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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 68451 to 68500:

  1. Huber and Knutti Quantify Man-Made Global Warming
    dagold - as Tom Curtis said, the global surface temperature record extends back to about 1880. HadCRUT goes back to 1850, but it's biased lower than the other two main data sets, and its measurements from 1850 to 1880 are based on fewer measurements. These three groups include sea surface temperatures, while BEST only has land temperature measurements, which is why it's higher. The GHG emissions ramp-up also really began starting right around 1880 or so, conveniently. The global surface temperature increase since then is right around 0.8C.
  2. Plimer vs Plimer: a one man contradiction
    Ross at #16, the quote about a 4 degree rise due to CO2 is referenced as on p. 121 of A Short History of Planet Earth. The reference is unclear in this post, but the Plimer vs. Plimer page shows it clearly. Amazon won't show me all of p. 278, but you are even wrong that "Temperature and CO2 are not connected" is said to follow from the 180 ppmv numbers. After the CO2 numbers, there is a full stop, and a new sentence, the entirety of which is "Temperature and CO2 are not connected." No attempt is made to show that these two points in time prove the general statement; it is just given as given. (But see the graph in #13 above to see just how correlated T and CO2 actually are, and how wrong Plimer is.) Of course the point is not what evidence he uses, but that in the same book he says that temperature and CO2 both are and are not connected.
  3. Newcomers, Start Here
    I am curious if anyone has had the time to evaluate Natalie Mahowald's Science magazine paper 'Aerosol Indirect Effect on Biogeochemical Cycles and Climate'? She proposes an additional aerosol cooling effect that current climate models are generally not taking into account.Her conclusion is that it may be more costly to abate CO2 levels than previously thought. http://decadal.gsfc.nasa.gov/pace-2011sdt/Science-2011-Mahowald-794-6.pdf
  4. Plimer vs Plimer: a one man contradiction
    In agreement with #16, that it depends on the speed if we humans can adapt. I doubt that current biosphere can adapt at the same speed, so the humans left will run short on almost everything for the next couple of millions year.
  5. Huber and Knutti Quantify Man-Made Global Warming
    #8 Tom : thank you for this nice introduction. I’m pretty sure that we cannot explain the observed temperature trends without forcings, and mainly anthropogenic forcings, because it would be physically impossible (‘foolish’ as you say) to do so by ignoring their radiative and convective properties. But as we come to more precise estimates (the sense of the Huber et Knutti 2011 paper, but also Santer et al 2011 previously discussed on SkS ), the methodology underlying theses estimates becomes of interest in its details. The relaxation time of atmosphere being very short, the question of unforced / intrinsic variability concerns more probably the oceanic circulation, particularly ist long term change known as thermohaline circulation (THC) and connected to (more or less) low frequency oscillations in large basins (eg AMO, PDO, etc.). So, in order to calculate the temperature distribution histogram you reproduce from HK2011, I suppose the GCM models (or EBM) are obliged to begin by a kind of long term (centennial to millenial) simulation of oceanic heat distribution, so as to constrain the desequilibrium state at the beginning of the modern period of the simulation (that is, in the year 1956 in your figure). The AR3 (2001) had some mentions of this kind of reflexion among modellers, for example 14.2.2.1 (sorry, I can't link to the precise page of AR3 because the undefined url of the report don't allow this) : Another important (and related) challenge is the initialisation of the models so that the entire system is in balance, i.e., in statistical equilibrium with respect to the fluxes of heat, water, and momentum between the various components of the system. The problem of determining appropriate initial conditions in which fluxes are dynamically and thermodynamically balanced throughout a coupled stiff system, such as the ocean-atmosphere system, is particularly difficult because of the wide range of adjustment times ranging from days to thousands of years. This can lead to a "climate drift", making interpretation of transient climate calculations difficult Or in the same report, 8.4.1 : This "climate drift" can make interpretation of transient climate change simulations difficult, so models are generally allowed to adjust to a state where such drifts have become acceptably slow, before starting climate change simulations. A number of techniques have been used to achieve this (see Stouffer and Dixon, 1998), but it is not possible, in general, to say which of these procedures gives "better" initial conditions for a climate change projection run. In the IPCC AR4 (2007), we can see in 9.4.1.2 and fig 9.5 an exercise very comparable to HK2011, with a forced and unforced simulation of the 20th century. As you can read, the legend of the figure stipulates : The simulated global mean temperature anomalies in (b) are from 19 simulations produced by five models with natural forcings only. The multi-model ensemble mean is shown as a thick blue curve and individual simulations are shown as thin blue curves. Simulations are selected that do not exhibit excessive drift in their control simulations (no more than 0.2°C per century). Each simulation was sampled so that coverage corresponds to that of the observations. So, we find again this concept of 'drift' in control (no forcing) simulations, with a selection of thoses simulations that do not exhibit more than 0,2 K drift. But why this limit value of 0,2K ? Does it come from a physical non-sense (beyond this value) or an empirical adjustment and, if the second solution is correct, adjustment to which set of observations constraining the signature of an unforced variability ? If there is such a secular drift, why temperature change from unforced variability on six decades would be centered on zero (your figure) rather than a positive or negative value ? The appendix of AR4 chapter 9 gives some information about methods (optimal fingerprinting and methods of inference), but beside the technical complexity (or because of it and my consequent poor level of understanding), it seems circular in my mind : Fitting the regression model requires an estimate of the covariance matrix C (i.e., the internal variability), which is usually obtained from unforced variation simulated by AOGCMs (e.g., from long control simulations) because the instrumental record is too short to provide a reliable estimate and may be affected by external forcing. Atmosphere-Ocean General Circulation Models may not simulate natural internal climate variability accurately, particularly at small spatial scales, and thus a residual consistency test (Allen and Tett, 1999) is typically used to assess the model-simulated variability at the scales that are retained in the analysis. To avoid bias (Hegerl et al., 1996, 1997), uncertainty in the estimate of the vector of scaling factors a is usually assessed with a second, statistically independent estimate of the covariance matrix C which is ordinarily obtained from an additional, independent sample of simulated unforced variation. I basically read this as : AOGCMs constrains the realism of unforced variability from… AOGCMs simulations of unforced variability ! That is : there is no reference to empirical (observation-based or proxy-based) assessment of the long term change in oceanic circulation, the best candidate for unforced variability. Of course, when you deal with a huge temperature change (eg 2, 3, 4 K), these questions are probably of minor importance. And if unforced variability could help us to restrain the climate sensitivity range, it is very unlikely it will change this range (it could even drive to higher values). But when you try to adress precisely the different contributions to an observed trend of a 0,79 K in one century or 0,55 K in six decades (HK2011), maybe theses questions of ‘drift’ and ‘control runs’ are to be adressed more precisely in the explanations of the results.
  6. It's Not About The Hockey Stick!
    SirNubwub and his students may benefit from a review of fingerprints. There are many, many independent lines of evidence for AGW. The hockeystick, which has been replicated many times, relies on modeling and proxy analysis which might not be very engaging for your class. Instead, show this video. Then compare the AGW hypothesis for observed climate changes to an alternative (e.g., it's the sun) with reference to facts like the stratosphere is cooling, nights warm faster than days, there's less infrared escaping to space, etc. Ask them: Which provides a better explanation?
  7. Huber and Knutti Quantify Man-Made Global Warming
    The scary thing in these graphs sis that aerosol and ozone are strongly negative. If we clean the air as we would like to do, temperature increase will be 1/3 larger. I think others authors got a similar result.
  8. Greenland has only lost a tiny fraction of its ice mass
    John Russell @13, not how my mind works, but yes (I think).
  9. Greenland has only lost a tiny fraction of its ice mass
    Thanks for the answer, Tom. I was imagining the Earth's crust as more elastic and linked, like the skin on a sloppy custard with a small weight sitting on the top in one spot, so, if that weight was reduced, not only the skin beneath the weight rises but so does the skin around it. What you describe seems to be more like contiguous sugar lumps floating on a pond of treacle, (the lumps representing the Earth's crust and the treacle below, the magma) so that a localised weight only pushes down the lumps it sits on. Then when the weight is reduced only the lumps immediately below the weight rise. I think what you're saying is that the lumps with the weight lifted off them pull down their neighbouring lumps, because they suck out the viscous treacle from beneath them? [Sorry to paint such peculiar pictures -- it's the way my mind works!]
  10. Huber and Knutti Quantify Man-Made Global Warming
    dagold @12, the BEST project currently only has a land temperature index. Land has warmed faster than the sea, so full global indices have a lower temperature rise over the century. The three data bases you need to consult for an accurate temperature are: GISSTemp (The column headed J-D is the annual mean) HadCRUT3v (the last column is the annual mean) NOAA. Of these, NOAA and GISS are the best, IMO, with HadCRU running cooler than the others because of flaws in their methodology. However, both NOAA and GISS only extend back to 1880, while HadCRU extends back to 1880 with dubious reliability due to limited land station data. The preindustrial era is generally taken as being prior to 1750. No global temperature record exists to that period, and reconstructions differ significantly. Temperatures where probably lower than in 1900-1910 (which was exceptionally cool), but not by much.
    Moderator Response: [John Hartz] Typo in the third paragraph re the start dates shown?
  11. Plimer vs Plimer: a one man contradiction
    John, page 121 of Plimer's book makes no mention of a 4 degree temperature rise due to CO2 - that page concerns mainly the Suns energy output. On page 186 Plimer comments that "The global warmth of the Cretaceous has been attributed to elevated levels of CO2 in the atmosphere". But, he follows on with the comment "However, there are some suggestions that the Cretaceous climate was decoupled from the CO2 content of the atmosphere". On page 278 when he states "Temperature and CO2 are not connected" this followed from the observation that "At 800,000 and 600,000 years ago, CO2 dropped below 180 ppmv yet temperature was unchanged". Plimer agrees CO2 in the atmosphere has a warming effect so his remark that it warms the planet does not seem contradictory. The logarithmic effect of adding more CO2 to the atmosphere coupled with the feedbacks (positive or negative) seem to be the contentious issues.
  12. Huber and Knutti Quantify Man-Made Global Warming
    Please excuse these basic questions, but 1)many sources I come across list the rise in land-surface temps in the 'last century' as O.8 or 0.9 C...but the BEST graph, for example, seems to show a rise of about 1.2 C when taking 1900-1910 as a start point. Is 1.2 more accurate? 2) What is the generally accepted figure of total warming from start of industrial age (i.e. Fossil Fuel Era)and what approximate date is used as the 'start date' of ramp up due to GHGs? I have found these basic questions a bit challenging to get a solid fix on and I am writing a book using my avoidance/denial to acceptance journey with major disease as a metaphor to how humans are facing (or not) climate change Thanks!
  13. The Monckton Maneuver
    Tsumetai @30, I agree. Monckton's method can give a ball park figure at best. Never-the-less, pointing that out is a far weaker response than pointing out that he was using the completely wrong figure for his method. I suspect any genuine climate scientists Monckton ran this past would have made several points: 1) That he should use the well mixed GHG forcing, not the total forcing including water vapour and clouds; 2) That the 100 W/m^2 figure was far to high for the well mixed GHG forcing, and too low for the total forcing; 3) That the climate sensitivity varies based on temperature, ice distribution, continental distribution and other factors, and so his method would give a rough estimate only; 4) That a proper application of his method would employ the change in temperature from a no well mixed GHG state to the current state, and that because of changes in sea ice, clouds, and water vapour content, that is probably not 33 degrees C (see this page); 5) If land ice is allowed to vary under (4) so that the Earth Sytem Sensitivity instead of the Charney Sensitivity is measured, the change in temperature probably involves a change from snowball earth to current conditions, so issues of hysteresis are involved; and 6) That because of the calculations needed in (4) and (5), the proper application of his method must employ the output of models. There may well be more points they could make, but I believe the first two are the most immediately fatal to his conclusions.
  14. CO2 is not increasing
    Stop the presses! The Mauna Loa November CO2 data is in: [Click to enlarge] 6 more months of increases before the next peak in May 2012. My WAG (Wild-A**-Guess) for then: 396+
  15. The Monckton Maneuver
    Well, yes, I'm sure unnamed scientists whose response cannot be independently checked would make so weak a response.
    It's not particularly weak. Attempting to infer current climate sensitivity from the total greenhouse effect is rather risky.
  16. Separating signal and noise in climate warming
    39, peacetracker, A quick note... you can find sources on the Internet which will show you that the USA has a lot more coal plants than China. This is true, because USA plants are much, much smaller in GW output, and what matters isn't how many plants you have, but how much coal you are burning.
  17. Huber and Knutti Quantify Man-Made Global Warming
    I downloaded the thesis and it has the proper caveat:"Therefore, we emphasize that the distributions of climate sensitivity estimates derived here cannot be regarded as proper probability distribution functions since the prerequisite of independence of both the climate models and the indices is not fulfilled in the framework of this study." on page 26. That applies to the picture Tom posted: not a probability distribution, but a model run distribution assuming particular models and model parameters.
  18. Huber and Knutti Quantify Man-Made Global Warming
    Thanks Tom. I zoomed fig. 1a and the solar there looks fairly representative. The flatlining of the data from 2000 on makes sense, since that is the date of those papers. It looks like ref 17 will help explain this paper, it is Huber's thesis (too big to download ATTM, but the abstract looks promising).
  19. Huber and Knutti Quantify Man-Made Global Warming
    Eric (skeptic) @7, if you look at figure 1 a, the solar cycle shows up in the solar forcing until 2000. Thereafter it is smooth. The fluctuations due to the solar cycle appear small due to the scale, not because they are ignored. Presumably in the chart of cumulative contribution the small fluctuations due to the solar cycle make so little difference to the cumulative change as to be indiscernible. Alternatively, that chart has an 11 year plus smooth that would effectively eliminate the solar cycle from the data. Please note that by flat lining the solar contribution at the average value from 2000 forward, Huber and Knutti over estimate the solar contribution on average over the last eleven years in that the most recent solar cycle was much smaller than the one that preceded it.
  20. Huber and Knutti Quantify Man-Made Global Warming
    skept.fr @6, unfortunately I cannot find any succinct discussion of the issue, so I'll have to do the best I can myself. The CMIP3 is a collection of model runs from 25 different models under different configurations. Some of the models are different versions of the same underlying architecture. For example, there are three GISS models, differing in ocean configuration and resolution. Each model did multiple runs. When set up for 1956 conditions and run for 50 years with no forcings, they show the following distribution of 50 year temperature trends (fig 4 a from Huber and Knutti, 2011): This is a histogram of the 50 year trends obtained by the CMIP3 constant forcing experiment. As you can see the mean of the trends is zero, and the 1, and 2 standard deviations being shown be blue bars below the graph. A quick measurement shows that the surface temperature record (red bars on the right) with the lowest trend is (rounded down) 6.8 standard deviations above the mean, which means that there is less than a 1 in 100 billion chance that the temperature trend over that period arose by unforced variability if the climate models fairly represent internal variability in the climate. I think the assumption of fair representation is a good approximation (though unlikely to be exactly true). More importantly, we definitely know that there have been forcings over that period, so attributing the trend to unforced variability while ignoring the known forcings is foolish. Turning directly to your question @1, assuming the models fairly represent internal variability, then we know that there are no significant natural internal variable cycles of greater of 30 - 100 year length because if there were the distribution of the histogram would not be so tightly constrained. Of course, many of the models had very simple oceans, so a long term internal cycle may exist but not be reflected in most of the models. However, as seen in the residual of the CMIP3 21 model mean from HadCRUT3, there is no apparent cycle in the residual. That means there is little statistical evidence to suspect a cycle. Indeed, to attribute the large scale temperature variations over the century to internal variability, you would need to find a reason as to why the known forcings did not apply. (Source PDF) Further, there are good physical reasons to doubt the existence of such long term cycles of internal variability. Specifically, such a cycle would mean the Earth must maintain a net energy imbalance for sustained periods. That is highly unlikely. Finally, the internal variability that exists in the climate can be analogized to a pendulum, and under forcing may well be analogical to a forced pendulum. That means the internal variability under an unforced state may well not match that under a forced condition, ie, the conditions that actually exist. In that case, we would expect an increase in natural variability with time as the forcing becomes stronger. Following the pendulum analogy, that increase would not be consistent over time, and may well include periods of reduced variability. But statistically, over time there would be an increase. There is in fact some evidence of that, but the increase in variability is uncertain with regard to ENSO and precipitation, and relatively small with regard to temperature. Therefore this possibility is unlikely to significantly alter Huber and Knutti's result.
  21. actually thoughtful at 12:25 PM on 10 December 2011
    The Monckton Maneuver
    I think Monckton scored a TKO on Monckton. The above is, I believe, what journalism is supposed to be. I don't see that happening very often (regardless of the issue, or the politics). I love this type of work - it makes it really easy to see how wrong these people are. Thank you Mr. Hadfield
  22. Huber and Knutti Quantify Man-Made Global Warming
    I'm not sure how the forcings in this study were determined. The text says "Although the estimates for most forcing agents are similar, we infer a larger energy flux from variations in solar irradiance as a result of the particular forcing reconstruction used. If anything our estimate of the solar contribution is likely to be overestimated (see Methods)." In methods they point to [15] Joos 2001 which has nothing on solar forcings and [16] Crowley 2000 which shows solar forcing quite variable (e.g. Crowley fig 2B) nothing like the smooth rise in the current paper fig 2c. Nor do other depictions of TSI (e.g. "It's the sun" thread) match the smooth rise in fig 2c. It looks to me like fig 2c is a model output in the current study. If that is the case, what is the model input, specifically for solar forcing, or is it simply an output (essentially what the simulation came up with to match observed temperature rises and other constraints).
  23. Not so Permanent Permafrost
    For the record, I want to note that Agnostic has corrected the caption on figure 2. He has also advised me privately that he is consulting with John Cook about how, and in what way it is appropriate to upgrade the caption. That consultation is necessary because of recent (and ludicrous) criticism of SkS for updating posts with more recent information.
  24. Huber and Knutti Quantify Man-Made Global Warming
    Dana : maybe one of the author will come here for comments, as Nathan Urban and Andreas Schmittner did in a previous discussion, so I’ll wait before disturbing Dr Knutti. (And it would be more informative for SkS readers than a private exchange.) But thanks for the information. Tom : unfortunately, I’m a layman and I cannot interpret the terabytes of data from CMIP3, I’m not even sure I could read them on my computer ! I hope my point refers to some published and free articles in the literature, where climate scientists discuss the challenges and methods for dealing with unforced change in the system. I did find some documents (like this Shukla 2010 presentation , but this is a bit elliptic and complex for my level of understanding, I'd prefer a more introductive paper.
  25. Economic Growth and Climate Change Part 2 - Sustainable Growth - An Economic Oxymoron?
    adamski @56, as skept.fr indicates, my 55 is sufficient response to your 56. If you require further comment, skept.fr @57 states it very eloquently. Beyond that I note that the comments policy states: No politics. Rants about politics, ideology or one world governments will be deleted Personally I believe that your 56 violates this policy, but presume you have been given leeway in light of the topic of the main post. Regardless, I do not believe that I can respond without violating the comment policy restriction against political discussions. In another context I would happily debate with you the virtues of market socialism (or at least my version of it), industrial democracy and my more idiosyncratic ideas (such that advertising should be true and informative). But this is not the time or place, and making such ideas a means to the end of reduced emissions (as opposed to pursuing them on their own merits independently) merely delays action on emissions.
    Response:

    [DB] Fixed html tag.

  26. Huber and Knutti Quantify Man-Made Global Warming
    skept.fr @1, information about the CMIP 3 model runs can be found . The data can be downloaded here (requires registration, and may require non-commercial institutional affiliation). The data listed is probably from experiment 1 or experiment 2.
  27. A_Gang_of_Loners at 10:50 AM on 10 December 2011
    Empirically observed fingerprints of anthropogenic global warming
    gnbatt @6 There is something you and all commentators on science and epistemology are going to have to learn about computer simulations and math modeling. And that is that it is ONLY abstract models that can determine cause and effect - NOT experience. And this is a fact for ALL phenomena, not just climate change. Whether those models are written explicitly in a computer simulation or we merely keep them in our heads, ALL experience requires an interpretation for us to be able to say "this caused that". If we were discussing, for example, the hypothesis of whether non-human aliens are the best explanation for many UFOs and USOs, or whether Bigfoot is the best CAUSE for the observed effects of large footprints found in forests and loud screams heard and for many spontaneous sightings by hunters and motorists, you can sure bet there'd be those who totally ignore the value of direct experimental observed evidence. They'd steer the entire conversation off into the direction of debating the abstract interpretation of these events. It is not, and never has been, "direct experimental or experiential" evidence that proves anything, especially cause and effect. Because the entire concept of PROOF, itself, is abstract. Direct experience is merely sets of atoms. The difference between lazy mindless speculation about cause-and-effect versus the difficult task of writing down one's model mathematically and encoding it into a computer is that the computer simulations and mathematical modeling actually require hard work and discipline, and are INFINITELY better at coming up with theories of cause-and-effect that are LOGICALLY CONSISTENT, not just internally, with themselves, but with all other cause-and-effect theories on events outside climate theory. Example: One CAN say that a human, dressed up in a gorilla suit and placed herself in the middle of a forest in the dead of winter so that a random traveller or hunter would catch sight of them, is the cause of a Bigfoot sighting. For this theory of cause-and-effect to be true, one would have to be consistent accept the theory that every event caught on security surveillance camera is just a staged event, because it is "too outrageous" to believe that anyone could commit a crime and risk arrest. To be completely objective on interpreting events, we would need artificial-intelligent robots, with vision and hearing capabilities, interpret events. We all know how difficult and expensive THAT is. It has taken YEARS of research and BILLIONS of dollars to get robots to categorize all those millions of pixels as separate objects. Since we don't have the money and means to pay robots with AI to interpret outside reality for us, we will have to rely on humans as the interface. In the case of the climate, that means climate scientists. But, just like it would be the robot brain that does the abstract work of turning all those pixels it sees and soundwaves it senses into a theory of cause and effect (if I walk here, that will cause me to bump into this object), the climate scientists and programmers HAVE to do the next best thing by mathematicallly modeling events and fitting it to data in a manner that is logically consistent with the way we model all other events we observe. Deniers are simply too <-snipped-> even to acknowledge that they are doing abstract modeling whenever they hypothesize an alternative cause for current global warming.
    Moderator Response: Please refrain from overt insults. And please do not use all caps for emphasis. Use italic or bold.
  28. 2011 AGU Conference Day One
    As documented below, at least one Argentine scientist is attending the climate talks in Durban with the objective of educating policy-makers. However, it’s still not a well-explored concept outside the scientific community. At the COP climate talks in Durban, for example, there is endless talk about atmospheric carbon and about how to control terrestrial carbon emissions through deforestation programs like REDD+. But there are still very few mentions of oceanic carbon. “Hopefully, by exposing the science to higher level decision makers, we will bridge a gap of communication for that necessary understanding” of the role that oceans play in climate change, said Alberto Piola, an oceanographer with the Naval Hydrographic Service in Argentina, speaking at a side event on Blue Carbon at COP 17 this week. The above two paragraphs are excerpted from "Blue Carbon: the role of the oceans in climate change" posted today on Climate Progress. To access this informative article, click here.
  29. Schmittner et al. (2011) on Climate Sensitivity - the Good, the Bad, and the Ugly
    skept.fr @73, they can be estimating either Charney Sensitivity or Earth System Sensitivity, depending on which forcings they consider. If they consider changes in albedo as a forcing, they measure Charney Sensitivity. If they consider changes in Albedo as a feedback, they measure Earth Sytem Sensitivity. Thus Hansen and Sato give CS as 3 degrees per doubling, but ESS as 6 degrees per doubling. I consider the latter a very suspect number for prediction of future events. With the retreat of ice towards the poles, albedo effects and hence ESS will become weaker. That is partly compensated for by an increased strength in the WV feedback with increased temperature, but none-the-less, a higher ESS in glaciated conditions than non-glaciated conditions is a persistent feature of the Earth's climate system according to Park and Royer, 2011. They find a best estimate ESS of 3-6 degrees per doubling of CO2 for non-glaciated conditions, but 6-8 degrees C for glaciated conditions. I should not that WV is a fast feedback, so technically this would indicate that CS increases with increasing temperature, while ESS decreases with decreasing temperature until the Earth reaches a non-glaciated state.
  30. Greenland has only lost a tiny fraction of its ice mass
    John Russell @11, your account of the situation is too simple. The land in many polar regions is rising because a loss of glacial ice has increased its increased buoyancy. Like a boat, because it has a reduced load above the water line, it floats higher in the water and occupies a reduced space below the water line. Of course, in the case of continents (and Greenland) they do not float on water, but on the magma beneath the Earth's crust. But they are rising not by thickening, but by floating higher in the magma. Because they float higher in the magma, the space they previously occupied must be filled by magma drawn from somewhere else. That somewhere else is beneath the oceanic crust, which is very thin and conforms to the magma beneath it. Consequently, where the land rises, the local ocean floor sinks due to the magma beneath the ocean floor moving from beneath the ocean floor and under the rising land. Hence the need for the Global Isostatic Adjustment.
  31. Huber and Knutti Quantify Man-Made Global Warming
    Dana: Excellent post. I especailly like the introductory paragprah that captures the essence of the article. You've set a good example for other SkS authors to follow.
  32. Pete Dunkelberg at 10:06 AM on 10 December 2011
    Huber and Knutti Quantify Man-Made Global Warming
    Link to liberated pdf. This result really just confirms common sense. There has been too much warming in too little time for it to be only coincidentally connected to the known drivers. As Gavin previously noted at RC about the fraction of warming likely due to human forcing:
    Over the last 40 or so years, natural drivers would have caused cooling, and so the warming there has been (and some) is caused by a combination of human drivers and some degree of internal variability. I would judge the maximum amplitude of the internal variability to be roughly 0.1 deg C over that time period, and so given the warming of ~0.5 deg C, I'd say somewhere between 80 to 120% of the warming. Slightly larger range if you want a large range for the internal stuff. - gavin]
  33. Plimer vs Plimer: a one man contradiction
    I'm very much in agreement with the thrust of your remarks Agnostic but I don't think we should become too wedded to the 4-5m mean SLR/4-6°C rise in average global temperature by 2100 scenario. On the best data we have about likely human responses over the next decade, this scenario is plausible, and perhaps as likely as not. The broader point you make is that human interest doesn't stop at 2100 and whether humanity gets there by 2100 or 2200 is neither here nor there. Unless we can turn the rend around, sooner or later there will be a very much diminished biosphere for the probably more than 9 billion people living on Earth. In an inequitable world, we know how that narrative goes. To wink at this and talk of the possibility that over geological timescales, the biosphere will recover, is to take a reckless and sociopathic attitude to the welfare of billions of human beings and human progress itself. It's astonishing that people who speak this way are not condemned as the the scary radicals in this conflict.
  34. It's Not About The Hockey Stick!
    @SirNubwub I would recommend using the information on NASA's site. All your students will of course know and respect the work of NASA and will therefore accept what their scientists say as the true facts about global warming. NASA has some very good educational material on their site which I use all the time to convince people that AGW is real, man-made and potentially dangerous. Best of luck with your important work.
  35. Economic Growth and Climate Change Part 2 - Sustainable Growth - An Economic Oxymoron?
    #54, 56 Adamski – As Tom in #55, and pragmatically, I’d say ‘the best is the enemy of the good’, whatever your definition of the ‘best’. (-snip-)
    Response:

    [DB] Please see my caution to adamski above, RE:  Adherence to the Comments Policy.  Thanks!

  36. Huber and Knutti Quantify Man-Made Global Warming
    skept - I can't answer your question, but you could try to contact Dr. Knutti, if you really want an answer. His email is listed in the paper, which is linked at the top of the post.
  37. Separating signal and noise in climate warming
    Thanks to everyone for your help. You have provided me with some very useful information. Cheers
  38. Plimer vs Plimer: a one man contradiction
    Mercury Scientist @ 11 writes – “I do agree that as a species, we will adapt and survive.” That depends on the speed with which change occurs. According to Hansen and others, what we can expect by 2100 is 4-5 metres rise in mean sea level and an increase of 4-6°C in average global temperature. And no one should think that this will be an equilibrium position. Sea level and temperature will continue rising long after 2100. We may well be able to adapt and survive such outcomes but in vastly reduced numbers and certainly not in our present socio-economic condition - but for how much longer beyond 2100? I for one do not share the optimism of Mercury Scientist. Unless we rapidly curb greenhouse gas emissions and do it now our ability to survive at all beyond 200 years or so is highly questionable.
  39. Philippe Chantreau at 06:35 AM on 10 December 2011
    Nils-Axel Mörner is Wrong About Sea Level Rise
    "If you asked me to use the data from 1993 to 1997 to predict following years I would say there is a serious up trend." That would be so grossly incompetent that even someone with a limited knowledge of statistics like me would call you on it. No trend can be identified from such a short period of time. If anyone asked you to do a prediction based on so few years, you should respond that it can not be done.
  40. The Monckton Maneuver
    very nice videos ... I am getting flooded here in GErmany with some EIKE claims (in German) which I would like to post here, some of them are PDFs. Will this be possible?
  41. Plimer vs Plimer: a one man contradiction
    I believe the term is kettle logic.
  42. Huber and Knutti Quantify Man-Made Global Warming
    Huber and Knutti write in their paper : "The basis for our energy balance model and a crucial step in determining the contributions of anthropogenic and natural (solar and volcanic) forcings to the observed changes is the magnitude of the internal unforced variability of global temperature and energy content. Figure 4 compares the observed trends in global average temperature and energy content over the past 50 years with the distribution of 50-year linear trends derived from unforced control runs in the World Climate Research Programme's (WCRP) phase 3 Climate Model Intercomparison Project." Where can we find informations about this "crucial step"? It is unclear for me how the EBMs / AOGCMs deal with unforced or intrinsic variability, either at low or high frequency, but particularly for hypothetical low frequency modes (> 30 yrs). If such a variability exists, what do we know about its physical mechanisms and how are they implemented in models? What are the methods used by modellers for assessing the quality (realism) of the "unforced control runs" from which they can deduce the forced variability? Thank you for any recent link centered on these questions.
  43. Schmittner et al. (2011) on Climate Sensitivity - the Good, the Bad, and the Ugly
    #72 ranyl : Thank you for the references. I didn’t find Schneider’s paper for free, any link ? The distinction by Lunt et al 2010 between what they called Charney sensitivity (CS), fast feedbacks, and Earth System sensitivty (ESS), slow feedbacks, is interesting. The robustness of the application to mid-Pliocene warm period depends ultimately on the robustness of the estimation of boundary conditions they considered (CO2 orography, vegetation, icesheet) and of the reconstructed temperature change (for checking model fiability), all derived from PRISM data. So, to be continued ( here the page for selected publications around PRISM). Anyway, this leave me with a question : when models compare LGM and Holocene, should we consider they estimate CS or ESS ? As far as I undestand, climate of the mid-Holocene is considered as stable, so I guess it is ESS.
  44. It's waste heat
    "Your link to 2011 world energy outlook states in the second line that it's about the energy market, so I prosume it only takes into account metered power or power that is taken from the grid. " Ah no. It is about the energy generated and measured at source. Much easier to measure.
  45. Plimer vs Plimer: a one man contradiction
    Thank you for the post John. Nice of you to remind Plimer since he seems to have a memory deficiency… If it’s any consolation; he has not made the impact with us yanks as he has down under. BTW, I hope you and the others that made it had a nice time up here on the left coast this week.
  46. Plimer vs Plimer: a one man contradiction
    With regard to past atmospheric CO2 concentrations and temperatures, a graph of the time series data over the past 800,000 years from Antarctic ice cores may be interesting. Below is a version (reduced from 609 pixels to 450 pixels wide) of Fig.1 in a paper by Alexey V. Byalko on the paleoclimate published in the journal Priroda [in Russian] (No.12, 2009, pp.18-28). The entire issue is downloadable as a pdf file (5 Mb). The x axis in the graph is time in thousands of years ago. In other words, "now" is zero on the left and the oldest data is on the far right. This is backwards to most graphs, which show "real" time (or "calendar" date) increasing from left to right. The green curve is a plot of methane (CH4) concentration in ppb, the blue curve is carbon dioxide (CO2) concentration in ppm, and the red curve is a plot temperature deviation from the current average global temperature in degrees C. These plots may suggest how often atmospheric CO2 concentration exceeded 300 ppm during the past 800,000 years, how often and for how long the average global temperature was higher than it is now, and so on. I suppose the temperature decrease from about current temperature to -2 at the exit from the most recent deep ice age was associated with the Younger Dryas. This event seems clearest in the CH4 data, where a decrease from about 700 to about 550 ppb is seen.
    Moderator Response:

    [Albatross] Fixed image width.

    [DB] As an FYI, the highest CO2 excursions in the ice core records is 298.7 ppm.

  47. Greenland has only lost a tiny fraction of its ice mass
    I've just read an article on the 'Physorg' site about research that shows that as Greenland loses ice, the bedrock is rising -- by 6mm last year. It occurred to me that if the land is rising, so must the sea bed around Greenland -- and if that's the case, then won't the rising sea bed displace water? So if that's correct, does anyone know whether this is being factored into sea level rise; and how much might global sea level rise as a result? It's, as journalists like to say, a 'double whammy'. I hope I put this post in the right thread -- I did consider one on sea level rise.
    Response:

    [DB] "does anyone know whether this is being factored into sea level rise"

    Yes; GIA corrections are made to the sea level analysys performed, as shown here:

    Click to enlarge

  48. Plimer vs Plimer: a one man contradiction
    Bernard (#3), I took a look at that posting, and it caused me pain. "Irreversible"? Well, yes, over thousands to millions of years. Over the course of a human lifetime or two, umm, no. But, the readers there jump all over the first 'yes', and conveniently ignore the fact that a reversal will not come soon enough for the great-great-...-great-grandchildren of anyone alive today. Sites like that are gathering places where people are free to make up their own facts, disregard others, overlook logical inconsistencies, and call well-established science "mantra". In that environment, there is no convincing someone to change their mind, because there is nothing tying them down to reality. People that get along there could come to sites like this one, but would quickly get frustrated by being restricted to claims that are relevant and can be substantiated. People from here could go there, but when they put out information that can readily be verified, and contradicts the information provided there, they are mocked, and the mockers receive applause. So, there are these fortresses that occasionally lob shots at one another, but for the most part, people in one don't communicate much with people in the other. And, meanwhile, the uncaring, unknowing masses proceed with BAU.
  49. Mercury Scientist at 04:54 AM on 10 December 2011
    Plimer vs Plimer: a one man contradiction
    A promotional flyer (http://www.iaq.com.au/images/Event%20Flyers/2009/IAQ%2023%20june%202009%20Flyer.pdf) states that Plimer "rejects the unscientific idea that the explanation of climate change can be reduced to one variable (CO2)..." Gee, last time I checked, scientists' consensus in the IPCC Fourth Assessment Report was that [anthropogenic???] radiative forcing was attributed to CO2, CH4 (methane), nitrous oxide, and CFC's. CO2's radiative forcing is ~1.5 W/m2. Sum of all the others is ~0.9 W/m2, so not insignficant at all. CO2 is a big one, but clearly it is wrong to suggest that the scientific community is reducing climate change to "one variable (CO2)." The flyer further states that "He [Plimer] rightly assumes that humans will be able to adapt to any future coolings or warmings." Funny how they have verified this assumption already, when we're just getting started with the warmup. I do agree that as a species, we will adapt and survive. However, I also believe it is wrong to assume that profligate dumping of greenhouse gases into the global atmosphere will be without serious consequences and costs to society. I believe it would me much more cost-effective, prudent, and conservative to be proactive on this issue: reduce energy demand, and adjust our energy portfolio by increasing non-polluting sources, and decreasing polluting sources.
  50. Mercury Scientist at 04:33 AM on 10 December 2011
    Plimer vs Plimer: a one man contradiction
    I wasn't familiar with this Plimer dude, so I did a google scholar search on him (plimer i r). Looks like his background is in hard rock geology and mineralogy. In the first 5 or so pages of google scholar hits, I did not see a single peer reviewed paper that appeared to have anything to do with paleoclimate. His papers have titles like "Tourmalinites from the Golden Dyke dome, northern Australia;" "Exhalative Sn and W deposits associated with mafic volcanism as precursors to Sn and W deposits associated with granites;" "The origin of the albite-rich rocks enclosing the cobaltian pyrite deposit at Thackaringa, NSW, Australia;" etc. If there's a climate connection in any of them, I hope someone will point it out. Google scholar does, of course, include his "Heaven and Earth--Global Warming: the Missing Science." I would bet that this book was not subject to rigorous peer review. I will concede that he must be quite knowledgeable on geology - particularly minerals & rocks - but his specific area of expertise seems quite disconnected from what he writes about in his popular book. I contend that "the Missing Science" is the fact that nothing on his own CV suggests any stature or relevant research experience in the paleoclimate field.

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