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Comments 94701 to 94750:
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Philippe Chantreau at 06:50 AM on 25 February 2011Motl-ey Cruel
And we'll continue hearing the endless belly-aching of so-called "skeptics" about being censored here on SkS. Same old. -
RobertS at 06:46 AM on 25 February 2011Hockey Stick Own Goal
Wow, I completely missed that section just below regarding hot MWP and high climate sensitivity. My apologies... -
MattJ at 06:31 AM on 25 February 2011Monckton Myth #14: Monckton's Hunt for the H-spot Leaves me Unsatisfied
Oh, and when I say "last sentence", I am not counting "Confused?", for which I now make the excuse that it is not a full sentence;) -
MattJ at 06:30 AM on 25 February 2011Monckton Myth #14: Monckton's Hunt for the H-spot Leaves me Unsatisfied
The final sentence is an excellent summary of the whole article. It is a great example of how to summarize the point of an entire article in one simple, memorable, powerful antithesis. Cicero would be proud! -
Chemist1 at 06:25 AM on 25 February 2011Models are unreliable
Muon I guess you will have to purchase the article to see what I mean. I also notice you do not address the other abstracts. Here is a hint, on google scholar, google books, and in many journals, missing, flawed and uncertain physics, are discussed. Dikran I am done posting here You are simply mistaken -
MattJ at 06:12 AM on 25 February 2011Motl-ey Cruel
You say, " I have to admit, I was rather stunned at being banned from a site for doing nothing more than posting four polite comments pointing out an obvious error made by its author." I would not have been stunned by such behavior. Despite all the bland pronouncements of a new age of opennness the Internet has started, I knew all along that such dishonest banning still rules the day. The Internet has done nothing to even moderate such bad behavior, far less to ban it. The public discourse is still controlled by the criminally dishonest. -
Rob Painting at 06:08 AM on 25 February 2011Dispelling two myths about the tropospheric hot spot
MarkR -Spencer and Christy made a genuine mistake and found out how to fix it, then fixed it. No. For 10 years or so Spencer & Christy claimed that the surface temperature record was wrong. Rather than go over their data to check it's accuracy, they chose to do diddly. Their errors were identified by others. -
Motl-ey Cruel
I had the same experience on Spencer's blog. -
Dikran Marsupial at 05:14 AM on 25 February 2011Motl-ey Cruel
Likewise I was surprised (and dissapointed) that my posts on Roy Spencers blog ended up in permanent moderation limbo, also for no apparent reason. -
dana1981 at 05:07 AM on 25 February 2011Motl-ey Cruel
Agreed Rob, as I said I was shocked and disappointed. Motl immediately began backtracking and moving the goalposts on his hot spot fingerprint claim. After just 4 of my comments on the issue, he folded and banned me for no apparent reason. It's no way to behave if you want to be taken seriously in the climate debate. -
dhogaza at 05:01 AM on 25 February 2011Dispelling two myths about the tropospheric hot spot
MarkR: Just FYI, Spencer and Christy aren't the ones who fixed it.
If you remember the beginning of W's first administration, one of the administration's storylines was the need for more research to determine whether or not global warming was true blah blah blah. Much of that was based on the claims of Christy and Spencer. There was a conference fairly early in the administration attended by Christy (and maybe Spencer) and the RSS guys and others, that pretty much led to the conclusion that the UAH people were wrong and the RSS people mostly right (there were a series of errors that had been found, and corrections made, by UAH over a period of a couple or three or so years). It seemed apparent that the administration had held out hope that sponsoring the event would lead to UAH being shown right, but no such luck. -
Rob Honeycutt at 04:57 AM on 25 February 2011Motl-ey Cruel
I was watching some of the debate at Motl's site as this was going on. I was completely surprised how fast Motl caved. I was excited to maybe see some interesting exchanges and maybe have the chance to learn a thing or two. But... zilch. -
JMurphy at 04:42 AM on 25 February 2011Meet The Denominator
MothIncarnate has suggested a tongue-in-cheek response like this to those who think the 850 list is worth mentioning : [W]hy don’t you go and do a point by a point refutation of every single one of the (200+ recent) papers on MothIncarnate's list. [W]hen there are over (200+ genuine recent) scientific papers supporting AGW, surrely to any same person, that would at least provide some reason to back the theory.Moderator Response: URL fixed. -
Michael.M at 04:39 AM on 25 February 2011Motl-ey Cruel
Well, again its "pseudo-sceptics" rather than sceptics. (No surprise there) And - as nearly every time - its also easier to disinform than to explain real science. That is why the work here at sks is so important: rebuttals from basic to advanced to point to, ready for informing the really interested. -
les at 04:36 AM on 25 February 20112nd law of thermodynamics contradicts greenhouse theory
KR - not at all, I was alluding to 350 damorbel (where one moment all the radiation is returning to earth and the next it's radiating to space) and 351. Your excel and SoD's series are, IMHO, spot on. That people don't find they match their thought models is, IMHO again, because those thought models are wrong. -
2nd law of thermodynamics contradicts greenhouse theory
les - "A number of these 'models', designed to contradict the standard physics..." I hope you're not talking about the simple Excel models I posted earlier. They both support standard physics, and were intended to demonstrate to various people that greenhouse gases warm the surface. -
muoncounter at 04:26 AM on 25 February 20112nd law of thermodynamics contradicts greenhouse theory
"R W Woods built two greenhouses – one rock salt, one glass" Call me curious, but a rock salt greenhouse? Watering time for the plants must be interesting. The experiment by RW Wood was done in 1909. WM Connelly aka Stoat pointed out the error in comparing this exercise to the greenhouse effect here. -
les at 04:14 AM on 25 February 20112nd law of thermodynamics contradicts greenhouse theory
A number of these 'models', designed to contradict the standard physics - as well described by SoD - reminds me of the joke: A biologist, a physicist and a mathematician were sitting in a street cafe watching the crowd. Across the street they saw a man and a woman entering a building. Ten minutes they reappeared together with a third person. "They have multiplied", said the biologist. "Oh no, an error in measurement", the physicist sighed. "If exactly one person enters the building now, it will be empty again", the mathematician concluded. (although, personally, I'd expect better of the physicist) Even though the SoD series uses simplified models here and there to explore specific aspects of the physics, overall you can only understand what's happening by understanding the full system and physics. As said above, if a body is illuminated - with photons from any part of the spectrum - from another body, it'll reflect some, absorb others. Those absorbed (depending on the absorptance and spectrum) rise the temperature... the body will always radiate photons (not the ones absorbed, of course) depending on it temp, a la Boltzman + emissivity ... some or all of which (depending on geometry) will impinge on the original body doing the illumination, which will do the same physics. Then, you must account for the spectral nature of absorptance and emissivity, so that the respective conversion to heat and reflection won't be symmetric. Build the model properly, in your mind at least, otherwise you'll end up like our trio above. -
JMurphy at 03:50 AM on 25 February 2011Meet The Denominator
Zvon.org lists 785 Journals referred to by the last IPCC Report, and the top ten have a total of 3979 unique article citations between them. The IPCC itself used "500 Lead Authors and 2000 Expert Reviewers" and it "confirms that climate change is occurring now, mostly as a result of human activities; it illustrates the impacts of global warming already under way and to be expected in future, and describes the potential for adaptation of society to reduce its vulnerability; finally it presents an analysis of costs, policies and technologies intended to limit the extent of future changes in the climate system". That is the conclusion, based on all that work. Makes you see how insignificant that other little list is, doesn't it ? -
XPLAlN at 03:40 AM on 25 February 2011Monckton Myth #13: The Magical IPCC
RickG: “The 1990 report noted that it was not clear whether all the fluctuations indicated were truly global (p 202). How is that sloppy?” You may notice that note applies to a range of 3 different schematics for 3 different periods. It may bear some relevance to the other two but as for the schematic in question (7.1c) then you’d be spinning a line as it was clear that NONE of the fluctuations from that one were truly global! Seeing as you ask I’ll respond to the ‘sloppy’ bit: but first some context courtesy of the IPCC FAR: “The issues confronted with full rigour include history of the Earth’s changing climate. The result is the most authoritative and strongly supported statement on climate change that has ever been made by the scientific community.” So, on the subjective question of what constitutes ‘sloppy’ at the IPCC please bear in mind they set their own bar to the fullest rigour possible. To the question “how is that sloppy?” It’s sloppy because the schematic is labelled ‘global’ when it was actually, as the above article makes clear: “based on Lamb's approximation of the central England temperature. It was intended only as a schematic diagram, and known not to accurately reflect the global average temperature.” ...but it was still presented as a curve of ‘global temperature variations’. And I don’t care if it’s a schematic, or rock art. That’s just a red herring. In effect; ‘we knew all along that the data for Central England wasn’t great, and wasn’t representative of global or even NH. But it’s all we had so we used the curve anyway and downgraded it from a graph to a schematic to cover our arses’. I find this most unsatisfactory. What isn’t clear is: did the IPCC know that this schematic reconstruction was solely based on Central England or not? As (contributor to that section) Prof Jones himself says: “Many in the palaeoclimatic community have known that the IPCC graph was not representative of global conditions (even when it first appeared)...Greater amounts of documentary data (than available to Lamb in the early 1970s) were collected and used in the Climatic Research Unit in the 1980s.” This begs the question, why use Lamb as a basis to extrapolate a global picture or even reproduce his curve at all? Nor is it clear whether - in the absence of something global to give us - the authors of section 7 simply took a reconstruction of Central England and presented it to us as “global”, or maybe due to sloppy fact checking they used the schematic in good faith having lifted it from the UK DoE 1989 publication ‘Global Climate Change’. Either way I consider this to be sloppy. I certainly wouldn’t describe it as an ‘issue confronted with full rigour” even back in that huge vacuum of climatic knowledge that was 1990. -
MarkR at 03:21 AM on 25 February 2011Monckton Myth #14: Monckton's Hunt for the H-spot Leaves me Unsatisfied
I hope that I explained this in a clear and correct way; the 'hot spot' is quite a difficult concept and every article I've read has just talked about conserving the moist adiabat, which makes about as much sense to a non-specialist as when a professor of ancient languages starts babbling in Babylonian... If anyone picks out mistakes, let me know so I can correct them. I kept it shorter than I'd like to try and encourage people to read: I didn't properly cover 2 side points: 1) the 'hot spot' also encourages positive water vapour feedback because of Clausius-Clapeyron... but it is a signature of the lapse rate feedback and net modelled water feedback isn't too strongly dependent on that. Plus direct measurements suggest the WV longwave feedback is significant. 2) there could be more evaporation lower down and subsidence leading to it condensing lower down. In that case the lapse rate feedback (negative/cooling) is still weaker. -
Jeff T at 03:12 AM on 25 February 2011Dispelling two myths about the tropospheric hot spot
Lindzen mentions corrections to data in this essay at GWPF. In the third paragraph, he discusses the tropospheric warm spot and concludes that ground-level temperature measurements must be erroneously high. After calling for corrections to those data, he goes on in the same paragraph to accuse the "climate science community" of corruption for correcting data. Did he realize that he was accusing himself of corruption? -
Rob Honeycutt at 03:06 AM on 25 February 2011Meet The Denominator
Poptech said.... "Rob, I never made any claim otherwise that there were not thousands of papers on climate change. I was well aware of this. My argument continues and has always been that only a small fraction of these explicitly endorse "anthropogenic global warming"." Do most papers on evolution explicitly endorse evolution? No. That's because it's well established. Same with climate change. -
cbrock at 02:32 AM on 25 February 2011Dispelling two myths about the tropospheric hot spot
This is a very nice post. I agree with Johnny Vector that axis labels are needed. If possible, convert the y-axes of the first four figures to logarithmic coordinates to match the later figures (although it looks as if these plots came from RC). -
Daniel Bailey at 02:12 AM on 25 February 2011The Dai After Tomorrow
For those readers living in the Pacific Northwest of the USA, there's an interesting new study just published in PNAS: Drought variability in the Pacific Northwest from a 6,000-yr lake sediment record Nelson & Abbott 2011 doi: 10.1073/pnas.1009194108 (Abstract, full paper is paywalled) Lake bed sediment core analysis reveals that the climate of the Pacific Northwest fluctuated more or less evenly between wet and dry periods for thousands of years. Droughts tended to be lengthier, with 25 percent of dry periods during the past 6,000 years persisting for 30 years (with a maximum of 75 years duration). Wet periods tended to be shorter with only 19 percent lasting more than 30 years (with a maximum of 64 years duration). The most recent 1,000 years has seen these periods become longer, shifting less frequently, and ushering in more extreme conditions. The wet cycle stretching from the 1940s to approximately 2000 was the dampest in 350 years (the only wetter cycle in the 6,000 year record began around 1650). Lead researcher Mark Abbott, a Pitt professor of geology and planetary science, said those unusually wet years coincide with the period when western U.S. states developed water-use policies."Western states happened to build dams and water systems during a period that was unusually wet compared to the past 6,000 years," he said. "Now the cycle has changed and is trending drier, which is actually normal. It will shift back to wet eventually, but probably not to the extremes seen during most of the 20th century."
Duration of dry and wet cycles by percentage over 6,000-year period. Another finding: the Castor Lake core matched the Palmer Index reconstructed with tree-ring data and expanded on it by 4,500 years, suggesting that lake beds are better records of long-term climate change. Finally, the change in cycle regularity found by Nelson & Abbott 2011 correlates with documented activity of El Niño/La Niña. When the those patterns became more intense, wet and dry cycles in the Pacific Northwest became more erratic and lasted longer. Fill up those canteens now. The Yooper -
rocco at 01:48 AM on 25 February 2011Dispelling two myths about the tropospheric hot spot
MarkR: Just FYI, Spencer and Christy aren't the ones who fixed it. -
2nd law of thermodynamics contradicts greenhouse theory
Fred Staples - "“Higher is Colder”, KR,337 is not “part of the greenhouse effect”. It is the only plausible way of explaining how increasing atmospheric absorption and emission can increase the surface temperature." Quite frankly, no. It's part of the story, but certainly not the entire thing. You might find the simple Excel models I posted here and here of interest. The first is a simple iterative single-layer atmosphere model (no convection/evaporation), so the numbers won't be accurate. But it starts with the surface of the Earth emitting exactly what it receives from the sun (240 W/m^2). Some of that energy is absorbed by the atmosphere, which radiates half of it upwards and half downwards. The end result (illustrative, if not numerically accurate due to model limitations) is that 240 W/m^2 come in, 240 go out, and the surface is emitting 267 W/m^2. A greenhouse gas atmosphere raises the temperature of the surface. The second is a more accurate radiative effect only zero dimensional model, which surprisingly (on my part) gets with 3% of real values. This uses the effective emissivity of the Earth, which drops as greenhouse gases rise (more re-emitted to the ground, also higher effective emission altitudes - both effects). Given an emissivity of .612 (as measured for Earth by satellites), 240 W/m^2 comes in, 240 W/m^2 goes out, and the surface is emitting at about 392 W/m^2 - just as expected. Radiative balances and emissivity decreases caused by GHG's drive surface temperatures to measured values. I'm not interested in convective greenhouses, with or without rock salt - those are red herrings in this discussion of radiative greenhouse effects. As to back radiation - the total energy received by the ground is the sum of solar and back radiation - both impinge on the ground. Arguing that the ground doesn't receive energy from back-radiation is the violation of conservation of energy, and hence the thermodynamic no-no. -
2nd law of thermodynamics contradicts greenhouse theory
damorbel - I begin to see some of your issues, and quite frankly shudder to consider where to even begin. First - Do you think thermal emission is monochromatic? It's not! It covers a broad band of photon energies, due to a large number of possible electron band transitions of different levels. Second - Absorptivity describes the spectral efficiency of absorbing a photon at any particular energy/wavelength. It turns out to be equal to emissivity when the object is at thermal equilibrium. The ground, for example, has about a 95% probability of absorbing a photon at 6 micron wavelength. The thing is, photons do not carry ID cards - a 6 micron photon may be coming from a superheated plasma or a cold atmosphere - there's still a 95% probability of the ground absorbing it, and hence receiving energy from it. The recipient of a photon cannot know and does not care what the source of the photon is. But that photon still adds to the energy of the receiving object. So your statement "The temperatures are the same because the energies of the photons from both sources are the same" is incorrect. The sun provides a bunch of photons at various energies, the atmosphere emits (downward) a smaller bunch of photons at various lower energies, and these sum up to the total energy received by the ground. Which then emits it's own photons of thermal radiation. The heat flow, the net/summed power, is from sun -> ground -> atmosphere -> space, but even a cold atmosphere adds a tiny bit of energy to the warmer ground. If you cannot understand these basics, well, I can't help you, and I can't see spending my time banging my head on the wall. -
Climate sensitivity is low
I believe the "atmospheric window" issue is tied (again) to George White - he believes the window of IR going straight to space is >90 W/m^2, whereas Trenberth estimates 40 W/m^2, and asserts that all greenhouse gas effects operate by narrowing that window. He seems to neglect lapse rate and GHG concentration effects raising the altitude (and dropping the temperature) of emission, and in addition argues that the 90 W/m^2 represents a limiting band on GHG effects. RW1 - The models operate by calculating upwards and downwards emissions from all levels of the atmosphere, and the 3.7 W/m^2 represents all the effects: band broadening due to higher GHG concentrations, band deepening due to higher effective altitudes of emission to space, higher reemission to the ground, etc. So the answer to your question is partially, although not readily picked out of the other effects. -
Fred Staples at 00:09 AM on 25 February 20112nd law of thermodynamics contradicts greenhouse theory
“Higher is Colder”, KR,337 is not “part of the greenhouse effect”. It is the only plausible way of explaining how increasing atmospheric absorption and emission can increase the surface temperature. Incidentally, it is a mechanism which G and T did not discuss, although it was current from 1900 onwards. Think about an atmosphere without a lapse rate – an isothermal atmosphere where higher is not colder. Add greenhouse gasses, increase absorption, and you suggest that the atmospheric temperature will increase. What would happen if it did? Apply the Stefan-Bolzmann equation to the radiation to space, and energy emission will also increase (proportional to the fourth power of the atmospheric temperature). But the incoming energy, from the sun, will not change. So the atmospheric temperature will fall back to its original value. My simple model, is designed to make the same point. With a lapse rate, you can suggest that the effective emission level moves up to a colder region, reducing energy emission. All the temperatures must then increase to restore the balance. The only snag with that argument is that the evidence from the last 30 years shows that it does not happen to any detectable extent. Neither G and T (nor I) claim that AGW contradicts the second law. It is just that some of the sillier explanations of AGW do. Most of them confuse heat and energy, which is where entropy comes in. The silliest explanation, which you can still find in modern text-books, (Houghton for example) is the original greenhouse radiative effect. Consider a greenhouse made of non-absorbing material, such as rock salt. It will absorb heat from the sun, the interior will heat up, and, with convective cooling eliminated, the internal temperature will be higher than the surroundings (G and T’s car interiors, for example). The greenhouse will radiate W watts per square meter, proportional to the fourth power of its temperature. Now replace the rock salt cover with glass, which absorbs infra-red radiation. Half of the outgoing radiation will return to the interior, which, so the story goes, will heat up until it radiates 2W. The original W will then be radiated to the atmosphere, and W will be returned to the interior. The ratio of the glass interior temperature to the rock salt interior temperature will be the fourth root of 2, or 1.19. An increase of 19% of the rock-salt interior absolute temperature, or about 60 degrees C. Does that argument sound familiar? You will find it in part 1 of the Rabett paper to which SOD contributed. It is, of course, nonsense. Back radiation from the cooler glass cannot heat the warmer interior. It would breach the second law if it did. To check this R W Woods built two greenhouses – one rock salt, one glass – so that their convective warming would be identical. Any back-radiative effect would heat the glass green-house preferentially. Their temperatures were the same. -
Tom Curtis at 23:59 PM on 24 February 2011Hockey Stick Own Goal
HR @108, in Hegerl 2007 on table 2, he lists "... the best-guess scaling factor for the model’s fingerprint", ie, the factor by which either forcing or sensitivity must be multiplied by to best reproduce the reconstruction. For his reconstruction, for solar forcings, that factor is 0.5, which means, on the basis of that reconstruction, either climate sensitivity to solar forcings are half those of CO2 and aerosols, or that the solar forcings are around half of those reconstructed at the time of his paper. As it happens, new evidence favours the later conclusion. Hence your previously stated concern that the new evidence on solar forcings might require climate scientists to adopt unphyscical climate sensitivities to explain the past is unwarranted. Hegerl used the forcing reconstuctions from Crowley 2000, which yields a difference between maximum and minimum net solar forcing of 0.6 w/m^2. Halving that sits very comfortably with Gray et al 2010. Having said that, my initial caveat still stands. Neither techiques for reconstructing past forcings or past temperatures are sufficiently exact to tightly constrain climate sensitivity - hence the large error bars in calculatons of sensitivity from data over the last millenium:
This is one reason to prefer sensitivity calculations based on the last glacial maximum, where the much larger changes in forcings and temperatures restrict the potential error.
-
Johnny Vector at 23:55 PM on 24 February 2011Dispelling two myths about the tropospheric hot spot
I realize this is the advanced version, but please put some axis labels on the first four images. I assume the horizontal axis is latitude and the vertical axis is pressure in millibars, and that the word "Temperature (°C)" at the top refers to the color scale at the bottom. Thanks. -
MarkR at 23:45 PM on 24 February 2011Dispelling two myths about the tropospheric hot spot
Spencer and Christy made a genuine mistake and found out how to fix it, then fixed it. Nothing inherently wrong in that. That's proper science and a good thing. It should be a cautionary tale for everyone though. Going through the 'hot spot' controversy a bit and the physics (latent heat transfer & change in the moist adiabat) looks a lot more solid than the direct temperature measurements, which we know have serious problems at that altitude. I'm convinced that the most reasonable explanation is measurement error, in some combination of surface overestimate and upper atmosphere underestimate. Most probably dominated by upper atmosphere underestimate. -
macwithoutfries at 23:01 PM on 24 February 2011Dispelling two myths about the tropospheric hot spot
Maybe the best debunking to the Lindzen smear is to remind him of the 'observational data' from his buddies Spencer and Christy (which insisted they were right and models and thermometers were wrong) - for instance discussed here! -
damorbel at 21:26 PM on 24 February 20112nd law of thermodynamics contradicts greenhouse theory
Re 348 & 349 Thank you for your contributions, they enable me to appreciate how you calculate your results. But all that you write makes it increasingly clear that the idea that the upper atmosphere (UA) can raise the surface temperature simply doesn't work. Let us imagine for a moment that the surface and the upper atmosphere are at the same temperature. In this situation both surface and the UA are emitting photons with the same energy, that is a consequence of your formula SQRT(SQRT(B5/(Surface_E*5.6704*10^-8)))-273.15-4. The temperatures are the same because the energies of the photons from both sources are the same; there would be thermal equilibrium i.e. no energy transfer and no temperature change. In reality the UA is colder than the surface and your formula shows that the energy of its photons is lower than those of the surface, so the consequence is that energy is transferred to the UA (accordind to the 2nd Law of thermodynamics) where it is further radiated into deep space. Perhaps you find this difficult to accept but if the UA contained no GHGs at all it would not have a different temperature (apart from the stratosphere - which is warmed by O2 absorbing ultraviolet from the Sun) because heat is transferred in the atmosphere mainly by fluid flow e.g. convection. Below the stratosphere the temperature profile is largely determined by two factors, the temperature of the surface and the compression of the air due to gravity. -
kdkd at 21:17 PM on 24 February 2011Meet The Denominator
Poptech #729 Thanks for the fascinating insight into the psychology of climate change denial; where group think (assertion that poor quality evidence is good quality evidence) is not group think, and logical exposition of quality empirical evidence of climate change is group think. Welcome back to 1984! My work here is done :) -
Dikran Marsupial at 20:45 PM on 24 February 2011Models are unreliable
Chemist1 It would help if you actually read posts before responding to them. Here I explained that a model is only unreliable if the observations lie outside the stated uncertainty of the prediction, and you have ignored this point and are back here again saying the models are unreliable because the error bars are broad. If a projection has broad error bars, so broad that they swamp the variation in the ensemble mean, it means the models are telling you they don't know what is going to happen. If you ask someone if the planet is going to warm and they say "I think it may warm, but I don't really know, it could warm by 4 degrees, but it could cool by 1 degree, but the most likely result is that it will warm by 2 degrees", then if the planet cools by 0.5 degrees, their prediction wasn't unreliable, it wasn't even wrong, because they told you what happened was within the stated confidence of the projection. Large uncertainty does not imply unreliability. In fact it means that models are more likely to be reliable as the model projections cover a wider range of possibilities. If you ignore the stated uncertainty of the projections, that is your error, not a shortcoming of the models. As it happens, the error bars on projections for large time and spatial scales are not broad compared to the variation in the ensemble mean. See e.g. IPCC report chapter on attribution. If you don't take on board points that are made, or at least counter them, don't be surprised if contributors stop responding to your posts. -
HumanityRules at 20:24 PM on 24 February 2011Hockey Stick Own Goal
58 Tom Curtis "In fact, Hegerl produces the most coherent results, ie, with climate sensitivity of solar and GHG forcings being the same, if solar forcings are half that of the estimates which he used. With solar forcings only 1/4 of that which he used, the sensitivity of GHG and solar forcings will still be very close, within limits of error." Sorry Tom but I can't see in Hegerl were he says you need to 1/2 the forcing to get a good match. Are you sure you have this the right way around, not multiply by 2 (to 4)? The Foukal Nature Review that I referenced in #54 says "We also considered the case where the forcing by the dark and bright magnetic components was modified by adding a lowfrequency component69, amplifying the solar forcing range by 3 to 4 over this time period. In this case (red curve), the model cooling trend is closer to the reconstructed palaeotemperature trend." Foukal et al 2006 Nature Review And that is what I've been reading in the rest of the literature as well. "Although the most straightforward mechanism of the sun– climate connection is the direct heating of the earth by solar radiation [total solar irradiance (TSI)], it is unlikely that the entire solar influence on climate can be attributed simply to variations in the TSI (2–4)." Yamaguchi et al 2010 PNAS And from another review on the solar irradiance changes from MM to present based on multiple sources "These estimates for century-scale TSI changes of ~1.3-1.6 Wm-2 correspond to a change in mean global radiative forcing of only 0.16-0.28 Wm-2" Gray and many other 2010 The concensus seems to be changes in luminosity/TSI while often synchronous with temperature change are too small to suggest the direct energy changes are driving climate change. I don't know how Hegerl found that the magnitude of TSI changes were too high as you suggest. Anyway to bring this back to climate sensitivity. All these papers seem to agree there is no known mechanism by which solar can affect climate change on the scale we are looking at here. It does beg the question how you would calculate climate sensitivity on that basis. -
Albatross at 18:26 PM on 24 February 2011Hockey Stick Own Goal
Robert @106, "I haven't seen any comprehensive reconstruction of net forcing over the past millennia, so it would seem to be a non-sequitur to state that the Idso's are necessarily arguing for a high climate sensitivity in arguing for a warm MWP." Actually Hegerl (2006) looked into this. Estimates of the forcing data (solar, aerosol, GHGs etc.) are shown going back to 1000 AD, see Fig. 2. Mann et al. (2009) looked into the possible role of internal climate variability over the last 1500 years. -
Riduna at 18:14 PM on 24 February 2011Carbon Cycle Feedbacks
Andy S draws attention to the fact that as temperatures rise greenhouse gas emissions from sinks where they are now trapped will also rise. He notes that these include CO2 emissions from warming soil and tree destruction, now occurring, to which might be added the oceans as surface temperature rises in the future. More damaging are CH4 emissions, now becoming increasingly evident, caused by the thawing of clathrates and permafrost allowing embedded organic material to resume decaying. Hansen has warned that these emissions could result in runaway global warming and for good reason when one considers that I litre of solid clathrate yields ~165 litres of CH4. Millions of tones of methane clathrates are thought to lie beneath Arctic offshore sediments. They have started melting. Given the threat of these emissions, one is forced to ask why the need to limit average global temperature to no more than 2C above preindustrial temperature by 2100 is measured in terms of CO2 concentration in the atmosphere and not in terms of CO2-e? It is all very well to assert that the cooling effect of aerosols off-sets the effect of other warming greenhouse gas emissions but how can that be true when emissions of the kind described above are increasing? By ignoring their effect are we not underestimating the magnitude and rate of future global warming? -
RobertS at 17:44 PM on 24 February 2011Hockey Stick Own Goal
"The NIPCC report is claiming that the IPCC sensitivity range is too high by a factor of 10, but the Idso Prudent Path document, by claiming that the MWP was as hot or hotter than today, is arguing that the IPCC sensitivity range is too low. " I don't quite understand this argument; I haven't seen any comprehensive reconstruction of net forcing over the past millennia, so it would seem to be a non-sequitur to state that the Idso's are necessarily arguing for a high climate sensitivity in arguing for a warm MWP. A MWP comparable in temperature to today is virtually impossible given the slew of millennial temperature reconstructions showing otherwise, and there is little indication of any dramatic changes in TSI or volcanic activity that could lead to such a warm MWP, but I'm not sure the latter proposition contradicts Idso's concurrent argument that CS is low. -
dana1981 at 17:10 PM on 24 February 2011Hockey Stick Own Goal
Marcus don't you know? Whichever data set shows the least warming at any given time is the good one! -
dana1981 at 17:09 PM on 24 February 2011Hockey Stick Own Goal
Tom, thanks. Not tired, just doing too many things at once! Yes, I meant that if the original hickey stick were correct and the MWP weren't particularly hot, that would be good news. -
muoncounter at 16:07 PM on 24 February 2011Climate sensitivity is low
scaddenp - Yeah, I thought that was a peculiar phrase, which seems to add an unnecessary layer of complication. All I did was point to the link, as it seemed (in #105) that he couldn't find it. How he chooses to interpret this particular 3.7 W/m^2 is up to him, although both KR and you have made it very clear. -
kdkd at 16:00 PM on 24 February 2011Meet The Denominator
Poptech #727 The only people who take your inconsequential list seriously are you and your group think enthralled friends. The rest of us can see that it's seriously lacking on many many levels. End of story, and hopefully the end of this thread :) -
TOP at 15:22 PM on 24 February 2011Dispelling two myths about the tropospheric hot spot
Glad to see a discussion of SST effect on GW. -
iskepticaluser at 15:13 PM on 24 February 2011Carbon Cycle Feedbacks
Your comments re the photo of Yoho National Park (that the dead trees on the mountain slopes illustrate bark-beetle damage) contradict the wikipedia info for the photo. Poor choice of photos, however doesn't negate the point about warmer winters and the exploding range of this insect: see this RealClimate post for example. -
scaddenp at 15:09 PM on 24 February 2011Climate sensitivity is low
muon - the issue is does "reduction in the atmospheric window" mean the same thing to RW1 as I think it means. You can say yes, but I suspect that RW1 then has corollary from that shows a very different understanding. -
Daniel Bailey at 14:38 PM on 24 February 2011Carbon Cycle Feedbacks
The actual GHG values from gases released from melting permafrost are almost a lock to be worse than projected. Schaefer et al 2011 presumes (for purposes of ready calculation, I believe) 100% of emissions to be in the form of CO2, while in actuality much will be in the form of CH4 (methane). Should this stand up to further scrutiny & be confirmed by subsequent studies, this means an effective CO2 doubling from permafrost melt alone by 2200. In addition, Schaefer et al 2011 do not consider methane hydrate releases, which are currently underway in the East Siberian Arctic Sea. Needless to say, no current model begins to take this all into consideration. The edge nears. The Yooper -
muoncounter at 14:25 PM on 24 February 2011Climate sensitivity is low
Rahmstorf 2008, linked in the Advanced version of this post, gives 3.7 W/m^2 as an undisputed figure for CO2 forcing. Without any feedbacks, a doubling of CO2 (which amounts to a forcing of 3.7 W/m2) would result in 1°C global warming, which is easy to calculate and is undisputed. ... consensus holds that a doubling of CO2 causes a radiative forcing of 3.7 W/m2, which in equilibrium would cause 3°C±1.5°C of global warming.
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