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Comments 119101 to 119150:

119101. Riccardo at 05:42 AM on 20 May 2010
        Has Arctic sea ice returned to normal?
        Eric, indeed they show the comparison with ICEsat for 2003-2007 here.
119102. Stephen Baines at 05:36 AM on 20 May 2010
        The significance of the CO2 lag
        @ Frogstar "A review of biospheric feedbacks on temperature suggests that the effect may be small on a time-scale of years (about 3 ppmv CO2 /0C), and moderate at millennium time-scales (about 13 ppmv CO2 /0C), but large at a scale of centuries (about 20 ppmv CO2 /0C)" ? This sequence of scales refers to effects of soil microbial and plant physiological responses to temp (short term: years to decades), changes in soil and terrestrial plant carbon inventories (medium term: centuries), and deep ocean turnover, glacial loss and (perhaps) vegetation expansion (long term: centuries-millenia). Different mechanisms working on different time scales may have opposite effects on the relationship between temp and CO2. Unfortunately, most of the ones working in the short-medium scales seem to exacerbate the problems facing us. Of course, I'm mostly interested in getting through the next couple centuries...unless Monckton has a cure for old age as well as AIDs, that is.
119103. actually thoughtful at 05:35 AM on 20 May 2010
        Has Arctic sea ice returned to normal?
        Today the ice extent, which was reported in late March at various skeptic sites to be completely recovered, compared to the 30 year average, intersected the 2007 (lowest recorded year) line. And it intersected it at a steep slope. Compared to 2007, the 2007 extent was limited the whole time and followed the curve pattern of the 30 year average. This year, the decline is much steeper than the 30 year curve. How shall we hide THIS decline? http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png (usual caveats about weather is not climate apply, and of course I am just eye-balling the graph. For those who complain that 30 years isn't long enough – here is a graph that incorporates data back to 1900. http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seasonal.extent.1900-2007.jpg
119104. Riccardo at 05:32 AM on 20 May 2010
        There's no empirical evidence
        PaulK, my bad, not willing to be bothered by the constants i screwed up everything, or better, i didn't notice that the two constants c and b were the same. For the sake of this retraction, below I'll re-formulate the equations. Strange enough, I'm kind of happy that I did this error because before finding it I could not resolve some inconsistencies of the model results. :) As for the problem at hand, i'd like first to point out what the value of the response time τ should be. In the heat balance model, it is defined as the ratio of the relevant heat capacity (of the oceans, mainly) and the climate sensitivity. The oceans do not have a single response time for sure so we're forced to admit that it is the one relevant to the time span considered. In the Schwartz 2007 paper quoted above he gives numbers between 5 and 16 years based on two different approaches. The former looks definitely too small and is probably due to some error. So, in a time span of a some decades and in the presence of a linear forcing one would exepect a essentially zero OLR slope. A positive OLR slope indicates a negative change the in slope of the radiative forcing and viceversa. Looking at the radiative forcings provided by GISS, there has been a slowing down of the GHG forcing around 1990 which could have produce an increasing OLR. But the OLR data are in my opinion too noisy for any definitive assessment (see for example the annual global averages here). In any case, GHGs can still be (and in fact are) the primary (not the only!) forcing but some other effect may just have slowed down the overall forcing. ======== Correct equations from my comment #56 the temperature change is as before ΔT(t) = β*((t-τ )+τ *exp(-t/τ ))/λ OLR(t) = β *((t-τ)+τ*exp(-t/τ))-β*t for t > > τ : OLR(t) ~ -β*τ d OLR/dt = β*(1-exp(t/τ))-β = -β*exp(-t/τ)
119105. monckhausen at 04:52 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        Stephen Baines # 25: Thanks! I knew it must have been something really simple that had been overlooked.
119106. Stephen Baines at 04:28 AM on 20 May 2010
        The significance of the CO2 lag
        @ fydijkstra #29 Your analysis is not correct on several levels. Some clarification. First, it makes no sense to subtract out the effect of feedbacks from the direct effects of CO2 on climate. Just because they are indirect effects doesn't mean they won't respond add to the direct effects of increasing CO2. You're basically assuming the feedbacks that amplify the effects of CO2 on climate will magically cease to apply to the next century. Second, the feedbacks you are talking about are not the ones discussed in this paper. There are fast feedback mechanisms -- like water vapor, clouds, lapse rate -- that are involved in the response of our current climate to CO2. These sorts of feedbacks are included in typical climate sensitivity estimates based on modern models and empirical measurements. The paper here is addressing SLOW feedback mechanisms. These are not included in typical climate sensitivity measurements because they take a long time (often a century or more) to be manifest. They often include complex processes that are hard to predict. One example includes the feedback of temperature on albedo through ice sheets, sea ice extent and sea level. The topic of this paper -- changes to the carbon cycle in response to temperature -- reflect changes in the processes that store C in the oceans and land and take centuries to adjust to new temperature regimes. Time scales are governed by lifetimes of soil carbon, vegetational shifts and lags in ocean temp and deep water circulation. Given the complexity and the slow development of these feedbacks, it makes sense to look back in time to see how the system as a whole responded, so as to calibrate our expectations for the future. Because these feedbacks have not had time to manifest, they add to the sensitivity we estimate based on the direct effects of CO2 and the fast feedbacks. Moreover, because they are slower and have not been manifested yet, they actually mean the climate is more sensitive to CO2 that we think based on the fast feedback mechanisms we can observe over short time scales and in the models.
119107. chris at 04:21 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        The Ville, the CO2 molecule doesn't stop vibrating. A CO2 molecule is constantly undergoing translation, rotational and bond vibrational motions according to the thermal energy (temperature) of its surrounds. Absorption of a photon of LWIR of appropriate energy excites a specific bond vibrational mode promoting the molecule to an excited "high energy" state. The equilibrium state appropriate to the local temperature is a lower energy (ground state) and the relaxation back to this ground state is achieved either by re-emitting a photon, or by transmitting the energy to local molecules (which need not be IR absorbing; e.g. O2 or N2) by molecular collisions (thus raising the temperature of the gas a tiny amount).
119108. Paul D at 03:59 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        Interesting! My introduction to Kirchoff was as a teenager in electrical engineering! http://en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws Now he turns up in climate science. OK. I understand Kirchoffs law, applied to large bodies. But I don't really understand how at the quantum level a CO2 molecule stops vibrating and suddenly re-emits the IR electromagnetic wave. What makes this happen. I can understand the absorption, but not so clear on the emission.
119109. John Russell at 03:33 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        KR: I can't remember reading yours before but it looks like we both came up with exactly the same analogy independently, right down to humans raising the sides; so I guess it must be a good one but I'm happy to acknowledge you were first. I arrived at it as a re-think of the 'bucket with the hole analogy' where naturally-produced CO2 (the tap) is balanced by the same amount of CO2 being locked-up by natural processes (leaking through the hole), thus keeping atmospheric CO2 in equilibrium -- before a small but steady amount of human-produced CO2 causes the level to slowly rise and the bucket to overflow. But that's off topic and I guess will probably hit the cutting room floor. I agree; analogies are very useful.
119110. Stephen Baines at 03:31 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        Monckhausen at #23 Besides the fact that they start by understating the direct contribution of CO2 to the GH effect (more likely 15-25% depending on whether you include clouds), they are ignoring the feedback that increased temperatures due to higher CO2 have on water vapor in the troposphere. That water vapor amplifies the effect of CO2 on the GH effect substantially. Water vapor is the most powerful greenhouse gas This seems to be a common "mistake."
119111. thpritch at 03:19 AM on 20 May 2010
        The significance of the CO2 lag
        It should be noted that while increases in the CO2 concentrations measured in Antarctic cores lag observed increases in calculated temperatures obtained from isotope ratios from those same cores and from Southern ocean sediment cores, that same lag is not seen in mid-latitude core samples. In the March 14, 2003 issue of Science, page 1730, Caillon et. al. state the following: "We follow Petit et al. (1) in assuming that CH4 can be used as a time marker of the glacial- interglacial warming in the Northern Hemisphere. The CH4 increase at 2810 m, which occurred when _40Ar reached its first maxima, would thus signal a first warming in the North leading to some equivalent of the Bølling-Allerød interval. We point here to the existence of a cold reversal at the start of termination III (1), now firmly identified in both our detailed deuterium and _40Ar Vostok profiles. The sudden increase of 150 ppbv practically coeval with the _40Ar maximum would be linked to the main deglaciation, thus indicating that Vostok temperature began warming _6000 years (Fig. 3) before the associated warming in the Northern Hemisphere (1)" (Their reference 1 is 1. J. R. Petit et al., Nature 399, 429 (1999).) In other words, while changes in the Earth's orbit relative to the Sun may have been the driving force for the warming of the Southern Ocean and Antarctica, the elevated CO2 concentrations from the outgassing of the Southern Ocean was likely a major, if not the major, driver in the warming and deglaceration of the Northern Hemisphere.
119112. Doug Bostrom at 03:18 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        I don't think it's too off-topic to contrast G&T's kamikaze attack on climate science w/the National Academies of Science release today of three reports regarding climate change. This NAS effort excellently illustrates just how far off track G&T have wandered with their thought experiment. Follow this link to get to the NAS materials: Strong Evidence on Climate Change Underscores Need For Actions to Reduce Emissions and Begin Adapting to Impacts For us amateurs and bystanders including G&T, here's the significant nut of the entire rather overwhelming set of three reports: Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities. That's the NAS speaking, not known for its rhetorical liberality. In this arena G&T are no better or worse or more importantly useful to the advancement of understanding than most of us other odd ducks who natter away on climate. We offer our best interpretations and guesses regarding a topic that we can't actually attack in a serious way because we're innocently too ignorant of the specialized information and practice needed. Like most of us, G&T's perspective, level of information and specific skills on the topic of climate change are not sufficient to produce useful contributions.
119113. monckhausen at 03:08 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        In a Geocanada 2010 talk last week, the presenter claims that the greenhouse effect is 34.5C and that CO2 is responsible for 10% of it, which is 3.45C. From this he concludes that a doubling of the current CO2 concentration in the atmosphere adds only 0.345C to global temperatures. Can anybody explain, how someone can arrive at these numbers? The talk was recorded as an mp3 and is found here.
119114. chudiburg at 02:29 AM on 20 May 2010
        It's cooling
        We have just experienced the warmest January-April period on record when considering the combined land and ocean temps. Here is the link. http://www.ncdc.noaa.gov/sotc/index.php#global_highlights
119115. Albatross at 01:36 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        "Has the greenhouse effect been falsified?" No it has not. IMO, G&T should have never gone to press and represents yet another attempt by the contrarians to create the impression of debate based on sub par science (and some might argue that that description is too generous) and sow doubt amongst lay people. Steve Carson also does an excellent (and thorough) debunking of G&T. That all said, the terminology "greenhouse effect" is clearly a misnomer and as such remains problematic and confusing to some. Anyhow, congratulations (and a big thanks) to Halpern et al. for making the effort and taking the time to soundly refute G&T.
119116. sylas at 01:12 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        HumanityRules, I am open to clearer ways to express this! On the other hand, there will always be a need to explain it further, and that's ok. The current two sentences to which you refer are: The Earth's surface is about 33 degrees Celsius warmer than required to radiate back all the absorbed energy from the Sun. This is possible only because most of this radiation is absorbed in the atmosphere, and what actually escapes out into space is mostly emitted from colder atmosphere. The surface of the Earth is around about 15C, or 288K. If you take a uniform temperature and high emissivity you get about 390 W/m² emitted. The real value is a few W/m² higher mainly because temperatures are not uniform, which gives slightly higher total emission thanks to a 4th power relation from temperature to emission. But the energy we actually absorb from the Sun, in total, is about 240 W/m², which is what you get from a sphere at a temperature of about 255K, or -18C. What the Earth radiates into space is about 240 W/m², in total. This is huge difference between what is radiated at the surface and what gets out to space. This is only possible because surface radiation mostly never gets out to space, but is absorbed in the atmosphere. What eventually gets out to space is mostly emitted within the atmosphere, where it is colder. You also ask: Do you know if there has been a change over time for the past couple of decades to the results seen in Fig 1? I just noticed the other day, as I was browsing this site, a nice discussion of the changes from 1970 to 1996. It's described, with some good illustrations, at Empirical evidence that humans are causing global warming. Note that you get different emission spectra at different seasons, times of day, and locations. So changes actually refer to a global mean, and not the specific observations on a particular day, and a certain place, which I am using here to show direct observations of the greenhouse effect at work. I think we are best to continue to focus on the existence of the greenhouse effect in this page, rather than how it may be changing. As for the absorption spectrum of water; it is intrinsically complex in any case, with a large number of distinct absorption bands. On top of that it is not well mixed in the atmosphere. And to finish things off, you get the differences associated with phase changes, which apsmith is speaking of.
119117. KR at 01:11 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        Hey! The tap/bucket analogy was mine! LOL... I'm certain that I'm far from the only person who has come up with this comparison - I first used it years ago when discussing evolution with some people who thought that it violated entropy/thermodynamics. I think it's a useful mental image for GHG warming, and I've found it helpful in explaining these concepts to a number of people. One nice thing about it is that you can directly see in it that energy is flowing in the correct direction. But as sylas said, it's much better to actually understand the system itself, rather than analogies.
119118. Eric (skeptic) at 00:53 AM on 20 May 2010
        Has Arctic sea ice returned to normal?
        Riccardo, thanks for the reply. The PIOMAS seemed to be used for projection in the paper, namely 7 experiments to test the predictive skill of the model. I was hoping for a followup paper here: http://psc.apl.washington.edu/publications/publications.php?year=2009 but there was only a Jan 2009 paper talking about the model, but not the predictions made in the previous paper or the success of those predictions. Direct independent measurements would seem appropriate and they are at least partly available for 2008 to compare to the predictions.
119119. HumanityRules at 00:46 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        18.sylas Thanks I sort of guessed that somebody was going to tell me that all that energy in the ocean was irrelevant to this. I'm not sure those two sentances go well together. I think something is wrong with the wording in the first, it doesn't seem to make sense. Do you know if there has been a change over time for the past couple of decades to the results seen in Fig 1? Also you make the following point "Water vapor has complex absorption spectrum". I thought water as a vapour has a discrete absorption spectrum. Isn't it condensed water droplets that's more complex? (So says apsmith on your forum)
119120. PaulK at 00:23 AM on 20 May 2010
        There's no empirical evidence
        Riccardo, Just a couple of points: 1) I have never had a problem accepting the possibility of OLR increasing (even if CO2 is having some warming effect at the same time). If you re-read my first post again, you will see that my argument is that you cannot have CO2 as the PRIMARY driver of heating from the 70s, and have the OLR response which is critical to that heating overwhelmed by thermal emissions derived from some other unspecified source of heating - unless, that is, some other basic assumptions are wrong. 2) You wrote: "Even assuming its validity, for example, the position of the minimum in the OLR critically depends on the choice of the parameters involved, not just the actual time response of the system. There's no point in pushing a model beyond its limits." I disagree strongly with this statement. For a geometric growth in CO2, the minimum (perturbation) in OLR is always achieved at exactly the equilibration time. This is completely independent of the choice of any other parameters. Small variations away from the geometric model, provided they are fitted to the actual data, will always yield a minimum very close to the equilibration time. This is dictated by simple mathematics and requires only two assumptions: (a) CO2 does not cause planetary cooling at some stage in its affect on the system (but it can be multimodal in its affects) (b) Equilibrium temperature change is linearly proportional to the total heat energy gained/lost by the system (i.e. constant specific heat capacity). If the issue here is that I did not adequately explain the maths behind this, then please let me know and I will be happy to provide a more formal proof of this.
119121. sylas at 00:15 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        Humanity rules, the sentence you quoted speaks of "this" radiation, which in the context of the preceding sentence, means the thermal radiation emitted from the surface. Most of this radiation is indeed absorbed in the atmosphere.
119122. sylas at 00:10 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        Followup to Berényi's correction. How's this. I propose to get rid of some technical terms not used in the rest of the essay anyway. I have suggested the incorrect phrase be replaced to read: In some frequencies, thermal radiation is blocked very efficiently, and the backradiation shows the temperature of the warm air right near the surface. Thanks again -- sylas
119123. sylas at 00:03 AM on 20 May 2010
        Has the greenhouse effect been falsified?
        Thank you Berényi, you are quite correct! I have emailed John to get that fixed. Much appreciated! -- sylas
119124. Berényi Péter at 23:46 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        Chris Ho-Stuart at Wednesday, 19 May, 2010 wrote: In some frequencies, thermal radiation is blocked very efficiently, and the "optical depth" of the atmosphere is very small. Come on. If radiation is blocked efficiently, optical depth is not very small, but huge. If I₀ is the intensity of radiation at the source and I is the observed intensity after a given path, then optical depth τ is defined by the following equation: You can easily verify for yourself that whenever I gets tiny compared to I₀ ("radiation is blocked very efficiently"), τ should be large.
119125. Arkadiusz Semczyszak at 23:24 PM on 19 May 2010
        The significance of the CO2 lag
        Notes about "not ocean": 1st Ocean - a direct exchange of gas (CO2) is really small - as indeed gives literature cited here. 2nd ... and soil: "We estimate that the global RS in 2008 (that is, the flux integrated over the Earth’s land surface over 2008) was 98 ± 12 Pg C", "The scientists [B. Bond-Lamberty and A. Thomson, JGCRI/Pacific Northwest National Laboratory] also calculated the total amount of carbon dioxide flowing from soils, which is about 10-15 percent higher than previous measurements. [80.4 (range 79.3-81.8) Pg C - CDIAC]". 3rd Currently, all the time, the ocean absorbs more CO2, than emits. 4th So now as in the past high concentration of CO2 in the atmosphere was strongly correlated with the delta 13C (then always increase the amount of carbon isotope of light, ratios to heavy isotope of carbon). 5th During El Nino is strong growth in CO2 emissions (from carbon-light). Airs on maps (eg http://www.nasa.gov/images/content/403382main_portalBigPollution.jpg) often observed a significant increase in the concentration of CO2 in some the areas of high NPP in the oceans. This is most likely the result of violent mortality of algae (and subsequent strong development of putrefactive bacteria) in the phase of El Nino, rather than reduce the solubility of CO2 in warmer water. The study of this compound (algae - bacteria putrefaction - El Nino - CO2) has been neglected in the science - now I could only quote the work of research showing the agreed methodology.
119126. John Russell at 23:06 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        I would have thought that energy absorbed by the atmosphere can then, in turn, migrate to the sea, HumanityRules. Surely the whole nature of energy is that it's not in a steady state, it moves around and gets converted from one state to another but is never destroyed? I guess my terminology might be wrong but in principle that's what's happening.
119127. HumanityRules at 22:56 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        "This is possible only because most of this radiation is absorbed in the atmosphere" I thought most of the energy is absorbed by the ocean?
119128. michael sweet at 22:26 PM on 19 May 2010
        The significance of the CO2 lag
        Thingadonta, Your "guessing" based on "the few papers I have perused" does not sound to me like a serious review of the relevant literature. The effects you mention are normally included in models of the climate. If they were not included the models would not be state of the art and publishable. The papers do not give a laundry list of everything in their model, it would take too much space. If you want to participate in an integellent discussion you need to inform yourself of what is already known. It is not the responsibility of those you are debating to find all this information and "proove" it to you. Why do you think these effects were not included in this paper? The only reason I see offered is that it allows you to discount the findings. You need to offer evidence to support your claim that these effects were left out, a "guess" is not evidence.
119129. CBDunkerson at 21:39 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        Has anyone seen graphs similar to those above, but covering a wider range of the EM spectrum? If we look at the wavelength factors along the top of each graph we see that the lowest value (on the right) is 6 micrometers... while the visible spectrum would be all the way down around 0.4 thru 0.7 micrometers. Ultraviolet light would go all the way down to about 0.01 micrometers. On the other hand the full range of infrared would go off the left side of the chart up to 1,000 micrometers. My understanding is that microwaves and x-rays (the ranges beyond those described above) represent a minuscule portion of the Earth's energy balance and can thus safely be ignored, but I think it would be very interesting to see the incoming and outgoing visible light range and how the atmosphere is impacting the rest of the infrared and ultraviolet light coming in from the Sun.
119130. pdt at 21:33 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        "The surface of the Earth actually receives in total more radiation from the atmosphere than it does from the Sun." The confusion about the meaning of this sentence might be clarified for some by noting that the origin of all the energy is from the sun, just like the energy from the gas in your car is from the sun, it has just been transformed to another form (wavelength) by processes in the atmosphere, just like the energy in the gas in your car has been transformed from solar energy by biological and geological processes.
119131. Riccardo at 21:06 PM on 19 May 2010
        Has Arctic sea ice returned to normal?
        Eric, you may have noticed the meaning of the last three letters of the acronym PIOMAS: Modeling and Assimilation System. This means that it is not a pure model for projection; instead, measured relevant weather data are used to calculate actual ice volume. Projection ability relies on the quality of the weather data input and eventual failings do not disprove the ability to assess current ice volume. Assuming no trivial errors in the model, the only way to disprove its calculation ability is with independent direct measurements of ice volume.
119132. Riccardo at 20:57 PM on 19 May 2010
        Accelerating ice loss from Antarctica and Greenland
        The mass loss acceleration from GRACE data appears to be independently confirmed by high precision GPS land uplift measurements in western and southeastern Greenland.Here's the paper (paywalled), here the story reported by ScienceDaily.
119133. Eric (skeptic) at 20:34 PM on 19 May 2010
        Has Arctic sea ice returned to normal?
        Re 54: the PIOMAS model is already falsified by the failed predictions in GRL "Ensemble 1-Year predictions of Arctic sea ice for the spring and summer of 2008" by Zhang et al. Of course there were uncertainties such as initial conditions, weather patterns changes, weather chaos and water temperatures, but some of those were controllable within the model (some like weather are not). Is there a follow-on paper to this? Don't know, I am still looking.
119134. thingadonta at 19:33 PM on 19 May 2010
        The significance of the CO2 lag
        "it would be highly useful if you were to beaver through some of the relevant literature and discover whether the factors you mention are indeed actually missing from simulations. " Granted, but the few papers that I have perused do not investigate/discuss possible/modelled cloud cover changes and their effects on T. Cloud cover is also one of Roy Spencer's pet skeptical arguments against strong AGW, I think. There is no discussion in Sheffer 2006 of other various factors in their LIA c02 feedback calculations, a fact they readily acknowledge. They only mention that the various models/simulations are consistent with each other. But they are obviously not incorporating some modern cloud cover trends and their known effects on T. For example, the point on cloud cover and its effect on average T has been used to criticise some claims made about Australia's more recent warming trends. Australia's SE current/recent extended drought means that average annual temperatures are going to be superficially enhanced because cloud cover is obviously reduced during drought periods, and temperatures will therefore average out higher (eg annually), even if there is no 'background' warming. Furthermore, any changes in prevailing wind regimes, at low or high levels, will also change average T, regardless of 'overall' warming. Changes in wind regimes could also enhance night time average temperatures as well, if the wind changes during drought periods are towards a more northerly direction for eg Australia (eg from the Indian ocean-inferred for SW WA extended lower rainfall totals since the 1970s). The same goes for before/after the LIA. Not only can cloud cover changes affect T, but changes in European wind regimes could also affect T. (The recent European winter was bad partly because of the prevailing winds. Changing European wind regimes were even mentioned by some ancient historians about the time the Roman Empire collapsed, I think, but I will have to look that one up). I'm guessing these sort of effects are not 'covered' in any of the paper simulations, whether past Ice Ages, or recent LIA.
119135. Riccardo at 18:38 PM on 19 May 2010
        There's no empirical evidence
        PaulK, in the comment i responded to you were making a general point on the possibility to have an increasing OLR. What I tryed to show in my comment is that it's actually possible. But we cannot go much further than the overall behaviour with such a crude energy balance model. Even assuming its validity, for example, the position of the minimum in the OLR critically depends on the choice of the parameters involved, not just the actual time response of the system. There's no point in pushing a model beyond its limits. As for the details you're asking for, well, you know, it's a travesty that we cannot track the details of the energy flow through the climate system ;). Stay tuned, hopefully climatologists will come out with a solution or at least with a better aproximation to the short time variability issue. P.S. The easiest "solution methodology" of the energy balance equation I think is to transform the differential equation into an integral equation (see here, for example) which is much easier to solve numerically for any arbitrary forcing.
119136. fydijkstra at 18:34 PM on 19 May 2010
        The significance of the CO2 lag
        Interesting article! Now we know, that the positive feedback is 15 to 78% on a century scale. But does this mean that we should expect an additional warming in the next century? No, because the positive feedback – if it exists – is already included in the observed warming of the last century. From 1910 to 2009 the global temperature rose 0.71 degrees while the CO2-concentration rose 87.7 ppm (from 299.7 to 387.4 ppm). If the positive feedback is 15-78%, we can calculate that 0.40 to 0.62 degrees of the observed warming were due to direct heat trapping and 0.09 to 0.31 degrees due to the positive feedback. A simple extrapolation to the next century: in 2110 the CO2-concentration could be 560 ppmv. We can expect a total warming of 0.71 x (560-387.4)/87.7 = 1.4 degrees. Of this warming 0.8 to 1.2 degrees will be due to direct heat trapping (supposing that this effect is not yet saturated) and 0.2 to 0.6 degrees to positive feedback. Not much to be worried about, I think.
119137. sylas at 18:18 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        perseus, on radiation balance, we never speak of radiation balance at the surface itself. We speak there of energy balance. Radiation balance applies at the top of the atmosphere, because this is the only way energy arrives at Earth or is taken off Earth out into space. Radiation balance also applies in the stratosphere (or very close to it) because there is no convection, no weather, no precipitation. In fact, this is a defining quality of the stratosphere for any planet. It is that part of the atmosphere which is in a radiative equilibrium, with negligible vertical energy flows by convection. But note that the title of the diagram I provided is "Global energy flows". At the surface and in the troposphere it is all about energy balance, not radiation balance.
119138. sylas at 18:11 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        John, the tap analogy is a very good one, and can be used to good effect. It is just an analogy of course, but such things can be excellent stepping stones to understanding of the actual system itself.
119139. sylas at 18:09 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        perseus, in the paragraph you have quoted, I am speaking of a continuous flow of heat between the surface and the atmosphere. Since the atmosphere is (and remains) cooler than the surface, there is a continuous flow of heat from the surface to the atmosphere. The backradiation is large; but it is not as large as the thermal radiation up from the surface. The actual heat flow, in the proper sense of a flow of energy between two reservoirs at different temperatures, is difference between thermal radiation up and thermal radiation back down. This is 63 W/m² of radiant heat flow, using the numbers from the energy balance diagram. To this we add 97 W/m² of sensible heat flows (convection and latent heat). This never comes to equilibrium; or rather, it is a dynamic equilibrium, because the Earth is continually receiving energy from the Sun. This means it maintains its temperature, and there is an unending flow of heat from the Earth to the Atmosphere. You are quite right that the heat sources within the Earth itself are negligible. The temperature of the Earth and the atmosphere are maintained by a continuous flow of energy from the Sun, to Earth, and then back out to space.
119140. John Russell at 18:03 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        Sorry, I now get it. Thanks for a very clear explanation, sylas. I wrote my comment and then yours appeared before mine after I'd posted. I think what is being said is that the Earth is like a bucket with a tap running into it. The inflowing water from the tap is matched exactly by the water flowing over the rim of the bucket. It's in equilibrium. What's happening within the bucket (the planet and its atmosphere) is irrelevant. Of course, what humans are doing at the moment is raising the sides of the bucket... and increasing the pressure at the bottom -- or is that taking the analogy too far?. Sorry if I'm being simplistic but it's the only way I get my head round things.
119141. perseus at 17:56 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        17 Upwards atmospheric convection 80 Upwards latent heat of evaporation Yes any radiation imbalance under a steady state scenerio has to be made up from these other heat transfer movements, really this should be made clear.
119142. perseus at 17:48 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        "The net flow of radiant heat is still upwards from the surface to the atmosphere, because the upwards thermal emission is greater than the downwards atmospheric backradiation. This is a simple consequence of the second law of thermodynamics" I think this extract is at best confusing. If we ignore the heat source in the earth itself and direct anthropogenic heat which are insignificant, surely the net heat flow must balance at any point under steady state conditions, that is in the absence of a greenhouse effect. Radiative differences may occur of course due to convection within the atmosphere. There will be a small net radiative input with a greenhouse effect of course. Neither is it clear what this has got to do with the 2nd law.
119143. John Russell at 17:47 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        Forgive me interjecting; I puzzled over the same sentence but I'm not a scientist. Should not the sentence therefore read, "The surface of the Earth actually receives in total more longwave radiation from the atmosphere than it does from the Sun." Or have I misunderstood?
119144. sylas at 17:44 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        Surprisingly, this is correct as given. Here's a rather more detailed account. The energy balance for the Earth is described in: Trenberth, K.E., Fasullo, J.T., and Kiehl, J. (2009) Earth’s Global Energy Budget, in Bulletin of the Amer. Meteor. Soc., Vol 90, pp 311-323. (open access link) The following diagram from that paper summarizes the situation: Basically, we are comparing the 184 W/m² from the Sun which gets to the surface, and the 333 W/m² which comes to the surface from the atmosphere. It may also help to do a quick accounting with these numbers: Total input to the surface (in W/m²): 184 Solar radiation 333 Atmospheric backradiation --- 517 Total Total out from the surface: 23 Reflected solar radiation at the surface 17 Upwards atmospheric convection 80 Upwards latent heat of evaporation 396 Thermal radiation emitted by the surface --- 516 Total Imbalance: 1 W/m². These numbers are not perfect. In fact, the lead author of the paper has been particularly strident in calling for better measuring systems to nail down the balance much better. There are several good pages here on that matter. See, for instance, Trenberth can't account for the lack of warming, and John's recent blog Tracking the energy from global warming, which explains some of the more direct attempts to measure the imbalance, and obtain values around about 0.6 ± 0.2 But to understand the point you have quoted, a crude estimate will suffice. The Earth's surface is quite warm (fortunately for us) and so it radiates a LOT of heat. On top of that, heat is carried away by sensible heat flows: convection and latent heat. By conservation of energy, that has to balance what is being received, with any small imbalance being because the planet warming or cooling by absorbing extra energy or shedding it. At present, we have global warming, and the ocean is sucking up some of the available energy as it slowly increases in temperature. But even when there is no warming or cooling, you still have all that energy leaving the surface, which must balance with the energy coming in. Most of the energy coming to the surface -- about 65% or so -- is atmospheric backradiation. Note that this has the advantage of coming in both night and day. Solar input in the day is larger, but at night it is zero. Without the natural greenhouse effect, nighttime temperature on Earth would plummet as the surface radiated away its energy straight into space.
119145. PaulK at 17:30 PM on 19 May 2010
        There's no empirical evidence
        Riccardo #56 Thanks again. The solution methodology I outlined (superposition) does not have to assume a constant linear forcing with time, but I believe should give an identical analytic answer to Schwartz for this assumption. (I will check this as soon as I have a little time.) Schwartz was roundly criticised as I recall for underestimating tau. The CMIP models have an effective tau in excess of 80 years. If you substitute realistic values in Schwartz's derivative term for a tau of 80 years or greater, you should see a negative gradient over the period 70s to end of century assuming a perturbation from quasi- radiative equilibrium, because over this time period t is much less than tau. This is exactly my point. So why did we see a rising gradient in OLR over this period? Either (a) the CO2 response was overwhelmed by other SW effects over this period (such as decreasing aerosols, decreasing albedo, etc), in which case CO2 was not the primary driver OR (b) there was a planetary oscillatory effect of released energy causing a rise in surface temperature, in which case CO2 was not the primary driver OR (c) that the equilibration period is a lot less than inferred by the IPCC from the AR4 "constant composition" experiments, in which case the climate sensitivty to CO2 has been overestimated OR (d) that there was a historic commitment to a trend of rising OLR following a period of 30 years of decreasing temperatures, in which case the CMIP modeling of quasi radiative equilibrium using aerosol forcing as a matching parameter becomes highly suspect. In any event, it seems to me that one hits a major problem of consistency.
119146. e at 17:25 PM on 19 May 2010
        There is no consensus
        Poptech, Yes and I pointed out that you were wrong, the link did not "completely" refute that video. The video points out that practically anyone with a B.S. degree is eligible to sign this petition. This is the key flaw in the Petition Project. The link you provided did not refute this claim.
119147. MarkR at 17:25 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        RSVP: I think this makes sense, if you divide the Earth's temperature^4 by the blackbody temperature^4 (i.e. temperature minus 33C) then you get a factor of 1.75, i.e. yes, more downwards longwave than solar longwave! Sounds nuts. I did the same calculation for Venus a while back and the factor is obscene; over 90% of the heat flux to Venus' surface can't be solar in origin.
119148. thefrogstar at 17:04 PM on 19 May 2010
        The significance of the CO2 lag
        We should not abandon our sense of humour either, which is why I post this bit separately. Did anybody else start sniggering at the back when they read: "A review of biospheric feedbacks on temperature suggests that the effect may be small on a time-scale of years (about 3 ppmv CO2 /0C), and moderate at millennium time-scales (about 13 ppmv CO2 /0C), but large at a scale of centuries (about 20 ppmv CO2 /0C)" ? -So it's the middle bit that's the problem (which can be another way of saying that you can get any result you want from a model by selecting the starting and end points of your observations). This suggests two approaches to reducing problems associated with “global warming”: Either a) Wait a few hundred years until the “long term” sets in, and any problem will auto-correct, or b) Start taking measurements later on (or, better still, not at all) because then you will never progress from the short-term to the medium-term, which seems to be where the main problem lies. In either case the solution is to simply ignore the problem or don't try and measure it at all. Now that's what I call kinetics! Discuss.
119149. RSVP at 16:36 PM on 19 May 2010
        Has the greenhouse effect been falsified?
        "The surface of the Earth actually receives in total more radiation from the atmosphere than it does from the Sun." I think there is a typo needing correction here, but if not, (as in the last article), taken on face value, the implication is another runaway scenario.
119150. thefrogstar at 16:10 PM on 19 May 2010
        The significance of the CO2 lag
        I'm glad you keep returning to this topic John, and I hope you continue to do. (Not least because I usually seem to arrive late when the insults have already been hurled and everyone seems to be packing up and going home). I also think it's helpful to remind our selves what we may be arguing about, and that we may arrive at rather different conclusions from reading the same paper. Reading the Scheffer paper, I found it to be a worthy and cautious academic paper which presents an alternative (not better) method of modeling, primarily, the effect of temperature on atmospheric CO2 concentrations (this being the more problematic side of the issue). They highlight, and seem well aware of, complexities, and seem quite honest and open about assumptions and possible sources of error. In fact, most of the discussion appeared to be acknowledging these matters. Now, what I did not find is this: I did not find a masterful tour-de-force of non-linear mathematics modeling systems with multiple feedbacks. I expect the authors didn't think so either. That was why I was so pleased to find the "Science of Doom" site that you directed people to earlier this week. It seems a great educational site, and I was fascinated by the "Strange Case of Stratospheric Water Vapour, Non-lineaities and Groceries". Fascinated, but not surprised at learning about one more variable to throw into the pot. I too would urge peole to go and read on this site. Am I expecting too much from the Scheffer paper? I don't think so, because as some one else has already commented elsewhere on this site, if this science is being used to justify proposed changes to our economic and technical way of life (not to mention taxes!), then it's gonna have to be exceptionally good. A model using "the mid-range IPCC estimation of the greenhouse gas effect on temperature [to] suggest that the feedback of global temperature on atmospheric CO2 will promote warming by an extra 15-78% on a century-scale" just doesn't do it for me. Sorry. As far as other details of the Scheffer paper goes, it doesn't really seem to say much about lag phases (not to me, anyway). Enzyme kineticists commonly observe lag-phases with simpler sytems that don't have the feedback mechanism of CO2-based warming. A lag-phase doesn't necessarily rule-in or -out the meat of the argument which is the quantitative aspect. The existence of a lag-phase certainly merits a qualitative explanation of the deviation from a simple rate-equation, and I think it is always important to keep in mind what assumptions underly a model. Assumptions that are forgotten can come back and bite you if a model is applyed to cricumstances where they no longer hold. Thank you to Ned (post#13), interesting abstracts though I doubt I shall find time to read the whole papers.

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