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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 111951 to 112000:

  1. The main culprit in mid-century cooling
    Yes, good post. Something I am mildly curious about is why the post 1975 heating doesn't converge on the trend line up to 1940, but runs parallel and offset down. Is it because there is still substantial (even if lower) aerosol presence?
  2. The Strange Case of Albert Gore, Inconvenient Truths and a Man in a Powdered Wig
    TOP:
    The Scopes trial got evolution pretty close to being the codified into law in many places. At least you can't teach or even discuss opposing viewpoints.
    Of course you can. You can't teach creationism in *science* class, because it's not science. This would be true even if evolution were false. But you can certainly teach creationism in the context of *religious studies*. In case you haven't noticed, the Torah is a religious work, not a scientific work.
  3. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    A sudden epiphany, theendisfar? Too much torque, your credibility is snapped.
  4. There's no empirical evidence
    Look, folks the precedent on this site is that assuming you can wrestle him/her to the ground w/regard to basic physics, theendisfar will then apply this dog-eared joker from the skeptic deck: "Without going into motivation, Yes, I think many climate scientists are purposely misrepresenting conjecture as empirical and repeatable evidence quite frequently using subjective terms to provide wiggle room and plugging conjecture into GCM's, passing the predictions off as reliable." Once you actually get back to empirical evidence as opposed to heading back into the 19th century to rehash classic thermodynamics and the like, whatever data you may end up discussing will be dismissed as the result of a vast conspiracy or whatever it would take to support theendisfar's hypothesis of rampant corruption in the scientific community. So I really wouldn't bother w/rejoinders, attempts at correction or the like. I'll hazard a guess that theendisfar is here for kicks, nothing more.
  5. There's no empirical evidence
    Berényi - Delamere et al 2000 is an interesting paper. But they fail to show actual data for TOA emissions.
  6. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    Doug, I can understand your skepticism and can only say that time is the best measure and that #55 is sincere. Trust me, if you look at the Empirical Evidence thread you can see how stimulating the AGW community is being. Mind numbingly For what's it worth I repeat Making claims, to date, that are unfounded and accusations without the accused present is not worthy of discussion and upon reflection is amateur and low respectfully and arguably inclusive. I was raised and educated to be above this behavior and will seek to reinforce this claim. Take it or leave it, so long as I an free to comment here I will do so in the manner described above.
  7. There's no empirical evidence
    Berényi - do you think that in other wavelengths the top of atmosphere (TOA) emissivity has increased? Note that the measured TOA emissivity has decreased at all observed wavelengths in that graph. Can you produce evidence to that effect? If not, I can't take your comment seriously.
  8. There's no empirical evidence
    There's a phrase by Wolfgang Pauli that I find appropriate, "That's not right - that's not even wrong". What you've posted is nonsense. In particular, "Trapped radiation will only serve to slow the radiative cooling exhibited by black body radiation" is completely insensible - random words that don't mean anything to me. How could energy accumulation slow radiative cooling? That completely reverses cause and effect - slowing of radiative cooling traps energy, not the other way around. You're just not making sense. When you do, great. Until then, well, babble just isn't worth my time. In the meantime, I would suggest reading up on the Greenhouse Effect, and how it actually works.
  9. There's no empirical evidence
    Tom et al, To those that think 107 - 110 are gibberish, can at least one of you provide an example? Pick the first obvious one, the understanding is progressive so an early error will likely falsify the rest of it. Does Temperature as 'Energy Pressure' not make sense? Makes sense if you take into account that a joule = a newton with regards to Energy. They are equivalent. Energy/Volume = Pressure. Anyone?
  10. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    Re: Karl Popper Popper was a wonderful man, a great philosopher, and a brilliant writer. But there is much more to the philosophy of science than Popper and he has his detractors. His "falsificiationism" is probably a bit old hat today, but is a wonderfully useful rule, like Ockham's Razor or Hume's Fork. His best book is actually a work of political philsophy The Open Society and its Enemies. A contending branch of the philosopy is Thomas Kuhn's Structure of Scientific Revolutions, which is a more sociological view. Kuhn points out for example that for centuries Newton's Laws did not explain the orbit of Mercury. But scientists did not immediately abandon Newton's Laws - they were much too useful. So Kuhn believed that science works in "paradigms" (a word he invented, and later regretted!). Basically "normal science" continues with its paradigms until evidence begins to contradict a formerly accepted theory. Scientists will try to "save the theory" by modification, but eventually a new paradigm in the case of "revolutionary science" is accepted. The eventual acceptance of continental drift, along with plate tectonics, is a good example of this. There are other manifold and variegated views of science, like the Duhem-Quine thesis Duhem-Quine. Climate science actually depends on fairly straightforward paradigms of radiation physics and atmospheric physics. To falsify it, these would need to be undermined to a significant degree. But anyone is welcome to try.
  11. There's no empirical evidence
    theendisfar, the problem is not your typo of "combined" instead of "combines." I'm going to make a pretty wild guess at some of your major misconceptions, but again, what you wrote is so bizarre that I might guess wrong. The system at issue is not just the Earth's solid and liquid surface. Nor is it that plus the atmosphere. The "system" is the entire Earth, from the outermost wisps of the atmosphere down to the Earth's core, as seen from outer space. Convection, conduction, and evaporation happen only within that system, and do not--can not--exchange energy with anything that lies outside that system. So convection, conduction, and evaporation cannot cool that system. But radiation from that system can escape that system, thereby carrying energy out of that system, into outer space. Such radiation is emitted toward outer space by everything in that system that has a temperature above absolute zero--which is everything. All those everythings also emit radiation in every other direction at the same time. Radiation that does not head toward outer space eventually gets absorbed by more things in that Earth system. On average, half of the emitted radiation heads toward outer space at least initially. But even radiation headed toward outer space faces obstacles--objects that absorb radiation. (But radiation does not get absorbed by other radiation it encounters. Only objects can absorb.) Some of those obstacles are greenhouse gases. When they absorb radiation, they attain higher energy states. Some of that energy they give to other objects by banging into them (that's "conduction"). But some of that energy they radiate. Just like all the previous radiating, the radiation goes in all directions, but half of it heads toward outer space. But now some of that radiation hits more obstacles in the form of greenhouse gases, and so on. This process causes a smaller proportion of outgoing radiation to make it all the way out of the system (to outer space) than would make it if there were no greenhouse gases in the way.
  12. Berényi Péter at 07:26 AM on 22 August 2010
    There's no empirical evidence
    #113 KR at 06:39 AM on 22 August, 2010 If you look at Figure 2 at the top of this page, the emissivity of the Earth has decreased due to greenhouse gasses You know that's not true. Figure 2 only shows it has decreased in certain narrow frequency bands relative to the rest. The offset in the figure is arbitrary, it is not measured with acceptable accuracy at all. Also, it would be very interesting to have a look at the curve below wavenumber 710 cm-1. Arctic window, between 400 and 600 cm-1 plays a crucial role under certain circumstances.

    Figure 2

    About that and nooks and crannies of arctic clouds read Delamere & al. 2000. As usual, it is not about actual measurements, but modeling. However, it presents the basic concepts quite clearly.
  13. There's no empirical evidence
    :) Dang! 107 should say COMBINED with a D, with regards to evaporation. HTML tags are causing trouble :) I can see how COMBINES with an S could cause confusion
  14. There's no empirical evidence
    KR, Can you please explain what is wrong in 107? Note; Should be "Convection combine with evaporation" and I failed to state the assumption 'where evaporation is available". And Trapped radiation implies an atmosphere where convection is available given Ian's "greenhouse effect". Other than that, I can see no other areas that could be in question. Are you saying that restricting a method of energy transfer where another is available will not increase the rate of the other? Thanks
  15. There's no empirical evidence
    If I may be so bold as to interject and declare that I'm more with Theendisfar.Surface heat loss must be by conduction,convection and radiation.99% is lost by cond/convect. Radiation fom the surface is trifling and as for "back radiation"...no go,completely contrary to 2nd Law of thermodynamics.There is no greenhouse(ie limiting of heat loss by convection)in operation whatsoever.Arrhenius was wrong.The greenhouse effect is a complete misnomer.The model of the atmosphere that is conveyed to the general public is simply wrong.Gravity and surface pressure accounts for the "warm" atmosphere....and not CO2 or any other gas. To mentally image the effect of CO2 on the atmosphere that some claim, then each molecule of CO2 would have to be a 2 bar electric fire with a parabolic mirror directed earthwards.
    Moderator Response: If you really want to argue about the 2nd law of thermodynamics, please start by reading the post "2nd law of thermodynamics contradicts greenhouse theory." If you still aren't convinced, read the more detailed material that you get to by clicking the links in the "Further Reading" green box below the post. Still want to argue? Then please read the comments on that post first. To save everybody the time of repeating all that. Again.
  16. There's no empirical evidence
    theendisfar, I agree with the other respondents. Your explanations are gibberish. By that I mean "nonsensical." I can't even argue against it, because it is so confused. You really need to set aside everything that you think you know, and read some very basic explanations.
  17. There's no empirical evidence
    Ian, This is just gibberish. I cannot follow what you are trying to say. I doubt that even you know what you are saying. Sorry, Temperature is a measure of kinetic energy within a given volume. Kinetic energy, when viewed as Force and when divided by Volume, can be represented as Pressure. The higher the density per unit volume, the higher the temperature or 'pressure'. You can simply replace 'energy pressure' with 'Temp...', and that should clear things up. Oh, and to be clear, any references in those posts to 'Law', all apply to the 3 Laws of Thermodynamics. 4 if you count the Zeroth Law, which seems obvious, but I imagine it has some use. You are right to doubt me. AGW is real and is caused by an increase in CO2 and other green house gases. No other science can dispute that statement. ? That is not gibberish, but understand that I am not so experienced as you, so my ability to read between the lines is not as refined. For give me but I only got, basic English mind you; "AGW is real and is caused by an increase in CO2 and other greenhouse gases."
  18. Can't We At Least Agree That There Is No Consensus?
    Poptech wrote : "So yes I told them the reason why I listed them and under what criteria." You just can't help yourself, can you ? Lucky you're around to tell these authors how their papers were something that they didn't think they were, and how they were wrong to ask for their papers to be removed/mystified as to how anyone rational could see in their papers something that wasn't actually there. Amazing.
  19. There's no empirical evidence
    theendisfar - Nope. Your posts here, here, in fact all of your posts on this thread - nope. At the top of the atmosphere the only energy pathway is radiation. If you look at Figure 2 at the top of this page, the emissivity of the Earth has decreased due to greenhouse gasses - so that since the 1970's, at the 1970 temperature of the Earth, it wasn't radiating as much as it received. Energy accumulated, the temperature of the Earth/atmosphere increased, and and the energy radiated to space increased as well. It got warmer. In the simplest view possible: The equilibrium temperature of IR cooling bodies (energy output) with equal energy inputs and different emissive spectra depend on the integrated energy of their emission spectra - objects (or planets) with lower integrated spectra will come to equilibrium at a higher temperature than objects closer to a black body spectra. Note that greenhouse gasses tend not to affect the visible wavelength energy coming from the Sun - I think less than 1% (numbers, anyone?) of the solar spectra is in the affected IR bands. So the input energy does not change. CO2 directly reduces the emissive IR spectra of the Earth - and temps go up as a direct response, as the Earth system moves back to equilibrium energy exchange at the top of the atmosphere.
  20. What were climate scientists predicting in the 1970s?
    RSVP wrote : "The hubris has to do with wanting to believe we have all the answers, when in reality the problem is much more complex than we think." How has said that they have all the answers ? And the only hubris I have ever seen on this site has been from so-called skeptics claiming that they know better than scientists who spend their working lives on the problems and complexity that is Climatology, and claiming that their pet theory has never been thought of before and is a better answer than AGW. There never seems to be any complexity involved when the so-called skeptics make their bold assertions - they have usually come up with the answer while surfing the Net and discovered secret knowledge from playing around with figures and seeing patterns that no-one else has !
  21. There's no empirical evidence
    theendisfar - I am sorry but would appear to have an extremely flawed understanding of physics which is guiding you to some very wrong conclusions. I have no idea where you got this from but short of starting again from a text book, how about you look at science of doom. Its impossible to have a discussion with any meaning in face of this kind of misconception.
  22. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    An apology for: "Without going into motivation, Yes, I think many climate scientists are purposely misrepresenting conjecture as empirical and repeatable evidence quite frequently using subjective terms to provide wiggle room and plugging conjecture into GCM's, passing the predictions off as reliable. That statement seems quite purposeful, almost a recitation, perhaps reflective of something oft-repeated and deeply seated. I wonder if the apology is based on a durable internal integration of actual contrition, or is simply a facile way of being assured of continued conversational stimulation?
  23. Berényi Péter at 06:03 AM on 22 August 2010
    The Past and Future of the Greenland Ice Sheet
    #57 Peter Hogarth at 01:18 AM on 22 August, 2010 One of the points of this post is that there is plenty of evidence and peer reviewed research which shows that the Greenland Ice Sheet volume has varied in step with the NH high latitude temperature variations in the past, see Vinther 2009 Yes, no question about that. However, it is the rate of change we are talking about here. I have copied Figure S2 b here from the Supplementary information to Vinther 2009. As you can see depositional elevation over the Greenland ice sheet has decreased by 200 m during 8 millennia when both local air and sea surface temperatures were 2-3°C higher than today. That translates to a rate of -2.5 m/century. The area of the ice sheet is about 1.78×106 km2. Therefore the century scale loss of ice volume was 4400 km3 what makes 4000 km3 meltwater. Surface area of all the seas is 3.6×108 km2, therefore it implies an eustatic sea level rise at a rate of about 11 mm/century. Hardly alarming, even if we take into account that holocene melt rate was highly variable, for short periods it could have been 3-4 times the average. Eight thousand years of ice sheet response is a bit better sample from a climatic point of view than a decade. You guys are making a fuss about weather noise.
  24. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    Ian, As for Popper, I simply looked up 'falsification' and his descriptions of how to reinforce a theory were very similar to the methods I was instructed on. I never heard of him till today either. I didn't recognize that I invoked someone hostile to your position, so in my own words. Quickly, I was taught to: 1. Prepare a Hypothesis statement that had the opportunity to be confirmed or denied with the ability to test within mind. 2. First attempt to confirm the hypothesis to see if I was on track using known Laws of physics and methods. 3. If no methods were available, determine and execute a method to confirm. If no method to confirm can be found, the exercise is over since this can only lead to falsifying a negative. Proving the unverifiable is a futile exercise. 4. Once evidence is obtained, this is the important part, try vigorously to break the hypothesis with the ferocity as the biggest skeptic would apply. 5. Once I was not able to break my hypothesis, I was to ask a trusted colleague to attempt the same. 6. Once they could not, though it would be better to have it reconfirmed again by someone who respects you, then it was safe to publish, with all the methods, conclusions, and areas that might lead to falsification for the Skeptical community to confirm or deny. I was taught to expect hostility, especially if what you were proposing was especially novel or would impact your audience in a dramatic way. This an other streams validate this all too well. To me, this method (I was taught it under the name 'scientific method') renders consensus/opinion moot which vastly reduces the number of questions that could arise. Does this seem at all unreasonable? Do you have a better method?
  25. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    sorry link was deleted for some reason http://www.skepticalscience.com/argument.php?p=3&t=107&&a=105#22448
  26. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    :) Ian, I must man up and recognize my inflammatory comments have invited this level of scrutiny. I'm afraid that you quoting Popper does not equate to a scientific education. You are correct. Assume I have no proper education in any sense other than I am indeed the one typing these posts and I'm not simply reciting this to someone to make up for my lack of reading and writing abilities. Heck assume I'm using voice software to read and write these messages if it pleases you. I repeat that my statements going forward are of my understanding and not simply recited from other sources. I recognize your vastly superior titles, tenure, and intellect. I invite your rebuke.
  27. There's no empirical evidence
    theendisfar re 107, 108, 109 and 110. This is just gibberish. I cannot follow what you are trying to say. I doubt that even you know what you are saying. AGW is real and is caused by an increase in CO2 and other green house gases. No other science can dispute that statement.
  28. There's no empirical evidence
    Ian, 107, 108, and 109 cont . . . From 109 No energy has been created or lost, the system has only lost it's ability to cool an additional 2 Watts at the speed of light and instead has to cool at the speed available to convection. Now this begs the question, is the difference in the cooling rate enough to create a back pressure that holds the energy at or near the surface increasing that region's pressure/temp? My understanding is that the elasticity of the atmosphere combined with the readily available room for an increased convection rate will offset that kind of back pressure. No energy was created or lost from my understanding, I believe I have met all Thermodynamic Laws. Will save that in the event I am understanding this incorrect.
  29. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    theendisfar said:
    I can only offer that this paper accurately describes the scientific education I received and has been reliable to me.
    I'm afraid that you quoting Popper does not equate to a scientific education. In my over 40 years as a scientist (undergraduate, graduate, post doc and work as a research scientist) I had never even heard of Popper until I found him discussed on creationist anti-science sites. Shortly thereafter I found his name used by AGW deniers. Anyone, in my view, who uses Popper to support science is probably an anti-science sufferer. Does this mean that scientists are not aware of his theories? No, we called it sticking to the scientific method and real scientists still follow this regime. The theory of AGW is valid not because of all the results confirming it but because no-one has produced one iota of evidence disproving it. Non-science editorials and opinion pieces by AGW deniers do not count as scientific evidence.
  30. There's no empirical evidence
    Ian, 107, 108 continued . . . A uniform surface creates equal pressure going up and will have equal resistance going down. Varying the surface in both energy pressure and specific heat allows for currents to form which allows for an increased convection rate. Land Sea breezes come to mind. While the surface and atmospheric energy pressures have adjusted, no energy has been created or lost. Now let's place a resistance on the Radiation rate. If 2 Watts is correct for CO2, that is a .005% restriction at 390 Watts. Convection rates within the Earth's atmosphere are highly variable, from dead calm to reaching dozens of meters per second. Thermal currents and hang-gliding come to mind. If a radiative resistance is encountered, and if my understanding of the 2nd Law is accurate, then any energy trapped by radiative resistance will simply be picked up convection given that it very rarely reaches it's physical limits. No energy has been created or lost, the system has only lost it's ability to cool an additional 2 Watts at the speed of light and instead has to cool at the speed available to convection. One more cont . . .
  31. Dust-Up On Mars: Should Martians Be Sceptical of Global Warming?
    I think papertiger is saying that because we can observe the geology in some detail, we can infer something about the ancient climate (e.g., the existence of certain kinds of sedimentary layers suggests the presence of standing water at some point in the planet's history). Not just of the ancient climate on the Red Planet, but because of the lack of water erosion, even of the recent history, right up to the present day. Extra terrestrial astronomical forcing are the origin of all these cycles, long term (last 2.4 Ma, Pleistocene), middle term (last 127Ka, last interglacial - last glacial time-span) and short term, (the last 10.000 years (10Ka)), on both planets Earth and Mars. See comment one at the "intermediate explanation" link.
  32. There's no empirical evidence
    Ian, 107 continued . . . A true Greenhouse comes to mind. If it has a constant source of energy and it is perfectly sealed, then it will increase in pressure/temp until it is radiating at the same rate it is absorbing, keeping the emissivity and conductivity of the container in mind. Place the greenhouse into an atmosphere, and now you include conduction to the atmosphere at the surface. With a uniform surface and in zero gravity convection is not in play so what you'll end up with is a steady stratification of the atmosphere's temperature moving from higher temps to lower temps the farther you get from the surface. The energy in the system has not increased, we have only added an additional component with the atmosphere. The energy pressure in the greenhouse has decreased by the amount of energy transfered to the atmosphere. By adding gravity to the equation, we introduce convection. Gravity on Earth is 99% the strength at the top of the troposphere as it is at the surface so gravity will pull more strongly on cooler denser air than it will hotter cooler air that is created at and near the surface. The higher the surface temp the quicker the air near the surface heats of and the quicker it becomes less dense than the volume above it. Gravity drags cooler air to the surface which creates a larger difference in temp between it and the warmer it it replaced creating a faster rate of cooling.
  33. There's no empirical evidence
    Ian, from the Oregon Petition stream Also please explain to us how convection and evaporation add energy to the atmosphere. They only move the energy around Convection and Evaporation do not add any energy to any system, they only move energy from areas of high energy pressure (temp) to areas of lower energy pressures with an increasing rate with increasing differences in pressure. This is precisely the core of my argument. the enhanced green house effect is what adds the additional energy. This goes against my understanding. Once you add energy pressure to a system, it is finite and does not add more energy to the system even if a portion is trapped, the 1st and 2nd Laws apply here. Trapped radiation will only serve to slow the radiative cooling exhibited by black body radiation. My understanding is that should a method of energy transfer experience resistance, then another medium available, in this case convection combines with evaporation, will make up for this resistance in the most efficient manner possible. Preserving the 2nd Law.
  34. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    Ian et al, I was wrong to even allude that anyone was attempting to deceive another under any, or with no, motivation at all. Having attempted to be clever with my position has only secured more resentment and mistrust. Strong claims are not easily retracted, however I offer that I sincerely retract any statements alluding to the deception or understanding of anyone contributing the AGW debate. Making claims of anyone's deception without their immediate availability to offer a rebuttal or clarity is just simply wrong and I apologize to the many and most climate scientists who's motivations and contributions I surely do not fully understand. I also retract any claim or allusion that I am more well versed on this subject than anyone else. From this point forward I will only offer my understanding of the subject. You are just arguing from a baseless "I don't like it therefore it is wrong" attitude. I will offer that it is not baseless. I do not like it because my education and experiences demand, of me, a more rigorous set of methods and conclusions than what I have been exposed to. I can only offer that this paper accurately describes the scientific education I received and has been reliable to me. Making claims, to date, that are unfounded and accusations without the accused present is not worthy of discussion and upon reflection is amateur and low respectfully and arguably inclusive. I was raised and educated to be above this behavior and will seek to reinforce this claim. Also please explain to us how convection and evaporation add energy to the atmosphere. See Empirical Evidence stream for my reply.
  35. The Past and Future of the Greenland Ice Sheet
    Berényi Péter at 01:05 AM on 21 August, 2010 You state: “However, people here are denying both air and sea surface temperatures were considerably warmer in the Arctic during the Holocene Climatic Optimum than they are today just to make the present feeble warming unprecedented and alarming” I do not think this is generally being denied, though we should quantify “considerably warmer”. The high resolution ice core data from Greenland and nearby (eg GISP2, NGRIP, Agassiz) is proxy evidence that Northern Greenland temperatures were up to 3 degrees warmer around 8000 years ago than the average for the 20th century, (your suggestion of regional variations is also validated by the evidence, eg Agassiz shows a more pronounced “Holocene Climactic Optimum”). The Bednarski 1989 paper you cited, and many other more recent ones also provide convincing circumstantial evidence (such as driftwood deposits) that at least some of these coastal Arctic areas which are now ice bound were bounded by areas of open water for at least some periods since the last glacial. This is generally accepted and is consistent with the proxy temperature data. The current global decadal temperature trend is upwards, and appears “amplified” in the high latitude NH. If the current or centennial trend is sustained as modeling suggests, Greenland temperatures will exceed post glacial Holocene temperatures in a relatively short timescale. The word “feeble” is perhaps inappropriate given the likely persistent nature of GHG forcing. The recent Arctic temperature rise is not unprecedented over geological timescales, but is highly significant compared to the past 2000 year proxy records (see Kaufman 2010 update and the zoomed in ice core record from Agassiz (Vinther 2009) and GISP2 (from Alley 2004 update). It should be emphasized, that the orbital parameter forcing which is thought to have driven the gradual fall in NH temperatures since the post glacial temperature maximum is not global in effect, it is not clearly apparent in the deep sea sediment alkenone temperature proxy records for much of the rest of the globe (as is clear in Rimbu 2003) and is not apparent in the Antarctic ice core records. The Greenland Ice Sheet mass is currently diminishing at an accelerating rate due to localized warm waters and warm currents transported from lower latitudes Hannah 2009, Di Iorio 2009, Straneo 2010, Rignot 2010 as well as recent rapidly warming Arctic air temperatures. The recent rapid change in positive forcing from increasing anthropogenic GHGs is a new factor not present in previous glaciation/deglaciation cycles. It is effectively a global effect (rather than a high latitude effect such as NH insolation) – which combines with the effects of other forcings. The oversimplistic point you make about higher relative NH insolation forcing levels in the past does not strictly hold. Perhaps more importantly, the massive ice sheets that covered much of the NH in the last glacial period did melt (in most places completely) over the “deglaciation” time span, and we know rapid changes in temperature have been triggered by a combination of the slow change in solar forcing combined with positive feedbacks possibly from changes in the Atlantic Meridional Overturning Circulation and/or changes in GHG. This shows how sensitive our climate can be to proportionally small changes in forcing. I also do not expect the massive central Greenland ice sheet to vanish overnight, but the relatively rapid recent increased rate of loss is of legitimate concern and should not be belittled.
  36. What caused early 20th Century warming?
    miekol at 13:27 PM on 21 August, 2010 I think I can speak for everyone who contributes to this website when I say that we share your concerns about energy availability and poverty. For me, personally, I can say that my concerns also include biodiversity loss and food availability. Please understand that we don't take any satisfaction in the fact that humans are changing the climate, complicating other issues. I really wish a magic wand could make the AGW problem disappear. I think we 'warmists' -- or whatever you want to call us -- just recognise that everything will be that much worse if the majority refuses to recognise the problem and bury their heads in the sand. To overcome the world's problems, first we must all agree what they are and how they interact. I urge you to read the links others have provided and understand the science for yourself. The facts will speak for themselves -- provided you're willing to be open and objective. From the way you end your last comment I think you are.
  37. Is the sun causing global warming?
    As it says at the top of the page "This post is the Basic version (written by John Russell) of the skeptic argument 'It's the sun'" The comments at that page number over 550 covering a period of 3 years. Is this page, and indeed the other Basic versions not in danger of rehashing old points? I mention this as the chances are that the points Kamilian brings up here and at other Basic pages may have been covered over the last few years at the relevant main page. Is the intention to have Basic, Intermediate, Advanced share the same set of comments or will each have their own? I've seen moderators note things as being Off-Topic so should they note things as being Off-Level?
  38. Communicating climate science in plain English
    - I think tabs make more sense than a slider: Discrete choices vs. a continuous range. - However, I think the choices should be: 1) The one-liner 2) The "basic" explanation 3) The "in-depth" explanation I think it's going to be hard to do a really good job on the previously discussed "advanced" explanation, because you're really talking about an expert's level of understanding re-packaged in layman's language. The most I would do for this site is to find pointers to appropriate existing discussions (if any). So this should be a 4th tab, but mostly with pointers. - With respect to writing style: 1) One-liner: From what I've seen of the examples, they look about right. 2) "Basic" explanation: Should really aim for an 8th-grade level of language use. I think this is about what writers aim for in documentation that they really need people to understand. As I've remarked elsewhere, this doesn't mean the argument is "dumbed down", just that the style is trimmed and the vocabulary not too extensive. 3) "In-depth": I think the current level of writing is about right. 4) Pointers to advanced presentation: Same level as 3). - Just one more comment on the importance and dignity of explanation at the audience's level: The great experimental nuclear physicist Ernest Rutherford once remarked: "If you can't explain to a barmaid what you're doing, you don't understand it!"
  39. Dust-Up On Mars: Should Martians Be Sceptical of Global Warming?
    I think papertiger is saying that because we can observe the geology in some detail, we can infer something about the ancient climate (e.g., the existence of certain kinds of sedimentary layers suggests the presence of standing water at some point in the planet's history). But, no, we don't know much about climatic trends in the last century. But even if we did, it wouldn't tell us much -- that's the point of the article. We can directly measure solar output and we can measure how much of it is reaching the Earth. Using Mars as a proxy would introduce huge amounts of uncertainty under the best of circumstances, and we have anything but the best of circumstances with respect to our understanding of Mars' climate. gpwayne, John -- I think each of these short explanations should end with a sentence like: "If you'd like to know more, see our intermediate explanation." Where "intermediate explanation" is a link to the more detailed entry.
  40. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    theendisfar said:
    Calling someone a liar could be considered ad hominem
    Wrong. Calling someone a liar who has obviously just told a porkie is not an ad hominem attack just a reflection of the truth. As far as I am aware the only proven liars are all on the side of the deniers: Monckton, Singer, Michaels, Lindzen et al. If you have proof of climate scientists lying then please provide evidence otherwise you are the one guilty of an ad hominem attack. You are just arguing from a baseless "I don't like it therefore it is wrong" attitude. Also please explain to us how convection and evaporation add energy to the atmosphere. They only move the energy around, the enhanced green house effect is what adds the additional energy. Please read some simple physics texts.
  41. The Past and Future of the Greenland Ice Sheet
    Berényi Péter at 09:21 AM on 20 August, 2010 “SST was more than 2°C above its present value for several thousand years with no adverse effect on the Greenland ice sheet” The second part of this statement is doubtful. One of the points of this post is that there is plenty of evidence and peer reviewed research which shows that the Greenland Ice Sheet volume has varied in step with the NH high latitude temperature variations in the past, see Vinther 2009. Areas at the ice margins may have completely melted over periods as short as decades (Alley 2010 cited above).
  42. How climate skeptics misunderstand past climate change
    Perhaps you may like to illustrate how this blog, and climate science in general, doesn't seem to understand past climate change. This site suggests that warming starts in the SH, is amplified by greenhouse gases and other positive feedbacks, and greenhouse gases transport this to the NH. 1) Richard Alley (at ~38m) suggests the "physically realistic" models show reduced summer sun causes ice sheets to grow in Canada eventually leading to a globally average reduction of ~5-6 °C, yet this page contains Vostok ice core data suggesting temperature falls before CO2 does. If the change starts in the NH, how does CO2 still lag temperature (during these cooling periods) in the SH if CO2 has such a significant effect, particularly in transporting heat from one hemisphere to the other? 2) This page suggests charts provided by Ned (located here), which don't appear to bear any relevance to climate science, are a good example of how positive feedbacks don't lead to a runaway climate. Looking at the Vostok data here: a. How do you explain the almost linear temperature rise in the three warming periods at ~125,000, ~240,000, and ~325,000 years BP? If positive feedbacks don't lead to a runaway climate they need to illustrate asymptotic behaviour, which the empirical evidence doesn't support. b. In the most recent warming (~20,000 years BP), where in the EPICA Dome C data (which is what I look at, but it's seems to also be visible in the Vostok data) there's warming for a few thousand years, then cooling for about 1,500 years, then warming again for about 1,000 years. If positive feedbacks are so strong, how do you explain such (relatively) rapid changes in gradient (as they're significant, rather than being almost zero)? c. How do you explain the significant (~10-15 %) drop in CO2 around ~325,000 years BP with no corresponding change in temperature? In response to Dappledwater (Comment #28) and the Moderator Response, thank you for illustrating what seems to me as the biggest issue with this ice core data, the correlation between temperature and numerous variables that apparently cause the change. Hansen et al. 2008 Figures S18 and S19 illustrate the strong correlation between temperature and CO2, CH4, and surface albedo. Page 2 attributes the change in temperature between the LGM and pre-industrial Holocene to a radiative forcing of ~6.5 W/m^2 with ~54 % surface albedo, ~35 % CO2, ~6 % CH4, and ~5 % N2O. We also know that warmer climates lead to less snow and ice as well as cause vegetation changes, which are changes in surface albedo, and warmer climates also lead to greater concentrations of CO2 due to out-gassing. In other words, temperature has some influence over at least two of the supposed forcings. My reasoning is along these lines. If the data showed perfect correlation between these variables, then the only possible explanation is that changes in temperature caused all the other changes and they had no influence on temperature (as climate science suggests there are external forcings of temperature such as solar variability, orbital effects, etc.). In reality there's strong correlation (particularly between the LGM and pre-industrial Holocene) suggesting that change in one variable (independent) is the significant cause of change in the other variables (dependent), since external forcings only directly influence temperature it's unlikely to be a common cause for all variables. It also suggests that changes in any of the dependent variables would have little if any influence on the independent variable. There's a couple of things that suggest temperature would be the independent variable: 1) Temperature is directly influenced by external forcings. 2) The relationship describing the correlation doesn't correspond to the forcing (e.g. the trendline for CO2 appears to be a quadratic which is contrary to the logarithmic relationship provided by climate science). I'm not worried about the lag between temperature and CO2, how do you explain the strong correlation between all these variables if there are multiple drivers of climate which would tend to break the correlation?
  43. What caused early 20th Century warming?
    Please refer to this comment as it's relevant here as well. In response to Dappledwater (Comment #14), perhaps you may like to do your own investigations, the page you linked to here is misleading at best, and just plain wrong in some cases. First, Figure 2 combined with the paragraph preceding it suggests it shows the measured change in outgoing radiation, which it doesn't, it shows the simulated change. You can see this here which quite clearly labels that same graph as simulated. It also shows that in Figure 1b) the middle graph offset -5 K (simulated) shows a reduction in the CO2 band (~540-800 cm^-1) up to ~740-750 cm^-1 while the graph above it (observed) doesn't show any change. It also refers to the Griggs 2004 paper which appears to be available here as well. Figure 2 in that paper again clearly shows little if any change measured in the CO2 band with the simulated results suggesting there should be a drop between ~700-740 cm^-1. Also, there's a measured increase in the CH4 band between 1997 and 2003, which the authors do not provide an adequate explanation for, and conclude that the simulations (which are meant to be based in physics) require more work as they were unable to predict the change. Secondly, Figure 3 has this description before it: When greenhouse gases absorb infrared radiation, the energy heats the atmosphere which in turn re-radiates infrared radiation in all directions. Some makes its way back to the earth's surface. Hence we expect to find more infrared radiation heading downwards. Surface measurements from 1973 to 2008 find an increasing trend of infrared radiation returning to earth (Wang 2009). A regional study over the central Alps found that downward infrared radiation is increasing due to the enhanced greenhouse effect (Philipona 2004). Taking this a step further, an analysis of high resolution spectral data allowed scientists to quantitatively attribute the increase in downward radiation to each of several greenhouse gases (Evans 2006). Which misleadingly suggests that Figure 3 illustrates the change in downward radiation, even though Figure 3 is correctly labelled. I would have thought it was more important to explain how the Evans paper can conclude that a measured/calculated change of 3.52 W/m^2 "compares favourably" with a simulated change of 2.55 W/m^2. On what planet (with or without a greenhouse effect) is a ~27 % error considered to compare favourably? Another important issue that description raises is a qualitative idea floating around this site about how a tropospheric hotspot is not a signature of an enhanced greenhouse effect (it would be caused by any warming at the surface), apparently it's the warming troposphere and cooling stratosphere due to more energy being "trapped" in the troposphere. Climate science says that the stratospheric cooling is due to increased greenhouse gases in the stratosphere having a net cooling effect, suggesting there would also be additional greenhouse gases in the upper troposphere. As that description suggests, greenhouse gases absorb radiation, become warmer, and then emit more radiation. If the tropospheric hotspot is not a signature of an enhanced greenhouse effect, it suggests that the additional greenhouse gases in the upper troposphere are not absorbing any significant radiation (from any direction), otherwise it would be a signature in it's own right. This leads to: 1) If this region is not absorbing any additional radiation to any degree, then no radiation can be passing through this region (from any direction) that could be absorbed by greenhouse gases, otherwise the additional greenhouse gases would absorb the radiation and become warmer than if there was some other cause of surface warming. How is it be possible for less radiation at greenhouse gas wavelengths above the tropopause that originated from below the tropopause if the upper troposphere is not absorbing any radiation to any significant degree? 2) If everything below the tropopause is getting warmer and emitting more radiation at all relevant wavelengths, and the stratosphere is cooling as it can emit more radiation at greenhouse gas wavelengths, why would there be less radiation reaching space? This leads to another explanation often given, that adding greenhouse gases increases the "optical thickness", leading to radiation being emitted from a higher altitude which is cooler. The problem here is I'm yet to find one that provides a quantitative approach and include tropospheric warming. Explaining this more completely, at pre-industrial times the radiation was emitted at a height h1 at temperature t1, and there was another height h2 at temperature t2. Between then and now greenhouse gases were added and the temperatures increased, increasing temperature t1 to t1' and increasing temperature t2 to t2', also changing the emission height from h1 to h2. The question that doesn't seem to be properly addressed is if t2' is less than t1, as opposed to the explanation given that t2' is less than t1'.
  44. Is the sun causing global warming?
    So, while there is no credible science indicating that the sun is causing the observed increase in global temperature, it's the known physical properties of greenhouse gasses that provide us with the only real and measurable explanation of global warming. No credible science? So you're suggesting that this site isn't about credible science? Seeing as this page quite clearly states: The other consequence of the warming ocean is it means there is additional "warming in the pipeline". Even if CO2 emissions were to start falling now, we already face further global warming of about another half degree by the end of the 21st century (Meehl 2005). So even if the forcing was reduced, there'd be warming for potentially 90 years. Considering this page suggests that the temperature in the graph on this page also corresponds closely to SSTs, then the cooling trend around 1940-1950 doesn't correspond to the increasing solar activity. Seeing as the temperature fell or remained stable while solar activity increased between 1940 and 1960, and a reduction in CO2 now would see continued warming, it suggests that temperature doesn't directly correlate (temporally) to the forcing. It seems far more likely that the increase in solar activity of ~0.8 W/m^2 up to 1960 in that graph is the cause of recent temperature changes rather than the CO2 change since 1960 of 5.35*ln(390/317) = ~1.1 W/m^2 (i.e. they're of similar magnitude) due to the thermal inertia of the system. Perhaps you would also like to put things in perspective. From 1880 there's been a minimum ~0.5 W/m^2 increase in solar activity (~0.8 W/m^2 until 1960, then a decrease). In the same time there's been a change in CO2 of 5.35*ln(390/290) = ~1.6 W/m^2. According to the IPCC there was a change in CO2 between 1750 and 2005 of ~1.7 W/m^2 and a net change in anthropogenic forcing of ~1.6 W/m^2. How can solar variability be completely discounted, since the graph here suggests it's at least ~30 % of the change due to anthropogenic sources? How do you explain why the IPCC graph suggests ~0.1 W/m^2 due to solar irradiance when this graph suggests otherwise? Perhaps the IPCC doesn't consider it cherry picking, but ~0.1 W/m^2 doesn't show the full story even if it is an accurate delta between 1750 and 2005. Furthermore, what known physical properties of greenhouse gases are you referring to? When I think of physical properties, I think of this as an example. We see that the Stefan-Boltzman constant is considered to be known to a standard uncertainty of 4e-13 W/m^2 and relative standard uncertainty of 7e-6 (68 % confidence interval). For two standard deviations (95 % confidence interval) it would be an uncertainty of 8e-13 W/m^2 and relative uncertainty of 1.4e-5. I would have thought that the effect of CO2 is pretty important in climate science, Section 6.3.1 of this document says: IPCC (1990) and the SAR used a radiative forcing of 4.37 Wm-2 for a doubling of CO2 calculated with a simplified expression. Since then several studies, including some using GCMs (Mitchell and Johns, 1997; Ramaswamy and Chen, 1997b; Hansen et al., 1998), have calculated a lower radiative forcing due to CO2 (Pinnock et al., 1995; Roehl et al., 1995; Myhre and Stordal, 1997; Myhre et al., 1998b; Jain et al., 2000). The newer estimates of radiative forcing due to a doubling of CO2 are between 3.5 and 4.1 Wm-2 with the relevant species and various overlaps between greenhouse gases included. So it used to be 4.37 W/m^2, which was revised to between 3.5 and 4.1 W/m^2, leading to the current 3.7 W/m^2, all of which are estimates as opposed to physical properties. These estimates have an uncertainty of 0.2 W/m^2 and relative uncertainty of 0.05 (with no mention of confidence interval). Interestingly, IPCC AR4 WG1 Section 2.3.1 suggests 3.7 W/m^2 +/- 10 % for a 90 % confidence interval, giving an uncertainty of 0.37 W/m^2 and relative uncertainty of 0.1, which could be considered worse than the TAR! I don't think they really compare as physical properties, and don't see how they can be considered to be known when they're estimated.
  45. The Oregon Petition: How Many Scientists Does It Take To Change A Consensus?
    KR, First, regarding the 'CO2 is not the only driver' post, it seemed as though the replies were stuck at 250, my posts were not showing up, I thought the post had closed so I abandoned the effort. I see that it is not closed so I'll pick it back up, I have more to add. This is about our futures, our descendents futures. (Moderator, this is not an attempt to inject my beliefs, just motivation) Precisely, without knowing whether an afterlife is reality, I believe my best chance at immortality is to raise children who can take care of themselves to better raise children who can do the same. The better job I do, the better the chances that what my parents, mentors, and experiences have taught me will live on and be expanded. Not as fancy other's beliefs, but it's the best I can come with and it seems a worthwhile effort. It is truly in my best interest that a healthy environment exists for as long as possible. We want the same things in that regard. If you have actual issues with the data or the conclusions drawn from them, we can talk about it. I welcome the offer and hope to make it worthwhile for you and SS as well. Looking back over some posts I recognize that we and others have traded many jabs, it is obvious you and others are learned in this subject and I would not be interested in discussing this if you all were not. With that, I believe that the confirmation or falsification of AGW can be achieved within a year if subjective influences are put aside. I recognize that many here do not share my position that AGW has not been confirmed, or falsified for that matter, and this presents additional challenges, but I'll do my best to earn your patience.
  46. Philippe Chantreau at 00:43 AM on 22 August 2010
    Dust-Up On Mars: Should Martians Be Sceptical of Global Warming?
    So let me get this straight papertiger: you are arguing that the statement that we don't have historical data on Mars prior to the 70's is not true because an orbiter has been observing since 2006? Makes sense...
  47. The main culprit in mid-century cooling
    Tamino over at Open Mind has a nice post showing just when (1975) the warming "resumes" (pollution controls kick in, allowing the true warming signal to no longer be masked/inhibited by the aerosol cooling effect). The CO2 concentration/temperature climb continues unabated to this day. Good post, Anne-Marie The Yooper
  48. Plain English climate science - now live at Skeptical Science
    First: I applaud the effort to boil down the arguments to the basic gist: People can always find more detail in the intermediate-level discussion. However: My impression is that even the basic-level discussions are written at an advanced-undergraduate level of English. If you want to get through to the majority of American readers, I think something more like 8th-grade level is called for. It doesn't mean that the argument needs to be "dumbed down", but that the manner of expression should be a little plainer, and the range of vocabulary should be cut back. I hope this makes sense to you. Best regards!
  49. Eric (skeptic) at 22:28 PM on 21 August 2010
    How climate skeptics misunderstand past climate change
    CB, that's hardly a fair comment (no effort), I looked up C-C and found the reason you quoted it and KR assumes constant RH. I believe that Soden and Held are oversimplifying by using C-C globally. I don't disagree that a warmer world has more water vapor in the air, my question at beginning of the thread was when does the positive feedback stop. Your answer was two-fold: never (22) and use the math (37) which I answered in 38. It may interest you and others to know that there were number of days here in the DC area this summer where our humidity was higher than Miami including total precipitable water. Also his year we had many days that were warmer than Miami where it never got above 95 (we were above 100 several times). Here's our plot: http://www.erh.noaa.gov/er/lwx/climate/cliplot/KDCA2010plot-2.png and theirs: http://www.srh.noaa.gov/mfl/?n=cliplot
  50. The Past and Future of the Greenland Ice Sheet
    BP, the Stott graph shows SST cooling from 11 to 10 kyr BP onwards, whereas the Greenland ice core record has a thermal optimum between 8 to 6 kyr BP. There is also evidence of the Northern coast of Greenland being free of sea ice between 8.5 to 6 kyr BP. See here beach ridges, striated boulders & marine sediment

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