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Doug Hutcheson at 19:57 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
owl905 @ 23, Thanks for the link, it has cleared up some of my confusion. Much clearer now. Fascinating subject, with all its twists and turns. -
Lloyd Flack at 19:17 PM on 29 February 2012Mythbusting with fewer explosions
John, I was thinking about those graphs that you show showing changes in the spectra radiated into space and re-radiated back to Earth that show the changes due to CO2 Changes. Has the effect of water vapour also been done? I ask this because you have denialists who say that they concede the effect of CO2 but they dispute the water vapour increase. But the effects of non precipitating greenhouse gases combined with those of water vapour together put the sensitivity most of the way to the usual estimate of the Charney sensitivity. You do not need a large cloud effect to get the usual estimate. You would need a large negative cloud effect to get a low sensitivity. It puts them on the spot.Response: [JC] The graph I showed comes from Harries et al 2001 and takes the water vapor effect into account. There's a link to the full paper including graphs including the water vapor effect at http://sks.to/greenhouse -
Doug Hutcheson at 19:16 PM on 29 February 2012Global Extinction: Gradual Doom as Bad as Abrupt
If we are talking of Gradual Doom (or Abrupt, for that matter), it would be a mildly interesting mental exercise to come up with a means of storing our accumulated knowledge in such a way that it would be available for the next sentient race to evolve on Earth. It would have to survive global catastrophes like volcanoes and earthquakes, perhaps even meteor strikes. It would have to provide a full training manual, to explain how to access the information it stores. That would mean it would require a 'bootstrap' section explaining our language and sufficient physics to enable the discoverer to apply the correct kind of power to the correct terminals of the box. Something like the discs in H. G. Wells' "The Time Machine" might do it. But then, who would want the knowledge acquired by a race that learned how to destroy a perfectly satisfactory biosphere? -
Jose_X at 18:53 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
Chris Colose, if there is some value to the idea that pressure of the atmosphere (assuming it has some amount of ghg) is intimately linked to lapse rate and temperature, observations on earth at our human life timescale do appear to show strong correlations between unpredictable and human changes to the atmosphere and results in temperature. These drivers cannot be called natural cycles. In fact, even natural cycles, as long as they are not driven by the sun, would appear to contradict any such theories. There at least would be a strong argument that the best descriptions of short-term changes have been captured in climate models. A steady state over millions of years perhaps is immaterial to the main question over our fate. -
Jose_X at 18:43 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
Tom Curtis, I think the problem is at step b because eqn 2 forms part of a criticism of the 1 shell model, and I don't think it goes with section 3, where a new theory is covered. @IanC >> Their argument that temperature is driven by pressure is just pure non-sense. There is nothing in their argument that prevents me from arguing that temperature is driven by pressured. I think you meant that we could argue the converse, that pressure is driven by temperature. What do we know about restraints on volume (or concentration of particles)? I had seen a wikipedia reference (that I can't find this second) relating adiabatic polynomial adiabatic 7/2 power to degrees of freedom polynomial 5/2 power to predict some natural balance in volume increases ... ??? -
owl905 at 18:33 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
@Doug 21 - decent summary, same page as you. The balance is restored after the change in GHG's levels out ('in the pipe' lag). In a picture of the heat balance, allow for absorption by land and water. Another fly in the ointment is the cooling effect from upper atmosphere ozone (the CFC issue). fyi: This looks like a decent synopsis site: Global Warming: Man or Myth -
Tom Curtis at 17:54 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
Looking at the "Unified Theory of Climate", I notice form equation (7), you have that: NTEPs = Ts/Tgb Substituting into equation (8), we obtain: Ts = 25.3966(S0 + 0.0001325) 0.25 * Ts/Tgb Dividing both sides by Ts/Tgb, we have (a) Tgb = Ts = 25.3966(S0 + 0.0001325) 0.25 Substituting from equation (2), we then have (b) 2/5 * {(S0 + 0.0001325) * (1 - Agb)/(es)}0.25 = 25.3966(S0 + 0.0001325) 0.25 where A stands for albedo (alpha), e stands for emissivity (epsilon), and s stands for the Stefan-Boltzmann constant (sigma). Hence we have: (c) [{(S0 + 0.0001325) * (1 - Agb)/(es)}0.25]/(S0 + 0.0001325) 0.25 = 63.4915 Cancelling out and distributing, we have (d) (1 - Agb)0.25/(e0.25*s0.25) = 63.4915 and hence (e) (1 - Agb)0.25/e0.25 =~= 0.8239 or, by raising both sides to the fourth power: (f) (1-Agb)/e =~= 0.4607 We are told that (g) Agb =~= 0.125, and hence (h) 1/e =~= 0.5265 or (i) emissivity approximately equals 1.9 which is impossible. OK, maths is not my strong suite, so it is entirely possible I have made an algebraic error above. If so, could somebody please point it out to me. But if not, why are we paying attention to this ridiculous theory which can be true only of the laws of thermodynamics are false. -
Glenn Tamblyn at 17:31 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Boba10960 and others "There were comments at this site some time ago (too long for me to find them now) that led me to believe that increasing the CO2 content of the atmosphere raises the average altitude from which IR radiation escaped to space. Ever since that time I have wondered how that works (if true), and your post has stimulated me to ask." Yes, when you add more CO2 the average altitude at which IR is able to escape to space does increase. But it is more complicated (and more interesting) than that. Whether IR can escape to space requires that the amount of GH gases above it is low enough that the probability of it being absorbed by those molecules drops to something significantly below 100% And this probability depends on 2 things. How many GH molecules are between the IR photon and Space and the probability that the GH molecule will absorb it if they happen to interact. No GH molecule will automatically absorb an IR photon that passes close enough to it. There is a certain probability that it will. And this probability isn't constant across the entire frequency range that a GH molecule can absorb at. It is more likely at some frequencies than others. So the altitude at which escape to space is possible varies with frequency. At frequency f1, the probability of a CO2 molecule absorbing a photon at frequncy f1 mght be X. At frequency f2, if CO2's probability of absorbing at f2 is X/2, then there need to be twice as many CO2 molecules available to give the same effective probability of absorption. So the altitude at which f2 photons have a clear path to space is lower than the altitude for f1 photons. And this behaviour is clearly visible in the graph's Tom has put up. But to understand this we need some extra information. What the temperature profile of the atmosphere is like. As we rise from the ground, air temps drop by around 6.f DegC / km. This keeps happening for between 11-17 kilometers, depending on what latitude you are at. Then as you go higher temperatures don't drop any further. This point is called the Tropopause and is the dividing point between the Troposphere and the Stratosphere. Then as you go higher into the Stratosphere temperatues don't change for quite some period. Then in the upper Stratosphere temps actually start to warm again. And we can see exactly this in the Graph. CO2 has a distribution of absorption probabilities that is highest at the centre of the notch and declines fairly linearly as we move to frequencies on either side. Notice the spike at the centre of the CO2 notch. This is the frequency where CO2 is most likely to absorb. It is so likely that the altitude at which the path to space for that central frequency is in the upper stratosphere where temps are somewhat warmer. Then as we run our eye slowly to the left from that central spike the intensity drops. That is us moving down through the upper Stratosphere and temps are getting colder. Then the spike reaches the 220K line on the graph and roughly stays there as we keep moving out. At this point our decrease in altitude has taken us into the lower Stratosphere where temperatures don't change evean as our clear to space altitude keeps dropping. Finally as we move further out the IR line starts to climb again, to warmer values. Now we are descending even lower, below the Stratosphere into the Troposphere and we are seeing it's temperature profile as we descend further. Eventually, the CO2 notch meets the region on the left that is all 'ragged'. This is H2O absorption lower in the Troposphere. This doesn't mean that CO2 still plays no part. Rather its probability of absorption is now so low, its clear to space altitude is so low, that even if an IR photon could get past all the CO2 molecules, the probabilty of being absorbed by H2O molecules means they still can't escape. So here H2O's behaviour dominates. If you keep coming back from time to time, I intend to put a post up here at SkS sometime in the next 2 weeks that will go into all this in some detail, including graphics that will make it a lot easier to understand than just words. -
Chris Colose at 17:20 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
galloping- You are free to believe pseudoscience. I couldn't care less, nor does it have the slightest impact on the progress in scientific literature. -
Jose_X at 16:59 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
gallopingcamel, 3: So if you read point 2, you know that I am definitely open (based on my limited experience solving equations of the atmosphere) to the idea that the greenhouse effect may be neutered in general.. at least in the long run. However, all the planets and astral rocks considered (and I haven't read the main part of the article/paper yet, but have seen discussions related to observed patterns of natural pressure/temperature linkages in the atmosphere) have not been impacted by man. There is no direct evidence from other planets of what can or can't happen under a scenario just like the one we have on earth. These rocks in space don't have huge bodies of water, for example. And, they also don't support diverse lifeforms. Driving the planet beyond the natural range, at some point, can definitely lead to harm to (human beneficial) organisms (including humans) at a wide scale. In other words, we need something more quantifiable and germane to our current planet and the times scales key to our survival and well-being. -
IanC at 16:42 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
gallopingcamel, Just because there are thermodynamics equations in Nikolov & Zeller does not mean that they have been applied properly. N&K first argues that the usual simple radiative balance model (which by the way is valid for a rapidly rotating planet with large heat capacity) is bad, and then proceeds to apply an even worse model (i.e. one that is valid for a slowly rotating planet with low heat capacity) to argue that the greenhouse effect can't explain the large temperature difference; in reality this difference is mainly due to their model being wrong for a rapidly rotating planet like earth. Now in order to explain this large dubious difference between observed and their model, they proceed to invent a way to explain the difference. Their argument that temperature is driven by pressure is just pure non-sense. There is nothing in their argument that prevents me from arguing that temperature is driven by pressured. The ideal gas law does not tell you the causality. What they did manage to show with their data is that the ideal gas law holds very well for all planets with an atmosphere. Onto their main claim: The surface temperature is governed by nothing more than the solar irradiance and surface pressure (i.e. Ts=f(S0, Ps )). This analysis is fundamentally flawed. In the previous section they've demonstrated precisely that the ideal gas law is a good model for the atmosphere, which implies that there is a strong relationship between surface temperature and pressure. If they don't remove this effect, they are essentially asking how temperature depends on temperature itself, rendering their analysis moot. I have to check the above carefully, though my intuition tells me that this is not right) Even ignoring the above, they have eight data points, where two (mercury and the moon) is fitted automatically with the choice of function. They are left with 6 data points, and they have FOUR free parameters in their best fit. If this is not curve fitting, what is? -
Jose_X at 16:41 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
gallopingcamel, 1: I called it curve fitting partly because I skimmed very fast on my first pass and saw very few equations. It seems the curve was fitted to data points, that it was derived through linear regression without a core physical model to justify the form and approximate values of the equations. When you derive something from more basic physical principles you leave a clear math trail that shows how the formulas led to the solution. No such trail exists was apparent, and, even if computers did much of the work of solving complex equations, I would have expected to see summarizing details of such equations. The only thing discussed significantly (that I noticed when skimming) in section 3 or 4 was pv=nrt. Even if that was at the core, you don't get the two exponential terms with very precise exponents by calling praising pv=nrt, but you can get it from a good computer program doing linear regression (which they acknowledged fit the data very well). If you want to point out to me the model/math from which their two exponential terms fall out, please do so, as it would save me time. 2: Ultimately I might be convinced that the "greenhouse effect" does not dominate. I have not derived any answers, so I don't know. I do find the greenhouse effect reasonable, and I give the benefit of the doubt that others have used computers to produced the math that separates the roles done by convection from that done by radiation (maybe this hasn't been done yet, I don't know). I don't doubt DLR and the radiation effects; however, while absorption might happen at a rate dictated by radiative theories, LTE and convection (or something else) can certainly mean that the lower gases absorb in much higher concentration than they emit. Emission can still be naturally based upon the local temperature which is regulated through some other mechanism (eg, convection) to match a natural (gravitational potential based?) lapse rate. In fact, this idea basically comes from current radiative theories (I think), except that they might not be realizing that the convection effect, when the proper physical solution is derived, dominates whatever extra absorption potential more CO2 would produce [to absorb more easily would have no effect on emission rate thanks to LTE, convection, and lapse rate tendencies, for example.] -
PT_Goodman at 16:29 PM on 29 February 2012Climate change models underestimate future temperature variability; food security at risk
logicman @ #1: In the Western New York State area and, I assume, in a considerably larger area we are having "snow drought" this winter and temperatures are generally above average. Snow fall is well below average...I believe about half of normal so far this winter. No real end in sight to the current weather pattern. We do get some now from time to time, but not much. This is an extreme contrast to last winter when, after 10 months of above average temperatures in 2010, we got hit hard in Dec. 2010 with cold weather and one snowfall of 48", a record snowfall for my small town. We made the national news on two major TV networks. I doubt that we've had 48" of snow this entire winter so far. And last year, the weather continued to be cold and snowy throughout the winter. Really a miserable winter and people could not remember one like it. Of course this set the climate skeptics to saying "see, the climate *is* getting colder." It's the variability of the weather recently here in my area that seems most striking, with winters seemingly swinging to extremes one way or the other. -
Doug Hutcheson at 16:24 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
owl905 @ 20, Thanks for the reply. I think the penny has dropped: For a given stable level of insolation and a given level of CO2, the surface temperature will be a constant inversely related to the temperature at the top of atmosphere. The radiation at TOA plus the energy of the heat trapped near the surface equals the energy provided by the insolation. By adding CO2, we are keeping constant insolation, but trapping more heat near the surface, so the TOA becomes cooler, to keep my equation in balance. So, for any increase in CO2, we will see TOA cooling and surface warming, but the whole equation remaining in balance. Have I understood correctly? -
BaerbelW at 16:12 PM on 29 February 2012German translation of The Debunking Handbook
chriskoz - Actually, we had already almost finished the German translation when we learned that the iPad app of a big German newspaper (Süddeutsche Zeitung) published an article about The Debunking Handbook. The article was therefore based on the English version as the German translation wasn't quite ready yet for publication. -
owl905 at 16:01 PM on 29 February 20122012 SkS Weekly Digest #8
Site lists are about the same here, with some daily visits to: Current Global Temps Solar Activity Arctic Ice (30% concentration) Arctic Ice (15% concentration) currently offline -
owl905 at 15:55 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Doug H @19 "What I am missing is why the top of atmosphere does not warm as well" Just to hit the spin button, the outer atmosphere actually cools during the early imbalance. Wundergroun NOAA Straosphere Chart It's coupled to earlier research that showed a connection to solar cycles and stratospheric temperatures. It doesn't "warm as well" because the same amount of heat is ... (drum roll) ... being trapped at the (near-)surface. -
gallopingcamel at 15:19 PM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
Chris @43, During our debates on "Science of Doom", Leonard Weinstein and I pointed out that for Venus it would make little difference to the surface temperature if the CO2 were replaced by an equal mass of Argon or Helium. In case you have forgotten, here are the links: http://scienceofdoom.com/2010/06/12/venusian-mysteries/#comment-2949 http://scienceofdoom.com/2010/06/12/venusian-mysteries/#comment-2953 The DALR depends on efficient heat transfer processes. In the troposphere of rotating planets heat transport is primarily achieved through convection and baroclinic eddies (mixing). Radiative processes are important only in the stratosphere where the lapse rate is usually of the opposite sign (temperature rises with altitude). Like Weinstein and this camel, N&K conclude that gas composition has an insignificant impact on planetary surface temperatures. Observations support this idea. As this thread includes "Runaway" warming let me say that if such a thing were possible it would surely have occurred during the last billion years and we would not be having this discussion. Here is a comparison between the IPCC's models that include strong positive feedbacks with one that places more emphasis on natural processes. Please note that Scafetta is making some progress on quantifying the processes that support his model using the ACRIM satellite: http://wattsupwiththat.com/2012/01/09/scaffeta-on-his-latest-paper-harmonic-climate-model-versus-the-ipcc-general-circulation-climate-models/ I must confess to some bias as Nicola Scafetta and Robert G. Brown are members of the Duke university physics department as I was for many years. We don't always agree but they have my respect and admiration. Jose_X @48, The references I provided are from physicists who are applying thermodynamics, Stephan-Boltzman etc. To dismiss this as "curve fitting" tells me that you need to take another look at the equations. -
Doug Hutcheson at 15:13 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Tom, thank you for this post, especially the list of points:- That if you reduce the escape of heat, but do not reduce the incoming heat, things warm up;
- That the atmosphere contains molecules that absorb Infra-Red radiation;
- That radiated energy depends on the temperature of the radiating object; and
- That the atmosphere gets cooler as you get higher, so that the Infra-Red absorbing molecules in the atmosphere radiate less energy to space than they absorb from the surface.
-
skywatcher at 14:58 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
#17 heijdensejan, hmmm, the skeptic choir clearly does not read any literature, where there is ample empirical evidence. Tom's OP provides one part of that evidence, but there's plenty more: 10 indicators of a human fingerprint on climate change Empirical evidence that humans are causing global warming And will it be a lot?: Empirical evidence for positive feedback lots of evidence for high climate sensitivity Two of the 10 human fingerprints in the first link show increased downwelling longwave radiation and reduced outgoing longwave radiation at GHG-specific wavelengths, which are direct observations of the enhanced greenhouse effect. Skeptics don't mention them too much... -
Composer99 at 14:44 PM on 29 February 20122012 SkS Weekly Digest #8
I read Deltoid regularly because I read a bunch of other ScienceBlogs blogs. Not much else on climate science. I live in Eastern Ontario. Incidentally, in this comment I linked to a report by CFI-CASS in Canada documenting a course taught at Carleton University recently which featured a great deal of climate science misinformation. Interestingly, the CFI-CASS report links to a lot of Skeptical Science posts on climate science as additional reading. -
Albatross at 14:40 PM on 29 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Prof. P. Body @95, I'd like echo/second your thoughts. Additionally, first people should use the correct nomenclature, traditionally "THC" refers to the thermohaline circulation. Second, the oceans are obviously significantly deeper than 700 m. Third, it is strange how fake skeptics continue to focus on statistically insignificant short time periods when we know the increase in temperature and OHC is not going to be monotonic-- they will still be playing that game when knee deep in water. It is called denial. Fourth, as I show below, you are correct, the links provided do not support their claim. One wonders whether or not they will cede that fact? So, regarding this as yet unsubstantiated claim. "The rate of SLR has slowed down over the past 5 years. ARGO data, while short, shows a reduction in THC of the oceans in the 0-700M volume." This is a badly worded argument. They speak of last 5 years of sea-level (since 2007), but then go on to mention the ARGO data which has been providing more-or-less uniform global coverage down to 700 m since the beginning of 2005 (see here), so let us use those data. I downloaded them from here. So the fake skeptics can check the numbers themselves. Since 2005 the 0-700 m global OHC has been increasing at a rate of 0.28x10^22 J/year, or increase of about 1.97x10^22 J between 2005 and 2011. So the claim that 0-700 m OHC is decreasing is demonstrably false. Further, since 2005 the 0-2000 m global OHC has been increasing at a rate of 0.732x10^22 J/year, or an increase of about 5.13x10^22 J between 2005 and 2011. But this is all for a very short period, so caveat emptor. -
scaddenp at 14:27 PM on 29 February 2012It's not bad
Reiterating skywatcher - its not whether warming is better or worse, but the rate at which change occurs. Rapid change (and this is very rapid change in geological terms) is associated with mass-extinctions. I doubt very much that humans would go extinct but the disruption to our agriculture will be very considerable. The question to ask is with the cost of mitigation is less than the cost of adaption. Studies so far say better to mitigate. -
scaddenp at 14:23 PM on 29 February 2012It's the sun
ShadedX - sorry, but it not clear what you do mean then. The statement "Since the sun has loss heated mass, it has less to burn and therefore less heat " does not follow. Since the CME happen all the time, if your statement were true, the sun should be gradually cooling which it is not. -
heijdensejan at 14:12 PM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
The skeptic choir is preaching this typical line Arthur Rorsch issued a new report here where he specifically states in this he states "The IPCC asserts that dangerous anthropogenic global warming (DAGW) is occurring, and that this is caused by the accumulation of human-related CO2 in the atmosphere. As yet, however, no indisputable scientific proof, or even strong empirical evidence, has been provided for such an effect, which therefore remains a matter of speculation." Simple explanations are required.... -
Albatross at 14:02 PM on 29 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Tom, Camburn needs to learn above a little concept known as "non-contributing areas" and infiltration (that is how aquifers are recharged). There seems to be an assumption that all the incident precipitation becomes runoff. That is obviously not what happens. -
New research from last week 8/2012
It would be interesting to see more detail of the Cohen et al paper. Do you know what temperature series they used?Response:[DB] An open-copy of the paper is available here:
http://web.mit.edu/jlcohen/www/papers/Cohenetal_GRL12.pdf
Datasets used were CRUTEM3 and NASA MERRA. -
Composer99 at 13:16 PM on 29 February 2012DenialGate - Highlighting Bob Carter's Selective Science
It turns out Bob Carter was a guest lecturer for a 2nd-year university course at Carleton University in 2010/2011 (see this report here). All I can say is that, while in general I'm sure Carleton has a strong science programme, this makes me ashamed to be an alumnus. -
Prof P. Body at 13:08 PM on 29 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Camburn old chap, you do realize, don't you that (even if on some ephemeral level) that you are just play-acting at analysis here. You specifically quote Mr. Rob P's graphic but miss-state what it shows. The referee called you one it and you just offer up bluster instead of substance. And now, without apparently even reading the study forming the basis of the graphic in question, you employ bravado and presumptuous hand-waving in your above comment. I do note your statement...and that your newer links simply do not support it. If you think analysis consists of "eyeballing" (as the Yanks seem to refer to it) a graph then you simply do not understand anything about science or statistical analysis (even my half-witted assistant Sherman gets this point). Fake-skeptic-fail. This august forum deserves a better class of troll. -
skywatcher at 13:04 PM on 29 February 2012It's not bad
ShadedX, the problem is that even if temperatures, say, in northern Canada or Siberia became suitable for growing wheat or whatever, or if it starts raining regularly in somewhere currently desertified (not generally forecast, but lets imagine for a moment)... you will not develop the soils required to sustain agriculture or forestry for many hundreds or more likely thousands of years. Soil development (pedogenesis) is a very slow process - a good example is the vegetation successions you see after ice retreat at the end of past glaciations - trees only thrive thousands of years after the first colonising grasses and shrubs. -
skywatcher at 12:54 PM on 29 February 2012It's the sun
ShadedX, coronal Mass Ejection (CME) activity varies with the activity of the Sun in it's approximately 11-year cycle, see for example this SEC plot. The ~2000 peak was reasonably large, and followed by the deepest solar minimum in many decades near 2009. The next peak is forecast to be much smaller, peaking in 2013 or 2014. The cyclicity does not explain long-term global warming, and the past decade has been dominated by the progression from the last solar max to the deep solar min. CMEs themselves have little to do with Earth's climate, except that there are more when the Sun is a bit more active. -
ShadedX at 12:21 PM on 29 February 2012It's not bad
I bet this has already been metioned, but what happens when the ice caps melt? Wouldn't high up northern places become habitable? How about the deserts , which will border the oceans, creating new forests for all. And most of all, wouldn't it be great for microorganisms (especially Archea) to live, therefore giving us new lifeforms that take the place of the old niche of the old lifeform -
ShadedX at 12:16 PM on 29 February 2012It's the sun
And as for you scaddnep, I am not talking about a star's lifetime. -
Camburn at 12:09 PM on 29 February 2012Satellites find over 500 billion tons of land ice melting worldwide every year, headlines focus on Himalayas
Prof P. Body@ 92: Yes, Rob's graphic at 29 would have used the data that supports slide number one of the following site. NODC global ocean heat and salt content You will note that the graph confirms my statement concerning THC of the 0-700M volume of the ocean. The trend of surface sea temperature would also seem to confirm the 0-700M OHC. SST 2003-2012 -
Jose_X at 11:24 AM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
That WUWT thread was closed, but it does present a number of questions to simpler radiative balance models. The main problem with the article is that it claims to present a model that is better than what climate science uses but it attacks a weak model that is not used by climate science. 2.1 A) The authors fail is to ignore an assumption of the model. Their criticism is thus not accurate. The 1-shell model assumes global surface temperatures are relatively similar. This assumption is why the simple model gets ballpark figures. This assumption implies that diffusion of heat through the atmosphere, wind/advection, and even side-to-side radiation together are highly efficient and help preserve the temperature everywhere on earth within a very "narrow" range. Because of this assumption implicit in the model, convection and 3D radiation need not be modeled explicitly, but their existence is leveraged as it is clearly a requirement for justifying using S/4. While observed temperatures around the world are not all even, these assumptions appear to be acceptable to first approximation. Note that clearly no significant chunk of earth's surface air temperature is near 0 K or near 120 C, the two extremes based solely on sun's irradiance. So the authors ignored this assumption of the model. Were it not that the model *does* consider convection indirectly, the points raised in this section would have merit. Their math is accurate. Although, the cs constant is virtually redundant (doing little beyond adding at least 2 extra irrelevant "significant" digits to a term). Yes, it is true that if you average many temperatures near 0 K as well as a few near 100 C and everything in between (weighted largely towards the low values), you get something rather different and significantly lower than the actual average. [I spent some time making sure the integral was set up properly (that the error from the strips making up the approximating polyhedron to the hemi-sphere did go to zero as the partition sizes got smaller). It was accurate (and I got to practice and gain insight into describing surfaces of integration). To come to that understanding, I first recognized that the outer integral with no phi dependence meant we were going around the circle adding up symmetrical "tangerine peel" slices. The d(cos (theta)) was also expanded to -sin(theta)d(theta), where theta varies from pi/2 to 0. We see that each differential (tiny) rectangle in a peel slice approaches the exact area of the underneath sphere (which looks like a flat plane). This is so because the sin (theta) factor makes sure the differential rectangles nearer to the poles are smaller exactly as dictated by the ratio of the minor circle at that latitude to the major circle at the equator (that ratio being sin(theta)/1). Since a tiny rectangle's % error goes to 0 as it gets teenier, we know the overall sum error also goes to 0 (eg, factor out the %-bounded error of each rectangle being added). With this verified, we return to d(cos (theta)) to enable a painless integration. The actual calculation is essentially K * integral (x^1/4 dx) = K*(4/5)*(x^5/4) to be evaluated from 0 to 1. Note that the dark side of the earth gets zero solar radiation, and this is accurately modeled since the integral approximating limit adds "tangerene peel" slices around only a hemisphere... yet then divides by the full surface area of the unit sphere, 4*pi.] 2.1 B) A few flaws exist in this section. First, we are adding convection to a model that already implicitly accounts for it in the lateral direction. This means that the conductance values given cannot be used since air cannot simply flow up and down at calculated linear rates while also flowing to the sides at possibly comparable rates. [Simple solution is to reduce the conductance value by 10-30%.] Second and most importantly, it fails to account for the gravitational potential energy cost of rising air, that is, for the natural equilibrium lapse rate. This mandates at least that Ta be made dependent on height (another change to the model). The simplest approach here is to set h to the height of TOA, but there are other possibilities (and emissivity would depend on height as well). Ts - Te will not be near zero but to first approx will be near the lapse rate requirements. Third, the equations solve for a steady state value. The equations are essentially devoid of a time dependency so assume S is constant. Since the earth rotates, the equilibrium values may not be reached, or at least S should be modeled as a function of time and other time dependencies should be introduced. [This point may be negligible. I haven't studied this physics, but I wanted to also list some *potential* flaws that have crossed my mind.] 2.1 C) This says very little. Keep in mind that it is criticizing what is known to be a weak radiation model. The model fails to explain the high DLR near the ground, true. One major reason for this is that H2O has a tremendous GHG effect here. A one shell model that is bound by TOA requirements obviously will fail. We would need a minimum of two shells (or a thick shell that has Te1 at the top and Te2 at the bottom). And the bottom layer would need to have an emissivity value to match the higher ghg effect of concentrated H2O. [Hottel, Leckner, and others have measured emissivity values. We can also use Beer Lambert law.] -
Camburn at 10:43 AM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
Ok....I didn't miss that thread, but I didn't spend much time reading it either. Within a few paragraphs it got so silly that it wasn't worth wasting time on. Somehow, I don't think the Unified Theory of Climate is the deathbed of AGW. I could be wrong, but if I am I promise that I will buy back that bridge I am now offering to anyone who believes this theory. In fact, I will even buy it back at twice the purchase price. And this is one inexpensive bridge. In fact, 100K will make a downpayment on it. Please respond to this offer via this site. IF the site slows down because of the interest in the bridge, just give it time, and I am sure your offer will make it through. Good luck on the bidding. -
DrTsk at 08:40 AM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
KR correct ~0.4% change in area vs. 15% change in pressure -
GillianB at 08:36 AM on 29 February 2012Mythbusting with fewer explosions
I went to the session in Lane Cove's fabulous new library (it's gorgeous!) and found it to be an interesting evening. Most attendees were already concerned about climate change and no diehard deniers were vocal. The format was fun because it promoted active learning by putting the audience in charge. Most of us learnt something new, or were reminded of things we had forgotten. What do I remember 12 hours later? Two things stand out.. I remember John's fridge door analogy that explains why a warmer arctic can lead to a colder Europe. I remember a couple of the graphs... the graph of 20th century temperatures is memorable because of John's explanation for why temps were stable in 1950s and 60s. That's a good example of the point in John's ABC article that it is memorable when a 'knowledge gap' appears and is filled. (John gave industrial sulphate pollution in the 1950s and 60s as the reason. Which leads me to wonder how much MORE warming we would see now if Chinese/Indian industry was clean.) All in all, it was very worthwhile. It's great to see John developing these excellent communication skills. I hope he continues to speak out, and that he can withstand the garbage thrown at effective communicators in this field. -
skywatcher at 08:30 AM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
And Steve Case, perhaps you could educate GallopingCamel (comment #40 on this thread) as to the greenhouse effect operating. GC believes some crackpot theory about gravity he read on WUWT... Very few people, indeed, disagree with the basic radiative forcing properties of CO2 that have been demonstrated for many decades, yet there are still enough to sow all sorts of confusion and misinformation. -
skywatcher at 08:23 AM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Lovely post Tom, very nicely explained. Steve Case, so you accept the fundamentals of CO2 causing warming (which puts you in a different league to Yogi, who clearly does not think this), but you don't accept the feedbacks. Some reading for you, then. Read the following post, the sixteen peer-reviewed papers that are referenced therein, and the five linked blog posts with further references to the literature: Empirical evidence for positive feedback. If you doubt the evidence presented there, maybe you could comment over there as to why positive feedbacks don't exist. And also then give us your hypothesis as to how we had ice ages... -
Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
DrTsk - Given that the radius of the Earth is ~6350km, and changes in top of troposphere are <1km, effective area changes are a trivial influence. And more than balanced by the fact that lower pressure requires a slightly higher temperature (as there are fewer molecules) to emit the same energy. However, those all represent very small changes in the spectra. -
Kiwiiano at 08:15 AM on 29 February 2012Mythbusting with fewer explosions
owl905: Neville Chamberlain knew damn well what he was up against, he also knew that the British military were woefully wound down and ill-prepared for the inevitable. The "peace in our time" was a charade to give them time to frantically remobilise and rearm. back to the topic.... ;^) -
DrTsk at 07:57 AM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
@11/boba/Kevin As the altitude increases the effective area increases and so the same amount of energy can be radiated at a slightly lower temperature -
scaddenp at 07:55 AM on 29 February 2012Radiative Balance, Feedback, and Runaway Warming
Camburn - it is GC's link unified theory of climate. Spenser has take on it by the way too - see his 30 Dec 2011 article. -
Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
boba, Kevin C - As the effective emission altitude increases, and given that the lapse rate means cooler air at higher altitudes, the amount of energy radiated to space will (initially) decrease. That means less energy leaving the atmosphere, and the climate warms. To a first order approximation, the atmosphere warms enough that the effective altitude is emitting same amount as the incoming energy - so it ends up near the same temperature (although pressure effects play into it as well), radiating away the same energy as before. -
scaddenp at 07:47 AM on 29 February 2012It's the sun
ShadedX - sorry but it doesnt follow. The path for stellar evolution is that heat from the sun will rise very very slowly (and has been doing so through geological time). As fuel is spent, it will expand and eventually engulf the inner planets, including possibly earth. But not for a few billion years. -
Kevin C at 07:41 AM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
boba: I believe that is the case. My crude explanation of the effect is that the increase in CO2 content increases the opacity of the whole column of gas. However the gas gets thinner as you go up, reducing the opacity. At some point the opacity gets low enough that a good proportion of the IR photons can escape without further re-absorption. As the opacity of the whole column increases due to increasing CO2, that height gets higher. I think it must be rather more complex than that though, because the emitted radiation higher up is at a lower temperature. Which means there are different number of photons being emitted in the transparent and opaque bands. I presume that codes like MODTRAN have to deal with that. -
RonManley at 07:40 AM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
It was predicted that one of the fingerprints of climate change would be warming of the troposphere at around 10 km altitude. I did my own analysis a few years ago and showed that this was indeed the case. -
New research from last week 8/2012
keithpickering - Good references. One important point in the discussions of those threads is that a step-change (although easy to fit to the data) is not meaningful unless the underlying physics would include such a step change. The model fit to the data has to make physical sense - and 'step changes' with large instantaneous energy changes really do not. -
Alexandre at 07:05 AM on 29 February 2012Greenhouse Effect Basics: Warm Earth, Cold Atmosphere
Steve Case: don't know if you challenge the accepted climate sensitivity, but denialists claims don't really know many boundaries. They freely wander from denying the warming, to denying the causes, to opposing the policies... and back step 1. One claim can be refuted, but moving goalposts are impossible to catch up with, specially in the attention span available from the broader audience. Like the Denial Tango goes, "I'm skeptical of everything I just don't wanna know".
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