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Comments 125101 to 125150:

125101. Marcus at 21:52 PM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        More points jpark. Inquiry or not, the denialists who hacked & distributed the CRU e-mails have now had close to 3 months to find something truly damning about the way in which CRU has collected &/or manipulated the data. That they've not presented any case of fraud in this time strongly suggests that this is because no evidence exists to prove it. I'd personally like to know when there is going to be an inquiry into who hacked CRU-& who paid them-& when those responsible will be brought to justice (last time I checked, Hacking was a MAJOR CRIME in most constituencies). That such an inquiry hasn't taken place suggests that some very powerful vested interests were behind the hack. One wonders what you want, jpark? If graphs showing the warming trend don't suit you, then what about the images of the Earth covered in ever greater shades of orange & red showing the extent of warming over the last 30 years? Graphs remain the very best way of showing how the minimum & maximum temperature anomalies for each decade have changed. As to why certain stations are omitted, it might be for any number of reasons. Maybe local conditions meant the station was off-line for too many days out of a year, or maybe some localized event caused the station to become an obvious outlier. Maybe they simply had enough replicate data points, from a specific region, to get an average with a sufficiently small margin of error. The point is that the deletion of a handful of stations across the globe isn't suddenly evidence of a conspiracy. What is evidence of a conspiracy, though, is how many of the official denialist groups & individuals have strong ties to the mining & fossil fuel industries.
125102. Marcus at 21:40 PM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark, can you be a little more specific about how the Met Office "got it wrong"? If you're talking about the recent cold snap, that was caused by an unforeseen change in the Arctic Oscillation, & has absolutely nothing to do with broader warming trends. What Menne's paper shows is that, in spite of the claims by people like Watts, so-called "poorly sited" weather stations are showing only a negligible difference in both their minimum & maximum temperature readings-over time. This therefore means that poor siting of US weather stations cannot be used to explain the global warming trend of the last 30+ years. This is hardly news, as satellites have shown an almost identical warming trend over the 30 years they've been taking readings. Your claim about "managed data" is meaningless, as *all science* is dependent on the manipulated-or management-of raw data. To try & equate "management" or "manipulation" with fraud is to essentially impugn the entire scientific establishment. Also, as someone who actually *knows* people in the IT industry, I can assure you that Y2K was not a hoax (though some news agencies deliberately overstated the threat). Had nothing been done about it, many industrialized nations would have been disrupted for days-if not weeks. Last of all, many of the people who helped create the sub-prime mortgage crisis walk in the same circles as those who're pushing the denialist cause in the media. Their motives are also identical-*profit*. That's why I'm so skeptical of the denialist case.
125103. Riccardo at 20:36 PM on 24 January 2010
        The IPCC's 2035 prediction about Himalayan glaciers
        Charlie A, i did NOT say it's correct, i did say it's just simple math. Try yourself 2840/(1966-1845)=23.4 and 2840/(1966-1945)=135.2 and you'll see where the inconsistency in that table comes from. They guy who wrote the table probably mistyped the number and came out with the wrong rate. Or you mean it was intentional? In my life i've never seen a thousand pages book with no such errors and sometimes even happen in peer reviewed papers. Anyway, being the error really irrelevant for the whole picture I find the pertinacity you show by cross-posting the same "question" really pointless.
125104. jpark at 19:16 PM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Albatross - guys, thanks. The trend and climate models are great. I will study them some more, and of course I find them persuasive but my immediate reaction is 'oh, more graphs with dots on, is that it?' Others here have parried my question rather than answered it. Is the actual data duff or not? If the data going into all the trendy models is bad then we, the public, will simply dismiss the model. The Met Office in the UK got their predictions (and models) badly wrong this year while, to their utter horror, a chap called Piers Corbyn got it right. So much so that the BBC are considering using a different company. I know this has to do with 'weather' rather than 'climate', but let's face it if you cant predict one then the other looks fanciful. The UK Gov are setting up a parliamentary inquiry into the CRU leaked emails - this is good because it should be thorough and open. But it does mean, Doug, that you cannot say there is nothing to the emails and everything is fine. The IPCC report is, I am afraid, also important. If it includes rather wild speculation about Himalayan glaciers then the whole report looks rather suspect. Ian says that deleted stations are showing greater increases of warming - then why the heck are they not included in the data? Why do we have this adjusted/deleted/averaged/smoothed picture of what is happening - why not real/complete/comprehensive? So back to the topic here - if Menne's paper just tells us that the surface station data does nice trends then I, for one, am still left scratching my head. The case for catastrophic global warming seems too dependent on 'managed data' to me. After the Y2K bug, the sub prime mortgage/financial crisis there is good reason to be sceptical. This is very very poor PR - there has to be better than this.
125105. Charlie A at 13:39 PM on 24 January 2010
        The IPCC's 2035 prediction about Himalayan glaciers
        Riccardo says at #28 "i just pointed out that plugging in the correct starting time the calculation of the rate is correct. " I ask again, what is your reference for saying that 1945 is the CORRECT starting date when all of the available literature points to 1845 (or 1847) as the correct starting date associated with the 2840 meters of retreat. To put it more simply, other references, such as 1958 reports make it clear that the 2840 meters of retreat is approximately correct, that 1845 is approximately correct, and that IPCC or whoever originated the chart incorrectly calculated the time span from 1845 to 1966 as 21 years rather than 121 years. These errors make it even more relevant that nominations for AR5 reviewers, which close on March 12th 2010, are not allowed to be submitted unless you are one of a certain list of privileged organizations chosen by the IPCC. I have been unable to obtain this list. The IPCC would be well served by including some reviewers without a strong confirmation bias in favor of AGW.
125106. Ian Forrester at 13:36 PM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Deniers are very good at confusing lay people in the use of absolute temperature and anomalies. For example Joseph D’Aleo and E. Michael Smith have accused "NOAA researchers of strategically deleting cherry-picked, cooler-reporting weather observation stations from the temperature data". They say that by ignoring these cooler stations the global temperature is artificially raised over what it would be if the stations were included. However, if you actually look at where the deleted or ignored stations are they are in areas of the world which are experiencing much faster rates of temperature increase than average (northern Canada, northern Russia). Thus their omission is actually lowering the global average, the exact opposite of what D'Aleo and Smith are saying.
125107. Marcus at 13:20 PM on 24 January 2010
        The IPCC's 2035 prediction about Himalayan glaciers
        nofreewind. It may not stop snowpack from forming, but it will effect the depth & total extent of the snowpack in the future-which *will* impact on future fresh water supplies. You see, even without global warming, we're already running into problems providing water to our populations. Imagine how much worse it will get if our sources of fresh water become depleted by global warming? That's not a "scare", it is something which we should be genuinely concerned about-in spite of efforts by the fossil fuel industry to try & cast doubt on the issue.
125108. Marcus at 13:14 PM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark. Trends are very important because they tell us a lot about the *rate* of change. This is especially important if we can compare it to rates of change in the past. You see, though climate has changed in the past, all the available evidence suggests that it has *never* changed as rapidly as it has in the last 30-60 years, in spite of a relative lull in Total Solar Irradiance. That is why climatologists are so concerned, in spite of the efforts of people like Watts to confuse the issue.
125109. yocta at 13:01 PM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        I've been following these threads and seeing how everything is going back and forth. Considering when somebody turns on the news and watch the weather report, we are presented with it in absolutes. So to an average laymen I could see how it seems to make more sense to want to see the data presented like that. And considering that the pdf on WUWT is very pretty and professional looking I could see how people will believe it. (He must have an army of dedicated followers, no wonder he doesn't want to report anything different, he will lose his crown) It wasn't until I started playing around with temperature data myself (DIY-Statistics) that I could understand it a whole lot better!! Is there any room for a post John or Mark on "anomalies verses absolute" or "this is what a raw reading looks like, this is what has to be done to extract sense from it..." (with lots of pictures of course, people like their pictures)?
125110. Ned at 12:49 PM on 24 January 2010
        The chaos of confusing the concepts
        I think batsvensson's distinction between linear and nonlinear forcings is a red herring here, though I could be wrong (I'm not an expert in this). We can predict that (outside the tropics) it will be warmer in summer than in winter because we have a conceptual model of a forcing (the time evolution of the solar zenith angle at a given latitude as determined by the earth's axial tilt) that is large enough to override short-term variability in the weather. There are of course all kinds of feedbacks, positive and negative, that amplify or reduce that radiative forcing. Nonetheless, we can be confident that the magnitude of that forcing is large enough to make the winter-to-summer difference semi-predictable. Likewise, we have a good conceptual model of another radiative forcing (absorption of outgoing long-wave radiation by greenhouse gases) that is also becoming large enough to have a detectable influence on climate. We can't predict the weather in 2050 (just like we can't predict the weather next July), but in both cases we know there are predictable radiative forcings that will make it warmer (on average) in summer than in winter, and in a 500 ppmv CO2 atmosphere than in a 300 ppmv CO2 atmosphere.
125111. Doug Bostrom at 11:45 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark: You're starting to get all mixed up here. "...last year we found out that CRU scientists made a hash of doing the data." Wrong. Be careful, there are a number of people with an unhealthy obsession with old email, to the point they've actually set up a web site all about it and apparently spend their days sifting through this stuff. There's really no "there" there. "Then Copenhagen fails." And that does not have anything to do with surface stations in the US. "Then this week Pachauri gets it in the neck ..." Again, nothing to do with this topic. "What does a trend mean..." A trend tells you useful things, such as whether you can expect your coffee to ever brew. "Because if those temps/trends are slightly higher than they should be and so, in reality, only slightly higher than older temp station data, or even older historic data then, yes, we have global warming but not very much..." There you go! That's the useful part! The trend provides confirmation of theory via observation, validation of models, etc. And that's why Watts et al are so determined to distract you from the importance of trends. Easy once you go through the steps, plus remember these folks are doing the same thing you used to see in word problems: throwing a lot of chaff in the air to confuse you so you can't come to a useful conclusion. Don't let yourself flunk the test.
125112. Doug Bostrom at 11:09 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark at 07:05 AM on 24 January, 2010 Hi Doug! Many thanks, nice explanation. - But still not good enough, and I'm sorry. "I do understand the paper but still feel it does not, like a lot of posts here, answer the quite basic Watts question of how accurate the stations are." When you use the phrase "how accurate the stations are" I think it betrays that you don't understand the paper. It does not matter at all if the stations are accurate. Their utility for telling accurate absolute temperature from day to day is entirely separate from their utility for revealing a climatic trend. All that matters for extracting a trend is whether or not there's a unidentified longitudinal change of bias in measurements resembling a trend in temperature. More, that unidentified longitudinal change must be approximately the same for a multitude of stations. As it happens, there is no unidentified longitudinal bias change that meets that requirement, but there is a -know- reason for observing a trend, namely a change in climate.
125113. Riccardo at 10:54 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark, "if those temps/trends are slightly higher than they should be and so, in reality, only slightly higher than older temp station data, or even older historic data then, yes, we have global warming but not very much" Exactly, but it ain't so. In principle it might be a resonable concern, in practice it does not stand up an in depth analisys. Remember, people working on it check the readings for possible biases/errors; something may slip through the check but, well, just some. And unless you belive in the bad intentions of the researchers, errors and biases (plural) tend to average out. Don't be confused by absolute temperature and anomaly. The former is more intuitive given that it's what we feel. The latter has the advantage of being more stable and correlated over long distance and time, then more easily shows an underlying trend, which is what we are interested in.
125114. chris at 10:31 AM on 24 January 2010
        The chaos of confusing the concepts
        re #22 hmmm...this is why I suggested in post #12 that we have to be careful what we mean when we use the term "chaos" in any particular instance. We end up misarguing around the meaning of a word or concept rather than the phenomenon itself. Meltwater-induced suppression of the Thermohaline Circulation happened many time is the past. So one can hardly say it can't happen! Of course the boundary conditions are different now (interglacial rather than the many instances identified during glacial periods). I (and everyone here, I think) was using it as an example 'though. It's not really chaotic behaviour (it has its chaotic elements on a microscale), but it's really a stochastic phenomenon that is essentially predictable, if not in relation to the precise timing of events, at least as a phenomenon that is a definite and predictable consequent of particular conditions. So, for example, it would likely be possible to model N. hemisphere ice sheet dynamics and ocean circulation during the last glacial period to reproduce the Daansgard-Oeschger (D-O) events, within an understanding of the conditions under which these events occurred (not sure if this is yet understood very well). Where this differs from chaotic phenomena (as I understand it), is largely the independence with respect to initial conditions. We wouldn't know exactly when a D-O might occur, but we would be able to predict that, independent of inital conditions, once the important factors tended towards threshold values, that a D-O event would have a high probability of occurring.. Two examples: (i) Knocking down a wall with one of those splendid balls on chain swung by a crane. We don't know exactly when the wall will tumble, or exactly the pattern of its disintegration (one might consider the latter to be chaotic). However the event (the wall falling down) is predictable (if not precisely defined temporally speaking), given that we understand the forcings that act in this situation, and is independent of initial conditions. (ii) In a warming world we expect coastal flooding events that might have 100 year probability (say) to occur more frequently, as a result of rising sea levels combined with more extreme weather events as sea surface temperatures rise etc. Now, however chaotic the weather is (chaos), the likelihood of an increased frequency of coastal flooding events is predictable. We don't know when any of these events will occur (stochastic), but our prediction of an increase of events in a warming world is likely to be robust, and increasingly so as our knowledge of the climate system increases.
125115. jpark at 10:14 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Albatross - thanks for the links - I will read. Carefully.
125116. jpark at 10:10 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Albatross - I think an illustration on temp anomaly might be a good idea. Ok I will give this one more go because I think you guys might be able to give me an answer and you haven't yet (apart from Kforestkat) Here is the problem: the world is getting hotter - I think we all agree - but last year we found out that CRU scientists made a hash of doing the data. However kindly you read the leaked emails you realise this was not good science. Then Copenhagen fails. Then this week Pachauri gets it in the neck for getting the Himalayan glacier date wrong and putting pure speculation in the IPCC report (apparently it was not the only error) and an error that had significant financial consequences. So when Watts puts out a report showing images of severely compromised temp stations and Menne replies with 'trends' people like me say...'er so what? What does a trend mean, I want to know whether the temp stations work or they are being lovingly heated by a/c units". Because if those temps/trends are slightly higher than they should be and so, in reality, only slightly higher than older temp station data, or even older historic data then, yes, we have global warming but not very much - which is what the report at Science Daily says. But of course I may be missing something...
125117. Albatross at 09:49 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Jpark "This means actual temps do matter and trends in this particular instance dont," The actual temperatures form part of a long-term trend. You can't have a trend in a time series without either increasing or decreasing time series of temperatures. Moreover, those tmepratures do not have to increase montonically to get a positive trend as illustrated by the surface air tmeprasture records. The long term temperature trend (globally) is about 1.7C warming per century, and yes, that is actually something to worry about. Regarding "why we have not warmed as much as we should have". You are probably referring to the work of Scwartz that is aboutt o be publishe din J. Climate. Perhaps John can again (Schwartz has done this before) refute the work of Schwartz et al. Jpark, be wary of site slike WUWT, their goal is to confuse. Really it is just that simple, and it is cleverly done under the guise of "science" and the pursuit of "truth". That is what makes the misinformation there seem so compelling. The long term observed warming trends is consisent with the projections made by the IPCC. Look here: http://tamino.wordpress.com/2010/01/13/models-2/ and here http://tamino.wordpress.com/2009/12/07/riddle-me-this/ and here http://tamino.wordpress.com/2008/01/31/you-bet/ I really encourage you to actually read the above articles carefully.
125118. Berényi Péter at 09:36 AM on 24 January 2010
        Skeptical Science now an iPhone app
        Back to the original claim. It is getting pretty cool in the Arctic (-35°C, -31°F) http://ocean.dmi.dk/arctic/meant80n.uk.php Still, it is not terribly hot elsewhere around it. I've just walked my dog in the park (lat=47.4717672, lon=19.0426755) and he was anxious to get back which is rather unusual. It is -10°C (14°F) here right now. US http://www.wunderground.com/US/Region/US/2xpxTemperature.html Alaska http://www.wunderground.com/US/Region/Alaska/2xpxTemperature.html Canada http://www.wunderground.com/global/Region/CN/2xpxTemperature.html Europe http://www.wunderground.com/global/Region/EU/2xpxTemperature.html
125119. Albatross at 09:35 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Reading some of the posts here is incredibly frustrating because it clearly demonstrates the stunning success Watts et al. have had in confusing and brainwashing people (even well educated professionals it seems)to the point where it is impossible to explain a simple concept of a temperature anomaly to them. I was going to chime in and try to dispel some of the confusion, but others have repeatedly and clearly explained the facts only for those facts to repeatedly fall upon deaf ears. What I will add, is that the Menne et al. study needed to be done and their results are incredibly important. Their results also represent the final nail in the coffin for the complaints from Watts et al. as to the validity of the US SAT record. There is simply no dobting the validity of the SAT record anymore, but I doubt this study will discourage the contrarians and denialists from perpetuating and rehashing old myths. Prof Mandia re #35, I too once tried to explain the science with the folks at WUWT, and it was a waste of time. Watts knows his audience and plays to that; he is very good at telling them what they want to hear. He is also guilty of confirmation bias and ignoring the inconvenient facts regarding AGW. Anyhow, I do hope that some of the misguided posters here represent the views of people who are in the minority, b/c if they represent a much larger segment of the populous then we have a serious problem on our hands in terms of communicating the science. Why is it so much easier to disseminate misinformation than the basic facts? Maybe someone with some time can show some schematics illustrating how one obtains anomaly values from a temperature record, and why systematic bias does not affect the trend? A picture is oftentimes far more convincing and informative than even the most carefully chosen words. PS: Actually those in denial are having a bad decade-- 2009 second warmest year on record globally, first decade of naughts warmest on record globally, warmest year on record in S. Hemisphere (lots of heat stored in the vaste southern oceans), continuing acceleration of rate of loss of summer Arctic sea ice and glaciers, PIG glacier in WAIS found to have exceeded its tipping point, and for what it is worth, January 2010 warmest lower trop. temps in the satellite record despite extremely cold weather in Eurasia and portions of N. America. The list goes on.....
125120. chris at 09:31 AM on 24 January 2010
        Why does CO2 lag temperature?
        re #39: thingadonta, the evidence tends not to support the interpretation of inception of polar ice sheets in Antarctica, and Greenland (see my post #38) that may have been the dominant theory in your uni days! In the intervening 20 or so years, that theory has been tested both for the N. hemisphere polar ice cap (see post #38) and the Antarctic ice cap (see following). In each case the evidence indicates that glaciations only occurred when CO2 levels dropped below thresholds that forced sufficient global cooling (these are thought to be of the order of ~ 700 ppm for Antarcic glaciations and ~ 300 ppm for Greenland glaciations). It’s possible that ocean circulation changes made some contribution (as likely did earth orbital properties). But greenhouse gas concentration seems to be the major player: (i) CO2 changes and temperature changes during the Phanerozoic (last 500-ish million years). The problem with the idea that changes in atmospheric CO2 concentrations in deep time are the response to earth temperature change is that these CO2 variations are simply too large. We can determine, for example, that during ice age glacial-interglacial-glacial transitions, atmospheric CO2 levels cycle rather faithfully between ~270 (interglacial) and ~ 190 (glacial ppm). These are slow (~5000 year) transitions (so CO2 re-partitioning between ocean/land and atmosphere will have come close to equilibrium), involving global temperature changes of around 5-6 oC. Therefore temperature-induced CO2 rises/falls are of the order of 13-15 ppm per oC of warming/cooling. Since the entire Phanerozoic temperature variation was likely no more than 10 oC overall, we don’t expect to see temperature-induced variation in CO2 levels of more than 150 ppm. However the CO2 changes observed in the record are much larger than this. The slow fall of atmospheric CO2 from 1000-1500 ppm during the mid to late Eocene to around 700 ppm at the Eocene-Oligocene boundary around 33.5 MYA and further to ~300 ppm and below by around 24 MYA (and ever since until now) are simply incompatible with temperature-induced changes in atmospheric CO2. (ii) Timing The steady long term cooling from the Eocene maximum global temperature at around 50 MYA began far in advance of any ocean circulation change resulting from isolation of Antarctica and possible effects on ocean currents. And the opening up of the Tasmanian gateway preceded the Eocene-Oligocene transition that heralded major Antarctic polar ice sheet growth by ~ 2 million years [*]. The steady cooling right through the middle-late Eocene to the onset of Antarctic glaciations ~ 33.5 MYA is associated with a long slow drawdown of atmospheric CO2 from 1500 ppm or greater to ~700 ppm [**]. As indicated in (i) the extremely large drops in atmospheric CO2 concentrations are incompatible with the idea of temperature-induced repartitioning of CO2 between oceans and atmosphere. Most likely the slow drop in atmospheric CO2 was due to enhanced weathering (possibly a result of the drifting of the highly weatherable volcanic Deccan Traps into the equatorial humid belt as the Indian subcontinent shuddered remorselessly Northwards for its eventually intimate rendevouz with Asia [***]). (iii) <>Attribution There are a number of studies that indicate that the ocean circulation effects associated with the isolation of the Antarctic continent are minor contributions compared to the effects of reduced-greenhouse-induced global cooling. Some of these are: a. The temperature changes associated with the cooling during the Eocene-Oligocene transition ~ 33.5 MYA and the onset of build up of a permanent ice cap in Antarctica, were global, and poorly compatible with the regional effects associated with changes in ocean gateways [****] b. As well as the timing mismatch in (ii), a number of studies have reconstructed and/or modelled the effects of ocean circulation changes involving isolation of the Antarctic continent, and concluded that the ocean circulation changes are simply not able to produce the localized cooling required for onset of Antarctic glaciations. This can have only occurred when atmospheric greenhouse gas levels dropped below thresholds that maintained the earth in a state without a significant permanent Antarctic ice cap [*****]. [*] Stickley, C. E et al. (2004) Timing and nature of the deepening of the Tasmanian Gateway, Paleoceanography, 19, PA4027 http://web.ics.purdue.edu/~huberm/STICKLEY.HUBER.PDF [**] P.N. Pearson et al. (2009) Atmospheric carbon dioxide through the Eocene-Oligocene transition Nature 461, 1110-1113 http://www.ncdc.noaa.gov/paleo/pubs/pearson2009/pearson2009.html http://www.nature.com/nature/journal/v461/n7267/abs/nature08447.html M. Pagani et al. (2005) Marked decline in atmospheric CO2 concentrations during the Paleogene Science 309, 600-603 http://earth.geology.yale.edu/~mp364/data/Pagani.Science.2005.pdf [***] D. V. Kent and G. Muttoni (2008) Equatorial convergence of India and early Cenozoic climate trends Proc. Natl. Acad. Sci. USA 105, 16065-16070 http://www.pnas.org/content/105/42/16065.abstract [****] Z. Liu et al. (2009) Global cooling during the Eocene-Oligocene climate transition Science 323, 1187-1190 http://www.sciencemag.org/cgi/content/abstract/323/5918/1187 E. Thomas (2008) Descent into the Icehouse Geology 36, 191-192 [*****] R. M. DeConto et al. (2003) Rapid Cenozoic glaciations of Antarctica induced by declining atmospheric CO2 Nature 421, 245-249 http://www.geo.umass.edu/faculty/deconto/deconto_nature.pdf Huber M et al. (2004) Eocene circulation of the Southern Ocean: Was Antarctica kept warm by subtropical waters? Paleoceanography 19, PA4026 http://doos.misu.su.se/pap/paleo2004.pdf M. Huber and D. Nof (2006) The ocean circulation in the southern hemisphere and its climatic impacts in the Eocene Palaeogeog., Palaeoclim., Palaeoecol. 231, 9-28 http://web.ics.purdue.edu/~huberm/huber+nof.pdf
125121. Riccardo at 09:25 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Obsessively repeating the same concept is the standard tool people in the media use to make it true. Anthony Watts is pretty good at it and the fact that even if true it does not have any pratical impact has no importance for him and his fellows. They'll stubbornly keep repeating "Poor siting! Poor siting!" ad infinitum.
125122. jpark at 09:06 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Thanks Prof! Again very helpful but to me a trend is not at issue. I am a newbie here and like many this area of science has only become a really hot (pardon the pun) topic for me since climategate. Before then I accepted the general consensus. Most in the blogosphere seem to believe in global warming - it is the extent and the 'unprecedented' nature of the warming that I think (from what I have read on blogs so far) is the issue, which is of course linked to the anthropogenic part. This means actual temps do matter and trends in this particular instance dont, to me at any rate. If it is getting a bit hotter then, well that is not too bad, climate does tend to do that. But if it is getting amazingly hotter then, of course, we are all going to be in big trouble. So are the temps showing something dangerous or something not so dangerous I read this "Why Hasn't Earth Warmed as Much as Expected? New Report on Climate Change Explores the Reasons" from Science Daily. I think you can understand my layman's puzzlement. http://www.sciencedaily.com/releases/2010/01/100119112050.htm Apologies if that is off topic.
125123. ProfMandia at 08:47 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        As others have said the bias does not affect the trend. "A rising tide lifts all boats." Increased GHGs are the rising tide. Watts refuses to admit the obvious. In fact, even today he has the following post: http://wattsupwiththat.com/2010/01/23/sanity-check-2008-2009-were-the-coolest-years-since-1998-in-the-usa/ He is using US data to try to cast doubt on global data. He knows better but loves the attention from his misguided followers. I used to post there as the loyal opposition but it ended up being a huge waste of time.
125124. stevecarsonr at 08:27 AM on 24 January 2010
        The chaos of confusing the concepts
        Jacob Bock Axelsen: First of all, a comment on the thermohaline circulation. You said: "However, the engine of THC is surface cooling in the Arctic which global warming might turn off." But there are 2 factors driving the ocean currents. One is temperature and the other is salinity. Both affect density in a non-linear way. The reason why it is potentially "a switch" is that as the oceans warm, as they are doing at the moment, there is increased melt from Arctic ice and the Greenland ice sheet. If this melt rate increases to a certain point - no one exactly sure what that point is - then the low salinity will outweigh the cold and this water will stop sinking and the "conveyor belt" direction will change. Therefore, a very complex situation, and one where increased temperatures will eventually (possibly) lead to a colder northern hemisphere and a refreeze of the Arctic with the consequent (positive feedback) of increasing albedo. More on your other points later..
125125. batsvensson at 08:12 AM on 24 January 2010
        The chaos of confusing the concepts
        Chris, you wrote in #17, "the THC could slow down or stop if sufficient freshwater from Arctic ice melt were to flood the Arctic ocean." Mostly anything can happen if sufficient conditions are present, but the interesting question is, if this is likely to happen or not. Afaik, current understanding says this is not likely to happen at all - if ever. "At some point we might well understand this process well enough that it might cease even to be considered “stochastic”." I don't think so. "stochastic" is just another way to label non-linear or "random" system, system we previously not been able to model or control properly. Chaos theory is in principle a theory about non-linear system and how to treat them as non-linear. Before the time we had the mathematical tool to model and understand such system (which wasn’t all that long ago) engineers was busy making sure any non-linear system was modeled with in a certain local region that could be approximated as linear, outside this approximated region the behavior can not be guaranteed. The mathematical tools to do this exercises with is know as ‘differential equations’, and one requirement for these tools to be “trivial” to use is linearity – nonlinear differential equations are extremely hard to solve. Stochastic processes lacks the linear properties, thus they are always hard problem to solve with differential equations. Only a few non-linear processes of special interest are understood this way, like fluid dynamics, but even these are solved with numerical methods. However, new mathematical tools and theories theory have help use to better understand system outside the approximated linear boundaries, but such understanding wont make them less stochastic, rather it will help use to even more appreciate the very special behavior of these system.
125126. jpark at 07:47 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Gordon, many thanks. I think what you say is wise, But do look at the Watts report - lots of stations, lots of pictures ( worked for Al, it might just work for Ant) http://wattsupwiththat.files.wordpress.com/2009/05/surfacestationsreport_spring09.pdf
125127. Gordon1368 at 07:26 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark, I doubt that Watts et al photographed all of the stations, including well sited ones. This study shows that both well sited and poorly sited stations show the same basic trend, and that the bias in poorly sited stations is to cooler temperatures. What could be clearer than that? You haven't seen a bad week in AGW yet. You may well see many in your lifetime. I hope we don't.
125128. batsvensson at 07:20 AM on 24 January 2010
        The chaos of confusing the concepts
        Errata comment #13 (and #20), "... less to weather being non-chaotic and more to weather being affected by a ..." Above is an editing confusion of mine. I usually edit text a lot before I make a post. I this case I was considering to use the word "chaotic" OR "non-linear", and apparently it all got mixed up in the final edit. :( There are also some editing confusion in post #20 as well. For instance: "because of the presence of a forcing from linearity in that make Ned able to do the predict as he did." Was intended to be: "because of the presence of a forcing from linearity in the system that one is able to do a prediction as Ned did"
125129. Gordon1368 at 07:07 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        I'm not a scientist, but this topic fascinates me. I do have 30 years of professional experience to help guide me. When a colleague speaks in abruptly dismissive terms, claiming something is "useless," "trash," or "not really worth serious discussion" I pay attention, but my guard goes up. My years of experience have taught me to listen, but be skeptical. I have rarely found that such a tone is warranted. Here again, I appreciate the careful explanations by people who have responded. I am not a blind believer, but I do have confidence that serious professionals are sincere and careful in their effort, and are correct more often than not. I think that the argument that temperatures are rising is well backed by the loss of sea ice extent, and especially the rapid loss of multi-year ice in the past couple years. The next few years may be telling.
125130. jpark at 07:05 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Hi Doug! Many thanks, nice explanation. - I do understand the paper but still feel it does not, like a lot of posts here, answer the quite basic Watts question of how accurate the stations are. http://wattsupwiththat.com/2010/01/23/quote-if-the-week-27/#more-15561 And the picture tells a 1000 words - how do you convince people of global or even just US warming when you get to see a weather station next to a/c. It has been a bad week for AGW.
125131. Doug Bostrom at 06:53 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark at 06:37 AM on 24 January, 2010 It's not actually a debate, instead repeated attempts at explanation. Try this one, at home if you like but it's so simple you'll probably find words do the job: Set up a thermometer in a large room where the temperature is steady. Let the thermometer stabilize at ambient temperature. Now, turn on a small lamp next to the thermometer, close enough to warm it a bit. You'll see an immediate bias in the reading given by the thermometer; the reading will be higher than ambient temperature in the room. Let the thermometer stabilize again. Now raise slowly raise the temperature of the room. The thermometer will still register the increase in the temperature of the room. We've learned that bias does not make it impossible to extract a trend in temperature. It's really -that- simple. Not so hard, really, but easy to lose in a detailed technical explanation. To me it seems what we have here after all the hat and light is stripped away is the famous "failure to communicate".
125132. michaelkourlas at 06:38 AM on 24 January 2010
        It's the sun
        @Tom Dayton Thanks, I hadn't seen that.
125133. jpark at 06:37 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Interesting debate. So we are talking measuring trends vs actual data, yes? But this does not really answer the Watts paper http://wattsupwiththat.files.wordpress.com/2009/05/surfacestationsreport_spring09.pdf To me Kforestcat, along with Watts paper, makes sense. I cant see the point of the Menne exercise - why bother with a trend when you could measure how good the station was at measuring temperature. Why not put the army of volunteers to good use - how long would it take?
125134. Tom Dayton at 06:35 AM on 24 January 2010
        It's the sun
        michaelkourlas, that 2007 paper by Friis-Christensen and Svensmark is old news. See Svensmark and Friis-Christensen rebut Lockwood’s solar paper.
125135. michaelkourlas at 06:31 AM on 24 January 2010
        Climategate CRU emails suggest conspiracy
        Regarding "hide the decline": If it is true that tree rings are definitely inaccurate after 1960 (having compared them with the instrumental temperature record), shouldn't we question the entire data set, as that might be flawed too?
        Response: This is a good question and is explored in Tree-ring proxies and the divergence problem. In short, tree-ring proxies show good agreement with other proxies before 1960 and also show good agreement with tree-ring proxies that don't show divergence (eg - at lower latitudes). This indicates divergence is a purely recent phenomenon (and hints that there's a good chance it's anthropogenic in cause).
125136. michaelkourlas at 06:28 AM on 24 January 2010
        It's the sun
        This paper (http://www.spacecenter.dk/publications/scientific-report-series/Scient_No._3.pdf/view), published in 2007 by Eigil Friis-Christensen and Henrik Svensmark at the Danish National Space Center, is a response to Lockwood and Fröhlich's paper disputing the correlation between solar activity and land surface temperature. This new paper discusses the correlation between cosmic rays (solar activity) and sea surface temperature/atmospheric temperature. In both cases there is a clear correlation. While Lockwood and Fröhlich are correct in saying there is a divergence between solar activity and land surface temperature, the correlation remains true for two other temperature data sets (sea surface temp. and tropospheric temp.) Thus, one must question the validity of the land surface measurements, and admit the possibility that the sun may be playing a major role in current global warming.
125137. batsvensson at 06:16 AM on 24 January 2010
        The chaos of confusing the concepts
        @chris, #15. "Surely Ned is basing his prediction on "the system itself". Sure, I agree with that, and I see I was a bit unclear with my point, my excuses for that. My point was to try to make a distinction, and to separate, linear and non-linear elements in a system, and to clarify that it is because of the presence of a forcing from linearity in that make Ned able to do the predict as he did. I didn’t meant to say this is not part of the system, but to say it can be seen as a separate from the non-linearity of the system. I sometime notice that some people seems to believe that there is proportional linear relation between CO2 levels and global mean temperature. This relation is thou not so trivial as the green house effect from CO2 is said to be a non-linear function of the concentration. In other words, the contributing effect from a linear increase of CO2 will not change as rapid as temperature, therefore, unless we are working with a system that locally can be said to be linear, if both CO2 and temperature increase linear in respect to each other then I would suspect there to be yet another factor in the equation.
125138. Jacob Bock Axelsen at 06:01 AM on 24 January 2010
        The chaos of confusing the concepts
        @stevecarsonr and Marcel Bökstedt Thanks for your questions, which I will try to comment on. Please bear with me for trying to answer arguing from the variables of the Rayleigh number. Consider two plates (hot and cold) enclosing a liquid convecting fluid: http://en.wikipedia.org/wiki/File:Convection-snapshot.gif http://en.wikipedia.org/wiki/B%C3%A9nard_cells This is the Rayleigh number. Ra = gravity * expansion coefficient * system size * temperature gradient / (viscocity * conductivity * diffusivity) = g*b*D^3*dT/(v*a*k). In the Lorenz attractor Ra must be above the threshold Ra = 13.926 to exhibit any chaos, and below the dynamics is predictable. For instance, my plots are for Lorenz' own choice of Ra = 28. The idea that chaos is prevented by boundedness can then be understood: just decrease D or dT sufficiently to end below the threshold. I was using the 'leash'- analogy differently: The mean global temperature is determined as a steady state of huge energy fluxes. It is suspended by the Sun pulling up and the heat loss to space pulling down. To exhibit chaos you need to be able to delay heat transport (advection) through fluid dynamics, and with El Niño being the largest phenomenon of relevance we are still far away from fully developed climate chaos. Notice that sea levels increase on the order of centimeters during an El Niño - this is the small expansion coefficient of water. Make b small and you move away from chaos. The thermohaline circulation (THC) is a true convection roll resulting from density change. However, the engine of THC is surface cooling in the Arctic which global warming might turn off. If dT cannot drive even laminar currents, then we have smaller dT and lesser probability of chaos. I mentioned aerosols in the post, but they are much more transient than CO2. Much like airborne water, aerosols is argued to be fighting a negative feedback: cloud seeding, gravity and precipitation. My understanding is that clouds more or less cancels out in climate models. If aerosols cool they lessen dT for possible oceanic chaos. Interestingly, dust depositions on glaciers is hypothesized to be part of the ice age trigger: http://forecast.uoa.gr/conferences/iamas/10july/4b/69_smn_dst_dam_iamas_200707.pdf I hope you find these comments useful.
125139. Riccardo at 04:29 AM on 24 January 2010
        The IPCC's 2035 prediction about Himalayan glaciers
        Charlie A, i didn't claim it was right or wrong; i just pointed out that pluging in the correct starting time the calculation of the rate is correct.
125140. dhogaza at 04:04 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Or maybe even restrain myself :)
125141. dhogaza at 04:04 AM on 24 January 2010
        On the reliability of the U.S. Surface Temperature Record
        " A poor station with an absolute temperature error of +5 degrees C still has a bias error of +5 degree C - no matter what the variation occurring due to instrumentation type." We're interested in trends, so a constant bias has no effect, nor does the choice of baseline from which to compute the anomaly. For any bias B, and any two temperature reading at points in time N0 and N1, (N0-B) - (N1-B) = N0 - N1. And you can extend that into any statistical trend analysis taken over a time series N0 ... Nn. "I'm a chemical engineer with U.S. government and 20 years of research experience in various areas including environmental mitigation. If one of my phD's came to me with this nonsense, I'd fire him on the spot. " I could make a snarky statement about 9th grade algebra students but I'll withstrain myself.
125142. nofreewind at 00:12 AM on 24 January 2010
        The IPCC's 2035 prediction about Himalayan glaciers
        I live in the East USA but have skied annually in California/West and talking about glaciers as a water supply seems awful SILLY. Whatever glaciers there are in California are teeny(most all of the snow melts by September) and their contribution to melt has to be very small compared to general melting snowpack. Worrying about glaciers, without considering an overall predicted rise in precipitation from AGW "theory", does not seem to be right to me. And even with the worst case AGW scenarios coming true, say a 4F rise in temp, is that going to stop a snowpack from forming? I don't think so. Here in the Eastern US snowfall is extremely variable with some years we have very little snowpack, yet our rivers flow all year long, except in periods of a true drought, when they just flow low. I conclude the glacier scare is nothing but that, another scare. I don't have the deep scientific knowledge of AGW "theory" that many of you have, but common sense appears once again to rule the day on the Himalayan glacier/melt issue!
125143. Ned at 22:44 PM on 23 January 2010
        On the reliability of the U.S. Surface Temperature Record
        kforestcat writes: "I'm fully aware of how anomaly data is used ( having used it in my own research)" I'm not sure you actually do understand this, because your comments still show the same kinds of errors and confusion. "NASA's individual station temperature readings are taken in absolute temperature (not as an anomaly as you have suggested)." NASA doesn't take temperature station readings, and nobody has suggested that the temperature sensors measure anomalies directly. "Menne has to have (and use) absolute temperature data to get the 1971-2000 mean temperature and then divide the current temp with the mean to get the anomaly. We are back to the same problem - Menne is measuring instrument error - he is not measuring error resulting from improper instrument location." That is very confused. The temperature anomaly is the current daily (or monthly) temperature minus the mean temperature on the same day (or month) during a given reference period. You don't "divide" any temperatures. And Menne et al. are not measuring "instrument error". They are analyzing measurements of temperature as a function of site quality in order to determine the difference in temperature trends between well-sited and poorly-sited stations. "Actual anomaly is 93F - 85F = 8F; Instrument anomaly is 105F - 90F = 15F. The data is trash. There is simply no way to recover either the actual ambient temperatures nor an accurate anomaly reading. What you are missing is that an improperly placed instrument is reading air temperatures & anomalies influenced by unnatural events." You still completely fail to understand what's going on here. Menne et al. are taking the temperature data and grouping them into categories based on the site quality. They then determine the difference in long-term trends between well-sited and poorly-sited stations. In the raw, unadjusted data, poorly-sited stations tend to have a slightly lower trend than well-sited stations. The network homogenization and adjustment process brings poorly-sited stations into closer agreement with well-sited stations. "The readings bear no relationship to either the actual temperature nor the actual anomaly - the data's no good, can't be corrected, and will not be used by a reputable researcher." That is just bluster. What the analysis shows quite clearly is that if anything, poorly-sited stations on average underestimate the warming trend, but that the network adjustment process is able to successfully compensate for this effect. And even if you were reluctant to accept that, the close agreement between in-situ surface temperature and satellite microwave temperature retrievals from the lower troposphere suggests that the surface temperature record is realistic. "Finally, it's not entirely surprising that Menne finds a downward bias in his individual anomaly readings at poorly situated sites. Because: 1) a poorly located instrument produces a higher mean temperature; hence, the anomaly will appear lower; " Huh? Again, this makes no sense. If a sensor always reads 5C too high, its anomaly will be exactly the same as if it were perfectly sited. If a sensor's environment changes such that the current temperature is biased high relative to the period of record, then it will have a positive anomaly, not a negative one. "and 2) generally there's a limit to how hot an improperly placed instrument will get (i.e. mixing of unnaturally heated air with ambient air will tend to cool the instrument - so the apparent temperature rise is lower than one might expect)." That is both confused and irrelevant to the paper at hand. "Had Mennen (NASA) actually measured both absolute temperature and calculated anomaly data using instrumentation at properly setup sites, within say a couple of hundred feet of the poor sites, as a proper standard to measure the bias against - our conversation would be different." (1) Menne et al. work for NOAA, not NASA, and the paper being discussed here is about NOAA's temperature data. (2) You still seem confused about the relationship between measured temperature data and calculated temperature anomaly. (3) The entire point of this paper is to compare poorly-sited and well-sited stations. (4) By doing this comparison using trends in the anomaly rather than using the absolute temperatures, there's no need to compare stations within "a couple of hundred of feet" of each other. "As it stands Menne's data is useless nonsense and not really worth serious discussion." Again, that is just bluster. It sounds to me like you don't understand the subject but are deeply invested in casting doubt on it.
125144. chris at 22:13 PM on 23 January 2010
        Skeptical Science now an iPhone app
        re #19 "The numbers don't seem to add up" The numbers add up pretty well if one considers the system in it's entirety (all the forcings and a realistic assessment of climate response times). So, for example, the 20th century global temperature evolution can be reproduced rather well by incorporating all of the contributions and climate response times [*](see Figure 1): [*] http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf It's possible to illustrate part of the difficulty with your analysis by considering the global temperature from the late 19th century to the mid 20th century [**]. The global warming during this period wasn't more than around 0.2-0.3 oC overall. It's just that the surface temperature was knocked back quite a bit for a while (see post just above) by volcanic activity. So the net warming in response to your net forcing of 0.5 W/m2 1910-1940 likely wasn't more than 0.2-0.3 oC (perhaps even a bit less, if there was a significant contribution from ocean current effects of the sort that Tsonis and Swanson have discussed). But the bottom line is that the nett effect can only be assessed by a realistic incorporation of all of the contributions and the earth's responses to these.... [**] http://www.cru.uea.ac.uk/cru/data/temperature/nhshgl.gif
125145. chris at 21:44 PM on 23 January 2010
        Skeptical Science now an iPhone app
        You're mistaking "lag" and "time constant"/"response time", HumanityRules (see my post #20) It's pretty straightforward: make a step change in a forcing to a new value. The earth starts to warm essentially immediately (no lag!). The time taken for the earth to come to equilibrium with the new forcing is a function of the time constants/response times of the system (rapid time response of a few years in the atmosphere; slower time constants for penetration of heat into the "deeper" elements of the climate system, with a very slow response time indeed for the vast oceans to come towards equilibrium with the forcing). It's the latter that gives the "heat in the pipeline" that you remarked upon. That's all very straightforward I think. The mistake is to think that the response of the surface temperature can be encapsulated within individual simple hived-off pieces of the whole. For example we could look at the temperature rise during the early 20th century. There was some very dramatic volcanic activity in the late 19th century/early 20th century and inspection of the global temperature record [*] shows that this knocked back the surface temperature by quite a large amount (0.2-0.3 oC) during a period of 20-odd years. However volcanic forcings are temporary; they have a significant short term effect on the surface temperature, which can be prolonged if there is a period of sustained volcanic activity [as in the period 1883 (Krakatoa) through to Soufriere, Santa Maria Mt Pelee in 1902], and so their effects don't penetrate "deeply" into the climate system. So much of the earth's surface temperature suppression due to volcanic forcing was recovered relatively quickly through the period 1910-1930's. There was also a small solar contribution and an enhanced greenhouse effect contribution to the early 20th century temerature rise. The earth responds to these again without lag, but the full response to these persistent in the long term forcings will take a long time to saturate the elements of the climate system that have a high intertia to change (i.e. the oceans). The earth still hasn't come fully to equilibrium with the enhanced forcing as it stood in 1940 (say), let alone with the forcing as it stands at this particular point in time. Obviously, 'though, if we want to attribute the contributions to the 20th century temperature evolution, we have to consider all of these (including the negative forcing contributions like anthropogenic aerosols), and the manner that the earth responds to these. It's not that complex. However it does require thinking (modelling) of the system in it's entirety. One can't insist on cutting everything right back to individual components and simplistic responses and then complain that reality doesn't conform to a grossly oversimplified view - that's essentially to use straw-man argumentation!
125146. angliss at 16:27 PM on 23 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Kforestcat, I'm sorry, but you're off in the weeds on this one. What you describe with your pavement example is an example of signal + bias + noise. Because the instrument's location is constant, we can eventually come up with a correction mechanism to remove the bias from the data. That leaves us with signal + noise. Removing the noise is simple filtering, of which averaging is one variety. Mathematically, averaging a signal removes noise (increases the signal-to-noise ratio) at the rate of the square root of the number of samples. Averaging daily samples over the course of a week increases the SNR by nearly 3 over any single sample. So if we picked up thermal noise from a car one day, then we merely have to average that data point with others from the same instrument in order to dramatically reduce the impact of that noisy sample on the overall data. I'll grant you that, if you only have a single data point, biases and noise on that data point will be a major problem. But that's not the case with the temperature record.
125147. chris1204 at 16:22 PM on 23 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Regardless of site, we see an obvious rising temperature gradient from 1980 to 2009 based on a line of best fit. However, ‘eyeballing’ the unadjusted data suggests a striking fall based on a line of best-fit beginning with an anomalously high 1998 to 2009. Now we certainly don't want to cherry pick. The 1998 data was attributable to a very large El Nino. However, following on from the preceding post (‘The chaos of confusing the concepts’) with its discussion of the Lorenz attractor, I find myself wondering whether we may indeed be seeing evidence of greater inherent unpredictability than we commonly suppose. Eleven years after all seems a long period, especially when we consider the preceding data set covers eighteen years. Should we be considering the two periods as one segment? Alternatively, should we be considering these periods as two distinct segments and asking why 1998 produced such a high El Nino (followed by a relatively warm period) and why 2007 – 2009 are producing a much lower gradient? Moreover, is this gradient likely to continue? I think the question of site location is clearly a furphy given the broad consistency between better and not so well located sites. However, deciding which periods we select to measure trends is of much more fundamental importance given the arbitrary nature of lines of best fit. Otherwise, we risk failing to ask obvious questions.
125148. Tom Dayton at 16:01 PM on 23 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Kforestcat, in your example you wrote "Say the mean 1971-2000 temperature well away from the parking lot...." But that's not of interest. Instead, the temperature on that given day, from that parking-lot-situated instrument, is differenced from the average temperature across 1971-2000 of that same instrument.
125149. Tom Dayton at 15:55 PM on 23 January 2010
        On the reliability of the U.S. Surface Temperature Record
        Kforestcat, of course the temperature stations produce absolute temperatures as their "raw" data rather than as anomalies from a baseline. I have never seen anyone claim otherwise. You are misreading quite drastically. The baseline against which the anomalies are computed, is the average temperature for that specific locality across whatever time range has been chosen as the baseline. Each station has its own, local, baseline computed. Then each individual temperature reading from that one given station is differenced from that baseline for that one given station. The result is a difference of that one reading, from that tailored baseline. That procedure is done separately for each individual temperature reading, each against its own individual, tailored, baseline. It is a simple mathematical transformation that has nothing to do with instrument error and nothing to do with instrument calibration. It is a simple re-expression of each individual temperature reading that preserves all changes from the baseline temperature. The resulting collection of individually transformed temperatures is the collection of "raw" anomalies. Those are the "raw" data that you see being discussed.
125150. From Peru at 15:37 PM on 23 January 2010
        Why is Greenland's ice loss accelerating?
        The paper states: "Our results show that both mass balance components, SMB and D (eq. S1), contributed equally to the post-1996 cumulative GrIS mass loss (Fig. 2A)." But then, Fig.3 shows: Ice Discharge: -94 Gt/yr Surface Mass Balance: -144 Gt/yr Isn't this a contradiction? Then comes this statement: "A quadratic decrease (r^2 = 0.97) explains the2000–2008 cumulative mass anomaly better thana linear fit (r^2 = 0.90). Equation S1 implies thatwhen SMB-D is negative but constant in time, ice sheet mass will decrease linearly in time. If, however, SMB-D decreases linearly in time, ashas been approximately the case since 2000 (fig.S3), ice sheet mass is indeed expected to decrease quadratically in time" What is this "r^2 = 0.97" and how it is related to the equations: MB = ∂M/∂t = SMB – D (S1) δM = ∫dt (SMB-D) = t (SMB0–D0) + ∫dt (δSMB–δD) (S4) Any idea?

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