but I’ve not heard a good intuitive explanation. Here are my best efforts: 1. When the model is poor, it contains features which agree and features which disagree with the data. Inflating the model increases both, but the parts that disagree quickly begin to hurt you more, so the optimum scale is smaller than the data. (From least squares.) 2. When the model is poor, you have to leave some variance for the terms that are missing from the model, and so the incomplete model must be on a smaller scale than the data. (From random walk.) This is related to the well known result that when calculating a best fit straight line through some data you get different results depending on which is the dependent variable. In other words, the scaling of the model is chosen to minimise artifacts due to the limitations of the model. It's trying to protect you from interpreting noise as signal. You can of course change the appearance of the graph by playing with the offset, scale and trend, or by adopting heuristics for setting each of these. However, there is only one ‘most probable’ model, and that is the one produced by the least squares calculation subject to the OLS assumptions. So to summarise, the two anomalies identified by Bob appear to arise from the confluence of 3 factors: 1. Bias in the trend and offset caused by the omission of the volcanic term. 2. The use of a single rather than double lag. 3. The scaling of the Nino34 data. That’s the analysis step. As I’ve said, the next step is validation. We need to test whether this model is robust - i.e. whether the results are strongly dependent on the choice of data, and whether it has predictive power.
  39. It's El Niño
    Further to my comment @146, in trying to follow up some further points I downloaded the HadSST3 data for the Nino 3.4 region, using a 15% data cutoff. I then calculated the anomaly average for 1912-1944, 1944-1976, and 1976-2006. (2006 is the last year with data available from the KNMI Climate Explorer. The calculated means are: 1912-1944: -0.068 C (compared to Tisdale's claimed 0.18 C); 1944-1976: -0.042 C (compared to Tisdale's claimed -0.05 C); and 1976-2006: 0.303 C (compared to Tisdale's claimed 1976-2011 mean of 0.16 C) Elsewhere Tisdale has claimed:
    "By smoothing NINO3.4 SST anomalies with a 121-month filter, Figure 3, the periods when El Nino and La Nina events dominated become apparent."
    While not agreeing with the supposition, the 121 month running mean of the data certainly shows Tisdale's claim that the mean of the period 1912-1944 is greater than that from 1944-1976, and even then 1976-2011 to be false: Tisdale does not specify which version of the HadSST he uses, so I obtained the graph of the HadSST2 anomaly data for the Nino 3.4 region to ensure the problem was not just the updated data set: You can easily detect the periods of interest. 1912 immediately follows the very large negative excursion just after 1900 (the largest La Nina event on record according to the SOI). 1944 immediately follows the large positive excursion following 1940. 1976 immediately follows the double troughed negative excursion preceding 1980. The data from 1912-1944 is a little noisy, even though I used the 0% cutoff on data to net every observation in the region. Never-the-less it is clear that the peaks (El Ninos) in 1912-1944 are not as strong as those from 1976 forward; and that the troughs (La Ninas) are both deeper and more frequent. Therefore the difference between my and Tisdale's result is not a consequence of the different data sets. It looks to me as though Tisdale has subtracted a linear trend from the anomaly. However, he does not mention doing so. Bob, would you please specify the exact methods used in obtaining your averages? And would you also specify the exact cutoff dates for your periods of interest?
  40. Rahmstorf et al. Validate IPCC Temperature Projections, Find Sea Level Rise Underestimated
    DSL, Doug, Ian and Stephen, Thanks for your help - I now understand where I went (very) wrong. SKL's point about the glossary is a good one - the acronyms in climate science are a minefield unless you are an aficionado!
    Moderator Response: [DB] A Glossary is under development.
  41. Stephen Baines at 03:58 AM on 4 December 2012
    Rahmstorf et al. Validate IPCC Temperature Projections, Find Sea Level Rise Underestimated
    Sorry...I meant the prediction based on equilibrium climate sensitivity should be substantially higher than observed over a short time frame, before equilibrium occurs.
  42. Stephen Baines at 03:50 AM on 4 December 2012
    Rahmstorf et al. Validate IPCC Temperature Projections, Find Sea Level Rise Underestimated
    Jim, As usual other respond before I do. First, the relative increase in CO2 emissions that you cite is not equal to the relative increase in atmospheric CO2 concentrations. Think of it this way. If one triples the rate of water coming into a pool, the volume of water in the pool does not instantly increase three-fold in volume. The response depends on how much water is already in the pool. Second, according to the earth system research laboratory, atmospheric CO2 concentration increased by only about 5.3% over the decade between 2000 and 2010, from 367 ppm to 388.5 ppm. Given a climate sensitivity of 3C/doubling that equates to a 0.16 C (0.1-0.24 C range)increase in equilibrium temperature. That's pretty darn close to you 0.15C! Finally, the climate sensitivity refers to equilibrium global temperatures. The climate system will not have reached equilibrium over only 10 years -- it takes a number of decades for the oceans, land and atmosphere to heat up enough that radiation leaving earth for space matches the radiation absorbed by the planet. So we would expect the temperature prediction based on the equilibrium climate sensitivity to be a bit lower than the observed value. So the good match actually suggests the IPCC could be underestimating sensitivity rather than overestimating it. I doubt you could make much hay of that though. You're dealing with a short rather arbitrary time frame, wide range climate sensitivities and the residual natural variability that was not removed by Foster and Rahmstorf's approach. Also, there was probably delayed warming in the pipeline from previous increases in CO2.
  43. Rahmstorf et al. Validate IPCC Temperature Projections, Find Sea Level Rise Underestimated
    Hi Jim, The 2.0-4.5 degrees range given by the IPCC is the equilibrium change expected from a doubling of CO2, which is equivalent to 280 parts per million (ppm) in concentration. Based on data at Mauna Loa, the concentration of CO2 has increased from about 370 to 390 ppm over the past decade, which is about only 7% of 280ppm. I suspect that the figure you've seen refers to the rate of CO2 emission increasing by a third, but not the CO2 concentration increasing by a third. In addition, the 2.0-4.5 degrees refers to the warming expected at equilibrium, and in reality it takes a while for the atmosphere and oceans to warm up. When atmospheric CO2 hits 560ppm, the warming observed at that point will in fact be a bit lower than 2.0-4.5 degrees, as it takes a few decades for the earth to catch up.
  44. Rahmstorf et al. Validate IPCC Temperature Projections, Find Sea Level Rise Underestimated
    Jim, if I'm understanding your question correctly that's a common point of confusion and has to do with the difference between short term and long term responses of climate to changes in GHG. IPCC is referring to "equilibrium climate sensitivity" or ECS, the expected result once the ocean-air system has stabilized around a new distribution of GHG. The ocean will absorb an enormous amount of heat before equilibrium temperature is attained, during a period dominated by "transient climate response" or TCR, the phase we're in now. Picture cooking a turkey from a refrigerated state in an oven that is well-insulated but with a small heating element. The air temperature in the oven will remain relatively low as the turkey warms. The turkey-air combination will reach equilibrium temperature after the turkey is completely warmed to the point where heat leaking from the oven prevents further increase of the oven chamber temperature.
  45. Rahmstorf et al. Validate IPCC Temperature Projections, Find Sea Level Rise Underestimated
    Hi jim. I suspect someone is going to answer you in much greater detail, but I'll try now. There is a difference between equilibrium climate response (ECR) and transient climate response (TCR). Much of the response from a given increase in CO2 comes through feedbacks to the initial warming. Those feedbacks are not immediately realized. Further, the oceans represent 92-3% of the thermal capacity of the climate system. They do not release stored energy immediately. Indeed, they may store energy for centuries. ECR is the final realization, in surface temp (if that's the metric you choose), of a given increase in CO2. TCR is what's happening right now. The IPCC uses ECR much more often than TCR, though I wonder if TCR will get further discussion in AR5, since it's one of the less well-understood concepts. SkS needs a glossary, people! (Don't look at me. I have grading to do!)
  46. Rahmstorf et al. Validate IPCC Temperature Projections, Find Sea Level Rise Underestimated
    I am a septuagenarian layman interested in understanding the science behind global warming even though it won't effect me. I find it difficult to reconcile fig.2 with the statement that it confirms IPCC projections. It shows a temperature rise of about 0.15 degrees over the decade to 2010. It is reported elsewhere that the annual tonnage of global carbon emissions increased by a third over the same period. IPCC report AR4 (WG1 chapter eleven, final par.) gives a range of 2.0 to 4.5 degrees for the projected temperature increase likely to be caused by a doubling of atmospheric CO2. If we divide by three to get a range for an increase in atmospheric CO2 of one third, we get 0.66 to 1.5 degrees - appreciably greater than 0.15 degrees. I realise that my approach is extremely simplistic, but the difference is so great that someone better qualified to comment than myself might care to do so.
  47. It's El Niño
    Bob Tisdale
    KR asks: “Finally, what about the greenhouse effect?” [more than sufficient to cause observed warming without asymmetric ENSO] Downward longwave radiation appears to do nothing more cause a little more evaporation from the ocean surface, which makes perfect sense since it only penetrates the top few millimeters.
    I'm afraid this rather glib dismissal of the greenhouse effect fails to substitute for science. Despite the short penetration depth of longwave radiation, it is more than sufficient to greatly warm the oceans by changing the skin layer temperature gradient, the top millimeter of the oceans. There's an excellent article on it here, including the experimental evidence - one of the better discussions I've seen on the topic, in fact. Again - the radiative greenhouse effect more than accounts for the observed warming of the last 50 years. Forcings during the early 20th century (in particular high insolation and quite low volcanic aerosols) account for early 20th century warming, too, despite your statements. Claims of asymmetric ENSO forcings (in addition to lacking a physical mechanism for asymmetry) simply have no support from the full temperature record. To be blunt, I consider both your (a) assertion of (recently) asymmetric ENSO's and (b) dismissal of the accumulated evidence for the radiative greenhouse effect to be equally glib handwaving. You've failed to support either with clear, testable hypotheses, or to even discuss the (multiple) lines of evidence contradicting your hypotheses.
  48. Climate's changed before
    Dan, depending on one's understanding of utilitarianism, one can argue either that ag civilization is more horrible because it brings misery to more individuals (in sheer numbers), or one can argue that the preceding h-g cultures caused more misery because lifespans were shorter, survival was much more in doubt for a given individual, and individual freedom was extremely limited. I disagree that ag society brought wars of territory and economy. I argue that climate stability brought those features. A long, warm, stable climate allowed territorial expansion and population growth. Eventually, h-g groups would have started to bump into each other, as they undoubtedly did during the glacial periods. Ag culture simply speeded up the process. Ag culture also allows the development of science, which gives us the chance--the chance--to become responsible about what happens next. dan: "start a fire in your backyard and reconnect with the primitive beast." Ok, but later on in the evening I'll come back to the internet. The more we disconnect with each other, the more willing we are to cause others pain and misery. If science and then engineering can force us to look into each others' eyes while we have our fingers on triggers (literal or metaphorical), then I'm all for it. If seven billion people go primitive right now, six billion die within two years.
  49. 2012: Record Arctic Sea Ice Melt, Multiple Extremes and High Temperatures
    The HadCRUT temperature anomaly map makes it clear why it's the favourite temperature series for pseudoskeptics. Look at all those gaps in coverage at the poles.
  50. It's El Niño
    Actually, I think I've misrepresented the cause of the artifacts in Bob's figure 13. I only get odd minutes to work on this, so I've only just got to the point of picking my model apart again to see what is happening inside. It now looks like the cause of Bob's artifacts is even simpler than I have suggested. The multiple lags thing is real and very interesting scientifically, but it's not the dominant factor in the features of figure 13. I'll try and give a fuller analysis over the next few days. Then move on to strict validation tests to confirm or refute my hypothesis next weekend.

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