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chris at 21:25 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
Exactly Dikram... it doesn't tell you anything interesting.. it's obvious really. And yet the abstract of the paper we're discussing contains the sentence: ”The greatest melt extent over the last 2 1/4 centuries occurred in 2007; however, this value is not statistically significantly different from the reconstructed melt extent during 20 other melt seasons, primarily during 1923–1961.” Call me picky, but apart from the falsehood of the sentence about greatest melt extent, the sentence contains a statement that I think we both agree doesn't tell you anything interesting. My point, which I keep banging on about (and I believe we both agree on) is that a reviewer might be expected to pick up on that. That sentence simply shouldn't be there. I have a feeling you are arguing for the sake of it somewhat (or seeing who can raise pedantry to its most extreme level - you might be inching ahead now!). The point about the Douglass analysis is that it was an inappropriate test of the comparison of empirical and model data to assess whether models could be invalidated (shown to be inconsistent with...) on the basis of some statistical analysis of uncertainty associated with the empirical data. They did it to attempt to pursue a misrepresentation most likely. I'd say that is a "pseudo" analysis. A pedant might disagree! But since I've hopefully made clear exactly what I mean when I use the prefix "pseudo" in this context, there really shouldn't be cause to quibble, should there? It's very important in science to try to convey clear what one means. Would that reviewer's of papers would be so careful... -
Alexandre at 21:03 PM on 3 May 2011Lindzen Illusion #3 and Christy Crock #5: Opposing Climate Solutions
Chris G, Bern China's economy is growing fast, and so are its emissions. But unlike the US, they're investing heavily in renewables too. The US is being held hostage of FF lobbyists. It's perhaps an important weak point of their democracy, and it's making them lead the world's denialism and delayed action. Which is ironic, given the fact that a lot of the climate science, research and monitoring is US made. China does not seem interested in a carbon tax, AFAIK. They're doing the transition from a central command, just because the government saw it strategically fit. The US and EU, as large consumers, could impose efficency and environmental standards to exporters. This could be a big impulse for cleaner practices. The carbon tax could play an important role here, making these cleaner energy and goods more attractive to the internal consumer. But the US is choosing to lag behind. This will not look good in future history. -
JMurphy at 20:56 PM on 3 May 2011Could global warming be caused by natural cycles?
It must be confusing trying to use the UAH figures each month to try to determine the state-of-play of the planet. As well as desperately trying to convince yourself that because March 2011 has the same anomaly as March 1980, AGW has magically gone away, you would also be up and down, from happy to sad, like a jack-in-the-box : Most of 2010 highest since 1998 ? The globe obviously hasn't warmed since 1998. Jan 2008 lower than since the beginning of readings ? We are now in global cooling. Early 2007 showing highest anomalies since 1998 ? The globe obviously hasn't warmed since 1998. Jan 2000 lower than since the beginning of readings ? We are now in global cooling. 1998 the highest since the beginning of readings ? That's obviously not right and can be ignored, or used to state that the globe hasn't warmed since that time. Nov 1984 lowest anomaly ever (since the beginning of readings) ? We are now in global freezing. -
Dikran Marsupial at 20:24 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
chris@73 I suspect the reason paleoclimate people don't perform such a statistical analysis isn't because there is any methodological problem but simply that it doesn't tell you anything interesting whatever the result. It is not a valid argument to cliam that thr FKM test is invalid/inapropriate because paleoclimate people don't use that test - there has to be a first time for everything. So far you have given no statistical reason why the test is not valid (the data being too noisy is not a good statistical reason - it certainly doesn't make it "numerology"). The interpretation of the result of the test is another matter (c.f. my comment regarding frequentist statistical tests - being unable to reject the null hypothesis does not mean the null hypothesis is true, it never has and it never will). BTW, there was nothing "pseudo" about the statistical analysis of Douglass et al. They correctly applied the wrong test, but the test itself was perfectly correct statistics, it just didn't test what they thought they were testing. -
chris at 20:09 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
since we're being pedantic, I really should have said: "Santer's paper was addressing something quite specific - the question of the extent to which uncertainties in tropical tropospheric temperature could be used to invalidate expectations from models." And even that's not quite right, but I haven't got time right now to rewrite that sentence, and I expect you can see what I'm trying to say... -
chris at 20:05 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
O.K. fine Dikram. Yes the IPCC's designations ("likely", very likely") map onto estimates of probability ranges. However they don't address these with a numerical statistical analysis and assign measures of statistical significance to comparisons of contemporary and historical (paleo) parameters Santer's paper was addressing something quite specific - the question of the extent to which uncertainties in tropical tropospheric temperature could be used to validate expectations from models. Since a (pseudo) statistical analysis was used by ohers to attempt to infer that empirical measures and their uncertainties showed that empirical measures were inconsistent with models, it was appropriate for Santer et al to address the comparison with a statistical analysis. [apols for the long sentence!] However (and I may be wrong, since I haven't devoured every last bit of published data), I haven't seen any attempt by the paleo community to assign statistical significance to comparisons of contemporary and historical data (e.g. the paleo analyses of Mann, Briffa etc.). The reasons why this is a dubious approach is indicated in my post you just responded to. Of course one can do a statistical analysis of anything and assess apparent statistical significance in differences between whatever one choses. However attempts to do this in comparing paleodata with large uncertainties, to contemporary data with lesser uncertainty is playing at numerology. Of course if the authors of the paper were to test the statistical significance of differences between their model of paleo melt and their model of contemporary melt, that would be more acceptable even if the 95% confidence level significance is still somewhat meaningless in relation to what we'd really like to know (difference in real melt now and real melt then). But it's not up to me to address this in detail. That's the role of the reviewers of the paper... -
johnd at 19:28 PM on 3 May 2011Could global warming be caused by natural cycles?
Marcus at 18:39 PM, where are you getting the information that La-Nina is officially finished? The El-Nino Index is still in negative territory, about -1, and though it is weakening slightly, it is expected to strengthen again and remain negative well into 2012. -
Dikran Marsupial at 19:26 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
chris@69 There is no reason why tests of statistical significance cannot be used to compare observations with model hindcasts/reconstructions - it is done quite regularly by climatologists working with specialist statisticians (e.g. the Santer 17 paper). If you have a reason why this particular comparison is invalid, then you need to explain why in more detail. Secondly, the IPCC do not use qualitative estimates - if you look at box TS1 on pages 22 and 23 of the most recent WG1 report, you will find those "qualitative" terms map directly onto quantitative probability ranges. Without tests of statistical significance, how do you suggest scientists working with models avoid drawing conclusions from spurious correllations? Having said which, frequentist hypothesis testing is a bit of a mess anyway and many scientists and most of the general public tend to misinterpret the results of such tests. -
RobertS at 19:04 PM on 3 May 2011Could global warming be caused by natural cycles?
"The problem fundamentally is the entire trend can be wiped out in just one year or so of natural variation." No, it can't. I think you're confused as to what a trend represents -- it's the average slope, not the temperature [anomaly] at a point in time. "In general, if the trend amount is less than the amount of observed variation over the trend, it's not outside the range of natural variability." If that were the criteria we would never be able to discern a trend in any observational series. I'd feel a whole lot better about my stock portfolio over the past 4 years... -
johnd at 18:50 PM on 3 May 2011How climate change deniers led me to set up Skeptical Science website
Marcus at 18:24 PM, you are confirming my point. Virtually everything I know about Monckton is through what I have read from the various threads devoted (did I say devoted?) to Monckton here at SkS. Unlike yourself I don't even feel the need to avail myself of even greater knowledge by scrutinising "The Australian" to see how much time they devote to him, or who invites him to speak. I only read "The Australian" online and honestly can't recall even seeing any mention of him there. Perhaps I need to seek out any mentions of him through their search function. Anyway, here seems to provide a more than adequate blow by blow coverage of his engagements. You now have me wondering who gives him the greatest attention, pro-rata that is, "The Australian" or SkS? -
Marcus at 18:39 PM on 3 May 2011Could global warming be caused by natural cycles?
Indeed, RW1 is doing a *mega* cherry-pick. Pick a single month from the *least* reliable source (UAH) of *satellite* data (so failing to see the warmth in the polar regions), & even then he can *barely* achieve the result he's looking for. April here in Australia was pretty well above average-especially now that the La Nina is officially finished-so I wonder if he'll compare April & May results? -
Marcus at 18:37 PM on 3 May 2011Could global warming be caused by natural cycles?
Wow, that's Cherry Picking at its *worst* scaddenp. I mean, hasn't he heard the saying "one swallow doesn't make a Spring"-the same can be applied to climate data. The simple fact that the monthly temperatures not only bounce back, but tend to bounce higher & higher every few years indicates that all that extra heat energy is still in the system, & continues to build up. -
Marcus at 18:24 PM on 3 May 2011How climate change deniers led me to set up Skeptical Science website
Well John D, you might want to ask that bastion of "Skepticism"-The Australian-why they frequently devote so much space to the rantings of Monckton & Plimer? Also, why is Monckton frequently invited to give testimony at Congressional Hearings in the US, & why do the various skeptic conventions around the world frequently feature one of these two people as Guest Speaker? You might not credit them with too much importance or influence, but I'm afraid you're still in a minority amongst your fellow "skeptics". -
johnd at 18:05 PM on 3 May 2011How climate change deniers led me to set up Skeptical Science website
It has always fascinated me the amount of attention, threads and posts that are directed against Plimer and Monckton by the more regular contributors here. They are obviously seen by many here as being far more important and influential than what I or most sceptics seem to credit them with. -
Ken Lambert at 17:52 PM on 3 May 2011How climate change deniers led me to set up Skeptical Science website
chriscanaris #53 "I don't recall any sceptic here citing Plimer or Monckton in support of their positions both of whom I find somewhat an embarrassment (but I'm happy to stand corrected)." Well I have never quoted the work of Plimer or Monckton in any of my arguments put forward on SKS. chriscanaris: "the sheer weight of ad hominem argument levelled at Ken beggars belief and can't go unremarked." The reason for that attack was the attackers were shown by my reasoned argument and calculations to be factually wrong on several important numbers.This unleashed the torrent of abuse.Response:[DB] Your failed attempts to recast the dialogue of the Flanner thread to cover your errors are transparent. Multiple transgressions of the Comment Policy have forced moderation; your subsequent blaming of the moderation as cause for your failure to prove your arguments ring hollow, as does your trying to reframe comments critical of your retreat & diversion escape plan as being "abuse".
You were in error, you were corrected on the error, and you have spent weeks trying basically saying "no I wasn't". Black Knight Syndrome embodied.
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logicman at 17:26 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
Chip Knappenberger 1 - Why are comments not allowed in response to your post on this paper at worldclimatereport.com? 2 - How is interesting historical data from a few sites relevant to the multiple integrated observations of warming and melting over most of Greenland, the Canadian Archipelago and indeed the entire Arctic? I ask question 2 in the context of Patrick J. Michaels' post at the Cato Institute in which he uses this already obsolete paper in conjunction with another debunked paper to conclude that: "...the recent increase in melt across Greenland (contributing to a negative trend in SMB) may in part a result of rising temperatures from sources other than dreaded greenhouse warming, and therefore extrapolating the observed trends in SMB forward may not be such a great idea." http://www.cato.org/... It is interesting that Michaels seems focused on the idea that beachfront property is - presumably - a good investment because coasts are not at risk. Would you do him the kindness of directing him to recent studies which show that he should rapidly dump any such investments which he may have in more northern latitudes? http://www.sciencenews.org/view/generic/id/73737/title/With_warming,_Arctic_is_losing_ground It is ironic that Michaels posts under the banner 'current wisdom'. Wouldn't the banner 'obsolete folly' be more apt? -
RSVP at 17:21 PM on 3 May 2011Waste heat vs greenhouse warming
KR 419 When the sun shines, it is because there is an open sky. The ground warms, and this heat sees the same open sky. Cooling by radiation is optimal. When the sun doesnt shine due to cloud cover, while conditions for radiative cooling are less optimal, there is also less heat to radiate in the first place (due to the clouds). Along comes humanity doing something else. Adding heat incessantly, regardless of cloud cover night or whatever. Then come the denialists saying this isnt a problem, and that things are warming mainly due to the extra CO2. Extra heat being trapped when radiative cooling conditions are optimal (i.e. see first paragraph above). -
scaddenp at 17:13 PM on 3 May 2011Could global warming be caused by natural cycles?
He is just looking at March and comparing to every other month, not the annual global average. Its not even especially low. -
chris1204 at 17:01 PM on 3 May 2011How climate change deniers led me to set up Skeptical Science website
The Albatross has landed. Best wishes to all. -
RSVP at 16:55 PM on 3 May 2011Waste heat vs greenhouse warming
muoncounter 420 "The waste heat is irrelevant." If the waste heat coming out of a power plant was on whole being lost in the form of thermal radiation, no one would be able to approach it. Instead of requiring an ultra sensitive CCD to amplify this energy for your photos, you could just raise your hand and feel it. The plant is cooled by the mass of fluids (air and water) carrying 99.999% of the heat away, and it appears you are underestimating the mass associated with these fluids. -
Marcus at 16:43 PM on 3 May 2011Could global warming be caused by natural cycles?
RW1, do you even bother to check your claims? The average global temperature anomaly for 1980 was +0.02 degrees C above the 1979-2000 average. In 2008, the temperature was +0.1 degrees above the 1979-2000 average. Given that 2008 was (a) a La Nina year & (b) the nadir of the previous solar cycle & (c) Given that there are some pretty significant holes in the coverage of the satellite temperature measurements, I think this kind of debunks your entire premise. Of course, looking at year-to-year variability is a complete strawman anyway, what is more important are the following facts: (1) The average temperature anomaly for each decade has been *warmer* than the decade before. (2) The difference between the temperature anomaly for each decade is getting *larger*. (3) That the trend-line for warming is statistically significant. Now, if this were all down to just internal variability, then at least one, if not all, of those facts above shouldn't be the case. The question then remains. How, in the absence of a downward trend in Total Solar Irradiance, do you explain a total of +0.5 degrees of warming between 1979 & 2009? -
chris at 16:13 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
skywatcher at 10:45 AM on 3 May, 2011 No I don't think it's reasonable at all. One cannot make interpretations about statistical significance when comparing empirical contemporary data determined using one method, with historical data constructed with a model. This is partly the reason that the IPCC use qualitative estimates in these sorts of comparisons ("likely"; "very likely" etc),and why papers on paleotemperature reconstructions don't include measures of statistical significance. It's easy to see some of the problems. For example historical date reconstructed with a model have large associated uncertainties. All it requires for contemporary data to be "not statistically significant" with respect to the historical reconstruction, is that one has large error bounds on the historical data. It then becomes very difficult for differences in the contemporary data to achieve statistical significance, especially at the 95% confidence level. So I think the inclusion of statistical significance was entirely unwarranted, and the truly offending statement shuld have been removed from the abstract. Unfortunately, at least one reviewer of the paper gave the authors a free pass on this. He's shown us his confidential review which remarkably classed the methodology as "good" and raised not a peep about the statistical analysis. It's very unfortunate.... -
trunkmonkey at 16:04 PM on 3 May 2011Models are unreliable
360. The signature of the burning must be included in the ice cores, so I concede this, except for the possibility that the models are initialized a bit too high. Mizmi is the real expert but grasses are C4 plants adapted to the declining CO2 levels of the Pleiocene. They use less CO2 that the forest they replace. -
chris at 15:57 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
Tom Curtis at 12:18 PM on 3 May, 2011 Tom, I can only say again that I agree with you. As you pointed out above, and I pointed out here (see point [4]), there are some categorically incorrect statements in the paper that simply shouldn't have been allowed to stand. Unfortunately the main reviewer of the paper chose not to address these. So we can only complain about the situation after the fact. In my opinion Dr. Box could hardly have done a better job of playing into the hands of the misrepresenters. It's unfortunate to have to say so. Dr. Box had an opportunity to re-review the paper in early Jan 2011. Apparently the temperature/melt data used to compile the MKF reconstruction wasn't available to update their model to include 2010, and the editor chose to over-rule the recommendation that the authors delay publication to wait for this (an acceptable editorial decision in my opinion). However the melt data described elsewhere was available at least by late December. Therefore Box was in a very strong position in early Jan 2011 to give very strong guidance to the editor that categorically false statements MUST be removed from the paper in the light of independent data that shows the 2010 melt to be a new record. If this was done MFK would have been in a much weaker position in their attempts to misrepresent the relationship between contemporary and historical melt. -
trunkmonkey at 15:51 PM on 3 May 2011Models are unreliable
scaddenp 359: "That would be why DO have climate effects coming out of interglacial but not now?" Does the system really care about glacial/interglacial stage? Isn't meltwater, meltwater, whenever it ocurrs? If our efforts have accelerated the melting, does it matter that the triple net Milankovitch "forcings" languish in the future? Berenyi Peter, 355., is saying that he sees no SST increase. (Alley 2005) has an interesting discussion of this. He states that several models predict meltwater, but that the results are equivocal. -
Ken Lambert at 15:38 PM on 3 May 2011How climate change deniers led me to set up Skeptical Science website
My comments are being deleted so I cannot respond to Chriscanaris and his useful opinions. Suffice to say that Chris is pretty right in his analysis.Moderator Response: [DB] You have forced the moderators to delete comments as said deleted comments contained complaints above having to comply with the Comments Policy. Compliance with, and adherence to, the Comments Policy is not optional, despite your railing against it. You are clearly able to formulate a comment that passes moderation: your not doing so & then complaining about the moderation you have then forced upon yourself is clearly a gambit meant to reframe this as bias towards yourself. Very transparent. -
Bern at 15:08 PM on 3 May 2011Lindzen Illusion #3 and Christy Crock #5: Opposing Climate Solutions
That's a very good point, Chris G. It's somewhat complicated by real world politics, though. If the US told China to apply a carbon price, or they'd tax all imports, what would China do? Considering that if they chose to play hardball, the US would almost certainly cave (given that a large portion of the US economy now depends on goods from China, and China is also the largest holder of US foreign debt, they're really over a barrel). On the other hand, if China chose to impose a carbon price, I don't think the US would have any real choice but to go along. Another complication is whether the WTO would regard a carbon tax on imports (from countries that don't have a carbon tax) as a form of protectionism. I'd hope they were smarter than that, but it's hard to say. -
RW1 at 14:51 PM on 3 May 2011Could global warming be caused by natural cycles?
Marcus (RE: 186), "Yet it hasn't, RW1, so why is that?" But it has. Look at the graph. The globally averaged temperature is already back to what it was 30 years ago in 1980. Just three years ago in 2008, the temperature was lower than it was at the beginning of the satellite record.Response:[DB] Umm, no. RW, you were recommended earlier to learn a bit more about statistical trend analysis; I'd advise you do so. For your own benefit. You are not doing well, here.
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scaddenp at 14:49 PM on 3 May 2011Could global warming be caused by natural cycles?
No it hasnt!! Learn some statistics. Does winter wipe out a whole summer of warming? Look at the first link in open mind which looks at trend as function of start date. When you have a lot of internal variability, then you have to distinguish trends over a long period and what he does hints at the method that you use to discover how long. That is what climate is 30 years, not what happened last year. You can only "wipe" a warming trend with enough years of cold data that long term trend is zero or less. One cold - or one hot - year does not tell you about trend. Furthermore, its not as if there is any particular mystery in whether one year is hot or cold. You can predict pretty confidently that this year will be colder than last. La nina. You can also see from trends that year will be a lot warmer than similar sized la nina year from 30 year ago which what we are talking about with AGW. -
Marcus at 14:41 PM on 3 May 2011Could global warming be caused by natural cycles?
"The problem fundamentally is the entire trend can be wiped out in just one year or so of natural variation." Yet it hasn't, RW1, so why is that? The warming trend for the past 30 years has been shown to be statistically significant-using a myriad of different tests-which disproves your entire "caused by natural variation" hypothesis. An hypothesis, I might add, which reads more like an article of faith. -
RW1 at 14:34 PM on 3 May 2011Could global warming be caused by natural cycles?
scaddenp (RE: 183), "Tamino attempts this at Open Mind and also sees what happens if you remove the known causes of variability. Can you do better than that?" The techniques he uses to try to remove known causes of variability are highly speculative at best. All he's really showing is when these are removed there is a clear warming trend of about 0.3 to 0.4 C from 1979-2010, which really isn't in dispute. The problem fundamentally is the entire trend can be wiped out in just one year or so of natural variation. This makes it very hard to distinguish whether the trend is mostly random natural variation or mostly from one particular variable, such as man's CO2 emissions.Response:[DB] Tamino is a professional time-series analyst quite versed in climate analysis. All you're really accomplishing here is demonstrating your lack of foundation in understanding statistical trend analysis.
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Dan Moutal at 14:13 PM on 3 May 2011Video and podcast about confusing the hockey stick with the 'decline'
Like I said, perhaps (hopefully) I am overly pessimistic. And there are a lot of promising solutions to the baseload issue. I just think getting off Fossil Fuels will be more difficult without nukes. As for the need for the need for baseload power, I had not heard this argument before, so I will need time to digest it. -
Marcus at 13:54 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
You see, this is the one thing that keeps being ignored-even if the total glacial melt between 1923 & 1961 could be shown to be equal or greater to the melt we've seen between 1995 & 2010, there'd still be the fact that we *know* what caused the former glacial melt (rising temperatures due to increasing solar irradiance), but *cannot* explain the current glacial melt with any known natural causes. So that *really* leaves only rising CO2 emissions as the culprit. If so, then unlike the 1923-1961 melt, there'll be no end to the current melt *unless* we stop pumping more CO2 into the atmosphere. -
Marcus at 13:49 PM on 3 May 2011Could global warming be caused by natural cycles?
What's all this +0.3 degrees over the last 30 years nonsense anyway? Last I checked, the planet was warming at between +0.16 & +0.17 degrees per decade, which puts total warming at closer to +0.5 degrees over the past 30 years-& +0.6 degrees over the last 50 years. Given that this 30 year period has been dominated by a general *decline* in incoming solar irradiance, I really don't see how even the most committed denialist can claim that this is all part of some mystical "natural variation". After all, we didn't get that much warming even when solar irradiance was climbing during the first half of the 20th century. -
KR at 13:20 PM on 3 May 2011An Even Cloudier Outlook for Low Climate Sensitivity
RW1 - Looks like both SW and LW; see the bottom of column 1, page 1524, where Dessler 2010 discusses combining the uncertainties of SW and LW measurements to determine total uncertainties. -
scaddenp at 13:20 PM on 3 May 2011Could global warming be caused by natural cycles?
RW1 - I think that is voodoo statistics here. Perhaps you might like to explain in detail how you would do that calculation? Tamino attempts this at Open Mind and also sees what happens if you remove the known causes of variability. Can you do better than that? and of course the way to account for it with physics is compare model outputs with only natural forcing compared to models with all forcings. -
RW1 at 13:09 PM on 3 May 2011An Even Cloudier Outlook for Low Climate Sensitivity
Can someone help me out here? In figure 1 A and 1 B of Dessler's paper, are the y-axis fluxes LW or SW? Thank You. -
Michael.M at 13:03 PM on 3 May 2011Medieval project gone wrong
Great post Hoskibui, shouldn't it be added to the arguments? e.g "Disproves global MWP the recent warming?" -
RW1 at 12:57 PM on 3 May 2011Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
muoncounter (RE: 61) "That works both ways. Please tell us exactly the range of natural variability and how you obtain that figure." Answered here -
RW1 at 12:54 PM on 3 May 2011Could global warming be caused by natural cycles?
muoncounter, "RW1#59: "unless the amount of warming is outside the range of natural variability" That works both ways. Please tell us exactly the range of natural variability and how you obtain that figure." Good question. In general, if the trend amount is less than the amount of observed variation over the trend, it's not outside the range of natural variability. -
Tom Curtis at 12:18 PM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
Chris @50, it is rather awkward for you that you agree with me, for I was disagreeing with you. In particular, I was indicating that "‘Greenland climate has not changed significantly’" seems like a very reasonable summary of the author's intended take home message. That take home message, according to Knappenburger is:"Our general conclusions were: • several recent years (in particular 2007 and from preliminary observations 2010) likely had a historically high degree of surface ice melt across the Greenland ice sheet, • on a decadal scale, there were several 10-yr periods during the 1930s through the early 1960s during which the average annual ice melt extent across Greenland was likely greater than the most recent 10 years of available data in our study (2000-2009), • that the ice melt across Greenland was particularly low at the start of the era of satellite observations (which began in 1979), such that a sizeable portion of increasing ice melt observed by satellite-borne instruments since then could potentially be part of the natural variability about the mean state, • that, for the next several decades at least, Greenland’s contribution to global sea level rise was likely to be modest."
(My emphasis) That's two out of three authors now publicly running the line that its all just natural variation, and that that was the conclusion of their paper. If you agree that that line is an over interpretation of the data to 2009, then including 2010 would have underscored that point and the omission of detailed discussion (if not a full analysis) becomes unwarranted. -
Tom Curtis at 11:35 AM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
skywatcher @64, I am also interested in that question. In particular, I am wondering about the idea of testing statistical significance against the subset of the 20 highest melt years. why not test for statistical significance against all years? -
scaddenp at 11:10 AM on 3 May 2011CO2 effect is saturated
If you google "comparison NCEP ERA-40", I think it gives you a good reason to be extremely cautious of conclusions based on NCEP reanalysis without support from other data. -
muoncounter at 11:02 AM on 3 May 2011Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
RW1#59: "unless the amount of warming is outside the range of natural variability" That works both ways. Please tell us exactly the range of natural variability and how you obtain that figure. Responses belong on the Natural cycles thread.Moderator Response: Indeed, responses here will be promptly deleted without warning. -
scaddenp at 10:52 AM on 3 May 2011Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
Well I disagree with "no way to quantify", but for outside natural cycles, the calculation has been done and a convenient graphic is here Oh, and first principle physics, how about the quantum basis for radiative adsorption by GHGs? -
muoncounter at 10:52 AM on 3 May 2011Waste heat vs greenhouse warming
RSVP#418: "In order for anything to have a "large mass", there is a need to consider just a little more than surface area." So you contend that the area shown in the power plant photo or the ground shown in the third photo do not represent large thermal mass? The power plant, a poster child for your waste heat, has not changed the temperature of the larger surrounding area. The waste heat is irrelevant. No, sir, continuing to cling to this thread, without showing a shred of evidence for your thesis; that's pure garbage. -
skywatcher at 10:45 AM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
One last question from me - their last statement about statistical similarity depends entirely on their calculation of 95% confidence limits (2x RMSEv, according to their methods). For the statisticians here - is this error calculation reasonable? -
RW1 at 09:37 AM on 3 May 2011Lindzen Illusion #2: Lindzen vs. Hansen - the Sleek Veneer of the 1980s
dana1981 (RE: 57), "Sure, the warming could be natural variation, if you completely ignore all physics and climate science. Just like if I start a forest fire, it could have been started by a lightning strike! Aren't hypotheticals fun?" The point is unless the amount of warming is outside the range of natural variability over a given period of time, there is no way to accurately quantify how much of it is due to man. Also, the only genuine first principle derived physics are that of the radiative forcing of CO2 (3.7 W/m^2 per doubling), the measured response of system to incident energy at the surface (about 1.6), and the constraints COE puts on the system. -
skywatcher at 09:33 AM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
(correction to my last comment: I've just mixed my reading of Mauri's mention of PDDs with the paper's use of average summer temperatures, but you can swap 'degree days' for summer melt in my comment anyway.) -
skywatcher at 09:29 AM on 3 May 2011Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?
I think an additional point to make, and one that the paper deals with very poorly in its conclusions, is that melt is not the only component of mass loss, and therefore sea level rise, from Greenland. Much mass is lost through calving, and termini such as Ilulissat (Jakobshavn Isbrae) have been observed to accelerate substantially between the middle and the end of the 20th Century. I would guess that the total volume of ice discharged by this prodigious glacier also increased substantially during that time (the glacier has since slowed, but also has a much wider calving front these days). So while surface melt values may be arguably statistically close to values in the mid-20th Century (notwithstanding Mauri Pelto's pertinent comment at #59), it is reasonable to think that total mass loss values, and sea level contribution are notably higher now than in the mid-20th Century due to extra calving? The relationship between degree-day melt and mass loss necessarily assumes a consistent relationship between PDDs and calving rate across many decades, ignoring that surface melt is immediate, but the calving mass loss has a time-dependent dynamical component. I may be wrong in this assumption, but it would partially explain how they got away with publishing their dubious statement on sea level. A strange paper - if you didn't know the subtext you'd say it looks OK for much of the way through, but then raises a whole bunch of red flags for the conclusions and especially the last sentence comparing past decades to the last few years.Moderator Response: [DB] Consider also the millennia-old ice shelves, widespread in the early-to-mid 20th Century, now gone.
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