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Ned at 22:59 PM on 24 August 2010What were climate scientists predicting in the 1970s?
BP writes: The layer of stratosphere channel TLS (57 GHz) is sensitive for may be too low (peak sensitivity at 17 km), the divergence grows large only above it. Do we have upper stratosphere temperature time series? That is exactly one of the things I was skeptical about in your chain of reasoning, given that the trends at different heights in the stratosphere are quite different (at higher altitudes CFC-associated ozone depletion also complicates the analysis of temperature trends, something that wasn't anticipated in 1967). See Randel et al 2009, fig. 19:
Figure 19. Vertical profile of temperature trends for 1979–2005 derived from each of the individual SSU and UAH MSU4 satellite data sets, averaged over 60°N–°S. Vertical bars denote the approximate altitude covered by each channel, and horizontal bars denote two-sigma statistical trend uncertainties. Results are also shown for trends derived from radiosonde data averaged over 60°N–°S.
The solar cycle also has a much stronger impact on stratospheric temperatures.
The data from the mid to upper stratosphere are not as reliable as those from the lower stratosphere, for a number of reasons. They do show strong cooling (around 0.5C/decade in the middle stratosphere, even more at higher altitudes), but it seems to happen in a curious stepwise fashion that I'm not sure anyone has completely explained:
Figure 18. Time series of near-global average temperature anomalies derived from SSU data, for each individual channel (as noted). Data for channels 26x and 36x are shifted for clarity.
I am agnostic about the causes of that stepwise downward pattern. I wouldn't be surprised if it turned out to be partially due to an interaction between the CO2-induced cooling trend, stratospheric ozone, and the 11-year solar cycle (which as mentioned above has a stronger effect on stratospheric temperatures). On the other hand I also wouldn't be surprised if it was partially due to problems with the intercalibration of different SSU sounders on different spacecraft. Given all the uncertainty in the SSU record, I have generally been reluctant to draw much in the way of conclusions about temperature trends there, other than that they superficially seem to be more or less in agreement with what we expect.
Randel et al. (2009) and Shine et al. (2008) seem to be very relevant (and very readable).
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Berényi Péter at 22:20 PM on 24 August 2010What were climate scientists predicting in the 1970s?
#42 Ned at 19:24 PM on 24 August, 2010 sources that can be cited a bit more directly than your convoluted chain of telephony here Here is the original Manabe paper. Vol. 24, No. 3 Journal of Atmospheric Science, May 1967, pp. 241-259. Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity Syukuro Manabe and Richard T. Wetherald Fig. 12 (Vertical distribution of radiative convective equilibrium temperature for various values of water vapor mixing ratio in the stratosphere) and Fig. 16 (Vertical distribution of temperature in radiative convective equilibrium for various values of CO2 content) show a possible cause. The layer of stratosphere channel TLS (57 GHz) is sensitive for may be too low (peak sensitivity at 17 km), the divergence grows large only above it. Do we have upper stratosphere temperature time series? -
theendisfar at 22:05 PM on 24 August 2010There's no empirical evidence
Moderator, If you're going to shut down the ability to post to a thread, can you please notify the audience? Thank youResponse: There is no feature to shut down posting on any thread. If your comments are not immediately appearing, just check that the number of comments isn't just over the 50 or 100 mark (or some other multiple of 50). Your comment might be appearing on the next page over. Or if it appears then is removed, it would be because its violating the comments policy. -
CBDunkerson at 22:01 PM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
Agnostic #9: Actually, extent does not DIRECTLY relate to albedo. Ice extent is the area of OCEAN containing at least X% (usually 15%) sea ice. So, an extent of 100 sq km might only have 15 sq km of actual ICE area. That said, there are actual ice AREA estimates as well and those are obviously relevant for albedo purposes. However, I still think volume is the most important factor to keep an eye on. If it continues dropping at the rate it has the past few years (unlikely) then we're only three or four years from all the ice being gone. More plausibly volume declines will level off in the next year or so once all of the multi-year ice has melted down to basically the same thickness as 'first year' ice. It'll be interesting to see how quickly that leads to the breakup of the mass of multi-year ice along the northern Canadian archipelago (the western fifth is already gone) and what that will do to Arctic currents and ice export. -
Yvan Dutil at 21:41 PM on 24 August 2010Station drop-off: How many thermometers do you need to take a temperature?
@gallopingcamel As I understand it. Nobody droped volontary 80% of the station. Essentially, validation process is long and tedious. You need time, manpower and computation capability to do that. Actually, a new version of the database is about to be released. This shoould close the gap. Expect an upward revision of the temperature change. This will certainly creates new claim of manipulation by skeptics. -
Yvan Dutil at 21:37 PM on 24 August 2010Dust-Up On Mars: Should Martians Be Sceptical of Global Warming?
Published in the Journal of Cosmology. This is a dump for crappy idea, whatever if the field of research. "Warming on Mars must therefore be real and be a result of a complex (including magnetic) solar activity (f. e .QBO). " This is a very farfetch idea that provide a lot of information about the structure of your logic. We have only a very few data point for Mars temperature. Also, I dont see any commun mecanism that could be invoke the have a comparable effect on MArs and Earth. In addition, in the observation perio, solar activities as gone done. In addition, nobody claim than Sun has no impact on climate. However, even the most supporting analysis claim that it cant exceed 50% and is much likely to be below 25% of the observed warming. -
Yvan Dutil at 21:29 PM on 24 August 2010Medieval Warm Period: rhetoric vs science
Ned, you are right. The bare minimum is to have a cycle with the length of the data span. This work only without any confonding factor. Maybe the thousand tears cycle comes from other data. -
CBDunkerson at 21:19 PM on 24 August 2010Pakistan flood: many more will die unless more aid is delivered quickly
Kernos #10: Did you not read any part of my comment except the last sentence? Killing off a few billion (or "thousand million" as you put it) non-industrialized farmers would not help slow global warming EITHER. They aren't the ones causing CO2 levels to increase. China and India have long had huge populations... but their CO2 emissions were virtually non-existent until they began to industrialize. The vast majority of their populations (in rural areas) still emit little CO2. Wiping out all of the Americas, Europe, and industrialized portions of Asia (your 'few billion' people) would have a major impact on global warming from CO2 emissions. But those areas have much better disaster preparedness and simply will not suffer those kinds of losses. The only places you get huge population growth and massive deaths from natural disasters are in poor rural areas which aren't contributing to CO2 emissions in any significant way. So again... no significant 'negative feedback' on CO2 emissions from natural disasters. At least not any time in the near future. Go out a hundred years or more and it might be a different story... depending on how much CO2 we've emitted and how well technology has kept up with allowing us to adapt to the climate. -
ProfMandia at 21:05 PM on 24 August 2010Hansen etal hit a Climate Home Run -- in 1981
Nice timing. Tom Fuller and others over at Bart's place are criticising Hansen for a supposed comment that he made about the West Side Highway being flooded today due to sea level rise in a Salon Magazine article. Fuller goes on to claim that Hansen has been discredited along with Dr. Mann. Going there now to post this link. Touche' -
Byron Smith at 20:59 PM on 24 August 2010Arctic Sea Ice: Why Do Skeptics Think in Only Two Dimensions?
I second the comments at #9. And also the concern for whether this post will date quickly (especially since it already refers to April and it is August). I thought basic level explanations were generally not going to include links to papers. Furthermore, I wonder about the register of "metric" and "satellite radar altimetry" in a basic level explanation. I think Graham does a great job, but a couple of improvements are possible in this one. -
JMurphy at 19:43 PM on 24 August 2010Can't We At Least Agree That There Is No Consensus?
Poptech wrote : "Pielke Jr. made no request to remove papers..." Maybe if I copy and paste his words again, you might understand Pielke Jnr this time (fat chance, though, because you wilfully don't want to acknowledge the truth) : A quick count shows that they have 21 papers on the list by me and/or my father. Assuming that these are Hypothesis 1 type bloggers they'd better change that to 429 papers, as their list doesn't represent what they think it does. Roger Pielke Jr's Blog - Better recheck that list Poptech wrote : "I never said Pielke Jr. asked for his papers to be removed (period)." And now you are getting very confused. You never said that because you cannot acknowledge the truth, i.e. that Pielke Jnr himself asked that (SEE ABOVE). There should be no confusion about that and the only confusing part is how YOU can be confused by that. Then again... Poptech wrote : "Everyone knows what my extensive list represents as it is explicitly defined, The following papers support skepticism of AGW or the negative environmental or economic effects of AGW." Only you know what your little list is all about and how you can square the circles of including those authors who have told you that their papers are not what you claim them to be. Only you can see skepticism in strange places that don't contain any. Only you. As regards your description, you leave out the word 'alarm' but include it in your title. More confusion on your part, it would seem. Do the "following papers" show skepticism of AGW 'alarm' (in your own mind, of course), or don't they ? If they do (in your own mind), why don't you state as such in your introduction ? Maybe it doesn't matter because you know what you are going on about, even if no-one else does ? -
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.
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