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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 63001 to 63050:

  1. Radiative Balance, Feedback, and Runaway Warming
    > It's not clear to many that H2O is a dominant effect that has only kicked in aggressively for temperatures in the vicinity of where we are (eg, say within the last 10 K, I'd guess) First of all, I am not clear on this since I have not thought about it for too long and haven't come across the statement above. Second, would I be guessing well by saying that, instead of "10K" (a mistake), 20-30K lower in global average temp would result in non-dominating ghg effect contributions from H2O and the correspondingly lower climate sensitivity, as judging by this graph http://upload.wikimedia.org/wikipedia/commons/4/41/Relative_Humidity.png and considering that H2O is about 70% of the ghg effect today with CO2 making up the majority of the rest?
  2. Radiative Balance, Feedback, and Runaway Warming
    Chris, [snipped] Your participation in discussions relating to radiative processes at the "Science of Doom" was stimulating even though we seldom agreed. Here is a question for you. I am a physicist. Other physicists such as Nikolov and Zeller and Robert G. Brown can explain planetary surface temperatures based on TSI, Stephan-Boltzman, albedos and the gas laws. So why do you think that Radiative Transfer Equations (RTEs) have any significant influence?
  3. Radiative Balance, Feedback, and Runaway Warming
    Point 1: I agree with sauerj#16 that more can be done to extend this article, eg, by looking at how H2O affects climate sensitivity all else remaining equal. It's not clear to many that H2O is a dominant effect that has only kicked in aggressively for temperatures in the vicinity of where we are (eg, say within the last 10 K, I'd guess). Of the 33 ghg warming, a major contributions is only "now" being added, because of H2O. In other words, the *average* sensitivity of the planet (eg, starting from no sun or from 1.0 albedo) is much lower than the current sensitivity. We note this by looking at instantaneous tangent line slope (derivative) vs the secant that represents the average slope between our current point and the origin. I started writing up something very similar (but instead TOA flux vs surface flux), as I think showing that graph would help commentator "RW" clear remaining doubts. Ie, it would explain what sensitivity is and how it grows much faster as H2O vapor grows appreciably for a given level of CO2; all other ghg gases remaining constant, add heat from the sun has a much more powerful effect once H2O kicks in past the level needed to match the other ghg effects (earth generally has existed in that range thanks to its distance from the sun, etc). Also, I would place temp on the y axis in order to make it easier for those with modest mathematical bent to follow. You want agreement with the climate sensitivity definition if possible. Greater climate sensitivity should be seen as greater slope on the curve (in the traditional mathematical sense of y_delta/x_delta) and not a smaller/flatter slope. The sensitivity question is a very important one and should be highlighted well.. Point 2: However, I would consider an article view (or related article) to appeal to engineers [can skepticalscience add an "engineer view" for select articles.. beyond the easy, intermediate, advanced views?]. I would clarify that "positive feedback", as it is used in system's analysis and various engineering disciplines, has a different definition than climate positive feedback. This article covered the essence of this point (runaway vs not runaway), of course, but more can be said explicitly to place it in the context of traditional "positive feedback". I have noted that many engineers are skeptic, and I can relate to this particular misunderstanding. So, what describes the earth system is "negative feedback" (in the engineering sense) with a small amplitude component that likely is positive but some skeptic scientists claim could be negative due to clouds. Climate scientists don't expect that positive component to be larger in magnitude than the base negative feedback (at least not any time soon and/or within the confines of existing parameters). The key point is that any net (engineering) "positive feedback" leads to runaway behavior, by the definition used by many engineers, and we want to clarify this issue. It should be clarified that climate scientists call positive feedback simply a less negative feedback. Also, the climate models aren't feedback models, so this distinction is not important for generating future projections. In other words, the scientists' "mislabeling" is inconsequential to the calculations they perform. The "negative feedback" (engineering definition) of climate models is implicit (as mentioned in this article) from the obvious cooling effect of the 0 Kelvin outer space boundary condition and how that is incorporated into the calculations. I will look more carefully at Lindzen's "tropics" feedback analysis (maybe others have already) to see if this issue crops up. It probably isn't an issue, but I am curious. Point 3: I suspect that the albedo might change significantly if ice cover starts to disappear in very large amounts. I might not be thinking clearly, but a change in albedo of say 20% (eg, .06) would be more than merely Apocalyptic when we consider how little the earth's effective emissivity to shortwave changes with a few degrees C change at the surface (right?). Isn't most natural variability equivalent to say +/- .5 C, and isn't this change associated with a tiny percentage change in solar irradiance? Now imagine an increase of 20% incident solar flux rather than a fraction of 1%. [Am I missing something?] [BTW, I am fairly new to this and have lots to learn so I might have misjudged various issues here.]
  4. Scafetta's Widget Problems
    andylee - "I would tackle it from a signal processing and noise reduction point of view - start by subtracting the effect of everything we know from the climate record - volcanic eruptions, ENSO, CO2 signatures etc, and see what is left over." And that's exactly what Foster and Rahmstorf 2011 did for the last 30 years, and what Lean and Rind 2008 did for the last 120 years. Turns out that there really isn't anything left after you account for solar, volcanic, ENSO, and anthropogenic forcings. No mysterious unknown cycles (MUC's), no 'recovery from the LIA', no cosmic ray influence, or distant supernovae, or orbital resonance from Jupiter/Saturn - it's actually just what we expect from the physics. Oh, and our own actions...
  5. Scafetta's Widget Problems
    I then read the paper... He's obviously spent a lot of time and intellectual energy on this, so I don't dismiss it out of hand. (I take issue with the use of the word "astronomical" - apart from our sun, the nearest star is 4.25 ly away.) He has a point and I don't doubt that planetary influences add some multidecadal red noise to climatic data, but his objective appears to start already from a denialist perspective by distancing himself from AGW advocates: "To understand the reasoning a good start is the IPCC’s figures 9.5a and 9.5b which are particularly popular among the anthropogenic global warming (AGW) advocates" The sun isn't stationary, it is wobbling around a barycentre following a complicated path with approximately a 0.01AU deviation. Consequently the Earth's orbit is not perfectly elliptical and its distance from the Sun also has an n-order Lissajous component. Instead of looking for cycles to fit and then attempting to match them to the climate record to try to mask recent warming, I would tackle it from a signal processing and noise reduction point of view - start by subtracting the effect of everything we know from the climate record - volcanic eruptions, ENSO, CO2 signatures etc, and see what is left over. Then, calculate the waveform of the *distance* of the Earth from the Sun modulated by the sunspot cycle to calculate the irradiance. This is the only method that the planets can affect our climate, short of a collision or extended eclipse. At this point a Fourier transform of both climatic history and derived planetary-influenced irradiance should reveal some common frequencies. Applying the irradiance function to the climate record should automatically damp the signal in the right places, subject to some phase shifting to identify possible latencies in climate response. Anything left over is attributable to something else. Lastly, my favourite sentence: How easy it would be to quantify the anthropogenic effect on climate if we could simply observe the climate on another planet identical to the Earth in everything but humans! But we do not have this luxury. ... ... yet! :-)
  6. The Deep Ocean Warms When Global Surface Temperatures Stall
    What changed during the 2000s? Little to nothing. It's barely ten years. You need at least another 7-10 years of the same before you could even _begin_ to detect anything different going on.
  7. The Deep Ocean Warms When Global Surface Temperatures Stall
    One more question: The upper ocean warmed during the 1970s-1990s period together with the land+atmosphere. Then in the 2000s the strange pattern of warming deep oceans despite non-warming upper ocean began. At the same time, the atmosphere and the land surface continued to warm steadily. What changed during the 2000s?
  8. The Deep Ocean Warms When Global Surface Temperatures Stall
    Sorry camburn, there are probably lots. But what came to my mind was something I read about flying. It referred to old-fashioned clunky type smaller planes of, from memory, 50s vintage. The instructor's words were that it was easier to control a plane in bad weather if you 'saw' yourself as swimming, diving or surfacing in currents, tides or waves.
  9. The Deep Ocean Warms When Global Surface Temperatures Stall
    59, Peru,
    How can the heat had bypassed the upper ocean in the trip from the atmosphere to the deep ocean?
    One of your problems comes from the way you phrased this question. You make it sound like the system is a simple path for heat from atmosphere to upper ocean to deeper ocean. It's obviously far more complex than that.
  10. Global Extinction: Gradual Doom as Bad as Abrupt
    JP40 @ 40, Yes the Foundation series has occurred to me as well, in this context. Perhaps we need to sequester as much of human knowledge as possible electronically, on another body in the solar system, ready to be discovered by some putative future generation after the Fall and Rise.
    It will be our technology that will liberate us from having to live in balance with natural ecology, and will save natural ecology in the far future.
    We place enormous trust in future technology. I hope it will save the day, but I am not so convinced that I could say with certainty that it will do so. I think you have misunderstood part of my last post, which was probably not very clear. My point is that greed drives the development of technology, not the other way around. Unless there is "something in it for me", I am unlikely to come up with a new tool or method. Our whole way of life revolves around satisfying our needs and that translates into greed when we seek to acquire more than we actually need as individuals. There is no basic 'need' to be a billionaire, but plenty of us aspire to it.
  11. The Deep Ocean Warms When Global Surface Temperatures Stall
    adelady@60: Do you have any papers showing this? That the "water language" is similiar to atmospheric functions? The sheer difference in density of mass difference would indicate a HUGE energy differential required.
  12. DenialGate - Infographic Illustrating the Heartland Denial Funding Machine
    Here is an interesting article investigating the funding and tax-deductable status of Australia's Institute of Public Affairs (IPA), which has links to Heartland. Looks like a similar setup - how strange.
  13. Global Extinction: Gradual Doom as Bad as Abrupt
    Sorry for the misunderstanding. It seemed that you were saying that humanity deserves to be punished for its "crimes," and that it would be better if we stayed Australopithecus Aferensis. I do agree with you that our civilization will collapse in the next few centuries, causing a lot of collateral damage, but I don't actually think that it is very likely that there will be a repeat of the P-T extinction. Here are the numbers: by the end of the main phase of the extinction, co2 levels reached 3000 ppm. The IPCC's worst case scenario for co2 by 2100 is 1000 ppm, which isn't enough to cause the gassification of methane hydrate en masse. I think that by 2100 there will be enough anarchy to stop most co2 production, so this projection is optimistic (or pessimistic, however you look at it).  I am confidant that civilization will rise again. However, most of our knowledge will be destroyed, and the recovery will be much slower than if a small portion of it survived somewhere other than earth. Our current situation reminds me of Isaac Asimov's Foundation series. In these books, a mathematician who has found a way to predict the future sees that the galactic empire will collapse, and builds a society on a planet on the edge of the empire, in order to compile and preserve all of the empire's knowledge, and to work to reunite it.  After the rise, we need to make sure that we don't ever rely on something that will have serious long term consequences. The earth may not be able to sustainably sustain very many people, compared to the number we have now, but that doesn't mean those extra people have to not exist, because we don't "only have one planet." There is the possibility of terraforming Mars and possibly Venus, which would give us 2 extra planets to live, outside domes, metal cans, underground complexes, and space suits.  You seem to be saying now that technology is the main cause of human greed, and only depletes resources. This view ignores both the cutthroat imperial politics before the industrial revolution, and technologies like wind and solar energy, that don't deplete any resources. Without our current fossil fuel-fuled economy, we wouldn't be enlightened enough to contemplate its demise. In fact, before the industrial revolution, most people were totally ignorant peasants who only knew what they heard by word of mouth. It will be our technology that will liberate us from having to live in balance with natural ecology, and will save natural ecology in the far future.
  14. Scafetta's Widget Problems
    It sounds preposterous that planets can affect our climate in any astrological sense, and I think we can safely discount any radiative forcing from them, but it is well known that Jupiter and Saturn are largely responsible for the Milankovich effect modifying our orbit's eccentricity, although this happens over hundreds of millennia. I looked for some details of orbital mechanics and found these, (the resonances are fascinating):    http://mrob.com/pub/planets.html    http://en.wikipedia.org/wiki/Milankovitch_cycles As the Sun and Jupiter are the most massive bodies, their barycentre causes the Sun to wobble with an amplitude of 1.5m km over 12 years (0.01 AU). My thoughts on a cig packet: As this period is 12x longer than our year, Earth wouldn't 'see' all of that differential as a significant (1%) change in intensity, but I guess there may be some tiny decadal signal (1/12%) though I'm sure it would average out and be insignificant. Far far less than the effect of the Milankovich Cycle.
  15. The Deep Ocean Warms When Global Surface Temperatures Stall
    "How can the heat had bypassed the upper ocean in the trip from the atmosphere to the deep ocean?" It's only a concern if the mechanism for heat transfer was entirely conduction or general turbulence. We can knock out general turbulence immediately, the oceans do not behave like an earth sized washing machine. Conduction? Obviously an issue at various depths and places, but we already know that there are layers and specific places where the water temperature is very different from nearby waters. What's left? Convection. As soon as you allow for water at various depths to exhibit the same kinds of behaviour as air at various altitudes, it all makes sense. Winds, storms, hurricanes, tornadoes exhibit extreme versions of focused or funnelled transport of air at temperature differentials. Local features like hills, mountains, seasides promote consistent winds, or lack of them in some valleys, and temperature profiles. Translate these various features into 'water language' and it's not so hard.
  16. 2nd law of thermodynamics contradicts greenhouse theory
    Stephen Baines "What is the point of bringing up clouds?" Its the only fair equivalent to a blanket. Full cloud cover at night is the surest way to keep the heat in. But as the Earth is externally heated, it will cool with total cloud cover, as the albedo will be huge. GHG`s have huge holes so are not exactly a blanket.
    Response:

    [DB] Way back here, you were asked to succinctly put forth the one objection that you wanted to hang your hat on.  You have made 6 comments on this thread since then and in exactly...none of them have you done so. Failure to do that amounts to a de facto admission that you are here to simply waste the time of others.

    Cease making unsupported assertions (i.e., lacking support in the peer-reviewed literature published in reputable journals) until you can demonstrate that you are able to carry on a science-based discussion in this forum.

  17. 2nd law of thermodynamics contradicts greenhouse theory
    While I strongly doubt YOGI is actually interested in understanding this, but Do Trenberth and Kiehl understand the first law of thermodynamics rather exhaustively covers this. Understanding however requires getting your head around the physics not looking for talking points. Claiming the diagram is "wrong" is tricky when those flows are from measurements.
  18. 2nd law of thermodynamics contradicts greenhouse theory
    Eric (skeptic) Venus has 92 bar surface pressure. Around 53 km up, pressure and temperature are comparable to those at Earth's surface.
  19. The Deep Ocean Warms When Global Surface Temperatures Stall
    When I say that "surface temperatures are warming steadily" I want to say that is not true that surface and atmospheric warming has stopped or even slowed down. That was an artifact of the moderate-to-strong La Niñas of 2007-2008 and 2010-2011. The thing that puzzles me is how we can have at the same time this on the surface/atmosphere: Source: 2011 Temperature Roundup This in the upper 700 meters of the ocean: Source: ENSO Dominates NODC Ocean Heat Content (0-700 Meters) Data And this in the upper 2000 meters of the ocean: Source: Introduction To The NODC Ocean Heat Content Anomaly Data For Depths Of 0-2000 Meters How can a forcing warm the atmosphere and the land, while at the same time producing a much smaller upper ocean warming, and then producing significant warming in the deep sea? How can the heat had bypassed the upper ocean in the trip from the atmosphere to the deep ocean?
  20. Climate change models underestimate future temperature variability; food security at risk
    During Niger's hotspell, the night-time temperatures sometimes do not drop below 100 degrees F.
  21. 2nd law of thermodynamics contradicts greenhouse theory
    How come if 239W/m go in and 239W/m go out, that 396W/m exists within the system ? surely that violates the conservation of energy law ?
  22. The Deep Ocean Warms When Global Surface Temperatures Stall
    From where do Peter Hogarth found the data to make the wonderful figure of comment 54?
  23. Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
    Tom Curtis and Rob Painting: I will continue where you have indicated.
  24. 2nd law of thermodynamics contradicts greenhouse theory
    Actually, I think every denier should be forced to read this thread, and then to look in a mirror, and recognize that to a lesser degree they are doing the same thing. It may be easier to argue their position, or to talk themselves into believing their position has substance, but in 99% of cases it comes down to the exact same thing.
  25. Global Extinction: Gradual Doom as Bad as Abrupt
    JP40 @ 37, I am sorry if you took the impression that I hate civilisation. That is too strong a view. Civilisation, with its opportunities for intellectual growth, has some wonderful aspects. What I regret, however, is the damage our advanced Western-style civilisation has done to the biosphere. Do you not find it depressing that we are candidly discussing the chances that humanity will cause the destruction of the very processes of nature that sustain it? The forces of destruction are largely fuelled by greed, which is arguably not a merit of civilisation. Technology allows us to exploit more of our resources and overpopulation places growing demand for that technology. Our growth is constrained by a limited quantity of exploitable resources as we only have one planet, but our economy collapses without perpetual growth. I have no problem with civilisation per se, but I do have a problem with our collective blindness. To quote from the original post:
    The world revealed by their research is a devastated landscape, barren of vegetation and scarred by erosion from showers of acid rain, huge "dead zones" in the oceans, and runaway greenhouse warming leading to sizzling temperatures.
    Is this not similar to the dangerous climate we are heading for, unless we change our carbon trajectory? Is this not the by-product of our greed-based economy? Yes, the sun will destroy Earth in some billions of years, but humanity has the capacity to cause mass extinctions well before that time. What you call "self-destructive nihilism", I call pragmatism. To avoid the worst outcome, we have to change course quickly and drastically. Being a pragmatist, I don't believe the vested interests of humanity will change quickly enough, or drastically enough, to avoid very bad consequences.
  26. 2nd law of thermodynamics contradicts greenhouse theory
    Sadly, this thread is the happy hunting ground for the wilfully ignorant. It's wasting time trying to teach those who are determined not to let facts undermine their fantasies.
  27. Climate change models underestimate future temperature variability; food security at risk
    Living in London, I've been hearing and reading all about our drought over the last few weeks - supposedly the worst since 1976 (which was more down to a Summer heatwave), but seemingly we've had the driest two-year period in 90 years. Temperatures are also the highest in February over the last few days since 1998 - now, what was the global temperature that year ? No rain expected for the foreseeable future but, then again, Scotland seems to have had the 20% that we are down. However, we are still the lucky ones, even with all that, compared to those in places like Somalia mentioned in the article.
  28. 2nd law of thermodynamics contradicts greenhouse theory
    OK cover the Earth with a blanket (FULL CLOUD COVER) and see how cold it gets Venus?
  29. 2nd law of thermodynamics contradicts greenhouse theory
    DM Yes, I totally agree. Were the doubters to take measurements and do the actual science, they would find that the GHE is perfectly in line with thermodynamics. But they don't do the measurements and instead engage in endless obfuscation, which indicates that they are not actually serious about the issue. It is downright laughable that physicists would not 1) recognize that the 2nd law was contradicted and 2) would not do anything about it if they did. It's also downright depressing that this thread is going on 28 pages!!!
  30. Climate change models underestimate future temperature variability; food security at risk
    Here in the UK we are having a drought. The declaration of drought in winter is unprecedented. "The South East of England recently joined a long list of regions in drought. On Monday 20 February, the Environment Secretary announced that the South East of England has officially moved into drought status. This is due to the combination of persistent dry weather and the continuing decline in groundwater levels and river flows and increasing the risk to public water supplies, agriculture and the environment. As a result Hampshire, West Sussex, East Sussex, Kent, Surrey, London, Berkshire, Hertfordshire, Buckinghamshire, Oxfordshire, and the east of Gloucestershire are now in drought." UK Environment Agency Food prices likely to increase The Mayans - a lesson from history.
  31. Dikran Marsupial at 08:16 AM on 27 February 2012
    2nd law of thermodynamics contradicts greenhouse theory
    Stephen Baines The back radiation is less than the heat radiated from the surface, so the net flow of heat is from warmer to cooler, so it evidently does obey the second law of thermodynamics. I suspect that the problem is that the common definition of the second law that crops up pre-dates statistical mechanics and concept of a photon, in which case it is perhaps understandable that it doesn't specify the net flow of heat (implying that there may be an exchange of energy, but that it is biased in the direction from warmer to cooler).
  32. Monckton Misrepresents Reality (Part 3)
    owl905 @9: 1) The flat lining of surface OHC gain, accompanied by a more rapid warming of the deep ocean did not start suddenly in the 00's. It is a periodic occurrence that has happened in at least two major prior episodes, and two minor episodes in the last fifty years: Consequently your assumption that the situation is remarkable is unwarranted. 2) Below 500 meters, the temperature gradients in the ocean are very small, being in the range of just 1 or 2 degrees C over several hundred, or even thousands of meters. Consequently small changes of temperature in the deep ocean can significantly change the temperature profile and hence the rate of heat transfer to the deep ocean: What is more, the effect can apply over very large areas so that a small change in the rate of heat transfer can add up to a lot of heat. 3) If you have an issue with this (and it certainly appears that you do), can I suggest that you discuss it on this thread where the issue is canvassed in depth, and where the relevant evidence is already presented.
  33. 2nd law of thermodynamics contradicts greenhouse theory
    I have to agree with Rob above. If there was some disagreement between the GH effect and the 2nd law, it would have been noticed by at least one of the thousands of scientists, all steeped in the Laws of Thermodynamics, who have studied some aspect of GHGs over the last 150 years. Instead of arguing about semantics and analogies, the doubters need to produce a reproducible experiment that can withstand peer review. The fact that haven't done so, despite the fact that it would yield a Nobel Prize, is telling.
  34. 2nd law of thermodynamics contradicts greenhouse theory
    Mods...Sorry about the triple posts...thread didn't update properly. Delete accordingly.
  35. 2nd law of thermodynamics contradicts greenhouse theory
    YOGI What is the point of bringing up clouds? The blanket analogy is meant to explain the effect of greenhouse gases on loss of heat from the earth's surface. Clouds require a different analogy entirely, one that also accounts for changes to albedo or incoming energy. As Phil notes, in this analogy the absorption of solar energy by the earth's surface is the equivalent of heat released by the human body as a result of metabolism. Both the earth and the human body are open systems thermodynamically, although they receive energy in different forms. From that point of view atmopsheric GHGs and blankets act similarly, both reducing loss of heat generated by absorption of solar energy or metabolism. The analogy does break down eventually if you take it far enough, as all analogies do. For example, the human body actively alters its metabolism to maintain a relatively constant core temperature, while the earth actually appears to amplify variations in solar radiation. That makes calculation of equilibrium surface temepratures different in each case. But the point of the analogy is not to represent energetics of the earth system, but simply to make the GH effect tangible by relating it to common experience. The blanket analogy succeeds on that front.
  36. Sceptical Wombat at 06:55 AM on 27 February 2012
    Monckton Misrepresents Reality (Part 3)
    Tom Curtis @6 All your points are well taken. However one thing that stands out to me is that the triangle at the bottom left of the diagram is remarkably similar to the one at the top right. That is is looks as if warming was accelerating to about 1940 then took a dive before accelerating again in the 1950s. Any comments?
  37. Radiative Balance, Feedback, and Runaway Warming
    A positive feed back can also be limited by the cause running out. For instance, if all the methane of the Arctic permafrost rapidly enters the atmosphere due to the observed warming of high latitudes, this will cause a run away green house effect until it is all used up. Over a few decades, the methane will oxidize to Carbon dioxide which will reduce its effect. We could see some severe bounces in temperature which then decrease to a higher level than before the bounce. I wonder how many of us will be around following such a rapid change in our climate.
  38. 2nd law of thermodynamics contradicts greenhouse theory
    YOGI... This is the point where I usually suggest to "doubters" that they need to collect and publish their findings, if they can. To everyone else reading this, we accept the past 150+ years of research that makes up the basis for the greenhouse effect. This is established physics and is not in question by... well, by anyone really. You're incomplete understanding, and your desire to find some fault somewhere, is driving you into a circuitous pattern that has no end. If, somehow, someway, you managed to connect all your dots and come up with a theory that was complete it would literally mean re-writing the past 150 years of physics. You'll please excuse me if I suggest that the likelihood of this is extremely low, to the point of being a near impossibility. But if you want to try, knock yourself out. Outside of that you are clearly exhibiting a Dunning-Kruger effect and wasting everyone's time and energy.
  39. 2nd law of thermodynamics contradicts greenhouse theory
    Daniel @ 1346... Actually, I think that's officially called the "He who must not be named" thread.
  40. 2nd law of thermodynamics contradicts greenhouse theory
    Phil#1347 We create our body heat internally from the calorific value of the food we eat. Excess heat may be lost through respiration or evaporation of perspiration, and body heat is continually lost in IR radiation from the body surface (when the surrounding air temperature is lower than the body temperature). Now as you know a blanket will reduce the IR emmission from your body in cold air by insulating it, and enable you to maintain your body temperature easier.
  41. 2nd law of thermodynamics contradicts greenhouse theory
    Dikran Marsupial OK cover the Earth with a blanket (FULL CLOUD COVER) and see how cold it gets. I really did mean your blanket analogy was not safe, and if you want to continue pushing it, I have no problem with de-bunking it at every step. Solar IR makes up a significant proportion of insolation. Your thought experiment proves that beyond a single photon or so, the second thermo law must also apply between the Earth`s atmosphere and surface.
  42. Radiative Balance, Feedback, and Runaway Warming
    David, Hansen's argument for why a runaway might occur is extremely unconvincing, nor do I really think he understands how a runaway greenhouse operates. The physics outlined in this post rules out a water vapor runaway because there simply isn't enough sunlight to sustain such a situation, as has also been outlined in a number of articles on the subject (see some older papers by James Kasting for example, or Selsis et al 2007, as well as Ray Pierrehumbert's new climate book). Clouds could, in principle, change that argument but if the Earth were relatively prone to a runaway greenhouse effect, it is very likely it would have occurred in many hothouse climates of the distant past, even with a slightly fainter sun during many of these intervals. Even CO2/CH4 feedbacks don't fundamentally alter that picture, because in the runaway limit the OLR is determined primarily by water vapor and clouds. That said, the fact that a runaway greenhouse couldn't occur is really a distraction from the point that climate sensitivity could be 3 or 4 C per doubling of CO2 (or even higher on longer timescales), and we are more than capable of tripling or quadrupling CO2 levels.
  43. Radiative Balance, Feedback, and Runaway Warming
    Regarding your statement: "it's worth mentioning that it is virtually impossible to trigger a true runaway greenhouse in the modern day by any practical means, at least in the sense that planetary scientists use the word to describe the loss of any liquid water on a planet" Hansen's discussed this issue in his December 2008 AGU Bjerknes Lecture. He also addressed this topic in Chapter 10 "The Venus Syndrome" in his book "Storms of My Grandchildren". He says he decided to bring the Venus Syndrome into the discussion because "it seems possible that strategic changes to fossil fuel use will not be adopted", i.e. civilization will burn every bit of fossil carbon that can be extracted from the Earth's crust. "So we had better examine what may happen if we push the planet beyond its tipping point". He says in the explanation in his book that Venus once had abundant water vapour in its atmosphere and "probably" had oceans. As the Sun brightened from its 30% less bright early solar system state, Venus heated up, "and the strong greenhouse effect of water vapor amplified the warming. Eventually a 'runaway' greenhouse effect occurred, with the ocean boiling or evaporating into the atmosphere". As the water vapor dissociated when it encountered UV at the top of the atmosphere, H escaped into space leaving O to combine with the C that had "baked out" of the crust until the atmosphere was 97% CO2 at a pressure of 90 bars. He says this theory is confirmed by the enrichment of heavy hydrogen, i.e. deuterium, on Venus today which is ten times more abundant there relative to normal hydrogen than on Earth or in the Sun. Ergo Venus was once wet. "So Venus had a runaway greenhouse effect". He displayed this graph in the Bjerknes Lecture as well as in his book: The graph, he says, "illustrates results of experiments with two different climate forcings: changing atmospheric carbon dioxide and changing brightness of the sun". "Qualitatively, this is the behavior that we know must occur: A sufficient negative forcing causes a runaway snowball Earth condition, with freezing temperatures over the entire planet, while a sufficient positive forcing causes a runaway greenhouse effect. We know that this U-shaped curve is correct - the question is, at what forcings do the sharp upturns to runaway conditions occur?" He suggests "that the forcings needed to reach snowball Earth or runaway greenhouse conditions are no more than 10 to 20 W/m2 when solar irradiance or CO2 change are defined as the forcing". After some discussion of the evolution of climate science, he says: "Now we are ready for the important part - trying to figure out how close we are to the climate forcing that will cause a runaway greenhouse effect. Until recently I did not worry too much about that", because much more CO2 had been in ancient atmospheres, "probably a few thousand parts per million", more than burning all the fossil fuels could produce. "So we should be safe, right? Wrong, unfortunately". 250 million years ago the sun was 2% dimmer, which is an equivalent forcing change to a doubling of CO2. "So if the estimated amount of CO2 250 million years ago was 2,000 ppm, it would take only about 1,000 ppm of CO2 today to create a climate equally as warm". But this is not the biggest factor, he says. Some estimates of early Cenozoic CO2 are as low as 1,000 ppm. He points to a Zeebe, Zachos, and Dickens 2009 paper which he quotes from: "Our results imply a fundamental gap in our understanding of the amplitude of global warming associated with large and abrupt climate perturbations". His estimate of Cenozoic CO2 depended on there not being this fundamental gap. If Cenozoic climate sensitivity was greater than 3 degrees C for 2x CO2 it favors lower estimates for how much CO2 there was. "The PETM results would be easier to understand if the baseline CO2, prior to the PETM warming was closer to 500 ppm. But even so, the magnitude of the PETM warming implies a climate sensitivity greater than 3 degrees for doubled CO2". He notes: "if we burn all the fossil fuels, the forcing wil be at least comparable to that of the PETM, but it will have been introduced at least ten times faster. The time required for the ocean to respond to this forcing is only centuries. Thus, carbon cycle diminishing feedbacks will not significantly reduce the ocean warming. The warming ocean can be expected to affect methane hydrate stability at a rate that could exceed that in the PETM, where the rate of change was driven by the speed of the methane hydrate climate feedback, not by the nearly instantaneous introduction of all fossil fuel carbon". "Carbon cycle diminishing feedbacks, which were important for keeping Earth away from runaway conditions during paleoclimate global warming events, are not likely to be as effective in drawing down atmospheric CO2 during the very rapid burning of fossil fuels by humanity". "It is difficult to imagine how the methane hydrates could survive, once the ocean has had time to warm. In that event a PETM-like warming could be added on top of the fossil fuel warming. After the ice is gone, would Earth proceed to the Venus syndrome, a runaway greenhouse effect that would destroy all life on the planet, perhaps permanently? While that is difficult to say based on present information, I've come to conclude that if we burn all reserves of oil, gas and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty". Hansen said this was his opinion. His "model blows up before the oceans boil". Schellnhuber, a leading figure at PIK, the Potsdam Institute for Climate Impact Research, at the 4 degrees and beyond conference held at Oxford UK September 2009 mentioned that PIK was thinking of fleshing out the Venus Syndrome concept by creating a model that doesn't blow up. He used these slides, i.e. 16, 17 and 18 during his audio presentation as he discussed "a number of exciting futures that are ahead of us, including a runaway greenhouse effect perhaps" which he cautioned we would not want to experience. "Is there something like a runaway greenhouse effect?" he asked. "We don't think there is such a thing on this planet, it never happened in history, the other thing happened namely snowball Earth, a runaway glaciation, that actually happened twice probably, but we have not seen... a runaway greenhouse effect. But there can be something like a limited runaway greenhouse effect where you enter a temperature T1 and then the system by itself pushes temperature to another level, here, and this could be a jump in temperature over centuries of 5 degrees or something. We cannot exclude that yet". He displayed this chart: "You see most of the feedbacks are red.... But Venus?.... I don't think it will ever happen, but unfortunately we have never calculated this. It can't be done with state of the art GCMs of course. But we are thinking in Potsdam about doing first conceptual models about it.... Just to open up this field".
  44. Global Extinction: Gradual Doom as Bad as Abrupt
    This technology debate is ignoring totally renewable technology like wind and solar energy. There are also renewable ways to produce food, like airoponic indoor farms, which use a very small amount of water, and nutrients that can be made by bacteria cultures. Currently, these technologies are expensive and impractical, and probably won't be able to save our civilization, but to say that all technologies just increase how fast we use up the Earth's resources is the fallacy here.
  45. Radiative Balance, Feedback, and Runaway Warming
    fixed, thanks
  46. Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
    mspelto#39: "At this point the detailed inventories are better validated." Are you saying that GRACE is under-reporting ice mass loss in these areas?
  47. Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
    In the high mountains of Central Asia detailed glacier mapping inventories, such as from (GLIMS: Global Land Ice Measurements from Space) using ASTER, Corona, Landsat and SPOT imagery, of thousands of glaciers have indicated increased strong thinning and area loss since 2000 throughout the region except the Karokoram. Links to below papers. In the Russian Altai mapping of 126 glaciers indicate a 19.7 % reduction in glacier area 1952-2004, with a sharp increase after 1997 (Shahgedanova et al., 2010). In Garhwal Himalaya, India, of 58 glaciers examined from 1990-2006 area loss was 6% (Bhambri et al, 2011). In the Nepal Himalaya area loss from 1963-2009 is nearly 20%, (Bajracharya et al., 2011), volume losses increased from an average of 320 mm/a 1962-2002 to 790 mm/a from 2002-2007 in the Khumbu region, including area losses at the highest elevation on the glaciers (Bolch et al., 2011). In the Tien Shan Range over 1700 glaciers were examined from 1970-2000 glacier area decreased by 13%, from 2000-2007 glacier area shrank by 4% (Narama et al, 2010). An inventory of 308 glaciers in the Nam Co Basin, Tibet, noted an increased loss of area for the 2001-2009 period, 6% area loss (Bolch et al., 2010). GRACE estimated Himalayan glacier losses at 10% of that found in the aforementioned examples for volume loss for the 2003-2010 period the (Jacobs et al, 2012). At this point the detailed inventories are better validated.
  48. 2nd law of thermodynamics contradicts greenhouse theory
    With regard to the Blanket analogy, it is worth pointing out that the heat humans (and other organisms) produce is derived from the respiration of foodstuffs, and so is not an internal source of energy and typically pass through a blanket unimpeded (unless you happen to have it over your head :-) ). Incoming Solar radiation is thus analogous to food in the Blanket analogy.
  49. Radiative Balance, Feedback, and Runaway Warming
    Thanks for an informative and well written article. It is helping me clarify my understanding and thinking about this issue, and will likely be more helpful when I reread it. Is there an editing oversight in the caption for Figure 4, where the caption says "blue circles," while the figure shows and text states "blue squares?"
  50. 2nd law of thermodynamics contradicts greenhouse theory
    There's always the Poptech thread...the Valhalla of mythic D-K.

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