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Ned at 19:41 PM on 24 August 2010NASA-GISS: July 2010-- What global warming looks like
Pete Ridley writes: Between ice ages the globe warms and glaciers retreat then cools and glaciers advance. It’s happened before and will happen again. Right. But you don't get a glacial/interglacial cycle of that magnitude based on Milankovich forcing alone without a CO2 feedback amplifying it. -
Ned at 19:35 PM on 24 August 2010Medieval Warm Period: rhetoric vs science
muoncounter, thanks for the comment, but I find this a bit hard to swallow: "Yes, there is an underlying long term 'natural cycle', with an apparent period of 1100 years. " I don't think one can confidently diagnose the existence of an 1100 year periodic cycle from 2000 years of data unless the repetition is very, very close to exact. That's less than two full cycles! -
Ned at 19:24 PM on 24 August 2010What were climate scientists predicting in the 1970s?
BP writes: either something was fundamentally wrong with a model leading climate scientists relied on in the mid 1970s or our temperature measurements are flawed [...] You say it was the model [...] Please. This is the second time recently that you have put words in my mouth that I do not say (see also here). I generally choose my words carefully here and would appreciate it if you would not rearrange them to suit some rhetorical game of your own. BP writes: Either ... or. There is no third possibility. It's plain logic. A third possibility would be that your interpretation of Manabe via Schneider & Coakley via Schneider & Dickinson is incorrect. It's not exactly like no one has thought about the radiative-convective fluxes between the troposphere & stratosphere since 1974. I haven't heard any concern that the calculated MSU TLS temperature trends are in deep irreconcilable conflict with atmospheric models. Maybe people are really concerned about this, in which case I would assume there would be references to it in the literature post 1974, and in sources that can be cited a bit more directly than your convoluted chain of telephony here. -
dorlomin at 19:14 PM on 24 August 2010Station drop-off: How many thermometers do you need to take a temperature?
You have left out steve mosher. Credit where credit is due.... -
Rob Painting at 19:08 PM on 24 August 2010There's no empirical evidence
Johnd @ 152 - "If variations in solar radiation was the sole means by which the rate of gain varied, what were the processes that adjusted the rate of loss?" Just call it an exercise in deductive reasoning -
Rob Painting at 18:26 PM on 24 August 2010Pakistan flood: many more will die unless more aid is delivered quickly
Pete Ridley, which GCM's project a long term cooling trend with increasing greenhouse gases?. -
Rob Painting at 18:10 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
John Brookes, but then they go on to assure us there's nothing to worry about (?), so it balances out. -
kdkd at 17:40 PM on 24 August 2010Station drop-off: How many thermometers do you need to take a temperature?
gallopingcamel #4 "Real scientists gather every bit of data available and only discard data for good reasons." This is incorrect. Real scientists will use the principle of parsimony to ensure that the data they can deal with is both accurate and manageable. -
gp2 at 16:58 PM on 24 August 2010Of satellites and temperatures
NOAA do not use anymore AVHRR data for sst since july 2009, they excluded avhrr data because of a cold bias in the middle and high latitude Southern Hemisphere where in situ data are sparse: ersstv3 Before that avhrr data were inter-calibrated using ship and buoy data and cloud/aerosol contamination removed. -
gallopingcamel at 16:04 PM on 24 August 2010Station drop-off: How many thermometers do you need to take a temperature?
The arguments of the statisticians boil down to the hypothesis that the result was not changed by omitting ground stations in high latitudes and high altitudes. As I have pointed out several times before, that is not the point. Can anyone tell me why it makes sense to prune over 80% of the ground stations? Real scientists gather every bit of data available and only discard data for good reasons. NASA, NOAA and the rest have discarded the vast majority of the data without bothering to explain why. Take a look at Peterson & Vose 1997 (An Overview of the Global Historical Climatology Network Temperature Database). While P&V are up front about dropping many ground stations they don't tell us why. I have emailed these good people but they don't respond. -
John Brookes at 15:37 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
The skeptical take on this, of course, will not be that Hansen et al understimated warming. Noooo. They will just say, "See, Hansen was wrong again." -
David Horton at 15:18 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
Bern, my impression is that the IPCC predictions are indeed conservative because of the requirement to reach consensus, which has the result that the most contrarian (philosophically and or economically) member nations force down the predictions so as not to frighten their own populations into asking questions about their policies. -
Bern at 14:13 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
Thanks for the article, muoncounter. Every one of these "what did scientists predict decades ago" articles I read seems to tell the same story - climate scientists have generally underestimated temperature rise and potential climate impacts. The question I would then ask - are the predictions now being published similarly conservative, or has the methodology changed to be more 'accurate'? It seems the IPCC AR4 predictions are conservative, which may be a cause for concern as authorities are basing long-term planning decisions on those predictions (particularly the sea level rise ones). -
dsleaton at 13:59 PM on 24 August 2010Can't We At Least Agree That There Is No Consensus?
kdkd -- that's true for me. I looked through the list and the arguments. PT has zero credibility for me. Not worth wasting time on. Indeed, after my look, I can't even believe that PT is attempting any real engagement with the science. It seems more of a rhetorical game designed 1) to fool people who don't have time to look into to the details and 2) to waste the time of those who might want to actually move forward. Zero integrity, based on the overall evidence of the postings, or else an integrity tied to a different goal--a goal that has nothing to do with science. -
yocta at 13:44 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
Good post ! :) The link for the 'critically reviewed' paper mentioned at the bottom of the post is not working.Response: Hmm, that link seems to have disappeared into the ether. I've updated it, linking to http://www.skepticalscience.com/Hansen-1988-prediction.htm (muoncounter, if that wasn't the page you were linking to, feel free to update the post). -
SoundOff at 13:25 PM on 24 August 2010Station drop-off: How many thermometers do you need to take a temperature?
It might be instructive to explain that stations were not really dropped. Rather the Global Historical Climate Network (GHCN), which collects and provides the raw temperature data to the other institutes, was built in ~1992 from retroactive climate records. GHCN doesn’t have resources to manually add millions of data points on an ongoing basis, so they sort of put the GHCN on autopilot thereafter, to receive CLIMAT reports electronically (for surface stations) but the database is supplemented by other sources. It’s largely up to national met agencies which stations they put on the CLIMAT system and how regularly each station sends data. Perhaps 20% (?) of stations automatically feed into GHCN. I suppose at some point they will add some or all of the accumulating manual records. -
muoncounter at 12:41 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
#1: "we need to explain what '1sigma' and 'temperature anomaly' mean" Sorry, I thought that 'temperature anomaly' was standard terminology; just about every temp graph you see (including the one in the original Fig 7) is delta T = T - (some average T). As for 1 and 2 sigma, I'm sure subsequent comments will take care of that. BTW, I stumbled on this paper after reading the 'What were climate scientists predicting' thread. -
MattJ at 12:31 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
O-o-o-o-K-k-k-k-k, so when we write up a 'basic' version of this, we need to explain what '1sigma' and 'temperature anomaly' mean. The latter in particular has a somewhat surprising technical sense, differing from the sense you would expect by combining 'temperature' and the usual meaning of 'anomaly'.Response: Bit of "intermediate whiplash", I see, after all those Basic posts :-)
There's no plan to write basic versions of every blog post. We're only writing basic versions of the rebuttals of skeptic arguments. Fair point though, even intermediate posts should explain the technical terminology. -
HumanityRules at 12:00 PM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
To be fair it's not just skeptics that favour extent and area it's the scientists themselves. Every online website from polar groups seems to have it's own measure of extent. In fact PIOMAS ice volume graph you show is a fairly unique online metric from my trawling. While PIOMAS seemed accurate before 2007 there does seem to have been a deviation between their modelled results and reality since. In 2008 and 2009 this model underestimated the minimum extent and looks like it will again underestimate extent. Surely a model is always under scrutiny going forward, this is the best test for how well it is modelling the real world, at what point do we say that a model is no longer accurate. It seems that continually referring back to 3 years when it matched well with a short satellite data set can't be enough to keep it afloat. There are still issues with ice thickness measurements specifically the lack of good spatial and temporal coverage which leaves uncertainty in any estimate of volume or trends. Looking back to the 1990's here's two papers covering that period which came to very different conclusions (Windsor and Rothrock). More recently I just read this paper Thickness sensitivities in the CICE sea ice model Elizabeth C. Hunke Ocean Modelling Volume 34, Issues 3-4, 2010, Pages 137-149 which suggests that the probable number of factors which affect ice thickness out-numbers the data sets by which those factors can be constrained suggesting we still don't have the data by which we can directly or through models accurately estimate thickness and more importantly trends. It seems there are good reasons why some are cautious about ice thickness. Why not highlight the uncertainty associated with this particular metric? It seems like an important aspect of the work. (Just for correction the Giles 2008 and Kwok 2009 only seem to cover 2008 data not 2008/2009 as you seem to suggest in your article. You've also managed to leave out the word modelled with regard to the PIOMAS graph.) -
Riduna at 11:51 AM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
Surely both measurements are important for different though related reasons. Decline in volume causes average thickness of sea ice to diminish and the speed with which it melts, so it effects the duration of ice cover. Decline in the extent of ice cover reduces its effectiveness in reflecting solar energy back into space, limiting ability of the Arctic Ocean to absorb it. It is the latter aspect we should be concerned about since loss of the albedo effect means that solar energy absorbed by seawater is gradually increasing, warming that water, further reducing the thickness, extent and duration of sea ice cover. -
kdkd at 11:39 AM on 24 August 2010Can't We At Least Agree That There Is No Consensus?
Poptech #60 "It is clear you are very concerned about anyone reading my list, which is why you spend so much energy unsuccessfully attempting to discredit it." On the contrary, I think you'll find for any serious person your list of papers is thoroughly discredited. The show stoppers for me are: 1. You don't really understand what peer review means. 2. You don't understand how jouranl quality is assessed. 3. You don't understand the importance of citations. 4. Finally you don't differentiate between political, economic and scientific work. It's just a very long list with no attempt at any critical analysis. Your list of papers is really irellevant to the scientific consensus for these reasons. -
muoncounter at 10:49 AM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
#7: "skeptics think in 2 dimensions because they never saw the movie." That's a hoot! But we should be thankful: 2 dimensions is better than the usual one D thinking that you see all over denier sites about the IARC-JAXA graphs. "The decline in extent during July (i.e. the June 30th extent minus the July 31st extent) was uncommonly low." See, you can make a silk purse out of a sow's ear. -
kdkd at 10:45 AM on 24 August 2010What were climate scientists predicting in the 1970s?
BP #40 "No. I just wanted to point out either something was fundamentally wrong with a model leading climate scientists relied on in the mid 1970s or our temperature measurements are flawed." You're going to have to spell it out unambiguously. What do you mean by "something"? Vague insinuations are not good enough, please be more specific. And just for good measure, remember that your recent posts are contaminated with language showing that you consider your preconceptions more important than the actual evidence (e.g. overstating hypotesis as findings). So if you want to be taken seriously, I suggest that you are very very careful indeed with the way that you explain what this "something" could be. -
Daniel Bailey at 10:41 AM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
Count me in agreement that the volume anomaly chart should be adjusted to show the current minimum anomaly. WRT to the title of this post, skeptics think in 2 dimensions because they never saw the movie. The Yooper -
Osthato at 10:03 AM on 24 August 2010Station drop-off: How many thermometers do you need to take a temperature?
Crap, just kidding. -
Osthato at 10:03 AM on 24 August 2010Station drop-off: How many thermometers do you need to take a temperature?
"So to conclude: Independent researchers have shown that there is no truth to the claim that cooling stations were removed, in fact evidence suggests that if these stations were included, warming would be shown to be slightly greater." I believe you meant "that if these stations were included, warming would be shown to be slightly *cooler*." -
Berényi Péter at 09:57 AM on 24 August 2010The Past and Future of the Greenland Ice Sheet
I just wanted to stress if both local atmospheric and sea surface temperatures were higher than today during the Holocene Climatic Optimum for thousands of years (they were) and the recent rate of ice loss is still considerably higher than any time after about 10 ka BP, then it is either a short transient ("weather") or there is something else at play here (soot?). In the past two centuries, the Arctic has warmed about 1.6 degrees. Dirty snow caused .5 to 1.5 degrees of warming, or up to 94 percent of the observed change, the scientists determined. 2007 J. Geophys. Res., 112, D11202, doi:10.1029/2006JD008003. Present‐day climate forcing and response from black carbon in snow Flanner, M. G., C. S. Zender, J. T. Randerson, and P. J. Rasch -
Peter Hogarth at 09:17 AM on 24 August 2010The Past and Future of the Greenland Ice Sheet
Berényi Péter at 20:28 PM on 22 August, 2010 On Black Carbon, I agree it is a more soluble problem than CO2, I will assemble some recent references (time permitting), but I believe most papers I have read place Black Carbon as below CO2 in importance. Am I correct in assuming the DMI chart you have shown is extracted somehow from the DMI images and not from the original data? I say this only because I have the data and cannot reproduce your chart. Have you defined melt season using some arbitrary thresholds? In all of my attempts to reproduce your chart, average temperature above 80 degrees N and melt season both show significant positive trends over the DMI measurement period - in agreement with independent temperature measurements from various satellites and published papers on surface records (again I’ll try to dig out references). You can check some of the actual DMI data values using the ERA40 re-analysis series which is virtually identical up to its end date and publicly accessible. I suspect you may not be integrating or averaging to derive your melt season values? You are also aware the near surface air temperature for the Ice cover in the Arctic Summer is constrained to just above melting point? -
johnd at 09:14 AM on 24 August 2010Pakistan flood: many more will die unless more aid is delivered quickly
Pete Ridley at 08:06 AM, the impact humans have on changing the landscape is often totally ignored when such disasters are being tied to climate change. Every piece of infrastructure whether buildings, roads, levee banks etc provide obstructions to the natural flow of water. The Mississippi being a good example. It has to be accepted that without any change in the magnitude of ANY weather event, such obstructions are going to magnify the adverse effects of ALL such events. The same with fires, cleared areas and particularly roads through thick forests apart from exposing the immediate surface areas to increased evaporation, provide funnels that allow extra oxygen into areas that in the normal course of events would have had more difficulty sustaining such an inferno, and of course all roads lead to areas of concentrated habitation which themselves provide even more highly combustible fuel also more open to the flow of oxygen in. There is no getting away from the tragedy of those caught by such events, but they should not be used to play with the emotions of others to push what is in many ways a political view. -
scaddenp at 09:03 AM on 24 August 2010NASA-GISS: July 2010-- What global warming looks like
And if you get CO2 higher than a certain value,(450? - pliocene level) then you wont get another ice age. Current rates of warming by any measure are an order of magnitude greater than warming within the ice age cycle. -
Berényi Péter at 08:59 AM on 24 August 2010What were climate scientists predicting in the 1970s?
#39 Ned at 05:13 AM on 24 August, 2010 we have a blog comment by BP who sees something in a citation of a 1974 paper by Schneider & Dickinson that contained a reference to another 1974 paper by Schneider & Coakley which in turn referred to a 1967 paper by Manabe that, BP assures us, must imply that the world has actually only warmed by 0.2C No. I just wanted to point out either something was fundamentally wrong with a model leading climate scientists relied on in the mid 1970s or our temperature measurements are flawed. Either ... or. There is no third possibility. It's plain logic. You say it was the model, which assumed constant relative humidity, therefore water vapor and cloud feedbacks increased with increasing temperature. For doubling of the CO2 content this extremely sensitive model had the effect of raising the temperature of the atmosphere by about 2.3°C. Somewhat lower than current estimates, but close enough. Still, this influential one-dimensional model, which produced convincing results and constituted an important step toward the ultimate goal of designing realistic three-dimensional climate models, which was also used to study the radiative properties of the stratosphere providing reasons to reject proposed supersonic transport (SST) airplanes, missed the relation between stratospheric and tropospheric temperature trends by a factor of three. Why? I think we could all learn a lot by having a technically correct answer to this question. -
Tom_the_Bomb at 08:54 AM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
"The Northwest passage is officially open." Most depressing opening ceremony in a long time. -
Peter Hogarth at 08:44 AM on 24 August 2010The Past and Future of the Greenland Ice Sheet
Berényi Péter at 20:28 PM on 22 August, 2010 The Simpson 2009 paper you cited is interesting. It presents results from “Huy2”, a complex three-dimensional thermomechanical model of the Greenland ice sheet, which has contraints adjusted for estimates of relative paleo-sea level derived from observations and also revised temperature estimates from the GRIP ice core. It is a revised version of “Huy1” from Huybrechts 2002. One of the conclusions is that early Holocene ice volume (and therefore overall Holocene volume loss to present) was greater than previously suggested, which suggests higher sensitivity of the Greenland ice sheet to temperature changes than previously thought. In this paper the authors state: "The reaction of the ice sheet to the Holocene Thermal Maximum may have produced a margin retreat of up to 80 km across the southwest sector of the ice sheet", and “Our results suggest that remaining discrepancies between the model and the observations are likely associated with non- Greenland ice load, differences between modelled and observed present-day ice elevation around the margin...” The paleo-elevation issue is a problem which Vinther 2009 attempts to address using the d18O values from several ice core sites to back-estimate (from the altitude relationship) -and more accurately constrain- elevation estimates. These results also resolve some previous disparities with bore-hole studies, bringing these proxy results closer. In doing so the results diverge significantly from previous so called “shallow ice approximation” based model results in that the elevation and probable ice thinning has been revised in Vinther 2009 to be greatest during the "Holocene Climactic Optimum", which may be an intuitive result. I have adapted the chart from Simpson 2009 to make it more comparable with that from Vinther 2009 shown later.
Figure 1: Ice volume estimates from 3-D ice sheet models Huy 2 (black) and previous Huy 1 (grey), from Simpson 2009.
The results from Simpson 2009 in terms of volume changes are of course not directly comparable with elevation changes, but the important result from Vinther is the likelihood of greater elevation (and again probably Ice volume) in the early Holocene, and thus again even greater sensitivity of ice loss to temperature changes.
Figure 2: revised elevation from Vinther 2009 (black) vs various 3-D thermomechanical model outputs including Huy 1 (orange) from Vinther 2009.
The revisions based on ice core proxy temperatures from the work of Vinther ties in to more recent modeling work ( Stone 2010) which uses much more up to date estimates of ice thickness and bedrock topography (compared with previous work such as Simpson 2009 or Lunt 2009 etc). The results from Stone et al suggest again a higher sensitivity to temperature and therefore greater potential changes in future for given temperature variations and CO2 concentrations than previously predicted (for example in IPCC 2007)
As for sea level budget contribution due to melting of the Greenland Ice Sheet, you are correct that Simpson does suggest a relatively low averaged value for the early Holocene, but as suggested above, this is likely to be an underestimate. The most recent IPCC (AR4, 2007) value for Greenlands contribution (based on 1993 to 2003 range) were between between +0.14 to +0.28mm/yr. Updated estimates suggest an increase to +0.46mm/yr for the period 2000 to 2008, van den Broeke 2009, Velicogna, 2009, with estimates for the most recent period as high as +0.75mm/yr . In a recent review Cazanave 2010 gives an average of several recent estimates of Greenland Ice Sheet contribution between 2003 and 2007 of 0.5mm/yr. The Alley 2010 paper Ned cites above also has a pertinent chart of various recent estimates of sea level contributions which show apparent acceleration of loss and recent values well above 0.2mm/yr. There is also corroborating evidence of resultant accelerating North Atlantic (precision GPS measured) uplift in coastal bedrock Jiang 2010. Uncertainties in this uplift, and uncertainties due to the relatively short observation period and also different mass loss derivations from GRACE, are still apparent from some of the differing values (by potential factors of two) of ice mass loss in the recent work to date, as noted by Bromwich 2010 and Sorenson 2010. Nevertheless very recent estimates (published August 2010) trying to account for GPS measured uplift estimates still show large and recently accelerating Greenland ice mass loss, even if the absolute magnitude of these losses is yet to be quantified with precision, see: Khan 2010 and Wu 2010. It should be noted that these estimates are placed in the context of general consistency with data from other sources (with longer measurement periods of the variables used to estimate mass variation), and with updated models. There is little argument that the recent Greenland ice mass loss is highly significant and currently increasing. In summary, this does seem to be rather more than “noise”.
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NASA-GISS: July 2010-- What global warming looks like
Pete Ridley - there are multiple lines of evidence supporting the conclusion that the Earth is warming "at unusual rates". These include sea level rise, ocean heat content, the well supported surface temperature data, the satellite temperature record, growing seasons advancing faster than anything in the record, the paleo data on climate sensitivity to CO2, on and on and on. All of this evidence points in the same direction - "unusual rates" of temperature increase. Unless you can provide solid, repeatable, confirmable data contrary to this conclusion, or have invalidated all the mutually reinforcing evidence supporting AGW, you have not made your case. -
johnd at 08:33 AM on 24 August 2010There's no empirical evidence
This may be a rather stupid question given the subject is referred to so often, but I get the impression that at times different people consider it as something different, or perhaps more commonly simply don't know how it is defined and blindly use it. So can someone explain where the Top of the Atmosphere (TOA) is actually located, and why that particular point has been declared as such, and what it would mean if different levels were to be considered the TOA instead. -
Pete Ridley at 08:13 AM on 24 August 2010NASA-GISS: July 2010-- What global warming looks like
KR, you are seeing a conflict that isn’t there. Between ice ages the globe warms and glaciers retreat then cools and glaciers advance. It’s happened before and will happen again. I repeat (but read the words carefully) “There is clearly no basis for the claims that the Earth has warmed at unusual rates in recent times...” most importantly those words “at unusual rates”. Best regards, Pete Ridley -
Pete Ridley at 08:06 AM on 24 August 2010Pakistan flood: many more will die unless more aid is delivered quickly
Anne-Marie, don’t overlook the fact that a major contribution to the extent of the catastrophe arising from this weather event in Pakistanis is not so much due to an extraordinary monsoon as to the manner in which the river(s) are being managed and the manner in which people are populating unsuitable areas. Dappledwater, there is enormous uncertainty about future changes to global climates and whether the globe will get hotter or colder. There is no convincing evidence that “these extremes will become common place in the not too distant future”. Kernos chooses to give the impression that we know that “humans are causing climate change by increasing CO2 and other greenhouse gasses into the atmosphere” but he is wrong. We do not know this, we speculate about it. From what he says he must be quite happy to volunteer to be one of those “few million (who he considers) will not make much difference”. I tend to agree with CBDunkerson. Best regards, Pete Ridley -
hadfield at 07:56 AM on 24 August 2010Medieval Warm Period: rhetoric vs science
Correction: the original post and several of the comments refer to "Moburg". It should be "Moberg" (as used in later comments). -
scaddenp at 07:48 AM on 24 August 2010There's no empirical evidence
Energy tracking is discussed here and excellent relevant discussion of the Trenberth & Kiehl diagram here And as for claiming there is no flaws in 107-110. Well we tried to help. I cant even parse what you are trying to say nor could Ian. We've pointed you to a correct interpretation. I give up.Moderator Response: Yes, theendisfar, if you want to post your version of an energy flow diagram, do it on that thread, not this one. -
chris at 07:04 AM on 24 August 2010Can't We At Least Agree That There Is No Consensus?
batsvensson at 06:05 AM on 24 August, 2010 "A "balance of evidence" or the "holistic view" consist of the evidence, that a) climate model shows that CO2 is the only thing that we can think of that can reproduce the current warming trend in conjunction with that b) no other credible cause has been identified. A "consensus" in climate science is an interpretation of, or a conclusion from, evidence that fits into the theory in such way that it helps explain observations with out contradicting any part of the theory." Those are unnecessarily cumbersome definitions batsvennson. Remember that words/definitions are shorthand signifiers for the things they describe. They are not the thing itself, and are used to communicate ideas and information. If we’re interested in what climate scientists consider to be the case concerning a specific issue (say the origin of increasing atmospheric [CO2]), then we might be happy to know that there is an essentially overwhelming consensus that the rise in [CO2] is a result of anthropogenic oxidation of fossil fuels. However we may be interested in the origin of this consensus and then we would wish to consider the evidence. This is pretty obvious if one considers real world examples that we might encounter on a personal level. If you return to the doctor following tests to examine the cause of deep chest pains combined with fatigue and recurrent bouts of bronchitis, and he tells you that (a) the balance of evidence indicates lung cancer, and (b) that he’s sent your X-rays to 6 specialist lung cancer oncologists, and had your tissue biopsies examined by three oncology labs, and that the consensus is that you have got lung cancer, you’d most likely take his views seriously. However, most likely you’d wish to see the evidence for yourself. Now I would say that the notions of “balance of evidence” and “consensus” in this example are essentially the same as when used in climate science, or indeed any scientific subject. I wouldn’t say that “consensus” is used when there isn’t “hard evidence”. Of course it depends what you mean by “hard evidence”! I would say it’s more likely to be used when there is strong evidence, but this evidence may not be immediately communicable to a layman. The term “consensus” is also used when a subject is reviewed to address the evidence base and the interpretations that are drawn from this. So going back to your definitions reproduced at the top of my post, “balance of evidence” has nothing necessarily to do with climate models, or things we can think of, and “consensus” has nothing necessarily to do with any particular theory. In climate science an interpretation based on the “balance of evidence” is something like: “an interpretation that considers all of the evidence that bears on a subject, and which is supported by each of these, not contradicted by any evidence at hand, and more strongly supported than other possible interpretations”. And a “consensus” is something like: “a strongly dominant expert interpretation based on a well-informed and thorough examination of the evidence”. There’s no reason why a consensus need support a theory, although if it doesn’t, there’s obviously strong grounds for considering the usefulness of the theory! -
robert way at 06:52 AM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
Anyone wanting to see the open passage can look here: http://arctic.atmos.uiuc.edu/cryosphere/NEWIMAGES/arctic.seaice.color.000.png -
batsvensson at 06:50 AM on 24 August 2010Can't We At Least Agree That There Is No Consensus?
"It [Consensus] refers to an expert interpretation based on a well-informed assessment of the evidence that bears on a particular issue." I recall an incident when I did my military service as a kid, we was training in doing visual range observations, and the Lt. asked use about the range to various object in the terrain. One guy started out "I guess...", the Lt. immediately interrupted and roared "Hold! We never guess - we estimating distance. Continue... ". -
muoncounter at 06:47 AM on 24 August 2010What caused early 20th Century warming?
#34: "With no other 'anthropogenic' forcings in 1750AD - and excluding volcanic effects, was the Earth warming or cooling in 1750 - or was it in 'balance'?" Based on data presented here, it appears that 1750 was slowly warming. Looking at the rising peaks on the sunspot graphs above and extrapolating TSI backwards to match (if that's a legitimate thing to do), that would suggest TSI was gradually increasing as well, albeit on a shorter period. Does the quantitative aspect of your question suggest that you feel earth temperature should match solar irradiance - volcanic effects exactly? If the 'natural climate cycle' is one that slowly oscillates on its own, what is the value of equilibrium, other than as a midpoint of the normal oscillations? Isn't it more significant to understand what causes the departure from that equilibrium condition? -
Phil at 06:46 AM on 24 August 2010The main culprit in mid-century cooling
I have posted a rebuttal to http://www.spinonthat.com/CO2.html in this thread. -
David Horton at 06:44 AM on 24 August 2010Medieval Warm Period: rhetoric vs science
"That's a difference many seem to forget: the big-picture rate of change of recent temperature anomalies is much too fast to be 'natural'. " YES. And it is linked to ever growing CO2 concentrations resulting from increasing industrial activity relying on coal fired power stations (and massive volumes of cars). This blind spot about recent temperature rise always stuns me. If we had, a few hundred years ago, decided, as a planet, that we would only industrialise using renewable energy, and had kept CO2 constant, and we had still seen a slow rise in temps in recent times comparable to the MWP then, while we might be curious about the underlying mechanisms, and might also be concerned about the effects of a temp rise on a planet of 9 billion people instead of a few hundred million, we wouldn't be concerned about the longer term prognosis of temperature rise. That deniers don't appear to recognise that we are not in that latter fantasy scenario is evidence of a rigid mindset determined to prevent any action to save this little planet. -
Phil at 06:43 AM on 24 August 2010Greenhouse effect has been falsified
In this thread user miekol is asked by the moderator to post a question about this article in this thread. I thought I'd "jump the gun" and post a rebuttal now! The article states that O2 and N2 are, despite claims by "warmists", Infra-red active and links to some IR plots. These plots are, in fact all due to molecules made up of different isotopes. Thus there are plots for 16O-17O, 16O-18O and 17O-18O and one for 14N-15N, but none for the symmetric counterparts. Note that for some of the plots the isotope details have been removed. Because these isotopic variants are very nearly symmetric, the absorption is weak (see the very small numbers on the vertical axis). So these isotopic variants make up a tiny percentage of the gases, and the small percentage that do absorb only very weakly. Moreover the O2 and N2 absorptions don't match the frequencies that earth emits at, so there is nothing in "earth-light" for these gases to absorb. Later in the page they state that because O2 and N2 melt at a lower temperature, they are "most sensitive to heat absorption". This is completely incorrect. The melting points of substances relate to the strength of the forces between molecules, which ultimately comes down to the distribution of positive and negatives charges within the molecule. H2O has a negative "end" (the Oxygen) and a positive "end" (the Hydrogen) and this makes a powerful attachment between the molecules. Symmetric molecules like O2 have much weaker attractions and so take less energy to melt and vapourise -
Tom Dayton at 06:41 AM on 24 August 2010Can't We At Least Agree That There Is No Consensus?
No, batsvensson, consensus is not invoked only in the absence of hard evidence. Scientific consensus is used constantly, even when there is "hard evidence." Consensus is needed to determine whether purportedly "hard" evidence really is hard. No matter how "hard" it seems to be. For more reading on the role of consensus in science, click the links in this comment of mine. -
muoncounter at 06:32 AM on 24 August 2010Medieval Warm Period: rhetoric vs science
The graph shown above (Figure 1) is remarkable. The data are available in the download link on this page. Moberg provides a low frequency component (labeled LF in the data file). It really didn't appear to be that low, so I created a really long period filter and plotted the original data, Moberg's LF (pink) and the long period curve (dark purple) in the graph below.
Click for full size
Moberg's data ended in 1979. Tacked on to the end is GISSTemp from that point forward (red), adjusted slightly down to merge.
This really puts the MWP and LIA into perspective: Yes, there is an underlying long term 'natural cycle', with an apparent period of 1100 years. And yes, we started on the long, gradual upswing after 1650 or so. But the graph of temperature anomalies from 1850-2009 looks nothing like the natural cycle.
That's a difference many seem to forget: the big-picture rate of change of recent temperature anomalies is much too fast to be 'natural'.
-
NASA-GISS: July 2010-- What global warming looks like
Pete Ridley, others - As an additional note on this thread, which is also relevant to the Are surface temperature records reliable: I wrote this a while back on the topic of proof and disproof. You cannot disprove global warming by pointing out what you perceive as flaws in individual lines of evidence. That only impacts that line of evidence, not the theory. If you want to disprove global warming, you need solid, reproducible data contradictory to global warming - and I've seen nothing of the sort. If John O’Sullivan or Charles Anderson have something worth saying (I read their articles, and I haven't seen any evidence of that yet), they should write it up along with their data for a peer-reviewed publication. Not blogs. -
batsvensson at 06:22 AM on 24 August 2010Can't We At Least Agree That There Is No Consensus?
chris, at 05:31 AM on 24 August, 2010 ok, thank you, my current understanding is that the concept of a consensus is invoked when there is no hard evidence (i.e. observations) to point at and that it is used losely (maybe even to losely) in many different context. That is, it nobody knows what it means until it gets defined.
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