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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 100851 to 100900:

  1. Conspiracy theories
    meercat writes: consensuses are temporary alignments and arguably the least productive periods of scientific activity What exactly does that mean? Let's take the case of another scientific consensus -- plate tectonics. Did the geosciences suddenly become less productive between the 1950s and 1970s, when the consensus over plate tectonics solidified? Would the field be more productive if there was a small but vocal community of "plate tectonics skeptics" who used their influence in the media to force the mainstream geosciences community to continually defend the existence of plate tectonics? Scientific consensus is a good thing, because it lets us focus more energy on the areas where there isn't a clear consensus yet. Let's say that a decade from now, we've all come to agreement on climate sensitivity (it's 3C). It's true that there would be much less energy and resources devoted to trying to understand climate sensitivity. People who are now doing that would then need to find other research topics. That's a good thing. There are plenty of other topics that need to be explored! meercat continues: I don't think the world is going to end soon, or that the AGW panic is helpful. Like CBDunkerson, I don't see how this kind of inflammatory talk is helpful. Are there people here who claim that the world is going to end, or who are promoting "panic"? My concern about AGW is that it will impose a lot of undesirable economic, social, and environmental costs on future generations. We are going to have to move away from fossil fuels anyway. If we can start that move sooner rather than later, we reduce the likelihood of adverse consequences from climate change. Like Alexandre, I agree that the actual problem we're facing is not panic but complacency.
  2. Conspiracy theories
    #2 meerkat - if we take a Kuhnian approach to the history of science then consensuses are temporary alignments and arguably the least productive periods of scientific activity. I'm no scientist nor historian, but consensuses are just the mounting evidence pointing to one particular explanation, reinforcing the possibility of the theory being truthful, or at least useful. Any problem about the consensus about the existence of Hadley Cells, or gravity or Ohm's Law? Any "period of low production" associated to them? But I don't think the world is going to end soon, or that the AGW panic is helpful. Panic? You mean overreaction? Take a look at the steady upward trend of the CO2 concentration. You see any reaction at all?
  3. Conspiracy theories
    Excellent post, Dr. Nic! Albeit one sure to bring out the wingnut contingent... The logical incoherence of denial is forced to rely on conspiracy because science, data and simple physics is not on their side. As to Fawkes, a part of him lives on in all of us. The part that focuses on the truth, fie the consequences. The theory which best explains all of what we see and measure is summed up in 3 letters: AGW. And it doesn't take being a rocket scientist to understand it. Just having an open mind. But, as Tamino recently said:
    "Keeping an open mind doesn't mean letting your brain fall out."
     Let it begin. The Yooper
  4. Lindzen and Choi find low climate sensitivity
    In the past, I've pointed out that most of our regular "skeptic" commenters appear to follow an unwritten rule never to say anything critical of another's "skeptic" arguments, no matter how far-fetched. So I have to note here how much I appreciate the tone set by Eric (skeptic), who has been very calmly and even-handedly responding to comments from both the pro-consensus and anti-consensus "side" in this thread. This is a real breath of fresh air ... and it's very reassuring to those of us who have been starting to wonder whether there's anyone on the "skeptic" side whose comments here are worth taking seriously. We need more of this. John has created a really great site here, but it's constantly in danger of succumbing to the typical pattern of two noisy "sides" yelling at each other. Anything that tends to break down the homogeneity of these two "sides" is a good thing, IMHO.
  5. Lindzen and Choi find low climate sensitivity
    Riccardo, I found this excellent exposition of the concepts by Chris Colose It turns out that the definition of the no-feedback temperature increase for a forcing is based on the effective emission temperature rather than the actual surface temperature. Using 255K as the effective temperature (that of a notional blackbody with overall emission equal to total net insolation TOA) that gives 1K for 3.7W/m2. I guess that the often quoted 1.2K comes from working through the calculation to give the surface budget accurately for real temperature, without feedbacks, but applying it directly to the effective temperature gets approximately the same answer much more simply. RW1 - if you want to understand this better, Chris's post includes how to calculate for solar forcings, albedo etc.
  6. Conspiracy theories
    meerkat wrote: "But I don't think the world is going to end soon, or that the AGW panic is helpful." Straw man argument. No one involved with AGW science claims it is going to cause the world to end. Just as nothing in the post above made the black and white 'corporations bad / scientists good' distinction you falsely ascribe to it. Panic is never helpful to decision making. Neither is fiction.
  7. Lindzen and Choi find low climate sensitivity
    VeryTallGuy I haven't seen any rough calculations and I don't think it is possible. The problem is that you need to consider the wavelength dependence of both emission by the earth surface and absorption by the atmosphere; also, other forms of energy other than radiative need to be taken into account. In other words, you're asking for the climate sensitivity which proved to be hard to calculate.
  8. Irregular Climate 16: a leak for all seasons
    Not to pick nits or anything but it seems like your "The Climate Show #4" post doesn't appear in your feed. It's not just my feed reader - I "manually" (with wget) downloaded the feed.xml file, opened it in an editor and searched for "Climate Show" and "#4". Commenting here rather than on the post in question so anybody else who relies on the feed can see the comment and maybe throw some light.
    Response: I found posts with YouTube code broke the XML feed so I exclude any posts with embedded YouTube movies. If anyone has some tech tips on how to resolve this in a better manner, please don't hesitate to let me know :-)
  9. Stratospheric Cooling and Tropospheric Warming - Revised
    KR #75 "Please stop with the inappropriate analogies" I will grant it is possible to draw poor analogies, yet all cognition ultimately depends on simple mental models. If what I posted is oversimplified or can be shown to be inappropriate, feel free to explain why. Alec Cowan #74... instead of clarifying your position, you attempt here to place the burden of explaining what you think on me. As above, why not simply say it as it is? archiesteel #76 You write that I am wasting everyones time, stalling the "debate" on AGW (herein admitting there is something to debate).... The idea being that you can debate it as long as you agree with it!
  10. Conspiracy theories
    A couple of things, hope they're reasonably on topic. They are written from a mildly sceptic viewpoint so my tin hat is firmly strapped on - if we take a Kuhnian approach to the history of science then consensuses are temporary alignments and arguably the least productive periods of scientific activity. Nancy Orestes paper looks a bit on the simple side to me, but even if it were possible to line up papers in the way she did, we still need to ask Kuhn's question about scientific practice. - it's just wrong to imagine there is a black and white distinction between the interests of corporations (bad bad bad) and the interests of scientists (good). Science is a complex activity full of interests and rhetoric. The AGW debate is fascinating in this respect. Personally I'd like to see more use of renewable energy sources. But I don't think the world is going to end soon, or that the AGW panic is helpful.
  11. Stratospheric Cooling and Tropospheric Warming - Revised
    #80 Patrick 027 at 16:47 PM on 22 December, 2010 True, where much is absorbed, there is also emitted much - but the importance of adaibatischen moist circulation for the temperature characteristic is forgotten, as well as changing the height of the tropopause.
  12. Lindzen and Choi find low climate sensitivity
    RW1, you're simply not listening, I'm done. Riccardo @141 do you have a reference or link for how the calculation for surface heat flux change and therefore temperature change is done from the TOA 3.7W/m2 ? As I said in the post, conceptually I'd expect the surface change to be larger, but I'm interested if a rough methodology is available to work through.
  13. Harald Korneliussen at 18:30 PM on 22 December 2010
    Conspiracy theories
    Conspiracy theorists sometimes argue that climate scientists and their co-conspirators have something to gain by convincing us that humans are causing global warming. But that's a gross distortion of the truth. If we reasoned that way consistently, then whenever medical researchers discovered a new health hazard we shouldn’t heed their warning, we should accuse them of conspiring against us. Not only that. You should not brush your teeth with fluoride toothpaste, floss, avoid eating between meals, and drink water when thirsty (instead of juice or soft drinks). See, all these things are recommended by dentists to avoid cavities, but dentists are economically dependent on filling your cavities! They have a strong economic incentive to lie, or at the very least downplay the risks. The perverse incentives of a scientist seeking funding pales in comparison. Yet we believe our dentists, and distrust our climate scientists.
  14. Lindzen and Choi find low climate sensitivity
    I'm pretty sure discussing perihelion insolation and albedo is quite off-topic. Please stop bloating the thread with such confused, irrelevant and repetitive arguments. Thanks.
  15. Lindzen and Choi find low climate sensitivity
    muoncounter (RE: Post 160), "The bulk of this change (as labeled) is due to 'ice amount'. This is used as some form of input to a 'power' equation. Do you include the fact that NH solar insolation above 60N lat is sharply reduced during winter months? So while there is higher albedo due to the greater ice extent, there is very little sunlight falling on that reflective surface. How can there be any material alteration to what you call your 'power' calculation due to these purely seasonal changes? What, then, does this 'gain' actually mean?" I don't get the question. The numbers used and inputed for each variable are global averages, so all of what you mention is automatically accounted for.
  16. Stratospheric Cooling and Tropospheric Warming - Revised
    re the main post - I think it's more straightforward to note that the CO2 molecules tend towards the same temperature as the rest of the air in a given volume, because of the frequent molecular collisions (reality diverges from this above some level where the air is too rarefied, but this is above the stratosphere), which means some fraction of them will be in various states. At a given wavelength, they can emit as well as they can absorb, in that a given path will absorb the same fraction of incident radiation as the fraction of blackbody radiation it emits, the later being a function of temperature; this fraction approaches 100 % with increasing path length and increasing CO2 concentration for a given path length (specifically it 'decays' from 0 to 100 % exponentially) - except that if the temperature varies, the emission from a path is a weighted averaged of the blackbody value over the path; greater opacity concentrates that weighting closer to the near end of a path, so the emitted radiation would become more similar to the blackbody radiation for the temperature near the end of that path. This weighting is the same distribution of absorption for radiation coming from the opposite direction; it corresponds to what you can see coming from that direction. When more CO2 is added to the atmosphere the outgoing radiant flux is reduced because the weighting is concentrated into the higher, generally colder levels of the atmosphere, and less is at the generally warmer surface, etc. Water vapor feedback does the same thing, at different wavelengths. Warming must occur in order to bring the flux back into equilibrium with solar heating - because the CO2 (and positive greenhouse feedback) reduce the net upward flux at the tropopause level, some warming must occur beneath, and given the convective coupling of the surface and troposphere, the surface and levels of the troposphere tend to warm together. Because the atmosphere is more transparent at some wavelenghs, and at least for the effect of CO2, it's transparency has not been decreased at all wavelengths, the warming that is necessary to bring the outgoing flux back to what it was before will increase the outgoing flux beyond what it was before at some wavelengths, which means it will still be less than what it was before at other wavelengths, which means that the highest portion of the atmosphere, from which the strongest parts of the CO2 band emit to space, will be colder than what it was before. (The H2O feedback could be more complicated). (PS I learned this from a discussion at RealClimate). There is some additional stratospheric cooling that is transient - the stratosphere is initially cooled by the addition of CO2 by a larger amount than the final equilibrium, because some (small) fraction of the increase in radiation from the troposphere+surface upon warming will be absorbed in the stratosphere and cause warming there - this is after the decrease in radiation from below (from increased CO2) that, along with increased downward radiation from the stratopshere (from increased CO2), minus the reduction in downward radiation from the stratosphere (from stratospheric cooling), forces the warming. Also, the solar heating of the ozone layer, making the upper stratosphere warmer than otherwise, increases the stratospheric cooling caused by addition of CO2 (in the highest part of the atmosphere that can emit signficantly, as the concentration of a greenhouse gas is increased relative to the concentration of a gas that absorbs solar radiation, the temperature will generally tend to fall).
  17. Lindzen and Choi find low climate sensitivity
    muoncounter (RE: Post 160), I wasn't getting my albedo numbers from that sight, but I don't think you are interpreting the graph there correctly. The referenced limit is the amount from the dashed line to dotted line, and the peak albedo is actually above the dotted line - making it greater than 0.304. So what numbers do you want to use for average yearly albedo vs. average albedo in January? I've been using a round 0.3 yearly average. How about we use 0.34 then for January? That yields a gain of 1.63.
  18. Lindzen and Choi find low climate sensitivity
    Eric, I'm sorry again. The increase in average solar power at perihelion is actually 350 W/m^2 - not 347 W/m^2. When this is corrected for, the gain calculation for a 0.4 albedo is about 1.78 and for a 0.37 albedo is 1.7 - pretty close to 1.6. Also, the original gain calculated from 288K is actually 1.64 (390/238 = 1.64). So again, it's very close and certainly same ball park. Most importantly, it's no where near 8 or significantly less than 1.6.
  19. Lindzen and Choi find low climate sensitivity
    #159: "At perihelion in January, the albedo is closer to 0.4" Your website's graph 'global monthly albedo' shows the average at 0.27 and appears to put the NH winter seasonal difference 'limit' at 0.032. Thus, in January, according to your figures, the albedo is closer to 0.3. The bulk of this change (as labeled) is due to 'ice amount'. This is used as some form of input to a 'power' equation. Do you include the fact that NH solar insolation above 60N lat is sharply reduced during winter months? So while there is higher albedo due to the greater ice extent, there is very little sunlight falling on that reflective surface. How can there be any material alteration to what you call your 'power' calculation due to these purely seasonal changes? What, then, does this 'gain' actually mean? Please note these questions are not an invitation to merely restate what you've already said here numerous times.
  20. Lindzen and Choi find low climate sensitivity
    Eric, To show you that the global temperatures being 3 C colder at perihelion still coincides with the average gain factor of about 1.6 for net incident solar power, here are some calculations: At perihelion in January, the albedo is closer to 0.4 or nearly 0.1 higher than it is on average. So if we take the increased solar power at perihelion of 347 W/m^2 and subtract out an albedo of 0.4, we get net incident solar power of about 209 W/m^2 (347 x 0.4 = 138; 347 - 138 = 209 W/m^2). At 3 C colder, the earth's average temperature is about 285K. 285K = 374 W/m^2 from S-B. 374 W/m^2 divided by 208 W/m^2 equals a gain of about 1.8, which is not far off from 1.6. The albedo is actually not quite 0.4 in January on average, so if we used .37 instead, it comes to a gain of about 1.7, which is pretty close to 1.6.
  21. Renewable Baseload Energy
    Interesting article here from Scientific American on wind farms and fish schools. Gist of the article (at least the part interesting to me) is that by studying fish schooling (optimized for minimum energy in moving from place to place) and taking that analysis to wind farms (vertical turbines, closer spacing, aiming to provide maximum energy extraction) can result in a 10x higher energy density for wind farms. That's 1/10 the land use for the same energy provided.
  22. Lindzen and Choi find low climate sensitivity
    "that site will provide some good practice in spotting incorrect assumptions, logic or math" Indeed. Starting with this one: According to HITRAN based simulations, the atmosphere captures 3.6 W/m² of additional power when the CO2 is increased from 280ppm to 560ppm. Of this, the atmosphere radiates half of this up and half down. One of us doesnt understand what HITRAN outputs mean. It seems the site author is also eccentric in usage of word "power". I had no luck finding publications by George White in physics and climate. Anyone else done better?
  23. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 148), Eric: "RW1, the sun, measured by TSI changes in the historical measurements and proxies, increased by about 0.5 W/m^2 from the depths of the Little Ice Age to about 1900, see fig. 1 in A-detailed-look-at-the-Little-Ice-Age.html The temperature increase, which also involved other factors, was at least 0.5C, maybe more like 1C. With no other factors considered the "gain" is something like 2.5 to 5W/m^2 divided by 0.5 which is 5 to 10, rather than 1.6 The problem, I believe, is you are calculating gain with full solar input (zero to current day) which will yield a much smaller result than a delta of solar input as I demonstrated, albeit crudely, using the LIA." You're assuming the temperature increase was caused entirely by the 0.5 W/m^2 increase in solar power. The overwhelming majority of it could have been caused by a countless number of other things or combination of things - most of which we still don't know. It's well known that the very small increases in total average solar radiance are not enough to cause the warming we've seen since the LIA.
  24. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 154), "RW1, the (lack of) perihelion increase is just another example of nonlinearity in the effects of forcing." How do you figure?
  25. Lindzen and Choi find low climate sensitivity
    RW1, it looks like the consensus is that site will provide some good practice in spotting incorrect assumptions, logic or math. I can't guarantee anything, but I'll give it a try tomorrow.
  26. Lindzen and Choi find low climate sensitivity
    RW1, the (lack of) perihelion increase is just another example of nonlinearity in the effects of forcing. The increased solar power hitting the SH is absorbed in the oceans which smooths the extra forcing much more evenly than the NH can. One bit of interesting evidence is that part of the Milankovitch theory is that seasonal extremes melt the ice and release us from an ice age. This occurred 11k years ago when the perihelion was in July and the summer extremes melted the NH ice.
  27. Lindzen and Choi find low climate sensitivity
    @muoncounter: hey, maybe RW1 *is* George White. That would explain a lot, actually... :-)
  28. Lindzen and Choi find low climate sensitivity
    @RW1: "I've never seen the information and analysis he presents here refuted anywhere" Has he every published in a peer-reviewed journal? The fact that you hold him in high esteem is quite meaningless; in fact, if he gets the same results as Lindzen and Choi are getting, he's likely just as mistaken as they are. Too bad your skepticism is only directed towards those you disagree with, and not those who reinforce your initial position. Meanwhile, many people here have successfully rebutted your assertions, and you have yet to offer a counter-argument. I guess we'll just have to take that silence as an admission of defeat on your part.
  29. Lindzen and Choi find low climate sensitivity
    #150: "Check out this ... " Why am I not surprised? I asked you if that website was your source 130 comments or so ago. Where is the published science from this 'originator'? Who are the other authors who've gone on to cite the 'originator'? That site (which begins with nonsensically throwing out 'anomaly analysis') seems to be the basic source for everything you've presented here. To the extent that Lindzen and Choi are debunked here and the extent that you've been shown to be incorrect, that site goes down the debunking trail too.
  30. Lindzen and Choi find low climate sensitivity
    Eric, Check out this more detailed explanation and satellite analysis of these things by physicist/climatologist and originator George White: http://www.palisad.com/co2/eb/eb.html I've never seen the information and analysis he presents here refuted anywhere, and I've seen many try and fail totally. It's the single most damning piece of evidence against AGW that I've ever seen. I also don't think it's a coincidence that G. White's sensitivity estimate is about the same as what Lindzen and Choi are getting - albeit via somewhat different methodology.
  31. Lindzen and Choi find low climate sensitivity
    Eric, Getting back to the perihelion point, here it is from a different angle: Let's say the total average incident solar power increases from 340 W/m^2 to 343 W/m^2 as a result of the earth's orbit moving closer to perihelion. This results in a new, higher net incident solar energy of 240 W/m^2 (343 x 0.3 albedo = 103, 343 -103 = 240), which is an increase in radiative forcing of 2 W/m^2 (240 W/m^2 - 238 W/m^2 = 2 W/m^2) - the same as from a doubling of CO2. If according to the AGW theory, the system's response will be to greatly amplify the additional 2 W/m^2 from CO2 to about 16 W/m^2 via large positive feedbacks, why doesn't the system do it with the same 2 W/m^2 increase in radiative forcing from from the Sun? The observed temperature changes are nothing anywhere near 3 degrees C for this additional 2 W/m^2 of solar power. Even better, let's take the last 3 W/m^2 increase that occurs at peak perihelion (347 W/m^2 to 350 W/m^2 for a net of 2 W/m^2 albedo adjusted). The system doesn't respond by amplifying that last 2 W/m^2 8 fold, but somehow it's all of the sudden going amplify the next 2 W/m^2 from C02 8 fold? Again, does it make physical and/or logical sense that the system is somehow all the sudden going to treat such a small increase radically differently than it does both the last 0.5 percent and the original 99+ percent?
  32. A detailed look at climate sensitivity
    #62: "So if the ocean has quickly absorbed the heat, it will also quickly absorb the CO2 as soon as we stop producing it." The oceans do nothing quickly; see the graphs here. Oceans are absorbing CO2 now, as they are acidifying. You can't just declare oceans 'quickly absorb the CO2 as soon as we stop', as the oceans might might just give it right back to us (if we stop; that's a good one). See the ocean acidification page; you will find some parts of the ocean are sourcing CO2, while others are sinking it. "the paleo record shows a distinct nonlinearity in the region we are in that indicates the opposite of "tipping points" but rather a stabilization in temperature." In this and in #60, you've made a lot of grand generalizations. In order for general statements like as oceans warm over hundreds or thousands of years, CO2 is released in a more or less linear fashion and longer term sensitivity only applies to glacial to interglacial transitions to be accepted into the debate, you must provide some evidence.
  33. Lindzen and Choi find low climate sensitivity
    RW1, the sun, measured by TSI changes in the historical measurements and proxies, increased by about 0.5 W/m^2 from the depths of the Little Ice Age to about 1900, see fig. 1 in A-detailed-look-at-the-Little-Ice-Age.html The temperature increase, which also involved other factors, was at least 0.5C, maybe more like 1C. With no other factors considered the "gain" is something like 2.5 to 5W/m^2 divided by 0.5 which is 5 to 10, rather than 1.6 The problem, I believe, is you are calculating gain with full solar input (zero to current day) which will yield a much smaller result than a delta of solar input as I demonstrated, albeit crudely, using the LIA.
  34. A detailed look at climate sensitivity
    e, thanks for responding. I will obviously have to look at each study. The biggest difference is that short term amplification from water vapor feedback cannot be compared with long term amplification from a CO2-temperature feedback cycle. Even if we argue that the paleo studies were correct (no other unmeasured factor caused the majority of the temperature increase which then caused the CO2 increase by many centuries of ocean warming), that CO2 to T to CO2 amplification factor does not apply to water vapor for many reasons (e.g. it is not seasonal or geographic unlike water vapor which is). Another key factor is that the ice age to interglacial transition used to estimate sensitivity encompassed a nonlinear change in the warming effect of water vapor (in the present climate there is a much larger ratio of cooling effects from water vapor to warming effects than in the ice age climate). The only valid use of paleo sensitivity is the argument that CO2 increases have short-circuited the long slow feedback process and will emerge in 3C warming after ocean inertia. My very simple answer to that dilemma is that CO2 is sequestered with ocean turnover just the way heat is sequestered. So if the ocean has quickly absorbed the heat, it will also quickly absorb the CO2 as soon as we stop producing it. You may see that as a good argument for the many ideas on the solutions threads here and I agree and I agree with those threads. But I also realize that the paleo record shows a distinct nonlinearity in the region we are in that indicates the opposite of "tipping points" but rather a stabilization in temperature.
  35. Lindzen and Choi find low climate sensitivity
    Eric, @Eric 144: "You then stated 1) that an increased radiative forcing in the system (atmosphere plus surface) would produce the same ratio of surface radiative increase (i.e. the gain again). And 2) the 3C rise in temperature postulated for the doubling of CO2 would produce a 12 W/m^2 increase in surface radiation by applying S-B to the delta T. And 3) 12 divided by 1.6 is too large for CO2 to produce." No, not quite. I'm saying the 3 C rise requires an increase in surface power of 16 W/m^2 for a gain of 8 (8 x 2 W/m^2 = 16 W/m^2), which is 5 times the 3.2 W/m^2 increase in the surface power from each 2 W/m^2 coming in from the Sun. The AGW theory of a 3 C rise in temperature requires the system to respond to each 1 W/m^2 of power from increased CO2 5 times more powerfully than each 1 W/m^2 of power coming in from the Sun.
  36. Lindzen and Choi find low climate sensitivity
    "3.7 W/m^2 is the total absorbed or captured power for a doubling of CO2, correct?" NO! It is not. 3.7W/m2 is the equivalent radiative forcing you would get from double CO2. eg. Doubling CO2 would give you the same impact say a solar forcing of 3.7W/m2. This confusion and insistence on halving it is getting in the way. All of the absorption, re-emission in all directions, re-absorption etc etc has to be done in the complex RTE codes. (eg you can find a MODTRAN calculator here). Net result is an intensity out which is used to calculate the radiative forcing. "power" is also a slightly confusing term to use - usually used in context of energy conversion. Here we are talking about an energy flux.
  37. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 144), The amount of power from the Sun that hits the surface and is re-radiated as LW infrared is about 238 W/m^2. However, the total power at the surface is 390 W/m^2 - not 238 W/m^2, because GHGs and/or clouds are absorbing and re-radiating some of that 238 W/m^2 back toward the surface, which in effect, is delaying or slowing down the release of the 238 W/m^2, causing the surface to be warmer than it would be; or causing the surface power flux to be 390 W/m^2 instead of 238 W/m^2. The gain represents the increase in surface power or increase in surface temperature as a result of there being GHGs and clouds in the atmosphere. In effect, the gain factor of 1.6 means that due to the greenhouse effect, it takes about 1.6 W/m^2 of power at the surface for each 1 W/m^2 of power to leave the system, offsetting each 1 W/m^2 entering the system from the Sun.
  38. A detailed look at climate sensitivity
    Eric, Paleo studies were not the only source for calculating climate sensitivity discussed in this post. Also discussed were measurements based on recent volcanic eruptions and on the modern warming trend itself. Both of these reflect short term sensitivity (and are obviously applicable to the current climate regime). The results from these studies agree with those from the long term paleo studies. Furthermore, the bottom-up physical simulations agree with the top-down statistical studies. Thus, the evidence does not support the suggestion that modern short term climate sensitivities vary substantially from those derived from paleo studies.
  39. Lindzen and Choi find low climate sensitivity
    RW1, thanks for the reply. Ignoring evaporational cooling for now, I think what you were trying to say in #61 is that a particular amount of solar energy absorbed in the atmosphere and on the surface (238 W/m^2) turns into 390 W/m^2 of surface radiation or a "gain" of 1.6 You then stated 1) that an increased radiative forcing in the system (atmosphere plus surface) would produce the same ratio of surface radiative increase (i.e. the gain again). And 2) the 3C rise in temperature postulated for the doubling of CO2 would produce a 12 W/m^2 increase in surface radiation by applying S-B to the delta T. And 3) 12 divided by 1.6 is too large for CO2 to produce. Statement (2) seems correct. But (1) means that the gain is always the same whether dealing with the full amount of solar forcing or a delta in solar forcing or a delta in CO2 forcing. I definitely agree that the "gain" should be the same whether for a delta in solar or a comparable delta in CO2. But gain is probably not a constant over the range of solar forcing. The "3C" proponents would have to show that gain is larger at the pre-industrial equilibrium than over the entirety of solar forcing, and I don't think it's hard to argue that gain is nonlinear with warming since water vapor is highly nonlinear. With a larger gain, they can argue that the relationship in (3) holds. In fact your analysis brings to mind a similar problem I have with the paleo sensitivity analysis. There is an assumption that the temperature to CO2 relationship in going from a frozen planet to unfrozen is the same as from unfrozen to slightly warmer unfrozen. Both your analysis and paleo one here detailed-look-at-climate-sensitivity.html seem to use the same basic but faulty assumption that forcing-to-temperature elationships over colder ranges of climate are applicable to warmer ones.
  40. We're heading into an ice age
    @kdfv: November 2010 is the hottest on record. Which is more significant? Summer snow in a La Niña year, or the hottest November in one of the hottest (if not *the* hottest) year?
  41. Lindzen and Choi find low climate sensitivity
    VeryTallGuy (RE: Post 137), Let's take this step by step: 3.7 W/m^2 is the total absorbed or captured power for a doubling of CO2, correct? If not correct, then your saying the total absorbed power is 7.4 W/m^2? Some other amount? I've read much of the IPCC reports and I've been studying this issue for quite a while now - nowhere have I seen that the total captured power from a doubling of CO2 is 7.4 W/m^2 for a net 3.7 W/m^2 because only half of the absorbed power goes down. Where and in what way specifically does the IPCC, or any other climate research paper or document, say this? Also, what you are describing above regarding the 4 W/m^2 increase at the TOA is the total amount of increased radiation to space that will occur to achieve equilibrium, assuming there is 4 W/m^2 increase in power at the surface. However, that is only possible if all the absorbed 4 W/m^2 of power is directed toward the surface instead of only half. If it's only half, the "net change in power emitted at the top of the atmosphere" would only be 2 W/m^2. What I'm getting at is the question boils down to what the total absorbed power is. Again, you're saying the total absorbed is about 8 W/m^2 for net of 4 W/m^2 because only half can affect the surface, correct? My orbital forcing reference is from Wikipedia, which I checked against a few other sources. According to them the range is 1,413 – 1,321 W/m^2 perihelion-aphelion. Divide by 4 to get the average, which is a little over 20 W/m^2 (actually 23). Subtract the Earth's albedo of about 0.3 and it's a net increase of 14 W/m^2 at perihelion. Also, I didn't say or imply there was an average increase in radiative forcing from orbital eccentricity. As stated before, I'm well aware that the increase from CO2 is on top of the current average total.
  42. It's freaking cold!
    #60: "attributing global warming solely to CO2" Guess you missed this page. Be sure to look for the key distinction between 'forcing' and 'feedback'. For example, many people seem to think its warming because of water vapor; something has to start the warming before an excess of water can evaporate. So water vapor is a feedback, where CO2 is a forcing. Your second point about temperature measurement uncertainty is also moot; satellite temps and ground temp records are resolved in a number of SkS articles (some by Ned). Keep digging, you'll find nuggets of gold buried around here.
  43. It's freaking cold!
    Ned, I agree that I was referring to our local (UK)situation, and I also concede that the shift in the jet stream that has led to these conditions has probably also caused higher than normal temperatures in Iceland. The difficulty I have is in attributing global warming solely to CO2 emissions, and I have now read the posts referred in the response to my original post, which seem to support the view that other factors have a much stronger influence - but governments (apparently guided by climate scientists)seem to focus only on rising CO2 levels. The other area of difficulty lies in the reliance upon satellite data where the measurement uncertainties are of a similar magnitude to the reported temperature rise / decade, and all this in an extremely complex environment with multiple independent variables.
    Moderator Response: The role of CO2 relative to other factors is discussed here.
    The reliability of temperature records is discussed here.
    Finally, the ability to make predictions given the complexity of climate is discussed here.

    Per this site's comment policy, please post your specific questions or comments in the appropriate thread. This ensures that your posts are viewable by anyone researching a particular question, rather than being randomly strewn about the site. In the future, please consult the List of Skeptic Arguments prior to posting and ensure your comments are made in the appropriate thread.
  44. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 139), Trenberth is just listing evaporation and thermals for reference purposes - neither actually contributes to the radiative budget and/or balance. It's just one more confusing and ambiguous component of that diagram. BTW, if you don't believe me or want to check yourself, run all the numbers he lists - the 80 W/m^2 for evaporation and 17 W/m^2 aren't included in the total radiative flows to achieve power in = power out.
  45. We're heading into an ice age
    @kdfv #186 Yes. Summer snow in Australia first ever recorded in: a) 2012 b) 1921 c) 1856 d) 1884 Guess!! (A hint: think about what you need to record summer snow) The Bureau of Meteorology of Australia has information about. For example, a page with recommendation for buildings in the cool temperate region states: "The cool temperate climate has mild to warm summers and cold winters. In the higher parts of the Snowy Mountains, snow can fall at any time of the year. In Tasmania, summer snow has been reported at elevations as low as 300 m." @archiesteel #185 The blunder in Tom Löber's link is announcing that in the middle of December. The same way I'll soon be able to report that last two weeks of December were hot record here in Buenos Aires, possibly some 3 or 4°C above the previous hot record for December. The link in 184 only claimed a similar period to be some tenths of degree below the "previous" record.
  46. Lindzen and Choi find low climate sensitivity
    VeryTallGuy when you increase emission at the surface by increasing surface temperature you won't get the same excess energy leaving the planet at TOA, part of it will be absorbed by the atmosphere. To balance a forcing at TOA you need a larger temperature increase then predicted by this simple calculations. Basically, this is the same mistake made by RW1 before.
  47. We're heading into an ice age
    @186 I think you'll find that snow on Mt Wellington is hardly a Christmas novelty.
  48. We're heading into an ice age
    #185 First ever recorded summer snow in Australia. Things are starting to get interesting now!
  49. Stratospheric Cooling and Tropospheric Warming - Revised
    @HR: "I'm really interested why molecules are more likely to collide while IR and molecules aren't more likely to collide when CO2 is increased in the stratosphere?" They will collide whatever their state... but if they have less energy than what they collide with, they will absorb energy from the more excited molecule(excitation is normally referring to increased T/energetic excitation, kinetic motion of a molecule) And if they have more, the exchange is reversed. So if CO2 is radiating away more energy than its receiving via absorption, it will remove energy from the surrounding molecules... simple, the net flow of heat is from hotter to colder.
  50. Lindzen and Choi find low climate sensitivity
    From the invariably excellent Science of Doom the 3.7 W/m2 is defined:
    "The change in net (down minus up) irradiance (solar plus longwave; in W/m2) at the tropopause after allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values."
    Note
    "the stratospheric adjustment is minor"
    so it's essentially the same as a top of atmosphere calc. Interestingly as noted in their post, applying this to the surface temperature does NOT seem to result in the 1.2 degrees warming: From the Trenberth link above: 1) radiative flux at the surface = 396W/m2 - equates to 289.09K blackbody temperature 2) Add 3.7 to that raises temperature to 289.76, so 0.65 degC temperature rise. 3) In order to get a 1.2 degC rise at the surface you need a heat flux increase to 402.6W/m2, so 6.6W/m2 at the surface. I'm not exactly sure how that calc is done to translate 3.7W/m2 TOA to 6.6 at surface, although you'd expect it to be larger so it seems about right. I can't find a reference for this calc - can anyone help? Are my sums right?

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