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Comments 100901 to 100950:
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adelady at 08:37 AM on 22 December 2010We're heading into an ice age
@186 I think you'll find that snow on Mt Wellington is hardly a Christmas novelty. -
kdfv at 08:30 AM on 22 December 2010We're heading into an ice age
#185 First ever recorded summer snow in Australia. Things are starting to get interesting now! -
Joe Blog at 06:51 AM on 22 December 2010Stratospheric 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. -
VeryTallGuy at 06:42 AM on 22 December 2010Lindzen 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? -
muoncounter at 05:59 AM on 22 December 2010Greenland Ice Sheet outlet glaciers ice loss: an overview
#27: Your linked paper "Testing hypotheses of the cause of peripheral thinning" makes a distinction between land-terminating and ocean-terminating glaciers. There was a four fold increase in mean marine-terminating outlet glacier thinning rates ... between the periods 1993 to 1998 and 1998 to 2006, while thinning rates of land terminating outlet glaciers remained statistically unchanged. This suggests that a change in a controlling mechanism specific to the thinning rates of marine-terminating outlet glaciers occurred in the late 1990s and that this change did not affect thinning rates of land-terminating outlet glaciers. This distinction argues for warmer water contributing to melting, rather than a strictly "solar influence," as you seem to suggest in #28. Would not a solar influence affect land and ocean-terminating glaciers equally? And isn't ocean warming a known symptom of the GHE? -
Albatross at 05:28 AM on 22 December 2010The Climate Show #4: Peter Gleick, AGU and climate sensitivity
Another interesting show guys. Excellent work as always. It was nice having Peter Gleick on. Maybe having a prominent guest can become a feature. I really liked that Glen was playing devil's advocate regarding the "warm Arctic cold-continents" phenomenon that we seem to be seeing again this year. Perhaps a post on this needs to be done on this soon at SS. Merry Christmas guys. PS: This bird really misses cricket..sigh. -
Stephen Leahy at 04:19 AM on 22 December 2010A Merchant of Doubt attacks Merchants of Doubt
An excellent essay by Clive Hamilton on why people can't accept climate change despite the evidence: http://www.clivehamilton.net.au/cms/media/why_we_resist_the_truth_about_climate_change.pdf -
Ice data made cooler
Thanks again to all for reviewing my Vostok graph. I've added many of the suggestions made here: labels, y-scale markers, and a means of rescaling graphs. These were essential features. Other features will be added as I can find time to do so. jg -
archiesteel at 03:31 AM on 22 December 2010Stratospheric 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?" I'd like to answer this question, but it's so badly written I can't figure out what it means. Contrarians, please try to eschew obfuscation in your arguments. Thanks. -
archiesteel at 03:23 AM on 22 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
@RSVP: "...at which point, the CO2 molecule cools." A more accurate description would be that it returns to its previous temperature. The extra amount of IR radiation is still in the system, therefore raising the temperature of the system until a new equilibrium is reached. Quod erat demonstrandum. "Furthermore, last time I checked, my pocket yields an interest rate of exactly 0.00000%" I am not interested in your incorrect analogies. Try logic instead. -
archiesteel at 03:19 AM on 22 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
@RSVP: "I think Socrates had to down hemlock for this same accusation." Socrates used logic, and pursued a quest for truth, while you appear to engage in scientific sophistry designed to stall the debate on AGW. There really is no comparison possible. "So I take this as a compliment which I really do not deserve." It isn't a compliment, and you do deserve it. -
CBDunkerson at 00:23 AM on 22 December 20101934 - hottest year on record
prosch, actually the United States does show a warming trend... just a less pronounced trend than the global average.Moderator Response: The comment you're replying to was actually spam, albeit cleverly disguised to appear on-topic. -
Stratospheric Cooling and Tropospheric Warming - Revised
RSVP - Please, you've been on this website for quite a while, and know better than to treat this as a zero-sum fixed quantity issue. Energy comes in continuously from the sun, greenhouse gases slow the exit of that energy to space at any particular temperature (higher emission altitude, lapse rate from there to the ground, or just by looking at effective TOA emissivity), temperatures increase, and outgoing energy increases as well as the Earth system tries to balance in/out energy. Please stop with the inappropriate analogies, such as fixed amounts of change in your pocket (unworkable analogy, it doesn't reflect any aspect of the climate system). We've had that discussion before, on the "Waste Heat" thread, regarding the Bad Analogy logical error. -
Ned at 23:34 PM on 21 December 2010It's freaking cold!
I would argue that if we observe record low temperatures [...] Well, we aren't observing record low temperatures, as far as the whole Earth is concerned. Maybe some individual place is ... but there's nothing especially noteworthy about that. Maximiliano Herrera has compiled data on met stations that set new high or low records every year since 2002. When I last looked at his site, earlier this fall, 2010 had set 337 warm records versus 13 cool records. In 2009, the ratio was 80 (warm) to 15 (cool). In 2008, it was 40 (warm) to 18 (cool). In 2007, it was 133 (warm) to 9 (cool). And so on... -
michael sweet at 23:15 PM on 21 December 2010Greenland Ice Sheet outlet glaciers ice loss: an overview
Arkadiusz: It certainly is a difficult problem to predict what the great ice sheets will do in the future. Past records, including paleo records, are not comparable to the present forcing: the current forcing is much bigger. Models of sea ice in the arctic have greatly underestimated current ice melt (see the IPCC report). The great ice sheets are also starting to melt long before predicted. On the other hand, if you check my reanalysis link at #20, the current anomalies over Greenland are 10C higher than historic over the ice sheet and 5 degrees higher over the ocean. Do the papers you cited refer to anomalies this high, or were they not anticipated? Most of this winter has been over 0C over the southern ice sheet. This unprecedented heat must have some affect on the ice sheet. Do you wait until the ice sheet collapses before you acknowledge there might be a problem? The ice sheet will undoubtedly have some sort of lapse time before it fully responds to the heat. How long do we have? -
Arkadiusz Semczyszak at 22:48 PM on 21 December 2010Greenland Ice Sheet outlet glaciers ice loss: an overview
“direct and indirect - of solar activity.” For starters I recommend all the latest works Lockwood's (et all. of course) and especially (and “consistently”) Solar Influences on Climate (Reviews in Geophysics, 2010). If J.C. “dusting of” about this topic, I will present the latest (last 2-3 years) work - papers, showing the changes, feedback resulting from changes - in the TSI, UV, ULV, volcanic activity, magnetic, phytoplankton - ENSO - clouds - ozone, conductivity of the atmosphere, etc. ... -
Eric (skeptic) at 22:43 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
RW1 (#132), thanks for explaining your numbers again. What doesn't seem to match Trenberth is the 80W/m^2 lost by evaporation (cooling) at the surface (plus another 17 for thermals). In your budget you only consider the energy radiated from the surface. Can you adjust your budget account for evaporation and thermals? Also like KR in 131 I am a little unclear on what you mean by "gain". You are saying that a certain amount of solar energy makes it to the atmosphere and surface (in Trenberth it is 341-79-23 which is about the same as your #'s) Then we measure the earth at 288K and calculate 390W emitted. You then define gain as the ratio of the solar energy caught in the earth/atmosphere (ok...) divided by surface radiation (doesn't make sense). Seems to me like you are comparing two fundamentally different numbers. -
Arkadiusz Semczyszak at 22:25 PM on 21 December 2010Greenland Ice Sheet outlet glaciers ice loss: an overview
All right ... In a “great” nutshell : For three years I deal with problem : „thinning rates of key Greenland outlet glaciers” - what is the effect and what is the cause ? According to this work: Greenland Ice Sheet Surface Mass-Balance Modeling in a 131-Yr Perspective, 1950–2080, Mernild et al. 2010. write: “The authors simulated an 90% increase in end-of-summer surface melt extent (0.483 × 106 km2) from 1950 to 2080 and a melt index (above 2000-m elevation) increase of 138% (1.96 × 106 km2 × days).” Most researchers claim that the outlet glaciers of Greenland (including those within the land) are very sensitive to even small temperature changes ("Arctic amplification"). Cited by me first work shows the difficulties in the interpretation of old data (Eemian). Other works show the great influence of the place and size of the snowpack (SnowModel) the movement of glaciers and the "thinning outlet" (see also: The Cryosphere Estimation of the Greenland ice sheet surface mass balance for the 20th and 21st centuries., Fettweis et al., 2008.) . Even so. “great warming” in Greenland of the 30s (according to many of Greenland's still bigger and more violent than at present) does not give answers, how would the glaciers. Then the loss of ice - the dynamics of movement of glaciers - was (30s) faster than at present, but in the 30's was negative phase of NAO and AO (now this are positive - of course, "most frequently"), concerned mainly the warming of spring, for now - autumn, etc. Her recent works are beginning to agree on one thing - it: “... highly sensitive to ocean Conditions ..." decide on the melting and traffic of Greenland's glaciers (not just those “ending” in the sea? - Testing hypotheses of the cause of peripheral thinning of the Greenland Ice Sheet: is land-terminating ice thinning at anomalously high rates? Sole et al., 2008.). Yes: highly sensitive - the temperature - "thinning rates of Greenland Outlet Glaciers key"- a very affects the movement of glaciers across Greenland. However, with mass loss of glaciers is increasingly important that the surface of Greenland's mountainous sculpture, geothermal activity. Glaciers are to be retained in the narrow mountain valleys, narrow valleys, fjords. For this walk "... negative feedback mechanisms ... " Conclusion. The loss of ice in Greenland is not (and will) linear with respect to temperature. We do not know whether an increase in snow accumulation will be the east or west (various atmospheric circulation, different topographic features) and this will have a decisive influence on the flow of glaciers into the sea: „The greatest difference in melt extent occurred in the southern part of the GrIS, and the greatest changes in the number of melt days were seen in the eastern part of the GrIS ( 50%–70%) and were lowest in the west ( 20%–30%).[ Mernild et al. 2010.]” Mernild et al. 2010., saying: „The rate of SMB loss, largely tied to changes in ablation processes, leads to an enhanced average loss of 331 km3 from 1950 to 2080 and an average SMB level of −99 km3 for the period 2070–80.” - may be wrong. The continental glaciers 2,080 years, particularly those from the deep interior of Greenland will be stable because such accumulation of snow will stop them. These coastal (eg Jakobshavns, Helheim) BTW much farther from the sea and - in this way - lose its dynamic ... P.S. A thorough knowledge of the PETM may tell us all - and the issue about of Greenland ice ... -
Alec Cowan at 22:09 PM on 21 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
@RSVP #72 I knew, as I called that paragraph A. Again, I insist you to start by explaining what UNEXCITED means in A. When you get it you'll comprehend the error in your initial thoughts ... if you're looking for knowledge. I want you to know that your comments are extremely valuable to me for educational purposes. I'm making a collection of your comments for some of my students to work on them during 2011. -
scaddenp at 20:53 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
" but it's assuming all of the absorbed 3.7 W/m^2 affects the surface - meaning all of it is re-radiated downward, instead of only half. " As others have pointed out, this is not true. The calculation used to arrive at 3.7W/m2 assume nothing of the kind and physically the situation is different. The number cannot not be used in the way you describe. See the definition in 2nd IPCC report. Essentially the same set of equations are used to calculate the added energy flux at the surface due to increased but its different no. From memory its about 3.5W/m2 for current GHG emissions since pre-industrial but I dont know the figure for doubling. -
Paul D at 20:45 PM on 21 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
RSVP: "If I move a dollar from one pocket to another all day as I go window shopping, my buying power hasnt changed." The US government isn't printing trillions and trillions (etc) of dollars per second all day. The Sun however... Your discussion is centred around a fixed energy scenario where there is no further input of energy. Even in the scenario you suggest no energy is lost, which is the point. The only way for the energy can escape is to be radiated to space eventually. To be honest your silly game is juvenile. -
RSVP at 19:57 PM on 21 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
Alec Cowen #52 "I suggest you to start by explaining what "unexcited" means in A. " Sorry, this was a quote from the featured article. -
RSVP at 19:43 PM on 21 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
The Ville #65 "That isn't clever and is considered to be morally corrupt by some. " I think Socrates had to down hemlock for this same accusation. So I take this as a compliment which I really do not deserve. -
villabolo at 19:39 PM on 21 December 2010A new resource - high rez climate graphics
But when you're communicating science to a broad audience, your visuals need to contain just the bare minimum required to get the message across. Cram too much detail in there and your meaning can get lost in a sea of factoids. So often when I scratch around for good climate graphics to communicate the required message, I can't find anything simple enough and am forced I create my own." John, I'd hate to be the one to point out the fly in the ointment but there may arise an issue of authenticity. If we were to "redo" charts and graphs we will be accused of cooking (No pun intended.) the charts by our beloved 'skeptics'. I realize that our intent is not to convince the inconvincible 'skeptics' but we have to keep in mind that our target audience will be weighing both arguments and could, due to their ignorance, be easily sidetracked by spurious arguments. I personally would prefer, to the best extent possible, to keep charts, graphs, etc. in their original state and then explain to my target audience what they should focus on and what they could safely ignore. -
RSVP at 19:35 PM on 21 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
archiesteel #59 "Indeed. However, without the GHG molecule, the IR photon would be more likely to escape into space, while here it is being captured by a CO2 molecule and re-radiated, possibly back to that rock, re-warming it." ...at which point, the CO2 molecule cools. If I move a dollar from one pocket to another all day as I go window shopping, my buying power hasnt changed. archiesteel #59 continues... "...but all this extra time the IR photons spend in the atmosphere and back to the ground means higher temperatures overall." Furthermore, last time I checked, my pocket yields an interest rate of exactly 0.00000% -
Mila at 18:59 PM on 21 December 2010An online resource for the IPCC 4th Assessment Report
Thanks for your support, it is greatly appreciated. #7 - at this moment I am focused on journal articles, for other entries I usually try to find links to WorldCat database. In the final version I hope to polish the links which are a bit special. -
Ebel at 17:43 PM on 21 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
#68 HumanityRules at 17:00 PM on 21 December, 2010 "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?" The collisions with CO2 molecules are a tiny minority of all collisions - but still makes sure that the ratio is of excited CO2 molecules to CO2 molecules in the ground state is the Maxwell-distribution corresponding to the gas temperature equals [exp (-hv/kT)]. If the radiation intensity corresponding to the local gas temperature, it would be Maxwell-distribution accurat. If the radiation intensity is lower, exist less excited states, at a higher radiation intensity exist a little more excited states. -
VeryTallGuy at 17:32 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
RW1 @119 I'm afraid my life is too short, but also the answer is too simple. I've pointed out on several posts (as have others eg KR@131) that 3.7 W/m2 is the top of the atmosphere number. You keep on trying to halve it by claiming that it is something else. It's not. 3.7 is the total increased heat absorbed by the earth's system for a doubling of CO2 - the net reduction in radiation to space. Absorption and re-emission through the atmosphere are inherent in the calculation which is done stepwise through the atmosphere. If you want to calculate the surface budget associated, feel free. Also, you asked for a response to your original question. I tried directly to do that @112 - even with the very conservative figures I put in there you can see that the energy change from CO2 is bigger than your figures for orbital eccentricity within 2 years. And you still haven't provided any reference for your numbers on orbital forcing, unless I missed them. Please do? -
Albatross at 17:27 PM on 21 December 2010An online resource for the IPCC 4th Assessment Report
Now only if I had the time to create a database of my journal papers on which Zvon could perform searches. Now that would be superb tool and save many expletives and much time wasted trying to track down papers...now where is Knutti and Hegerl again? Last time I saw it is was dumped on my Mac's desktop... Seriously though, Mila this is a fantastic tool. Thanks for sharing. -
RW1 at 17:08 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
In my example above, power in = power out. 168 W/m^2 absorbed and radiated upward out to space + 70 W/m^2 passing through the transparent window unabsorbed out to space = 238 W/m^2 leaving & 238 W/m^2 arriving. -
HumanityRules at 17:00 PM on 21 December 2010Stratospheric Cooling and Tropospheric Warming - Revised
#4 Alec Cowan "then it becomes "less rarified" by a factor of about 1.0009" Thanks for that but it didn't quite answer my question. I have no problem with the size of the increase. Bob seems to describe the KE method as revolving around the increase in collisons of molecules associated with this increase. Your answer would suggest this process is insignificant as well. 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? -
Tom Dayton at 16:46 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
No, RW1, you are incorrect that "multiple absorptions on the way down could cause half to be redirected back up out to space - equally offsetting any redirected back down." That's because: (1) The source of the radiation being absorbed is below the absorbing GHGs (on the surface). So there are far more GHG molecules to intercept radiation on its way up, than radiation on its way down. (2) Energy absorbed as radiation by GHGs mostly is transformed into kinetic energy by conduction with other molecules, most of which don't radiate that acquired energy. So much of the intercepted radiation's energy is removed from the radiation-to-space pathway, instead contributing to temperature rise of the gases. -
archiesteel at 16:40 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
@RW1: "I think VeryTallGuy can respond for himself." I'm not responding for VTG, I'm commenting on your poor appraisal of his knowledge - considering he actually understands the science, and you clearly don't. As others have said, the 4 W/m^2 already considers the omnidirectional emissions of CO2. You keep ignoring it, as well as the very strong rebuttals to your strange theories. When someone keeps repeating the same thing over and over again and ignoring rebuttals, it's a clear sign that they've lost the argument, and are only keeping at it to either save face or waste everyone's time. You've stated your opinion, many times. People have presented their counter-arguments. What do you say we let posterity decide who is right, and who is wrong? Anyway, it's not as if your approximate grasp of the matter is going to convince anyone here... -
RW1 at 16:39 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
muoncounter (RE: Post 130), I'm sorry, it's actually about 152 W/m^2 absorbed and sent down to the surface - not 150 W/m^2 (238 + 152 = 390 W/m^2). So that makes it 152 W/m^2 down and 168 W/m^2 up or about 52.5% up and 47.5% down (using Trenberth's numbers at least). -
Gareth at 16:37 PM on 21 December 2010The Climate Show #4: Peter Gleick, AGU and climate sensitivity
As for the cricket, I hope I'm not forced to choke on my turkey leftovers (served in Rick Stein's Nasi Goreng) ;-) -
RW1 at 16:27 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
muoncounter (RE: Post 130), Actually, the re-radiation from GHGs is in all directions (half goes more upward, half goes more downward, some goes more sideways). Only the downward going half can affect the surface. It may seem logical that multiple absorptions on the way up could cause more than half the power to affect the surface, but if this is true, it also would mean that multiple absorptions on the way down could cause half to be redirected back up out to space - equally offsetting any redirected back down. Whatever happens exactly, if you run some numbers, the net result shows that it's about half up and half down. For example at a temperature of 288K, the surface emits 390 W/m^2. With a gain of 1.6 at the surface, the amount power absorbed by the atmosphere and sent back toward the surface is 150 W/m^2 (238 W/m^2 from the Sun + 150 W/m^2 from atmosphere = 390 W/m^2 at the surface). To calculate the amount of power absorbed by the atmosphere and directed up out to space, we need to know how much of the surface power passes through the transparent window of the atmosphere totally unabsorbed. If we use Trenberth's 70 W/m^2, we get a total of 320 W/m^2 absorbed by the atmosphere (390 - 70 = 320 W/m^2). 320 W/m^2 total absorbed - 150 W/m^2 directed downward back toward the surface = 170 W/m^2 upward out to space, which using Trenberth's numbers at least, is actually about 53% up and 47% down. -
dana1981 at 16:20 PM on 21 December 2010The Climate Show #4: Peter Gleick, AGU and climate sensitivity
Good show, and nice plug for the Guide. Nice to hear that we're a bunch of nitpickers! :-) -
An online resource for the IPCC 4th Assessment Report
Awesome work, Mila. Many times the best information in the world is defeated by the difficulty of finding it. You've made that much less of a barrier. -
Lindzen and Choi find low climate sensitivity
RW1 - Your bookkeeping is off. 3.7W/m^2 is the forcing from doubling CO2 at TOA, not the surface effect. That TOA number already includes all internal re-radiation. You've been told this repeatedly - I don't know why you keep insisting on half that forcing not having an effect; you are consistently (and in an unsupportable fashion) underestimating the CO2 effect by half, and you are consistently incorrect. The '1.6 gain' for solar inputs is also you have mentioned is something I don't understand - the reaction to forcings is specifically describing equivalent inputs to the Earth energy balance, and there is no 1.6 factor anywhere I know of. Hence much of your #5 post here does not follow. As to Trenberth 2009 (you seem to be using numbers from an earlier version, but they aren't all that different), Trenberth puts quite a lot of effort into estimating the various components. If you feel he has not estimated one of the energy vectors correctly, please point out which one(s), with some evidence to back your claim(s). Preferably backed by some papers indicating why. -
muoncounter at 14:44 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
#126: "it's just that about half of it happens to be "forced" in the same in the same direction it was already going - up out to space." You have said a number of times that your calculations require cutting the radiative forcing in half because of this lost to space idea. I'm genuinely curious to know where that concept originated. Let's try a 'thought experiment'. Suppose a quantity of IR photons are on their way up from the warm ground. Some of these photons get absorbed by GHGs. Reradiation takes place and exactly 50% go downwards and 50% go upwards. In this thought-world, there are only either upgoing or downgoing, no 'tweeners'. Of the ones that go downwards, if your mechanism is correct, they return to the ground and are no longer part of this experiment. If your mechanism is correct, the remainder are gone. But let's look at the future of the photons that continue upwards upon re-radiation. Is it not possible for a 2nd absorption to occur, as these up-going photons meet other GHGs? If so, we repeat the partitioning into half down (and they are no longer part of this experiment), half up. These upgoers meet more GHGs and are again reabsorbed/reradiated. Why can this process not continue many, many times? Let's call the probability of any one photon being absorbed in a single stage of this cycle P. If N0 photons start up, after the first 'stop', there are N1 = (1 - P)N0 + 0.5PN0 still going up -- all of the ones that didn't get absorbed plus half of those that did. We can calculate the total number of ups left after a large number of iterations. For P=0.01, it takes just over 900 iterations to reduce the number of upgoing photons to 1% of the initial quantity. With P=0.001, it takes just over 9000 iterations. And in our thought-world, you're either going up or going down. So 99% of the original amount are returning to the ground. Now I have no idea what a reasonable value for P should be, nor do I know if there should be a max number of iterations, nor do I expect this 50/50 scenario to resemble reality. In addition, we should calculate the fate of the downgoing photons from each iteration using the same rules. But I'm not ready to do that until you agree that your single shot, 50% Lost-In-Space idea doesn't resemble reality either. -
RW1 at 13:57 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
Eric (RE: Post 127), Yeah, I tried to lay out everything as detailed as I could in post 5. -
RW1 at 13:54 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
Eric (RE: Post 125), I think Trenberth is just starting with an average surface temperature of 289K rather than my 288K. I was also using an average solar input of 340 W/m^2 - Trenberth using 341 W/m^2. My 238 W/m^2 is derived by subtracting out an albedo of 0.3, which equals 102 W/m^2 (340 x 0.3 = 102; 340 - 102 = 238 W/m^2). Trenberth is also showing 102 W/m^2 reflected (23 off the surface, the other 79 off the clouds). Many have said Trenberth's diagram is confusing because he doesn't separate out clear sky from cloudy sky, which behave quite differently from one another. Also, some of the incoming energy not reflected off of clouds is absorbed by the clouds and some makes it through to the surface. What exactly Trenberth is referring to with the 78 W/m^2 being absorbed by the atmosphere is unclear. I think a lot of his numbers are being determined ad hoc. This isn't hard to do because the the surface power is known from average surface temperature, and outgoing power is known from the effective temperature of the earth of about 255K as seen from space. With these two knowns, many theoretical energy flow models can be derived. -
Eric (skeptic) at 13:53 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
RW1, you already answered my question in #5: "The average incident solar energy is about 340 W/m^2. If you subtract the effect of the earth’s albedo (about 30% or 0.3 = 102 W/m^2), you get a net incident solar energy of about 238 W/m^2 (340 – 102 = 238)." That matches the Trenberth diagram. Now I am ready to try to understand the meaning and ramifications of the "gain" of 1.6 (390 / 238). Unfortunately it is also bedtime, so I will look at that tomorrow -
RW1 at 13:22 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
scaddenp (RE: Post 124), The 3.7 W/m^2 is the correct amount of increase in radiative forcing from a doubling of CO2 in the context your describing, but it's assuming all of the absorbed 3.7 W/m^2 affects the surface - meaning all of it is re-radiated downward, instead of only half. In order for half to be 3.7 W/m^2, the total absorbed power would need to be 7.4 W/m^2, which it isn't. They've gotten away with this because technically all the absorbed 3.7 W/m^2 of power is "radiatively forced" - it's just that about half of it happens to be "forced" in the same in the same direction it was already going - up out to space. Also, if they assume all of the power affects the surface, they can get more warming. -
Eric (skeptic) at 13:20 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
RW1, thanks. So your 390 seems to correspond with the 396 surface radiation in the Trenberth diagram. Your 238, which you describe as solar hitting the surface is listed as 184 in Trenberth (161 absorbed plus 23 reflected) That is a discrepancy I can't explain. What is odd is that Trenberth shows 239 outgoing LW at TOA which is very close to your 238 number. So my question boils down to: how is your 238 number derived? -
scaddenp at 12:50 PM on 21 December 2010An online resource for the IPCC 4th Assessment Report
Excellent stuff, however I notice references to past IPCC assessment point to book sources whereas the online version of old reports would be more useful. A small nitpick in an otherwise brilliant piece of work. -
scaddenp at 12:46 PM on 21 December 2010It's freaking cold!
What you could also argue is that in global warming, the no. of record highs in a year should exceed the no. of record lows if "record" is calculated on same basis for same spatial distribution. See here for some data.Moderator Response: [Daniel Bailey] Fixed link. -
scaddenp at 12:38 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
RW1 - I still think there is a problem of definition here. "Radiative Forcing" is a concept to put all forcings on an equivalent basis. Ie in terms of net downward energy flux measured at top of tropopause. So calculation of extra energy at the surface from GHG is recast so that it is equivalent to say extra solar but measured at top of tropopause (NOT the TOA). Thus 3.7W/m2 is the what the recalculation of energy flux works out to for a doubling of CO2. There is no feedbacks etc which affect the climate sensitivity involved in this calculation beyond dealing with overlaps in the water vapour spectrum. So an average, annual increase in energy of 3.7W/m2 at the top of the tropopause is surely going to warm the planet from 1st law consideration. If the 3.7W/m2 was from the sun, then you would expect warming surely? Well this is the equivalent. Day to night, season to season, solar flux certainly changes but the average annual change is small (or slightly decreasing). -
Justin Wood at 12:30 PM on 21 December 2010An online resource for the IPCC 4th Assessment Report
I'll add a +1 for the wow and the brilliant. I know it took me many, many hours just to extract a couple dozen of the WG I Chapter 2 references for my own work. Incredible effort! -
RW1 at 12:27 PM on 21 December 2010Lindzen and Choi find low climate sensitivity
Eric (RE: Post 122), 390 W/m^2 is the surface emitted power for an average global temperature of 288K calculated from Stefan-Boltzman. The power in W/m^2 is directed tied to temperature via S-B because the surface of the earth is considered to be very close to a perfect black body radiator, so an emissivity of 1 can be used. 238 W/m^2 is net amount of solar power that isn't albedo reflected, or it is the amount of solar power that hits the surface and is re-radiated as LW infrared. In essence, it's the amount of solar power that has the potential to be absorbed and re-radiated by GHGs and/or clouds - it is the amount of incoming power that can contribute to the energy balance and the greenhouse effect. As far as that diagram, I'm not sure - I need specific questions.
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