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johnd at 08:10 AM on 7 July 2010Tai Chi Temperature Reconstructions
skywatcher, your parallel is virtually what I was saying. The point being that more labs coming up with the same results only confirms that the methods used to process the data only confirms that they all use the same methodology given it is all the same raw data. It really is not confirming whether the data is a representative sample or not. Thus it is no different to carrying out a reanalysis of a urine sample. Your use of tree rings as an example is very relevant. The Briffa tree ring reconstruction began to diverge where the very highest quality data obtainable was available to validate all the assumptions made and equations developed inputted into the reconstruction model. ..................... KR, your last sentence also agrees with what I was saying. Repeated processing of the same sample only provides confirmation that the methodology used to process it is consistent with all other methods that produced the same results. Peter has obviously put a lot of effort into producing the work, and my response was to his own comment, "the fact that this resembles all of the other recent published reconstructions may (or may not)be surprising" I felt that the results were not surprising and set out to explain why I thought that. Perhaps anyone who found the results surprising can explain why they found them so. -
JMurphy at 08:01 AM on 7 July 2010Peer review vs commercials and spam
Sorry, previous comment directed towards hucmht -
JMurphy at 08:00 AM on 7 July 2010Peer review vs commercials and spam
You could do worse that have a look at (meteorology) Professor Scott Mandia's blog, where he has looked into that fallacy : Part I Part II Also, have a look at the Industry, Energy, Biofuel, etc. groups that are engaged in lobbying and spending millions of dollars (also shown in the previous link) : The Center for Public Integrity. -
daniel at 07:48 AM on 7 July 2010Sea level rise is exaggerated
Ok but it will take me sometime as, like the rest of you, I am a busy man. I would also like to point out to Peter that this comment: "Add to this data from other sources which also give points with high uncertainty but which also fit on the shallow curve (given the error envelope) increase the probability of the low amplitude variation fit being statistically robust, and diminish further the probability of your hypothesis being correct." has already been discussed in part by both of us. He asked me to examine Donnely 2006 and made the claim that the papers support each other but Donnelly 2006 is an even sparser data set than 2004 with all of the 2004 data fitting within the two latest samples of 2006. The 2006 data has just as much or even more uncertainty than the 2004 data. So how is it that either refine the other? I guess the answer will be read the other papers and they will do better? I will, but I doubt they will do the job. Also I have been told that high res studies are in agreement with the overall conclusion of Donnelly's paper. But I have read the Gehrels 2006 high res study and the uncertainties still undermine the validity of a recent unnatural uptrend (not to mention a highly suspicious uptrend when the method of age determination changes). Will the other papers cited like Grinsted do any better? We'll see but from what I've seen and keep seeing when asked to read these studies is that they will probably all have much the same faults because the nature of the measurement doesn't have the certainty required to detect a moderm uptrend. -
kdkd at 07:44 AM on 7 July 2010Astronomical cycles
Ken #135If there is no 'offset' in the Topex-Jason 1 splice, then the better curve match is non-linear - which may well be a true record of what is happening with SLR.
Nope, this is wishful thinking. You need to do the statistics to demonstrate this not eyeball the data and come to a conclusion based on your preconceived notion of what you want to find. There really is a lack of joined up thining in your argument. Addressing my questions at #133 would help address this problem of yours. -
scaddenp at 07:22 AM on 7 July 2010Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
Arkadiusz Semczyszak - so GW is caused by change in THC, rather than other way round? Explain then stratospheric cooling and CO2 signature in radiative spectrum please. -
Peter Hogarth at 07:15 AM on 7 July 2010Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
Arkadiusz Semczyszak at 00:11 AM on 7 July, 2010 I will not simply dismiss your “bold” claim. Let us see if there is evidence that weighs in its favour, and what evidence weighs against it. As you seem to propose something like GHG theory in reverse? (in terms of cause and effect) this could be interesting. If I am understanding your proposal that changes in the Arctic lead effects elsewhere, and I found evidence that peaks in Arctic temperature lagged behind both Antarctic temperature and CO2 peaks in ice core data, this would be a problem for your hypothesis, but might support a GHG hypothesis? See Ahn 2008, Ocean circulations may be involved, but what leads what?
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hucmht at 05:27 AM on 7 July 2010Peer review vs commercials and spam
I wasn't sure where to put this comment but I had the argument thrown at me: "Keeping the grant/research $$ flowing is a strong motivation. Scientists will write grant proposals and research questions they know will get them money and approval. Science is just another business, and global warming is just the current hot product. " Can you help refute this one please? -
skywatcher at 05:11 AM on 7 July 2010Tai Chi Temperature Reconstructions
johnd - you seem to be suggesting that somehow, by calibration to a 150 year temperature record, 2000 years of variations can be 'forced' to have a particular shape (do you mean the 20th Century 'uptick')? This is obviously crazy. If that were the case, you would get unusually good correlations during the instrumental period, and the relationships would degrade spectacularly as you headed back into palaeoclimate. Peter Hogarth's excellent graphs show this specifically not to be the case. That they don't diverge indicates no specific calibration directly to the temperature record. Each method will have its own calibrations, such as oxygen isotopes for the ice core records. but that does not force each reconstruction to have the same features, as you are suggesting. The reconstructions are free to vary dependent on the palaeo data, not on some forced 'fit'. That they can be simply averaged in this way shows that these methods and samples are providing generally the same pattern independently of each other. This is utterly different to carrying out a reanalysis of a urine sample. The parallel would be to take the same series of raw tree rings and sending it to different labs to produce a reconstruction - each lab ought to produce a very similar curve based on that specific sample. Another set of tree rings might produce a quite different curve, applying the same methods. Generally, the different curves have similar features, as Peter has identified, suggesting something about palaeoclimate. -
KR at 04:28 AM on 7 July 2010Tai Chi Temperature Reconstructions
johnd - I'm a little confused as to what you are getting at here. You (correctly) note that proxies are calibrated - for example establishing how growth rings vary with temperature. There have been in the past a few issues with calibrations for forensic and other samples, but not often - ground truth has a tendency to correct these errors over time. The only thing I can read into your post is an assertion that 50+ different proxies could be so poorly calibrated as to throw off the averages. Given that each of these paleotemp reconstructions has it's own calibration, experimentally determined by separate groups from multiple disciplines, I think there are more than enough independent samples to make this kind of reconstruction reasonable. "When a reconstruction is done that produces results similar to other reconstructions" - perhaps, just perhaps, they're accurate reconstructions! -
CoalGeologist at 04:09 AM on 7 July 2010Tai Chi Temperature Reconstructions
Fascinating trend. Nice work! Assuming it stands up to more rigorous treatment, the "smoothed" global trends are quite interesting. The author, Peter Hogarth, has been understandably careful about drawing any conclusions regarding causation, but Commenters arguably have greater liberty to consider this trend in the context of what is presently known about climate drivers (w.r.t. temperature, in particular). There is no significant energy source for warming the atmosphere and hydrosphere other than the sun, so we can limit the possible controls to two categories: 1) Variation in the amount of solar energy entering the atmosphere, and 2) Variations in the amount of solar energy retained (until the rates of emission and absorption are balanced, (any "missing heat" notwithstanding!)). The controls for past variations are uncertain. The present warming, however, is largely driven by the ever increasing concentrations of GHGs, together with associated feedback mechanisms, there being no evidence (so far, at least) that any other factors have played a significant role. We are left to speculate (or to investigate!) how the 1000 year trend from 900 to 1900 might have continued if it had not been influenced by human activity. Could anthropogenic CO2 have rescued us from continued cooling? More important, how will the unprecedented introduction of massive quantities of CO2 affect future warming? To the extent that we may have the ability to "tweak" Earth's climate in the future, it's a fascinating, and extremely important question. -
johnd at 03:59 AM on 7 July 2010Tai Chi Temperature Reconstructions
Peter, the fact that your reconstruction resembles most others is not surprising. Doing reconstructions such as you have done is similar to the situation with analytical laboratories around the world. Irrespective of whether the laboratory is testing blood and urine samples, or bulk materials, once the sample has been taken, it could be sent to any reputable laboratory anywhere in the world and the results should be all the same. The reason for this is that the methods used are all calibrated against the same bench mark, and this will be the case here too. All proxy reconstructions have to be calibrated against a known benchmark, and for proxy temperature reconstructions, that will have been the instrumental temperature record. Getting back to the laboratory analysis, if the results are doubted or subject to dispute, as does happen at times if the results form of a commercial arrangement, then there is little point in ordering the samples to be retested, or tested in another laboratory as procedures are such that all laboratories will generally produce the same results. If there is a real problem, it will be that the sample provided is not truly representative, and the solution is to collect a new independent sample and analyse that. The problem with doing temperature reconstructions is where do you get an independent sample that has not been validated against the same benchmark as every other sample? When a reconstruction is done that produces results similar to other reconstructions, what is really being proved is that the method used to produce the results is probably correct given it is basically the same samples that are being analysed. This is basically the same as doing "round robin" testing where one sample is tested by a number of laboratories to confirm that their in house procedures are in line with each other, and the industry standards. Such exercises do nothing to confirm or otherwise that the sample tested is indeed a representative sample of the what it was sampled from originally. -
Alexandre at 03:35 AM on 7 July 2010Tai Chi Temperature Reconstructions
Very nice post. I´d like to see more "playing around" with the data like this. It would be nice to see the difference between northern and southern hemisphere, or how robust the series is to different proxy choices, or how geographic distribution changes the result. In fact, if I find the time I´ll try some experiments myself. Thanks, Peter! -
Rob Honeycutt at 03:33 AM on 7 July 2010Tai Chi Temperature Reconstructions
Peter... You honor me greatly, most respected si fu (master). Looking at paleo climate charts I'm always struck by one thing. How it's almost impossible to get an unbroken perspective on current warming relative to historic warming. For the science crowd it's not a problem. This chart of shorter time scale picks up where the other chart of longer time scale leaves off. But for the broader lay person it creates a discontinuity that doesn't always translate. Take your figure 3. The current temp trend is SO vertical that it disappears along the side. I know you pick it up in the following charts but you've just published a chart that any climate "skeptic" can take out of context and say, "See, Peter Hogarth even says that we're not warmer that the MWP. Here's his chart." I believe Michael Mann does a pretty masterful job in presenting his charts in various clever ways that generally manage to avoid this. Of course he has funding and you're doing a blog post on your own nickel. The very best charts, IMHO, are the animated charts being created by NOAA for the Time History of CO2 which were reported on SkS here. This is an amazing reconstruction job you've done, Peter. (I love this stuff!) The one chart I'm longing to see, though, is this temperature reconstruction you've done in the style of NOAA's animated chart. Or, even better, the two overlaying each other. Temp and CO2. With a good narration I think this would be one of the most compelling graphics created on the issue of climate change. Unfortunately it's a task that is well outside of my own skill sets. -
Peter Hogarth at 03:30 AM on 7 July 2010How Jo Nova doesn't get the CO2 lag
Bill Stoltzfus at 01:52 AM on 7 July, 2010 I haven't checked the JoNova charts, but if you can drive Windows Excel or other chart/spreadsheet programs you can download more up to date data from the NOAA Paleo (Ice Core) website and make your own charts. For 800k years of CO2 look at Luthi 2008, EPICA Dome C data series (he has a composite including Vostok), and for temperature look at Jouzel 2007 from the same site. I think they have the most consistent EDC3 ice age/gas age dating. This and the quoted uncertainties are something to strongly consider when judging lag. -
Peter Hogarth at 03:07 AM on 7 July 2010Astronomical cycles
Ken Lambert at 00:16 AM on 7 July, 2010 I think a point I made in the sea level post was along the lines of the satellite trend and recent continuation of the overall longer term curve fit derived from tide stations is statistically indistinguishable. For the overall satellite trends a first order linear fit is as good as any. This trend may change, upwards (or downwards) with much passage of time, and I would hope in line with the overall tide station data, but currently if warming and increasing ice loss are accepted as drivers, and we accept what the ocean observing community is telling us on how close we are to balancing the sea level budget, then it is difficult to imagine the trend reducing anytime soon. I actually agree fully with your last point on respecting the uncertainties, and here we must strive to both improve the knowledge of deeper ocean temperature trends and look at the upper ocean values from the various sensors and other sources (GRACE and Acoustic methods) and see if the bias problems identified over the past few years have been completely "fixed" or not. However I warn against automatically seeing jumps where there is high variability anyway, and lack of knowledge does not disprove anything... We still appear to have rising sea levels with a strong thermal component. This "thermometer" is difficult to ignore. On balancing the energy budget I haven't read much as yet beyond Trenberth, and noting the high (relative to "unaccounted" heat flux) uncertainties in the satellite global TOA/Surface IR radiation measurements. -
chris at 02:43 AM on 7 July 2010Astronomical cycles
Ken - you're making a meal of this. If you wish to take "due respect for the uncertainties and inconsistencies with reconciling SLR and OHC given the current state of knowledge", then that should be applied across the board. If one looks at Trenberth's analysis of the heat budget during the short period 2004-2008, then there is an apparent shortfall, although the error bars overlap. You're correct that I made a double accounting of the TSI contribution - my mistake. Otherwise the apparent shortfall during this short period amounts to ~ 0.2 - 0.69 W. As Trenberth states, this might possibly be accounted for by sequestration of some heat into the deeper oceans during this period....there may be other explanations. Is there anything more to be said about this? I don't think we can draw any particular conclusion at this time. Sea levels have risen quite rapidly during the last 18 months and as Trenberth states the recent warming may be in indication that the "missing heat" is reappearing. I expect we will have a better idea of the situation during the next few years. Otherwise I'm not sure this really merits the degree of insult and monothemic badgering that you're engaged in. Perhaps it would help if you could be a little more specific about what you are trying to achieve or what you wish to draw from the data presented by Trenberth. And you do need to address the analysis more rigorously. Your "respect for uncertainties...." and "looking hard at composite charts....", apparently equates to drawing regressions of bits of the data and noticing that these don't meet at the ends. That's simply bogus with respect to identifying offsets. I've linked to a series of papers in which the question of merging satellite sea level data is addressed in great detail. You don't seem interested in that but you should be if you sincerely have "respect for the great uncertainties.....". Likewise, we have analyzed the satellite data with a quadratic fit. The quadratic fit is so close to a linear fit (the "acceleration term" of the quadratic is close to zero) that it makes little difference. So the satellite data conform rather closely to a linear fit (with some wiggles). That's a simple fact Ken. You seem sufficiently unhappy about the fact that current sea levels are pretty much smack on the long term linear trend defining the satellite era data that you feel I should be pilloried for pointing this out! Oh well.... -
Bill Stoltzfus at 01:52 AM on 7 July 2010How Jo Nova doesn't get the CO2 lag
I was looking at the Vostok graphs at Nova's site (specifically the last one), and was wondering about a couple of things. Perhaps I should ask this first, though--is her graph a valid one to look at, or is there a better one? There are a few places where the temp and CO2 lines go in opposite directions, or don't seem to follow the lag rule. Around 50,000 years ago they don't match up well. 160,000 to 170,000 years ago there are several temp spikes with no CO2 movement. About 375,000 years ago temp spikes while CO2 continues downward. I realize these are only a few places out of hundreds of thousands of years of history, and you've said before that CO2 is not the only climate driver, and it's possible that the time resolution isn't detailed enough to show all of the movements, but I am wondering what effects could suspend or negate the CO2 lag? Is the concentration change in CO2 not enough to overpower other effects? Thanks. -
robert way at 00:28 AM on 7 July 2010Tai Chi Temperature Reconstructions
Peter Hogarth at 23:29 PM on 6 July, 2010 Thanks, I've been looking into the topic myself because i've run into this problem in the past and I don't really know what to do. I tried one method which calculates anomalies based upon the entire series but with each series having different lengths it introduces large biases. I don't know which standardization formula to use really or if that is even the practice I should undertake. Thank you for your help though. -
Ken Lambert at 00:16 AM on 7 July 2010Astronomical cycles
Peter Hogarth #132 Peter, I have never argued that 9 years is not better than 7 years and 7 years is not a lot better than 1-2 years. Errors must get higher with shorter records. What I have said is there is no theoretical reason why these trends should be linearized - given that OHC-SLR and TOA-OHC etc are not likely to be linear relationships and complex interactions unlikely either. Having seen bogus splicing of XBT to Argo OHC analyses elsewhere on this blog, with impossible OHC jumps at the splice, I am looking hard at composite charts which mesh different instruments together. If there is no 'offset' in the Topex-Jason 1 splice, then the better curve match is non-linear - which may well be a true record of what is happening with SLR. This is not a 'refusal' to accept statistical analysis principles Peter - rather a due respect for the great uncertainties and inconsistencies with reconciling SLR and OHC given the current state of knowledge. -
Arkadiusz Semczyszak at 00:11 AM on 7 July 2010Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
@JMurphy I am not saying that if I quote Graversen'az 2008 - he is right, but I say that it had to quote. Because it's important work. "For the whole picture" - and unless such was the intention P.H. „This may counteract ...” Please - special attention to the word „may”. Moreover, once again I stress: it is not a weakening of THC (ie, how fast and how much energy carries), but as close to reaching the pole. Prior to 3.2 million years ago, when there were considerably warmer than at present, faint (but) THC reaches the same pole ... „Now I understand why so-called skeptics don't include links.” - is an absurd allegation. Using the example google, immediately (within fractions of seconds) you can find the desired position. There is no sense to quote the whole lichen abstracts, summaries or conclusions. @Peter Hogarth “... but you also need to ponder the "T" in THC ...” One could quote the enormity of the literature, it is an "H" is suspect - as the causative factor in the market. The change in salinity is probably the effect of other excitations. This change probably does not have even feedback. Simply put: first, change the pressure - wind (feedback to change the scope of THC) - he drives the THC, then there is a change in salinity (this is because the melting ice will never stop THC). In short, my scenario looks like this: change the range of THC - the impact on global and regional atmospheric circulation - a positive feedback “loop” - running - through the gradient - the transport of heat from above the tropics - increase the energy imbalance, increasing the capacity of the atmosphere to the accumulation of energy (humidity). My "bold" summary conclusion: global warming is secondary to changes in the Arctic. Changes in the Arctic are a major cause of global warming - are, therefore, earlier, faster and bigger. P.S. ... and the fact that the impact of the sun - the moon in the THC is still poorly substantiated and is not even pre-priced - this is not a good argument. Effect of CO2 is also very difficult to establish. -
Peter Hogarth at 00:06 AM on 7 July 2010Tai Chi Temperature Reconstructions
thingadonta at 23:31 PM on 6 July, 2010 I agree with your general comment about uncertainty increasing with age for some of the proxies, but for many here the measurements are extracted from within an annual layer, or equivalent, and barring other factors give high resolution. (For your information, I have recently got back from field operations, though not directly related to this topic). I have not seen many smeared tree rings or stalagmites or sea bed cores. If you have specific evidence on this, please give references. What you are arguing is that all historical trends tend to some imaginary zero as we go back in time? please think this through and explain how this comes about again? Ice cores anyone? -
Riccardo at 00:05 AM on 7 July 2010Sea level rise is exaggerated
daniel, you keep asking people to plot the data from table 1. Could you please show your graph with the linear fit to the data and the line with a slope of 2.8 mm/yr? This would be more convincing. -
Ken Lambert at 23:54 PM on 6 July 2010Astronomical cycles
JMurphy #131 Glad to see you defending Chris on a trival semantic point but missing the big one. "There was a short period (2006-2008ish) where the sea level rise slowed down a bit; the last 18 months or so has seen it return to its trend level." I called this 'back on track' rather than 'return to trend' Pretty much the same meaning I think. And: "We have to be careful not to attempt to make fundamental interpretations from these instances of short term variability." Chris tries to equate the 7 year trend of Jason 1 with 1-2 years of Jason 2 as both instances of short term variability. Not quite right I think. Anyway Chris should be able to answer for himself the mistake he made by double subtracting the "Solar minimum' forcing for the 2008-09 period. Dr Trenberth in his Table 1 had already accounted 16E20 Joules/yr for the dimming of the Solar cycle (equal to 0.1W/sq.m). This is because the 145E20 Joules/yr (0.9W/sq.m) already includes +0.12W/sq.m from IPCC AR4 Fig 2.4 which is a 2004-05 Solar Forcing number. Putting 16E20J/yr on the other side of the budget effectively subtracts 0.1W/sq.m, which wipes out the Solar forcing 0.12W/sq.m originally included. The net residual of 30-100E20 Joules/yr equates to about 0.2-0.6W/sq.m of unaccounted heat flux - and Chris then proceeds to subtract another 0.15 W/sq.m from this to account for Solar dimming. A double dimming Dunning-Kruger moment gentlemen?? -
daniel at 23:53 PM on 6 July 2010Sea level rise is exaggerated
Yikes pete, sure I'll read them. But did you reconstruct the data from table 1? We can see that using high uncertainty low res data we still have roughly the same linear trend into the modern age. This is evidence of undersampling of a higher amplitude trend. A high amplitude trend directly measured in recent times using a tide gauge. You seem to think that the data points lie perfectly on a linear trend when even the centres of the boxes don't do that. Coupled with the error margins there is indeed enough slack im the data for higher amplitude trends. Therefore the link to Anthropogenic CO2 as a driver is undermined. -
Peter Hogarth at 23:45 PM on 6 July 2010Tai Chi Temperature Reconstructions
chris at 23:22 PM on 6 July, 2010 You are absolutely correct and I don't want to mislead here. Global is really a misnomer. There are only eight SH proxies here, and only a further eleven from the Equator up to 30 degrees N. In the text I try to highlight that this is not a true gridded, weighted, interpolated, output. The averaged data is biased heavily towards the NH, and probably Northern Europe, and reflects a bias in the coverage of proxy records in general. Some of this is due to the nature of proxy records and different ratio of land mass to ocean, NH to SH. -
JMurphy at 23:45 PM on 6 July 2010Tai Chi Temperature Reconstructions
That shape in those graphs of temperatures over the last 2000 years, they look like, er, hockey-sticks. Shall we call them 'hockey-stick graphs'... -
thingadonta at 23:31 PM on 6 July 2010Tai Chi Temperature Reconstructions
There is at least one problem with your analysis that needs mentioning. -Generally speaking, with any type of scientific measurement, the further one goes back in time, the more smoothed, smeared, uncertain, and 'averaged out' the entire process becomes, from methodological selection, sample selection, collation, and interpretation, to the very response of the proxies themselves and the natural limits to the data that can be measured and inferred. Mathematicians usually fail to fully understand and appreciate this sort of thing; that their data contains a lot of structure, or in the words of Enrst Mayr when referring to the genotype as a whole, ‘cannot be understood by a purely reductionist approach’. I would contend that your analysis is largely reductionist, in that it ignores the basic structural features, limitations and variations that occur within any large scale proxy analysis. Most (all?) proxies you care to consider, whether response of corals to temperature shifts, or red shifts in galaxies, or radioactive dating in ancient rocks, will tend to exhibit a lagged/smoothed response to any rapid-real time fluctuation, such as temperature, and this smoothing will tend to increase the further one goes back in time, which therefore means that any comparison with actual measured (not proxy) temperatures, and proxies, particularly ywith regards to changes and variations in slope, is always misleading. Observations are always sharper than a response to a fluctuation, which is then collected and measured, and collated and compared over time; whether in proxies, or elsewhere. For this reason alone, one can't make the conclusion the recent temperature changes are faster than any former temperature changes in eg the last 2,000 years, (ie 'unprecendented') because one is a real time, direct, measurement (measured temperature in recent centuries), and one is a biological/ biochemical response to a fluctuation, which has to be selected (researchers bias), collected (sample contamination and availability), ‘inferred-measured’(significant figures and error bars change with time, and with differential response to short term fluctuations), and finally, submitted to mathematical analysis (including averaging out already-smoothed proxies, even further),and placed alongside and compared with real-time observations. It is no wonder that such reconstructions give a sharp slope in recent, measured, centuries compared to a flattened slope with older data, anyone who is familiar in the field (not in a air conditioned office) with limitations to proxy collection and analyses will tell you that you can get this sort of graphical features with virtually any averaged out collection of inferred times- series analysis, and the further back in time one goes, the stronger it gets. You don't even have to splice datasets to confront this kind of problem, any time series analysis of proxies will tend to exhibit a smearing of response/delineation of measurement, the further one goes back in time, and even more so if one then averages out the data between many types of proxies-all this does is further flatten older proxy responses compared with more recent ones. To repeat, proxy error bars increase with age, and the more error bars one ‘averages out’, over a longer and longer time period, the more smoothing occurs, compared to both more recent proxies and actual recent observations. -
Peter Hogarth at 23:29 PM on 6 July 2010Tai Chi Temperature Reconstructions
rway024 at 23:14 PM on 6 July, 2010 In my simplistic case, I am relatively lucky in that so many of these proxies overlap over considerable periods, and it is only the tapering of record density in the last century that presents problems. Here I used a long common period (of most of the record) for simplicity. This should standardise things to a good approximation and still allow us to average the extended records. I guess a standardisation formula could be used, but I'll try to have a look at the exact methods used in the official reconstructions. -
chris at 23:22 PM on 6 July 2010Tai Chi Temperature Reconstructions
which leads me to another question for Peter: Your Graphs 2 and 3 are depicted as "Global Average Anomaly of 50 Temperature Proxies". To what extent are these actually "Global" and opposed to N. hemispheric? i.e. what is the proportion of S. hemisphere proxies in the data? My understanding is that if one is sampling the past 2 millenia, the number of S. hemisphere proxies is very small. -
chris at 23:18 PM on 6 July 2010Tai Chi Temperature Reconstructions
RSVP at 22:22 PM on 6 July, 2010 Your argument isn't quite right RSVP. Although global temperatures have a large (especially latitudinal) variability, the yearly (or decadally) averaged temperature at a single location on Earth doesn't vary that much. Since all proxyreconstructions (Peter's included) determine a temperature anomaly, the large intraEarth variability isn't so relevant. Where it is relevant relates to the likelihood that there are location-specific responses to forcings. These do have a significant latitudinal dependence (e.g. polar amplification, and any response that involve significat changes in thermohaline circulation that carries heat to the high Northern latitudes, etc.). We are still in the situation that the S. hemisphere is poorly represented in paleoproxyreconstructions. -
robert way at 23:14 PM on 6 July 2010Tai Chi Temperature Reconstructions
How does one deal with proxy series which do not overlap in terms of the anomaly calculations. For example if only 15 of the 50 overlap but some extend further and so on? Would one use a standardization formula such as (X value - Mean of whole series)/ Standard Deviation of whole series? -
Peter Hogarth at 23:13 PM on 6 July 2010Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
Arkadiusz Semczyszak at 21:04 PM on 6 July, 2010 I cited Graverson 2010, and I have suggested that atmospheric and Ocean current contributions play a role. I don't disagree on this. The interaction of THC and NAO and Eastern boundary currents etc is something I am thinking of posting on, as part of looking at longer term variations. It will take a while. You have mentioned the possible freshwater effect on THC, I admit I referred to the measured freshening very briefly, but you also need to ponder the "T" in THC, and I try to cover oceanic warming in some detail, where does the warmth come from?, discuss. -
Peter Hogarth at 22:58 PM on 6 July 2010Tai Chi Temperature Reconstructions
RSVP at 22:22 PM on 6 July, 2010 Yes, this is partially the point. Lots of averaging should extract any common signal from noisy data. Of course official reconstructions do a lot more than this, but I hope the general idea gets across. -
Peter Hogarth at 22:53 PM on 6 July 2010Tai Chi Temperature Reconstructions
chris at 21:30 PM on 6 July, 2010 Difference is that the error bars are removed, which allows vertical scale to be zoomed a little, and annual and ten year averages are shown superimposed. Otherwise they are the same. HumanityRules at 21:34 PM on 6 July, 2010 The text is correct, there are 50 records given as temperature values which are easy to average in this simple approach, the other 18 are Sigma values, which are difficult just to add in (though I try to show an indication of how this may affect the average in the 1850 to present chart), the remaining 3 are not publicly available, though Ljungqvist gives visual charts of them. -
Peter Hogarth at 22:40 PM on 6 July 2010Sea level rise is exaggerated
daniel at 08:21 AM on 6 July, 2010 If "wordy" bothers you I can draw some pictures? As a professional scientist I have concerns about your recent comments and general analytical approach to this data set. As we have sparse data and Donnelly gives error estimates, might I suggest again a statistical approach? It also worries me that you have not followed through on physics or measurement based evidence which suggest your “short term large variation” hypothesis is highly improbable. High resolution temperature reconstructions are available and do not support your proposal - Grinsted covers this well. Please read it. Back to Donnelly, we have more plenty of points here near point 1. The uncertainty in point 1 is shown. It is consistent with the other data which has higher certainty and fits the given trend, statistically speaking. If your argument had any chance of surviving critical scrutiny you would expect deviation of the error envelope from the “curve” for at least some of the other points, which we do not see. The total error envelope would have smooth upper and lower bounds, and I agree we could see variation within these bounds, but this is relatively small and does not compare with the overall rise or the recent rise in rate. This is the point of Donnellys paper. Coupled with evidence of lack of variability in the drivers for your hypothesised variations, this greatly diminishes the probability of your hypothesis being correct. Add to this data from other sources which also give points with high uncertainty but which also fit on the shallow curve (given the error envelope) increase the probability of the low amplitude variation fit being statistically robust, and diminish further the probability of your hypothesis being correct. The recent acceleration in sea level is well documented as are the physics based drivers for this. The overall picture is consistent. For you to hide behind "ad hominem" when it is suggested that Donnelly has access to a great deal more data than he is presenting in one paper on one specific site, reflects poorly on your argument, and I expect better from anyone who claims a science background. Here are some further references (in no particular order) on proxy records, physical basis of sea level rise, recent acceleration, and extended tide gauge data, I hope you will read them, and follow through on a few of their references, and come back with a bit more knowledge and a bit less uninformed opinion: Woodworth 2008, Engelhart 2009, Woodworth 2009, Yasuda 2008, Romundset 2009, Engel 2009, Gonzalez 2009, Leorri 2008, Miller 2008, Goodwin 2008, Wopplemann 2008, Merrifield 2009 -
Arkadiusz Semczyszak at 22:34 PM on 6 July 2010Tai Chi Temperature Reconstructions
The primary disadvantage of most of the reconstruction is over-smoothing (especially multi-proxy). How to avoid this, I recommend: http://www.rni.helsinki.fi/research/info/sizer/. -
RSVP at 22:22 PM on 6 July 2010Tai Chi Temperature Reconstructions
I personally have no problem believing that world climate has warmed some (within the last 50 years), the most obvious proxy being the trend in Artic ice breakup and glaciers generally receding. On the other hand, temperatures around the world vary nominally within a range of about 50 degrees C, so in order to use proxies to detect a global anomaly of one degree, they would require linear accuracy of less than one degree for this full range. -
JMurphy at 22:15 PM on 6 July 2010Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
Arkadiusz Semczyszak wrote : Is the Thermohaline Circulation Changing?, Latif et al., 2006: “Analyses of ocean observations and model simulations suggest that there have been considerable changes in the thermohaline circulation (THC) during the last century. These changes are likely to be the result of NATURAL multidecadal climate variability and are driven by low-frequency variations of the North Atlantic Oscillation (NAO) through changes in Labrador Sea convection.” And to complete the abstract : Indications of a sustained THC weakening are not seen during the last few decades. Instead, a strengthening since the 1980s is observed. The combined assessment of ocean hydrography data and model results indicates that the expected anthropogenic weakening of the THC will remain within the range of natural variability during the next several decades. LINK. Arkadiusz Semczyszak wrote : Influence of the Atlantic Subpolar Gyre on the Thermohaline Circulation, Hátún et al., 2005: “ During the past decade, RECORD-HIGH SALINITIES have been observed in the Atlantic Inflow to the Nordic Seas and the ARCTIC OCEAN, which feeds the North Atlantic thermohaline circulation (THC).” And to complete the abstract : This may counteract the observed long-term increase in freshwater supply to the area and tend to stabilize the North Atlantic THC. Here we show that the salinity of the Atlantic Inflow is tightly linked to the dynamics of the North Atlantic subpolar gyre circulation. Therefore, when assessing the future of the North Atlantic THC, it is essential that the dynamics of the subpolar gyre and its influence on the salinity are taken into account. LINK As for the Graversen paper, if you actually have a link to it you will see that it has been opposed by three further papers : Cecilia M. Bitz & Qiang Fu A. N. Grant, S. Brönnimann & L. Haimberger Peter W. Thorne And just to round things off, there is a reply to these from the original paper's authors : R. G. Graversen, T. Mauritsen, M. Tjernström, E. Källén & G. Svensson So, things are not as settled as some would want us to believe, and some people prefer the original paper and would like to ignore the others. Is that what is known as 'cherry-picking' ? Now I understand why so-called skeptics don't include links. -
Dan Olner at 21:48 PM on 6 July 2010Tai Chi Temperature Reconstructions
Reading good analyses always feels drinking drinking cool, clear water. Reading bad ones is like eating mud. This is great. -
HumanityRules at 21:34 PM on 6 July 2010Tai Chi Temperature Reconstructions
Thanks Peter, The 2nd and 3rd figures both say 50 record but the 3rd is meant to be 50 plus an unstated number. This an error? Out of suspicious curiosity could you show just the non-NOAA average. -
chris at 21:30 PM on 6 July 2010Tai Chi Temperature Reconstructions
very nice indeed Peter. Your recent articles here have taken analysis to a level that beautifully bridges the gap between the layman and the science, and helps to show that the gap isn't as large as one might think. Can you clarify the difference between the 2nd and 3d figures? It's not obvious to me what you've done differently to the data in these two graphs. P.S. it would be worth adding Figure no's (i.e. Figure 1; Figure 2 etc.) to the figure legends since the figures are bound to be referred t in the comments... -
Arkadiusz Semczyszak at 21:04 PM on 6 July 2010Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
@ Peter Hogarth What about this paper: Vertical structure of recent Arctic warming, Graversen, 2008,? “We conclude that changes in atmospheric heat transport [tropic] may be an important cause of the recent Arctic temperature amplification.” First, a warmer upper layer [...] of the Arctic troposphere. Graverson 2008 argues that originates from the tropics to 25% of the heat in the Arctic. Significant Addendum: Influence of the Atlantic Subpolar Gyre on the Thermohaline Circulation, Hátún et al., 2005: “ During the past decade, RECORD-HIGH SALINITIES have been observed in the Atlantic Inflow to the Nordic Seas and the ARCTIC OCEAN, which feeds the North Atlantic thermohaline circulation (THC).” Is the Thermohaline Circulation Changing?, Latif et al., 2006: “Analyses of ocean observations and model simulations suggest that there have been considerable changes in the thermohaline circulation (THC) during the last century. These changes are likely to be the result of NATURAL multidecadal climate variability and are driven by low-frequency variations of the North Atlantic Oscillation (NAO) through changes in Labrador Sea convection.” -
Arkadiusz Semczyszak at 19:04 PM on 6 July 2010Archibald’s take on world temperatures
@Agnostic “As you point out, the highest global temperatures have been recorded during a low period in the solar cycle.” It has always been. The greater the change in to solar activity, the response (temperature) more remote in time. Take a look: http://upload.wikimedia.org/wikipedia/en/1/16/Sunspot-temperature-10000yr.svg, like circa 7400 BP - solar activity is very low. Temperature by EPICA Dome C - maximum. Delaying even a circa 800 years. But the last period (last millennium - less than 100 years). -
Arkadiusz Semczyszak at 18:26 PM on 6 July 2010Arctic Ice Part 2: A Review of Factors Contributing to the Recent Decline in Arctic Ice
@ Peter Hogarth 1.“It is unlikely that you have read all of the references ...” - It's true. But ... In many discussions on the Arctic ice I proposed on this page reflect on the main alternative scenario (at least for NIPCC) - increasing the coverage of THC to NH (Recent changes of the thermohaline circulation in the subpolar North Atlantic, Bersch, 2007). Generally, the amount of energy transported by the THC may even drop (it is irrelevant to other sources), but the change of the deposition of significantly changing albedo, atmospheric and oceanic circulation. It runs a lot of positive feedback, perhaps such as the release of CO2 from the Arctic sea and ice, feedbacks, which causes faster warming in the Arctic („Quadfasel continues by pointing out the significance of the possible implications, with palaeoclimate records showing drops of air temperature up to 10°C within decades, linked to abrupt switches of ocean circulation when a certain threshold is reached.” - based on: Oceanography: The Atlantic heat conveyor slows, Quadfasel, 2005). Reasons for amendment of the scope of THC may be different. Who will read my previous posts knows that I put on the gravity of the Sun and Moon (The impacts of the Luni-Solar oscillation on the Arctic oscillation, da Silva and Avissar; 2005). The influence of long tides on ecosystem dynamics in the Barents Sea, Yndestad, 2009; and: Lunar nodal tide effects on variability of sea level, temperature, and salinity in the Faroe-Shetland Channel and the Barents Sea, Yndestad et al., 2008.: “In addition, correlations better than R=0.7 were found between dominant Atlantic water temperature cycles and the 18.6-year lunar nodal tide, and better than R=0.4 for the 18.6/2=9.3-year lunar nodal phase tide. The correlation between the lunar nodal tides and the ocean temperature variability suggests that deterministic lunar nodal tides are important regional climate indicators that should be included when future regional climate variability is considered. The present analysis suggests that Atlantic water temperature and salinity fluctuations in the Nordic Seas are influenced by forced tidal mixing modulated by harmonics of the nodal tide and influencing the water mass characteristics at some point “down stream” from the Faroe-Shetland Channel. The effects of the modulated oceanic mixing are subsequently distributed as complex coupled lunar nodal sub-harmonic spectra in the THERMOHALINE CIRCULATION.” In another study, the authors arrive at the main - the final conclusion: “In this analysis we may understand the forced gravitation oscillation between the earth, sun and the moon as a forced coupled OSCILLATION SYSTEM to the earth. The tide and the earth rotation responds as a non-linear coupled oscillation to the forced gravity periods from the moon and the sun. This is a complex oscillation in periods between hours and THOUSANDS of years. The forced gravitation introduces a tidal mixing in the Atlantic Ocean. This tidal mixing introduces temperature and salinity fluctuations that influences climate and the eco system.” “In light of the DEFICIT OF THE SCIENTIFIC understanding of the thermohaline circulation and the feedback potentials between the two deepwater sources, it is difficult to predict the influence of global climate change on the dynamics of the thermohaline.” (Coastal Wiki) I agree. When you do not check everything, you can not say we do not understand what that's for sure CO2 ... 2.Lockwood papers shows how a small change in the sun is able to significantly change the temperature of winter in the vast areas - adjacent to the Arctic - the Arctic ice. Establishment of the locality of this change, for the fact that all the oceans - the World ocean currents form a whole - a system - it is unscientific. I recommend my favorite work based on a very wide literature ("pros and cons" - not only cherry picking): Holocene weak summer East Asian monsoon intervals in subtropical Taiwan and their global synchronicity, Selvaraj et al., 2008.: “PERSISTENT LINKAGE of weak summer EAM-tropical PACIFIC and NORTH ATLANTIC COOLING-reduced GLOBAL wetland extent during these intervals is believed to be driven by coupled OCEAN-ATMOSPHERE INTERACTIONS, especially reduced heat and moisture transport and enhanced El Niño-Southern Oscillation in the tropical Pacific, as well as SOLAR ACTIVITY.” -
Red XIV at 17:08 PM on 6 July 2010Other planets are warming
On the simplest level, if Pluto were being warmed significantly by increase in solar output despite how very far away it is, a much closer planet like Earth would be fried by that increased output. -
robert way at 13:20 PM on 6 July 2010Archibald’s take on world temperatures
Grace satellite measurements have been affirmed by radar interferometry, laser altimetry and melt modeling. Like I said, a post will be coming and this will be set straight because there are far too many people who are commenting without knowing the basics of glaciology. Ice loss (ablation) in antarctica is 90% through calving and NOT surface melting. Calving is caused by completely different mechanisms than surface melt which dominates the greenland signal (although recent measurements indicate that calving is taking over). In antarctica, glaciers accelerate and thin which causes more ice loss. Once again, I understand the dynamical nature of the west antarctic ice sheet and of other submarine basins in antarctica, but far too many people confuse melt with ice loss... nevertheless, i should have been more clear I guess. -
scaddenp at 12:58 PM on 6 July 2010Archibald’s take on world temperatures
rway024 can answer for himself, but I believe he means by "melt" is melting due to overly warm air temperatures and/or rain onto ice. Ice loss can be by direct melt (more important in Greenland) or by calving into a warm ocean (more important in antarctic). At least that is my take. Roy, I think you have been taken in by some skeptic site as virtually all those statement are wrong. eg "The test of math models is whether they work reliably. Observed data is below the model error bounds, so the models are wrong. " Pardon? Doesn't fit with this. Perhaps you point us to papers that support your assertions? -
Riduna at 12:32 PM on 6 July 2010Archibald’s take on world temperatures
rway024 at 26 Am I misunderstanding your claim that ..Melting is basically irrelevant in Antarctica and important in Greenland .. If GRACE satellite measurements are to be believed, ice loss in the Antarctic, particularly from WAIS is not only significant but has the potential to be disastrous. WAIS, being a marine ice sheet is particularly vulnerable to attack from warm ocean currents causing large areas of ice resting on the seabed to float. Hardly irrelevant where rising sea-levels are concerned. -
robert way at 11:25 AM on 6 July 2010Archibald’s take on world temperatures
previous post was to Roy Latham at 04:35 AM on 6 July, 2010
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