Prev  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  Next

Comments 451 to 475 out of 483:

451. KR at 08:04 AM on 10 June, 2011
     dana1981 - Yep, the reviewers (including #4, added when Lindzen complained about the others) really ripped it up. I have seen a pre-print of it from last year, and from the reviewer comments it hasn't changed much. Quite horrid, to tell the truth. Still using the x2 extension of tropical effects to global, ERBE data rather than CERES, no attention to extra-tropic heat transport, and high sensitivity to the apparently cherry-picked start/end dates. There's a thread on this at WUWT, which is where I found they had finally managed to get it published. In a Korean English language journal where it's off-topic. Sad...
452. Riccardo at 08:08 AM on 10 June, 2011
     Peer review working properly, judging by the consistency of the four reviewers comments.
453. Rob Honeycutt at 08:30 AM on 10 June, 2011
     Funny. I was just in a battle with some guy on one of Peter Sinclair's videos and be brought up LC09 as proof of low climate sensitivity. He's been trying to change the subject ever since. The PNAS rejection is perfect. One reviewer mentions there are two other responses to LC09 but I've never seen those. I only know Trenberth 2010.
454. dana1981 at 08:38 AM on 10 June, 2011
     Rob H - see here for references to all three KR - since you mentioned it, I'm surprised Lindzen didn't go for E&E!
455. KR at 08:39 AM on 10 June, 2011
     Rob Honeycutt - I've also seen Chung 2010 and Murphy 2010 referred to in this context. Both are rather serious critiques of L&C 2009.
456. KR at 08:55 AM on 10 June, 2011
     dana1981 - I suspect that E & E has a sufficiently bad reputation that they didn't consider it.
457. KR at 01:11 AM on 12 June, 2011
     For completeness on the Lindzen and Choi papers: LC11 PNAS rejected submission here. LC11 APJAS (in print) here. Some small differences, an additional 3 pages in the APJAS version (it apparently hit the PNAS size limitations). IMO - Lacking in sensitivity analysis for start/end dates of their temperature changes (cf. Trenberth 2010), extratropical heat exchange armwaved and asserted to be unity, etc. It's essentially LC09 with some added (and IMO fairly weak) explanatory text, no accounting for how the critiques pointed out contradictions with actual observations.
458. RW1 at 16:32 PM on 10 July, 2011
     And still no one can explain why GHG ‘forcing’ will be amplified by over 400% when solar forcing is only amplified by about 60%. Yet they vehemently object to a negative feedback of about 40% from Lindzen and Choi. I think the peer review process is broken.
459. Tom Curtis at 23:08 PM on 10 July, 2011
     RW1 @458 the first thing that needs explaining is that your statement is simply false. The expected change in mean global surface temperature from a 2% change in total solar irradiance (an approx 4 W/m^2 change in solar forcing) is about 3 degrees C, just as with the approx 4 W/m^2 change in forcing from doubling CO2. The second thing that needs explaining is the nature of your error. It is very simple, you are comparing the marginal climate feedback of CO2 forcing, ie, the incremental change in net Top of Atmosphere Irradiance given current temperatures and conditions with the average climate feedback of solar forcing, ie, the integral of the marginal climate feedback over the whole range of TSI values, from 0 to approx 1366. If we were to perform an impossible experiment and set TSI to zero and allow the temperature of the Earth to reach equilibrium, the equilibrium temperature would be approximately 4 degrees K. The Earth would have no atmosphere, for it would have condensed and frozen on the surface, hence it would have no greenhouse effect. Increasing TSE gradually, for a long time the surface radiation would rise proportionally to the change in TSI, as the Earth would not be warm enough for ice to melt and atmosphere to form. Hence there would be no feedbacks. After a while a thin atmosphere would form, but an atmosphere without any CO2. The albedo would probably start to rise at this time as the sun started producing visible radiation (which is reflected by ice) rather than just radio an IR radiation (which is not). Whether the net feedback would be positive (because of atmospheric redistribution of heat) or negative (because of the increasing albedo) would not be determinable without detailed modelling. Regardless. over this period the net feedback would be close to zero, so surface radiation would rise approximately with increasing TSI. As the TSI increases still further, till it approaches more modern values (and reaches values it has never been lower than in the last 4.5 billion years), CO2 will enter the atmosphere and the surface radiation will finally start increasing faster than the increase in TSI. (The OLR at the TOA of course, will continue to increase with TSI). Eventually, the equatorial snow and ice will start to melt, and with a declining albedo, surface radiation will rise still faster relative to TSI. When the Earth reaches that stage, it will flip from the snowball Earth configuration, and for the first time climate sensitivity will approximate to modern values, as it has for the last 500 million years. Because you are comparing the modern feedback factor (for both solar and GHG forcings) with the average of the solar forcings for all values of TSI, you claim an inconsistency - but the only inconsistency is yours. It is the same inconsistency found any those fool enough to claim that somebody else on the same income is getting a special deal from the tax office because that persons average tax rate is less than their own marginal tax rate.
460. RW1 at 00:14 AM on 11 July, 2011
     Tom, I didn't know you were still talking to me. Actually though, L&C is operating under the assumption of an 'intrinsic' 2xCO2 temperature increase of 1.1 C with the negative feedback reducing this to about 0.6-0.8 C. I was referring to the direct warming of 3.7 W/m^2 from S-B of 0.7 C, which if it were to become 3 C needs to be increased by over 400% (3.0/0.7 = 4.28).
461. RW1 at 00:40 AM on 11 July, 2011
     Tom, "RW1 @458 the first thing that needs explaining is that your statement is simply false. The expected change in mean global surface temperature from a 2% change in total solar irradiance (an approx 4 W/m^2 change in solar forcing) is about 3 degrees C, just as with the approx 4 W/m^2 change in forcing from doubling CO2. The second thing that needs explaining is the nature of your error. It is very simple, you are comparing the marginal climate feedback of CO2 forcing, ie, the incremental change in net Top of Atmosphere Irradiance given current temperatures and conditions with the average climate feedback of solar forcing, ie, the integral of the marginal climate feedback over the whole range of TSI values, from 0 to approx 1366." What is so unique about the next 3.7 W/m^2 that it is reasonable to think the system will respond to it so much greater than the original 342 W/m^2 from the Sun, which is only amplified by about 14% at the surface (390/342 = 1.14)? You should also explain why it doesn't take more like 1534 W/m^2 at the surface to offset the 342 W/m^2 from the Sun (16.6/3.7)*342 = 1534.
462. Tom Curtis at 01:09 AM on 11 July, 2011
     RW1, 1) I really don't care what Lindzen and Choi have to say. They have amply proved that what ever it is that they are doing, it is not science. 2) The total insolation is reduced by albedo, so the "amplification factor" (aka, the greenhouse effect) is 62.5% at the surface, not 14%. 3) Given that you wish to run your specious argument, one wonders why you don't run it with regard to Lindzen and Choi's paper. On that basis you would expect a climate response to doubling of CO2 of at least 1.2 *1.625 = 1.95 degrees, which is close enough to the IPCC range, and large enough to mean that anthropogenic emissions are dangerous. In fact, that you do not apply it in that way suggest that you are either disingenuous in presenting the argument, or disingenuous in insisting on a low climate sensitivity. 4) Finally, I have already answered your question in 461, or are you also going to pretend that you cannot understand the difference between a marginal and an average rate?
463. RW1 at 01:45 AM on 11 July, 2011
     Tom, RE: 2) You said that a doubling of CO2 was equal to about a 4 W/m^2 increase in solar irradiance, which is why I used those numbers. I always assumed the 3.7 W/m^2 was equal to post albedo solar power, which is amplified by about 63% (390/240 = 1.63) even though the IPCC doesn't even really even make any such distinction (to my knowledge, at least). RE: 3) The 1.63 applies to the power of 3.7 W/m^2 from 2xCO2 - not the 1.1 C in temperature, which has already been multiplied by 1.63 (3.7 x 1.63 = 6 W/m^2, which equals +1.1 C). RE: 4) I'm well aware of the difference between marginal and average rate; however, neither term is dictated by the laws of physics that govern the processes of energy flow in and out of the climate system.
464. RW1 at 02:08 AM on 11 July, 2011
     All I'm asking is for an explaination where the additional 12.9 W/m^2 is coming from to cause the 3 C rise (16.6 - 3.7 = 12.9). If the current atmosphere only provides an additional 2.3 W/m^2 (6 - 3.7 = 2.3), where specifically is the remaining +10.6 W/m^2 incoming flux required at the surface coming from?
465. RW1 at 02:31 AM on 11 July, 2011
     My main point here is how can a negative feedback reduction of about 25-40% from L&C be considered so unreasonable even though it is well within the measured bounds of the system from solar forcing, yet an amplification of 300% is considered so reasonable when it is so far outside the measured bounds?
466. Tom Curtis at 02:48 AM on 11 July, 2011
     RW! @463: RE 2) I used 4 as a convenient approximation. A 2% increase in TSI results in approx 4.8 increase in TSI. A 1.6% results in a 3.8 W/m^2 increase. So us 1.6% instead. Regardless, for a 3.7 W/m^2 increase in solar forcing, the expected temperature increase is within around 10% of the increase for CO2. The slight difference is because differences is the region of greatest relative warming. RE 3) The 3.7 W/m^2 increase in TOA forcing results in approximately an approximately 16.6 W/m^2 increase in surface radiation, regardless of the forcing agent. If the surface temperature were held constant, but the feedbacks still applied, the 3.7 W/m^2 increase in TOA forcing would result in a TOA energy imbalance of approximately 11 W/m^2, again regardless of the forcing agent. Of course, Earth the feedbacks are a consequence of the warming, so that 11 W/m^2 is theoretical. Another way of looking at your error is that you compared the 3.7 to the 16.6 for CO2, but the 11 to the 16.6 for Solar. (I know that is not what you did, but it is theoretically equivalent.) However, my approach in 459 is more informative about the nature of your error. RE 4) The laws of physics do not dictate any terms - they just are. We choose which terms we will use in describing them, and the difference between a marginal and average rate is a good way to understand the reason for your error. The crucial thing you need to understand is that the temperature response to an equivalent solar and GHG forcing under current circumstances are expected to be very similar in magnitude though different in spatial and temporal structure. This is easily seen in the following two modelled temperature patterns for a doubling of CO2 (first) and a 2% increase in insolation (second): There is a genuine difference between the expected climate sensitivity for marginal changes in solar and CO2 forcing, but it is small. If you look up the relevant values you can try to run your argument again in a coherent manner, but I warn you the figures won't impress anyone, including you. Alternatively you can ignore the evidence above that climate science expects similar responses for similar forcings from solar or CO2 concentrations and keep on running your apples and oranges comparison. That will convincingly show that you are only here to spread confusion. (PS: I thought I had posted this, but it has not appeared. If this is a duplicate, please remove.)
467. RW1 at 03:46 AM on 11 July, 2011
     Tom, I'm just asking for an explanation of where the +12.9 W/m^2 flux needed at the surface is coming from, or specifically how the 'feedback' will cause this much response? So far you haven't provided an answer to this. Now, I've also asked why the feedback doesn't cause this much response on solar forcing, but I'm willing to overlook that for now. Furthermore, I presume you understand that if the surface is to warm by 3 C then it must also emit 406.6 W/m^2 (16.6 W/m^2 more) and that COE dictates that this +16.6 flux at the surface has to be coming from somewhere? If 3.7 W/m^2 are provided directly from 2xCO2 and another 2.3 W/m^2 are provided from the atmosphere's the net transmittance of of 0.62 (3.7 x 0.62 = 2.3 W/m^2) to allow the 3.7 W/m^2 to leave the system to restore equilibrium (240 W/m^2 in and out), where is the additional 10.6 W/m^2 flux coming from? There are only two possible sources for this flux. Either from the Sun via a reduced albedo of about 6.5 W/m^2 (6.5 x 1.62 = 10.6) or from increased atmosphere absorption of about 13 W/m^2 (13/2 = 6.5; 6.5 x 1.62 = 10.6).
468. Camburn at 04:10 AM on 11 July, 2011
     RW1 & Tom: Very interesting. Thank you.
469. RW1 at 04:21 AM on 11 July, 2011
     Tom (RE: 466), "The 3.7 W/m^2 increase in TOA forcing results in approximately an approximately 16.6 W/m^2 increase in surface radiation, regardless of the forcing agent." I'm well aware that this is the claim. I'm simply asking specifically how the +3.7 W/m^2 surface flux from the 2xCO2 (or the Sun) will become a total of +16.6 W/m^2 required for a 3 C rise. If 3.7 W/m^2 only provides a direct warming of 0.7 C and the atmosphere provides an additional 0.4 C for a total of 1.1 C, how specifically does a 1.1 C rise cause an additional +10.6 W/m^2 flux at the surface? Also, keeping this in the context of L&C, how is a reduction of 25-40% considered to be so unreasonable, yet an increase of nearly 300% is considered reasonable when such an increase is so far outside the measured bounds of the atmosphere (about a 0.62 net transmittance to space)? In other words, why isn't the net transmittance to space more like 0.22 (3.7/16.6 = 0.22)???
470. RW1 at 05:01 AM on 11 July, 2011
     My ultimate point here is +300% amplification is a far more extraordinary claim than a 25-40% reduction. I would also argue that a 25-40% reduction is far more consistent with the system's overall behavior, which is very tightly constrained from year to year despite a significant amount of local, seasonal hemispheric and even global variability. And when global average temperature does rise by an abnormal amount (like in 1998 and 2010), it tends to revert to its pre-equilibrium state fairly quickly, which is anything but consistent with net positive feedback, let alone net positive feedback of 300%.
     Response:

     [DB] It would be better to wait for someone to get back to you with a response than to continue to run-on with suppositions.  Repetitive posting without waiting for an answer is little different than talking to oneself; little progress in understanding is achieved.

471. RW1 at 05:09 AM on 11 July, 2011
     DB, OK, fair enough. I'll give Tom (or anyone else) a chance to respond before I say anything else.
472. scaddenp at 18:19 PM on 10 November, 2011
     In case someone is thinking Lindzen & Choi 2011 is an improvement, please see here
473. oneiota at 11:45 AM on 26 November, 2011
     I noted with interest a recent paper published in Science where a lower median sensitivity is proposed with reduced uncertainty: "Abstract Assessing impacts of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 K as best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small but significant chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K 66% probability). Assuming paleoclimatic constraints apply to the future as predicted by our model, these results imply lower probability of imminent extreme climatic change than previously thought." Needless to say some of the less informative news outlets are trumpeting this as "another nail in the coffin" for AGW alarmism.
474. skywatcher at 14:07 PM on 26 November, 2011
     #473 oneiota, I think there's an SkS article in the pipeline about the relevant paper, but in this case it is intriguing to see what skeptics consider supports their position. This paper does not support their position at all, but I don't think they realise why. The paper uses a climate model to estimate a relatively low climate sensitivity - the climate model in question has a remarkably low temperature difference between LGM and present conditions (3.3C) compared to published estimates usually towards 5C or more. The consequence of this is that the paper implies a much greater impact on the climate system for every degree of warming. Although it suggests fewer degrees C per doubling CO2, we'll also need fewer observed degrees C to create a climate change as large as LGM to present. And we're already well on the way to doing that, if this paper is correct. To me, that make for particularly worrying reading, and not a cause for optimism, as various news outlets, including the BBC, have implied.
475. skept.fr at 14:47 PM on 26 November, 2011
     I haven't still read the paper, but a 2,3 K sensitivity is among the IPCC range and three models of the IPCC AR4 find a 2,1-2,3 K sensitivity for 2xCO2. So, that one study among many others arrives to the same conclusion from a LGM reconstruction is not a surprise, and certainly not the last word in a domain where there are many publications each year. #474 skywatcher : do you think to sea level rise? If it is the case, I don't know if a 3.3 K warming on a glacial condition will have the same effect that a 3,3 K warming on an interglacial condition (like ours). Intuitively, I'd say there was much more ice to melt 20ka ago than now, at mid latitude and low altitude. We should observe what semi-empirical ice models obtain with an imposed 2,3K sensitivity.

Prev  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  Next

Post a Comment

Political, off-topic or ad hominem comments will be deleted. Comments Policy...

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.