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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 100751 to 100800:

  1. Stratospheric Cooling and Tropospheric Warming - Revised
    His words:
    "Since 1996, lunar eclipses have been bright, which means the stratosphere is relatively clear of volcanic aerosols. This is the longest period with a clear stratosphere since before 1960."
    So what, exactly, is the point of your comment, Camburn? Because it seems to be along the lines of:
    "I drink coffee and marsupials have legs"
    To put confidence into a presentation at a conference funded by a petroleum-shill instead of work vetted in peer-reviewed publications by actual working climate scientists speaks volumes... An analysis of Keen's other body of work can be found here. The Yooper
  2. Lindzen and Choi find low climate sensitivity
    #107: "it doesn't take much time at all to change ocean heat content" Do you have any documentation for that? Again, credibility comes from being able to substantiate of your claims - preferably with reference to actual scientific literature. We're not talking about the surface temperature, despite your (similarly unsupported) claims to the contrary. Looks like a long, slow, but steady climb to me. No hint of seasonal variability.
  3. Lindzen and Choi find low climate sensitivity
    KR (RE: Post 106), Apparently, it doesn't take much time at all to change ocean heat content. If it did, we wouldn't see anywhere near the seasonal variability each year, nor especially would we see anywhere near the change in ocean temperatures the occur each year. I'm not saying the seasons make any long term changes, as they do average out globally. I'm saying there is no physical reason why the globe as a whole would respond any slower than the individual hemispheres do to increases in radiative forcing. Ocean water is ocean water - whether it's in one specific hemisphere or the whole globe. Or are you saying the fundamental physics of ocean water is different hemispherically than it is globally?
  4. Stratospheric Cooling and Tropospheric Warming - Revised
    This is an interesting observation by Dr. Keen: http://spaceweather.com/ all clear in the stratosphere.
  5. Lindzen and Choi find low climate sensitivity
    RW1 - In detail? Nothing much to say other than 'time constants'. It takes time to change ocean heat content, which drives much of global weather. It takes time to melt or freeze the Arctic and Antarctic, to change the state of glaciers and Greenland, to change the distribution of plant zones. And seasonal changes, unlike CO2 forcings, happen too fast to make those long term changes. They cycle up and down (like weather) too fast to affect long term issues like those. There's nothing mysterious about that. It's all a matter of thermal inertia.
  6. Arctic sea ice has recovered
    Heh! I'll put my surfboard on my little deuce coupe as I head North To Alaska, where the curl of the Arctic swells generated by the 6-month long summer Arctic Dipole warms the toes of the windsurfers cruisin' the Northwest Passage to Baffin Bay, where the scenery is beautiful and the women...did I mention the scenery? BTW, the longer you stare at the chart, the more it resembles someone diving in the water... The Yooper
  7. Lindzen and Choi find low climate sensitivity
    KR (RE: Post 103), That's my point, why are they separate? Why are they different. What specifically is physically different about increased radiative forcing on a seasonal/hemispheric basis and increased radiative forcing globally? And don't point me to some graph. Even if I assume the information in that graph is correct, it doesn't mean the rise is from increased CO2 radiative forcing. What I mean is explain the physics in detail.
  8. Lindzen and Choi find low climate sensitivity
    RW1 - also Figure 5 from that last posting.
  9. Lindzen and Choi find low climate sensitivity
    RW1 - "How can the response time be 40+ years globally but only be about one month seasonally and/or hemispherically?" By actually considering the separation between short term seasonal feedbacks and long term heat content (Figure 4).
  10. Lindzen and Choi find low climate sensitivity
    KR (RE: Post 100), @KR: "Please keep in mind that the perihelion/aphelion cycle is just that - a cycle. Which means it goes down as well as up." I know. @KR: "The added greenhouse effect, on the other hand, is a long term increase in both perihelion and aphelion irradiance, a long term uncompensated change in total irradiance. And hence an energy imbalance." I also know. @KR: "The climate response to shifts in overall irradiance appears to be (including ocean responses) at least 40 years for mid-length feedbacks, centuries for long-term (weathering) feedbacks." How can the response time be 40+ years globally but only be about one month seasonally and/or hemispherically?
  11. Arctic sea ice has recovered
    Yooper, We count on you to be first with the good news. Those bottom curves (August-September) dropped 50% (from 10000 to 5000) in just 3+ years! Never mind Lake Superior, you'll be body surfing Baffin Bay in no time.
  12. Lindzen and Choi find low climate sensitivity
    #96: "I mean only the intrinsic radiative forcing response - not any theoretical increase in temperature" In reality, isn't it the temperature increase that matters? The fact is that we have already observed more warming than your albedo-adjusted model predicts. In essence, you call for 0.3deg warming due to CO2 radiative forcing. To account for the observed 0.8deg global (1.0deg in the northern hemisphere), you must therefore invoke 'unknown forces' or 'natural causes' for more of an effect (0.8 observed - 0.3 CO2 = 0.5 unknown) than you calculate. I would be deeply troubled if that is where my calculations left me.
  13. Lindzen and Choi find low climate sensitivity
    RW1 - Please keep in mind that the perihelion/aphelion cycle is just that - a cycle. Which means it goes down as well as up. The added greenhouse effect, on the other hand, is a long term increase in both perihelion and aphelion irradiance, a long term uncompensated change in total irradiance. And hence an energy imbalance. The climate response to shifts in overall irradiance appears to be (including ocean responses) at least 40 years for mid-length feedbacks, centuries for long-term (weathering) feedbacks. The perihelion and aphelion cycles average out over those time scales. CO2 does not.
  14. Lindzen and Choi find low climate sensitivity
    archiesteel (RE: Post 95), I'm well aware that any CO2 warming will be in addition to, or on top of, the normal variations. I don't dispute this, and nothing I've written disputes it. Also, I know temperatures are affected by the seasons - I've written so multiple times in this thread. The +14 W/m^2 at perihelion is a global average addition - not isolated to just one hemisphere or the other.
  15. Lindzen and Choi find low climate sensitivity
    RW1 - No, CO2 at the poles will act like CO2 at the tropics - retaining a percentage of the thermal radiation at those locations. That's a bogus argument. As to water vapor - that's a feedback to any forcing, whether it's CO2 or solar or aerosol. It doesn't counteract CO2 forcing in itself. If you wish to argue for a cloud feedback, take it to the cloud sensitivity thread.
  16. Lindzen and Choi find low climate sensitivity
    muoncounter (RE: Post 85), I meant post 96 above to be in response to your post 85 (not 86).
  17. Lindzen and Choi find low climate sensitivity
    muoncounter (RE: Post 86), I now see the problem. When referring to the logarithmic response of CO2, I mean only the intrinsic radiative forcing response - not any theoretical increase in temperature in addition to the intrinsic response via potential feedbacks and so forth (i.e. a 3 C rise). The intrinsic increase in radiative forcing from a doubling of CO2 is 3.7 W/m^2. When I say we've already reached 70-80% of a doubling going from 300 to 380 ppm (or 280 to 380ppm), I mean 70-80% of 3.7 W/m^2 or about 2.6 to 2.9 W/m^2 of intrinsic forcing.
  18. A Merchant of Doubt attacks Merchants of Doubt
    Stephen and John at #6 Oreskes was definitely a working scientist. I remember a particularly interesting review of numerical models in geology that was published in Science in the 90's. I was surprised when I saw her being referred to as a historian a decade later. I think Kooti is probably right about Seitz's original intentions and O&Cs mistaken take on it - though we don't really have context so it's really hard to tell. But Bern is also right that Singer is dead wrong and likely insincere in his interpretation.
  19. Arctic sea ice has recovered
    Despite the offseason, Neven's blog (Arctic Sea Ice) continues to produce tasty morsels, like this comment by FrankD:
    "What comes out? A better than 50% probability of an ice free September by 2016, with the ice free period increasing by almost a month each year. By 2023, there is a good likelihood of five months ice free, from mid-July to mid December. After that it slows down somewhat, but March and April, the last months remaining, reach zero around 2032-33.
     Which he then links to the chart he created here: Melt season 2011 will be something to behold, now that Cryosat-2 is pumping out data... The Yooper
  20. Lindzen and Choi find low climate sensitivity
    @RW1: "My main point is the aggregate confluence of factors that actually determine global average temperatures don't appear to be even phased much by 14 W/m^2 increase in radiative forcing - an amount much larger than what would come from a doubling of CO2." Temperatures are very much affected by the seasonal effect - that's why we have seasons! The warming due to CO2 is in addition to the normal variations. That's why it matters. Also, RW1, by not responding to muoncounter at #85 you are ignoring a strong rebuttal to your argument. Are you conceding defeat?
  21. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 93), Well yes, but the polar regions are also largely snow and ice covered, which means a lot of the incoming power is getting reflected back out (back through the CO2), so incrementally more CO2 in those areas won't do much at all. Also, if there is a global increase in temperature from CO2, there will likely be a global increase in water vapor. That should offset any increase in CO2 for areas in the polar regions not snow and ice covered - as far as water vapor/CO2 absorption overlap is concerned.
  22. Lindzen and Choi find low climate sensitivity
    Because there is less water vapor in the polar regions so CO2 has a proportionally greater effect and so a change is CO2 would also have a greater effect than outside of polar regions. As for using average numbers, I'm not a big fan of those for many reasons, one of which is demonstrated in your #14 which didn't mention the large differences in seasonal responses between the hemispheres.
  23. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 91), Why would CO2 have more effect in the polar regions? The numbers I've used throughout are global average numbers.
  24. Lindzen and Choi find low climate sensitivity
    The "radical" difference comes from the difference in the way the two hemispheres respond to the seasonal solar changes. There's no way to get away from that fact and it means that the global average temperature response to CO2 which is evenly distributed worldwide, has more effects in polar regions, etc, is going to be radically different. It's sort of like saying that a giant fire in one hemisphere is going to have the same effect as a lot of smaller fires adding up to the same amount of heat and smoke, but distributed worldwide. Clearly the effects on weather and thus temperature will be quite different in those two cases.
  25. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 88), That last paragraph in my post 89 should have read: The perihelion point aside, what is so special about each 1 W/m^2 of increased power from CO2, that the system is all the sudden going to respond to it radically differently than it does each 1 W/m^2 of power from the original 238 W/m^2 sourced from the Sun?
  26. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 88), I agree that the difference between the hemispheres is one of the main reasons, but the whole climate is affected (i.e. about 3 C colder globally at perihelion - not just in the NH). Without the +14 W/m^2 at perihelion, the global average temperatures would probably be even colder in January than they are now. It should also be pointed out that global temperatures are actually 3 C warmer at aphelion in July when net incident solar power is about 14 W/m^2 less. My main point is the aggregate confluence of factors that actually determine global average temperatures don't appear to be even phased much by 14 W/m^2 increase in radiative forcing - an amount much larger than what would come from a doubling of CO2. The perihelion point aside, what then is so special about each 1 W/m^2 of increased power from CO2, that the system is all the sudden going to respond to it radically differently than it does each 1 W/m^2 of power from the original 238 W/m^2?
  27. A detailed look at climate sensitivity
    Hopefully this will answer chris on the Lindzen thread. Disregarding my critique of paleo studies of sensitivities above, I still do not believe that we can take a sensitivity calculated in paleo records and use it in a linear fashion. For one thing the paleo sensitivities reflect long term correlation which may be somewhat linear. For example as oceans warm over hundreds or thousands of years, CO2 is released in a more or less linear fashion. But the short term is nonlinear. Short term sensitivity is based on water vapor feedback. But water vapor feedback is highly nonlinear as evidenced by daily tropical weather cycles and seasonal changes in weather (larger NAO fluctuations in winter than in summer is just one of many examples). The sensitivity that was based on long term factors shown in the ice cores has nothing to do with a sensitivity based on the short term factors. Furthermore, neither sensitivity is applicable to our current interglacial regime. The longer term sensitivity only applies to glacial to interglacial transitions. So an attempt to use that sensitivity for a current increase (50%, doubling, or other) in CO2 requires waiting for the long term responses (centuries at least) and won't show up in a few decades of data.
  28. Lindzen and Choi find low climate sensitivity
    RW1, the 0.3 value may be an average over all seasons, but the effective albedo must be greater in January since the solar forcing is greater but the global average temperature is lower. My parenthetical statement about the SH oceans in #78 is probably incorrect. But my main point again is that your statement in #14 "That the global climate doesn't even appear to be phased by a 14 W/m^2 increase in radiative forcing, suggests the net feedback operating on the system as a whole is strongly negative - not positive,..." is not a logical conclusion. The reason why the global climate is not affected by the 14 W/m^2 is due to the differences between the hemispheres, not net global feedback.
  29. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 84), Why not? OK, so it's not about 14 W/m^2 net - but something less because the total albedo in January is greater than 0.3 you're saying?
  30. Lindzen and Choi find low climate sensitivity
    Eric (skeptic) at 12:29 PM on 20 December, 2010 I don't think that's right Eric. The climate sensitivity is defined by convention as the amount of warming at equilibrium resulting from a radiative forcing equivalent to a doubling of atmospheric [CO2]. But it can be (and is) used to determine the equilibrium temperature response expected from any change in forcing including that resulting from small increments of [CO2]. Clearly if the wealth of empirical data supports a climate sensitivity near 3 oC (say), then the warming contribution expected from a rise of [CO2] from 280 to 380 ppm (say), should be predictable within that climate sensitivity (according to the ln of the ratio of [CO2]s). It would be perverse to consider otherwise. Of course the climate sensitivity is obviously a shorthand estimate of a response in a complex world! So the climate sensitivity in a world with a certain amount of sea ice (say) will differ from that of a world with no sea ice (say), since the albedo feedbacks will differ. In the real world the "climate sensitivity" will likely "dance around" somewhat temporally and according to precise conditions. ----- O.K. I've just seen your correction so maybe my post doesn't quite address your point. But (re your correction), the climate sensitivity isn't being subdivided. We're considering the Earth's equilibrium temperature response to a forcing as parameterized within a single value of the climate sensitivity. What's being subdivided is the forcing and its response, not the CS! I suspect that we might be talking at cross purposes, btw! If you think I haven't addressed your point properly have another go and I'll try again in the morning.
  31. Lindzen and Choi find low climate sensitivity
    #77: "You cannot start with a conclusion, assume it is correct, and then derive the specific numbers ..." Indeed. We have to test the calculations that derive from a set of assumption to see if they match observation. On that fundamental point, I have no doubt we all agree. No such assumptions went into the preparation of the graphic for #57. The plotted curves are straight from the literature of radiative forcing which is not under discussion here. However, in #63, "incrementally more CO2 is not linear - but logarithmic, which means each additional amount added only has about half of the effect of the previous amount," a major flaw in your thinking is revealed. The function deltaT = 5.35 lambda log (C/C0) flattens as C (ie, CO2) increases; this gives the impression that adding more CO2 will gradually not be as bad. What you've ignored is the fact that C is a function of time that is strongly concave up. As a result, both the first and second time derivatives of the deltaT function are positive: deltaT is an increasing function of C and C is an increasing function of time. So while each additional ppm of CO2 causes a smaller temperature increase, we are adding CO2 at a rate that forces deltaT as function of time to increase at an increasing rate. Referring back to the figure in #57, your 0.6 deg C sensitivity produces neither the correct temperature anomaly nor the correct rate of change. One must therefore conclude that the assumptions made to calculate 0.6C sensitivity are incorrect, taking those calculations with them.
  32. A Merchant of Doubt attacks Merchants of Doubt
    @Kooiti - it may be that Oreskes & Conway misunderstood what Seitz was saying. But Singer has deliberately mischaracterised what O&C were saying, and framed it in such as way as to heap ridicule upon and undermine the message of the O&C book. As John said, it's the same techniques debunked by the book. Classic FUD (Fear, Uncertainty, Doubt) techniques.
  33. Lindzen and Choi find low climate sensitivity
    #83, RW1, I agree, but the bigger point is that the hemispherical asymmetry makes it impossible to use the 14 W/m^2 change and the global average temperature change as a case for much of anything and especially your last two paragraphs in #14.
  34. Lindzen and Choi find low climate sensitivity
    @RW1: "Those numbers are useless because they're all based on the assumption of a 3 C sensitivity to a doubling of CO2. You cannot start with a conclusion, assume it is correct, and then derive the specific numbers in support of it by simply back fitting calculations to your original assumption." That's not what has happened, here. Rather, multiple scenarios were proposed, and the one closest to reality (following observations) is the one that puts it in the 2-4.5C range. It is false to claim people decided that climate sensitivity was 3C, then tried to fiddle their calculations to make it fit. In fact, I'd say you're venturing dangerously close to accusations of conspiracy theories, there... Further reading: James Annan explains why sensitivity is at 3C. "Are you saying the response of CO2 is not logarithmic - but linear?" No, that's not what he's saying. Rather, he's (correctly) noting that your description of the logarithmic curve was too vague to be useful. Or perhaps you think all logarithmic scales are the same?
  35. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 78), Global average temperatures are about 3 C colder at perihelion because - yes, I think a lot of the increased power is reflected from off the ice and snow accumulations that occur in the NH winter in January. But most of the additional 14 W/m^2 at perihelion then still affects SH summer in January because at that time the SH is tilted toward the Sun.
  36. Lindzen and Choi find low climate sensitivity
    In #80, I meant to say CS is a constant that can not be subdivided.
  37. Lindzen and Choi find low climate sensitivity
    #76, chris, I think that assumes that "climate sensitivity" is a constant that can be subdivided like you are doing. My understanding is that sensitivity as it is defined here is the temperature response to a CO2 change of 280 to 560. It cannot be used for any other purpose in a linear fashion.
  38. Lindzen and Choi find low climate sensitivity
    Alec Cowan at 12:04 PM on 20 December, 2010 yes, I see your point Alec!
  39. Lindzen and Choi find low climate sensitivity
    RW1 (#73), yes, thanks, you were not referring to the last century and I thought you were. As for the difference at perihelion, my understanding is that the extra energy (14 W/m^2) falls on land masses in the NH winter which reflects away much of the extra energy (versus SH ocean which is a better absorber of solar energy). Hence the NH winter has a bit colder global average temperature than NH summer even though the energy from the sun is greater. If I am mistaken, someone will correct me.
  40. Lindzen and Choi find low climate sensitivity
    Chris (RE: Posts 60 & 70), Those numbers are useless because they're all based on the assumption of a 3 C sensitivity to a doubling of CO2. You cannot start with a conclusion, assume it is correct, and then derive the specific numbers in support of it by simply back fitting calculations to your original assumption. How about you address the series of individual questions I laid out in post 61?
  41. Lindzen and Choi find low climate sensitivity
    Eric (skeptic) at 11:50 AM on 20 December, 2010 "What is the forcing effect of incrementally more CO2?" Eric, I believe the temperature increment is proportional to the forcing increment i.e. deltaT = sigma.deltaF [where sigma is the climate sensitivity in units of oC/(W.m^2)] so I guess the forcing scales as the ln of the [CO2] increment much the same as the temperature in my post #70 above. Does that seem right?
  42. Lindzen and Choi find low climate sensitivity
    Alec (RE: Post 74), Are you saying the response of CO2 is not logarithmic - but linear?
  43. Lindzen and Choi find low climate sensitivity
    @chris #70 Why you bother? Evidently an assertion that states "logarithmic, which means each additional amount added [undetermined amount] only has about half of the effect [mensurable effect] of the previous amount." makes no sense. Don't offer your figures to people who doesn't offer them. Ask them to provide those figures. If they're commenting in good faith they'll do.
  44. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 68), Either. We know the actual total is about 238 W/m^2, and each 1 W/m^2 of that 238 W/m^2 is amplified to about 1.6 W/m^2 at the surface for a total of about 390 W/m^2. We also know that the net incident solar power is not constant - it varies by about 20 W/m^2 from perihelion to aphelion (a net of about 14 W/m^2 albedo adjusted). What I'm saying is that there is no difference between 1 W/m^2 of power from the Sun, existing or hypothetically added, and 1 W/m^2 of additional power from CO2. The AGW theory is saying that the system is all of the sudden going to respond to an additional 2 W/m^2 of power at the surface from a doubling of CO radically differently than it does the original 238 W/m^2, including the + 14 W/m^2 at perihelion, from the Sun. Understand?
  45. Lindzen and Choi find low climate sensitivity
    #69 RW1, the link in #68 shows it to be 1.5 W/m^2. Also the Lean/Rind paper.
  46. Lindzen and Choi find low climate sensitivity
    chris, when I asked about effect in #63, I should have said "forcing effect" not temperature effect. What is the forcing effect of incrementally more CO2?
  47. Lindzen and Choi find low climate sensitivity
    RW1 at 08:07 AM on 20 December, 2010
    "The response of incrementally more CO2 is not linear - but logarithmic, which means each additional amount added only has about half of the effect of the previous amount."
    That's obviously incorrect too. We can easily calculate the equilibrium temperature response expected from incremental enhancement of atmospheric [CO2]. If we use a climate sensitivity of 3 oC and normalize the Earth's temperature to near 15 oC at a [CO2] = 280 ppm, then the equilibrium temperature rise expected after each 20 ppm increment (all else being equal!) is: 
    [CO2]   equil. temp     increment
280	14.9567
300	15.2554		0.2977
320	15.5347		0.2793
340	15.7971		0.2624
360	16.0445		0.2474
    etc Clearly the assertion that "...each additional amount added only has about half of the effect of the previous amount." is quite wrong. In this case "each additional amount" adds around 94% "of the effect of the previous amount". Obviously the specific amount depends on the particular increment. So for 100 ppm increments: 
    280	14.9567
380	16.2786		1.3219
480	17.2898		1.0112
    etc.
  48. A Merchant of Doubt attacks Merchants of Doubt
    I think it is generally apt to describe Singer as a merchant of doubt. But I think it wise to avoid using this particular issue on oxygen as an example. It seems to me that originally Seitz did not mean that oxygen causes cancer by its own radioactivity, but that oxygen enhances the effects initially caused by radioactivity. If this is true, Oreskes and Conway mistook Seitz's intention, and Singer took it right. We should not blame Oreskes and Conway, however, since the wording of Seitz was obscure. We cannot blame Seitz with this particular fault, however, since his document was an internal one and also oxygen was not its main issue. So, while this may be another instance of failure of scientific communication, it can hardly play a role of a piece of evidence of malpractice of anyone.
  49. Lindzen and Choi find low climate sensitivity
    Eric (RE: Post 63), Something must be wrong with those calculations if the total isn't about 4 W/m^2 for a doubling (3.7 W/m^2 precisely). The initial 1.5 W/m^2 from 280 ppm to 380 ppm is probably wrong. It should be about 2.7 W/m^2 from 280 to 380 ppm.
  50. Lindzen and Choi find low climate sensitivity
    RW1, sorry to be a pain, are you talking about a hypothetical 1W/m^2 increase in solar forcing or actual? The actual increase over the last century was about 0.25 according to http://data.giss.nasa.gov/modelforce/ (link was in latest thread at WUWT)

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