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Comments 130651 to 130700:

130651. Patrick 027 at 15:14 PM on 2 December 2008
        Arctic sea ice melt - natural or man-made?
        I just realized I made a mistake in describing vorticity in comments 284, 287: pure orbital/curvature vorticity is NOT equivalent to solid body rotation. Solid body rotation requires a shear vorticity that is equal to the orbital/curvature vorticity, so that the total vorticity is equal to twice the value of either component. But it is true that fluid motion locally equivalent to solid body rotation occurs when dv/dx = - du/dy and regionally equivalent over some region in which both are constant in space. Suppose an x,y system is chosen not with respect to north and south but with respect to wind direction at a point O, so that the wind is in the x direction; v = 0 at O. If the wind is along concentric circlular streamlines (or locally fit a portion of such a pattern) centered at distance R in the y direction from O, so along the y axis, the wind is in the +/- x direction. If the wind speed does not vary along streamlines, then in this case, the shear vorticity is -du/dy. For solid body rotation, it can be shown that along y, u is linearly proportional to the distance R from the center of rotation (the center of curvature of the streamlines), so that -du/dy = u/R. For solid body rotation, the wind speed is the same along a streamline, and thus the spatial rate of change of wind direction along a streamline is proportional to dv/dx at the point O where the axes were defined. In this case dv/dx is the orbital/curvature vorticity. If A is the angle around a circle about the center of streamline curvature, then dx = R*dA; the change in the wind dv over a differential angle dA for constant wind speed equal to u is dv = u*dA; hence, dv/dx = u*dA/(R*dA) = u/R. The total relative vorticity = dv/dx - du/dy, which for solid body rotation is u/R + u/R = 2u/R. The coordinates defined above are called natural coordinates, and in general distance in the direction of the wind velocity is s and distance to the left (when the wind blows from back to forward) is n (See Holton and/or Martin). In general, when V (note the change in variable) is the wind speed, and R is the radius of curvature of a streamline, positive if the streamline curves to the left and negative if to the right, then the orbital/curvature vorticity = V/R and the shear vorticity = -dV/dn, and for equivalent solid body rotation, -dV/dn = v/R. planetary vorticity f could also be said to have an orbital/curvature and shear components, but they should at any one location always be equal since the Earth (and many other such bodies) spins essentially as a solid body (for atmospheric and oceanic dynamics purposes). Thus it makes some sense that a 'gradient wind balance', which is a balance in which the acceleration of the wind perpendicular to itself (proportional to orbital/curvature vorticity) and the coriolis acceleration and pressure gradient acceleration all sum to zero, can be defined and mathematically expressed using a total effective local f value (f_loc, see Bluestein p. 190) equal to f + 2*V/R (as opposed to f + V/R). But it is important to note that R in this case must be the radius of curvature of a trajectory - which may be different and often opposite the curvature of a streamline, although trajectories match streamlines in steady-state flow (in which streamlines do not vary in time over some region).
130652. Mizimi at 05:57 AM on 2 December 2008
        Temp record is unreliable
        Chris: we cannot adequately model climate right now, let alone model climate 'that was' millions of years ago. We assume land mass distribution, oceanic currents, atmospheric conditions and movement, biomass activity etc and then use proxy records to pin down climatic conditions. The best we can actually expect is an intelligent estimate of trends.
130653. Mizimi at 05:47 AM on 2 December 2008
        Water vapor is the most powerful greenhouse gas
        Sorry!! got my powers screwed up again, and having re-checked the sums there appears to me to be some overestimates in the AWV basic data, especially in respect of agricultural 'evapotranspiration' and the total for evaporation from reservoirs. So let's drop these out and concentrate on industrial figures which are a lot 'harder'. 90 billion tonnes of WV from industrial use ( excluding water from combustion) is 9 x 10E13 kg /annum or 3 times that produced by CO2 warming. AND it is increasing. There is still the 30% rise in usage recorded from 1980 to 1990 which just happens to coincide with the upturn in GMT. Just a coincidence? Also your figures comparing the 'turnover' of WV in the atmosphere (5 x 10E17kg/annum) only use the WV reckoned to be evaporated from cooling towers, not ALL AWV.
130654. chris at 03:39 AM on 2 December 2008
        Does model uncertainty exagerate global warming projections?
        Re #12: In fact we do know quite a bit about climate, atmospheric composition, temperatures and so on in the deep past. There are two points about the "graph" in post #8. First of all it's obviously incorrect, even for someone with an interest in these issues (anyone that posts here), but lacking detailed knowledge of the subject. For example we all know that the temperature hasn't dropped smoothly from "22 oC" to "12 oC" during the past several million years! And if we were skeptical we might question those long, long 10's and even 100's of millions of years of rock steady temperature. We might want to see the data points! The second point about the "gaph" is that it bears very little relationship to our real knowledge of any link between the Earth's temperature in the deep (and not so deep) past and the atmospheric CO2 levels determined from paleoproxies. In fact, these show a rather strong correspondence between atmospheric CO2 and the Earth's temperature over more than 500 million years. The data that informs us (anyone who wishes to be informed, including policymakers and their advisors) is cited below (see bottom of post). And anyone can find out about this themselves, for example by looking at University researcher or research institute web sites, or the IPCC reports, or even going to their local university library. It really depends on: (a) how well-informed one wishes to be (b) whether one wishes to address the science on these issues, or whether one has other agendas to pursue! --------------------------------------- The paleoproxy data for contemporaneous CO2 and temperature data is reviewed in detail here: D.L. Royer (2006) "CO2-forced climate thresholds during the Phanerozoic" Geochim. Cosmochim. Acta 70, 5665-5675. Even more recent studies supplement the information in Royers compilation and cover additional periods with new data sets right through the past several hundreds of millions of years: R.E. Carne, J.M. Eiler, J. Veizer et al (2007) "Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era" Nature 449, 198-202 W. M. Kurschner et al (2008) “The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of the terrestrial ecosystem” Proc. Natl. Acad. Sci. USA 105, 499-453. D. L. Royer (2008) “Linkages between CO2, climate, and evolution in deep time” Proc. Natl Acad. Sci. USA 105, 407-408 Zachos JC (2008) “An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics” Nature 451, 279-283. Doney SC et al (2007) “Carbon and climate system coupling on timescales from the Precambrian to the Anthropocene” Ann. Rev. Environ. Resources 32, 31-66. Horton DE et al (2007) “Orbital and CO2 forcing of late Paleozoic continental ice sheets” Geophys. Res. Lett. L19708 (Oct. 11 2007). B. J. Fletcher et al. (2008) “Atmospheric carbon dioxide linked with Mesozoic and early Cenozoic climate change” Nature Geoscience 1, 43-48.
130655. Arkadiusz Semczyszak at 01:39 AM on 2 December 2008
        Arctic sea ice melt - natural or man-made?
        …about “historical paleotemperatures in Fontainebleau” - The delta 13C indexes according to IPCC experts opinion, they are very reliable. Gamon, Fraser (1985) in “History of carbon Dioxide in the Atmosphere” writing about this method: separating periods - annual (for example ice core 20-300 y), accurate to 5 percent (2% in future). Many of papers are cited in the IPCC experts publications: Freyer, Balacy - 1983; Marino et al. 1992, Lauerberger 1992, Ferency 1998; Arus et al 1993, 7; Ferio et al., 2001; Keeling, C. D. m. fl., 2005: (Monthly atmospheric 13C/12C isotopic ratios for 10 SIO stations). More Data is in tree, but They are also at shallow water (Pedro Bank), deep water (Jamaica 150 m). However no about this dates don’t have annual separating periods, as in Fontainebleau… δ13C in research “crude” dates by Fontainebleau its very interesting: increase 1950 to 1960 has shape as increase 1985 - 2000; and the “slump” after around 1960 identically as Beck analyses. Becks picks specially: 1860, 1920; they are in Fonteinbleau too! Here also (as in Beck) increase of temperature (δ18O) preceded a δ13C increase… In the Beck analyses are a few errors - too higher CO2 level in 1820, no have s. d.…, However better that it’s, then nothing… Recollecting Gamon, Fraser (1985) writing about chemical methods: accurate to 3 percent…, besides the Results of research in 1920 - 1935 y, are very concentration - they have very small deviations - it’s confirm only 3% errors; as majority Becks date included in a photosynthesis researches - confirmed by photosynthesis product. Meijer and Keeling said, at Beck analyses: no background: “A quick tour through my car-traffic-saturated home town, Paris, can give us a good first impression: • Jardin Luxembourg (major but still tiny green spot in the center of Paris) 425ppm • Place de la Bastille: 430ppm • Place de l’Etoile (the crazy huge roundabout around the Arc de Triomphe): • 508ppm • And the winner was Place de la Nation: 542ppm (160ppm over background!).” (measurements by David Widory and Marc Javoy) but They give arguments for Beck. The differences dated only from present enhanced traffic of car !!! Difference between Mauna Loa - Jardin Luxembourg about CO2 concentration = 40 ppmv. Before 1950 y I think a background was not higher then 20 ppmv. Even however 40 ppmv background, gives for around 1940 y, 360 - 370 ppmv CO2… Besides, old universities were from car traffic, in the distance. "The persistency of the late 20th century warming trend appears unprecedented." writing i.e. N. Etien et al. I see on Fig 3b. - only “trend appears unprecedented” only in 1970 - 2000 period (likely: http://gsc.nrcan.gc.ca/geomag/nmp/long_mvt_nmp2_e.php), but temperature records are in 1911; 47; 49. 2003 is only fourth. Average in around 1950 is smallest in comparison 2000, only about 0,2oC… And here it is not possible to blame only “metal type screens “… The temperature biases in Fontainebleau are likely as in USA (by NASA)… “against the use of delta-13C measurements for long term temperature reconstructions” - I’m against too… None too big warming = more activity soil microorganisms - more CO2, 12C (correlations T - delta 13C, is high); only the big warming is can starts up the oceanic - TH circulations (= no correlations T - delta 13C). Unprecedented here is it, that delta 13C in 1950-60 period, violently fall off, as CO2 at Becks analyses, as mass moments the largest planets… - this last is accidentals ? Maybe, I don’t known… I’m only applied scientist – adviser for agro-meteorology…
130656. Arkadiusz Semczyszak at 01:37 AM on 2 December 2008
        Arctic sea ice melt - natural or man-made?
        Thanks, Patrick, Chris, Philippe Chantreau I can’t agree with You, The stomatal pores, their density in fossil plant leafs, it’s a fundamental legal instrument (not only in ice core context), that We not have a real unbalanced surplus of anthropogenic CO2, that CO2 don’t have long live of atmosphere, likely as present, variability of GHG was always; in finish: confirm it that first growing temperature, later CO2 concentration of air…, summary: not only man-mode melting glaciers… The density of stomata varies with such factors as: the temperature, humidity, and light intensity around the plant and also the concentration of carbon dioxide. The mature leaves on the plant detect the conditions around them and send a signal that adjusts the number of stomata that will form on the developing leaves. Not all plants We can take on experiments. Only some species have of the line relationship CO2 – stoma. They are tested in greenhouse - very wide range conditions – calibrated. First research works about it, makes in 1974… The results reported by Gregory Retallack (in Nature , 411 :287, 17 May 2001), his study of the fossil leaves of the ginkgo, was cited in the IPCC elaborations… “The reliability of this method testing on a total of 285 previously published SD and 145 SI responses to variable CO(2) concentrations from a pool of 176 C(3) plant species.” – Wagner said for students… A resolution this method is limited and "smoothed" because “…although the mechanism may involve genetic adaptation and therefore is often not clearly expressed under short CO(2) exposure times.” – “…don't show wild and massive up and down jumps…” (Wagner et al, 2002) “…to vary by around 295 +/- 10 ppm over a period of around 2000 years” – It is inadmissible “shortening”. Observed the variability in Fig. 2. is between ~ 275 – 330 ppmv CO2, and with standard deviation ~245 – 340 ppmv (the greatest down - certainly + s. deviations; in a few years ! ~7750 BP = 280 – 340 ppmv CO2, in a ~30-40 years 250 – 320 ppmv around 8700 BP; at the greatest grove – ~ 245 – 320 ppmv CO2 in < 150 years - ~ 8450 – 8600 BP). The range of variability in analyzed period for ice core is ~10 ppmv…, even around 55 ppmv (95 ppmv to vary range with s. deviation) contra 10 ppmv, is it: “relatively small disagreement”? Very interesting is comparison it with Fig. 3C in Baker at al. 1998. Correlation, even r-squadron, between a Europe fossil stoma and % C4 in America should be > 80 percent… If its true the range of variability CO2 in Holocene will be between ~200 – 340 ppmv CO2 with specially very quickly and big change between 4800 – 3400 BP. It is fine confirmation by the δ13C composition of stalagmites calcite (Fig. 3A) and… … for example, from news - about this variability; but “sedimentary total organic” is in „Holocene weak summer East Asian monsoon intervals in subtropical Taiwan and their global synchronicity” (http://www.clim-past-discuss.net/4/929/2008/cpd-4-929-2008.pdf - see specially Fig. 3). The four centennial periods: ~8–8.3, 5.1–5.7, 4.5–~2.1, and 2–1.6 kyr BP – “of relatively reduced summer East Asian monsoon” having a very interesting mark of reference whit all index in Baker et al., and Wagner at al.… Finished, I think percentage C4, maybe will by “fairest” proxy for reconstruction CO2 level (small influence of warm, rain, other falls, etc.) E. Steig i J. Severinghaus 27.04.2007 y. on RealClimate say: However very important is it, then concentration CO2 in last 650,000 years wasn’t never above 290 ppmv…, “I'd be very interested to know what they thinks will be achieved trying to cheat us in this way”… T. B. van Hoof et al (2008) – “CO2 levels varied by around +/- 10-15 ppmv” (often > 30 ppmv - more in s. d.; by a few years !) to base at early studies: “Coupling between atmospheric CO 2 and temperature during the onset of the Little Ice Age (van Hoof 2004)”. There is one: the shapes confirmations by D 47 core (however it’s only ± 6 ppmv); both: comparisons in other researching studies at fossil stoma (into L. Kouwenberg dissertation). Interesting is Fig. 2.6 (chapter 2) – growing of temperature with reconstruction Man and Jones 2003 (likely Moberg, Esper, etc.) ~ 1180; 1250; 1320 AD preceded a increase CO2 level… - “a temperature response rather” ? Kouwenberg in here research conclusion, said: “Four native North American conifer species (Tsuga heterophylla, Picea glauca, P. mariana, and Larix laricina) show a decrease in stomatal frequency to a range of historical CO 2 mixing ratios (290 to 370 ppmv). [!]” Well, well…
130657. chris at 00:34 AM on 2 December 2008
        It's the sun
        Not really Mizimi. The GISS update for October erroneously included September data for a number of Russian stations. The error was highlighted and the data corrected. So it's not a big issue is it! There are always errors in every endeavour in life. Science isn't an exception...it doesn't proceed without errors. The important point is that errors of substance are identified (they were) and corrected (they were).
130658. Mizimi at 06:10 AM on 1 December 2008
        Does model uncertainty exagerate global warming projections?
        As a reconstruction of past T and CO2 levels I would ignore it as it is predicated on a lot of (intelligent) guesswork. We simply do not know what the climate system as a whole was really like in the dim distant past. In addition, distribution of land mass was totally different and that affected climate. As an indication of trend (no absolutes here) it has uses.
130659. Mizimi at 05:48 AM on 1 December 2008
        Can animals and plants adapt to global warming?
        FYI; The sea of Cortes, off the coast of California, has been seriously overfished for many years, resulting in the loss of predators for the Humboldt squid. Because of this, and the squid's own predatory nature, its population has 'explode' to an estimated 20million+. (Much dismay and gnashing of teeth amongst marine biologists) However, the Right whale, which uses this sea as a stopover on its annual migration considers this squid as a great delicacy...as a result, Right whale numbers are increasing...........serendipity? Or 'nature' doing a balancing act?
130660. Mizimi at 05:36 AM on 1 December 2008
        Water vapor is the most powerful greenhouse gas
        "a significant part of the water vapour contribution arises as a feedback to CO2-induced warming," If we allow CO2 alone is responsible for a 0.17C rise/decade in GMT as per GISS data, and we allow ALL of the heat associated with that temp rise to evaporate water then an estimate of the increase in WV is around 0.07gm/kg of dry air. The atmosphere contains an estimated 5.135x10E18 kg of dry air (National Centre for Atmospheric research) which gives us a possible 5.135x10E18 x .07x10E-3 kg of WV added by this temp rise. Which ( providing I get my powers sorted out his time!) amounts to some 36x10E13 kg, PER DECADE. The current estimate for mm WV additions is 2360 cubic k's which is 2.36x10E12 kg....PER ANNUM. So over a decadal period we would add WV equivalent to 6.5% of that caused by CO2. Not insignificant. Dismissing AWV on the basis it precipitates out within 7-14 days does not do away with the fact that it does have a warming effect during that time period and it is a continuous effect at that.
130661. Mizimi at 04:40 AM on 1 December 2008
        It's the sun
        "What errors have there been in the GISS record?" Had a look at October's Giss data? Trivail? I don't think so. Look up Wattsupwiththat latest post on Russian data included by GISS.
130662. virbots at 04:12 AM on 1 December 2008
        CO2 lags temperature
        Has anyone discussed the possibility of bias between the two different ways of measuring CO2 and temperature as the source of the big jump near the end of the hockey stick graph? Thanks.
130663. chris at 21:33 PM on 29 November 2008
        Temp record is unreliable
        Yes, don't allow yourself to be taken in by "rhetoric" beam! In science it’s all about the evidence. I'm sure nobody would suggest that it doesn't matter if we "lose the validity of the surface temperature record". I've had a look through the thread and haven't found any post which claims that, let alone "claiming that you "Don't need" the temperature record"...that would be an odd claim indeed! Notice that in order to take action in response to real world observations we don't need "proof". Proof is a mathematical/philosophical concept. What we need is strong evidence. So the pertinent question is: "is there strong evidence that the temperature record is robust to the extent that we can reliably assess the Earth's temperature response in relation to our understanding/predictions of massive enhancement of greenhouse gas concentrations". The answer is yes I suspect we would agree for some of the reasons already outlined on this thread: (i) The record is independently assessed by three different organizations. Although there are differences in data compilation/analysis methods and some differences that relate to the nature of covering sparsely-monitored regions, the different compilations yield a consistent interpretation of the surface temperature evolution over the last 100 and a bit years. (ii) the surface record seems not to have significant contamination from the UHI since (a) a number of direct analyses indicate that the UHI isn’t significant [comparison of temperatures on windy days (with rapid excess heat dispersal) cf calm days, and other types of analysis, for example as described here: http://www.skepticalscience.com/Does-Urban-Heat-Island-effect-add-to-the-global-warming-trend.html, or in John Cooks introductory summary on this thread]; (b) one can remove all of the urban records from the analysis, and the temperature profile is pretty much unaffected; (c) those regions showing the largest warming are far, far away from urban centres and generally there is no correlation between local temperature evolution and local urban density [see for example: http://www.skepticalscience.com/urban-heat-island-effect.htm] (iii) completely independent records of the consequences of a warming Earth are consistent with the surface record [these include high latitude ice recession; independent temperature scales constructed from the record of high altitude glacier recession; tropospheric warming; enhanced tropospheric absolute humidity and so on]. So the evidence supports the interpretation that the temperature record is robust. Your point about scaling of the record with respect to the Earth’s “total existence” isn’t an important comparison with respect to the question of the consequences of massive enhancement of the atmospheric greenhouse gas concentrations at this particular time in the Earth’s long history. In any case we have a huge amount of information about temperatures in the recent and much more distant geological past. This also informs our understanding and provides strong evidence in support of the expected surface warming response to enhanced greenhouse gas concentrations. For example there is a good correlation between atmospheric CO2 concentrations and the Earth’s “temperature” in proxyCO2 and proxytemperature data stretching back right through the Phanerozoic So in general, the paleorecord reinforces the data from our contemporary temperature record and all of the vast amount of information from understanding of basic atmospheric physics, to the spectroscopy of greenhouse gases, ice core records and so on and on, that informs us on the consequences of massive enhancement of greenhouse gas concentrations. That’s not to say that there isn’t much more work to be done!
130664. Patrick 027 at 11:58 AM on 29 November 2008
        Volcanoes emit more CO2 than humans
        " “The loss of ozone allowed more UV light to pass through the stratosphere at a sufficient rate to warm the lower troposphere plus 8-3/4" of the earth by 0.48 o C (1966 to 1998).” " Now spread that heat out over the top 100 m of ocean and see what happens. ( 100 m * 70 % of area + 10/4 m** / (8.75 in* 2.54 cm/in + 10/4 m** (**water depth equivalent to atmospheric heat capacity)) = 72.5 m / 2.72225 m = 26.6 0.48 deg C / 26.6 = 0.018 deg C. But the quote refers to the lower troposphere, in which case the result is less; if the lower troposphere is the air below about the 500 mb level, for example, then I get 0.48 deg C/ 48.4 = 0.0099 deg C. )
130665. Patrick 027 at 06:09 AM on 29 November 2008
        Volcanoes emit more CO2 than humans
        A few of the problems with this: http://omsriram.com/GlobalWarming.htm 1. (at least one of) the IPCC figures are incorrectly interpreted - tropospheric ozone is increasing, NOT decreasing - this is also an anthropogenic effect. 2. some temperature graphs are off. 3. CO2 graph is off (though not as far off as another one I've seen). 4. The evidence really does justify a conclusion that significant CO2 increases cause significant global (tropospheric and surface) warming.
130666. Mizimi at 05:20 AM on 29 November 2008
        Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????
        Chris, I'm not sure I accept your view of solar cycle 'damping'. The annual response to orbital & axis fluctuations (which are basically the same as increasing/decreasing TSI) is quite rapid, even for large masses of water. I live on the coast and the seasonal fluctuation in sea temp is quite pronounced and predictable...peaking at around 27C and dropping to around 17C in the summer/winter cycle. These seasonal fluctuations are much greater than the solar cycle and I suspect the small warming of the solar cycle gets overshadowed somewhat rather than retarded.
130667. chris at 06:58 AM on 28 November 2008
        Models are unreliable
        Don't be silly Dan. You don't need to point out that you're parotting phrases from post to post..we can see that ourselves! The point is that your parroted phrases are illogical. The fact that insolation effects drive downtrends in temperature while CO2 levels remain high doesn't necessarily say anything about the net feedbacks to raised CO2 levels at constant insolation. This is explained in my post #64. You could look at the papers cited in that post which will enlighten you considerably about the rather straightforward phenomenon of Milankovitch-forced warming/cooling transitions. Look at the papers John Cook links to here, for example: http://www.skepticalscience.com/co2-lags-temperature.htm (Petit et al, 1999 and Shackleton, 2000 are two helpful papers.) You would also benefit from reading: Kawamura et al (2007) Northern Hemisphere forcing of climate cycles in Antarctica over the past 360,000 years. Nature 448, 912-918. Although your conundrum has been resolved by explanation several times already, here's another explanation: (i) raised CO2 levels stay raised for long periods, since CO2 is drawn out of the atmosphere rather slowly, for example in response to temperature downtrends. (ii) therefore if insolation effects (due to Milankovitch cycles) reduce critical insolation, the Earth's temperature will drop even 'though CO2 levels remain high. (iii) therefore during the ice age cycles, insolation changes that drive temperature changes will precede the CO2 responses. (iv) this doesn't mean that variation of atmospheric CO2 at constant insolation doesn't have associated positive feedbacks. All of the evidence (that we can measure in the real world, including an increase in tropospheric humidity as a feedback response to raised tropospheric warming, and reduced albedo due to surface ice recession and so on) indicates that the effects of CO2 variations are amplified by net positive feedbacks. (v) one can point out a simple analogy of the day/night cycle. Although atmospheric CO2 levels don't change overnight and remain very very high, as the sun goes down, the temperature measured at the Earth's surface drops. (vi) In other words a temperature downtrend at high/highish atmospheric CO2 levels only means that the particular driver of the temperature trend at that paticular time is variation in insolation. (vii) which we all know very well since it's rather obvious and well characterized!
130668. Patrick 027 at 06:55 AM on 28 November 2008
        Volcanoes emit more CO2 than humans
        Arkadiusz Semczyszak - "The annually production anthropogenic CFC = 750,000 T pure Cl, = one week by Mount Erebus productions…, at the all a World volcanoes, have a annually production 36,000,000 T Cl" CFCs are generally very unreactive until they reach the stratosphere and are broken down by UV, releasing Cl, etc. Volcanic Cl is probably much more reactive, and more likely to be rained out before reaching the stratosphere. I don't have time to read those papers right now, but I'll just note that the stratospheric cooling associated with AGW, (and also polar stratospheric cooling associated with increasing AO, which may or may not be a seperate matter, depending...) will make polar ozone holes more likely to result from any given ozone-depleting emission. Ozone depletion itself, while warming the troposphere below, cools the stratosphere by reduced UV absorption there, and also lets more longwave radiation from the surface escape to space, reducing any tropospheric warming that would result.
130669. beam at 04:48 AM on 28 November 2008
        Temp record is unreliable
        I'm amazed at the rhetoric. If you lose the validity of the surface temperature record, your hypothesis, that warming is greater than expected, is invalidated. It is a logical fallacy to claim that it doesn't matter if one of your premises are proven false. It is impossible for the conclusion to be correct if the premises do not hold. Here in lies the crux of the problem. --------------------------------------------------------- So If I'm not mistaken this is the AGW Hypothesis: 1. The world has been warming for a century, and this warming is beyond any cyclical variation we have seen over the last 1000 or more years, and beyond the range of what we might expect from natural climate variations. 2. Almost all of the warming in the second half of the 20th century, perhaps a half a degree Celsius, is due to man-made greenhouse gases, particularly CO2 3. In the next 100 years, CO2 produced by man will cause a lot more warming, from as low as three degrees C to as high as 8 or 10 degrees C. 4. Positive feedbacks in the climate, like increased humidity, will act to triple the warming from CO2, leading to these higher forecasts and perhaps even a tipping point into climactic disaster 5. The bad effects of warming greatly outweigh the positive effects, and we are already seeing the front end of these bad effects today (polar bears dying, glaciers melting, etc) 6. These bad effects, or even a small risk of them, easily justify massive intervention today in reducing economic activity and greenhouse gas production [1] http://www.conservapedia.com/AGW_hypothesis --------------------------------------------------------- In order for this to be proven true at this point in time, the surface temperature record needs to be accurate, because the other forms of temperature data collection have not been around long enough to be relied on. We simply do not have upper atmospheric temperature measures for long enough to see any long term trends. Let alone trends that are not expected. This is also true of the surface temperature record, although it is slightly older. Let's put it into perspective, if we scaled earth's total existence in time to a period of 1 year, the 50-100 years of data collection we now have would still be a fraction of a second on that time scale. So... claiming that you "Don't need" the temperature record is simply an act of hand waving by those too stubborn to admit defeat. At least for now, there is more work to be done.
130670. Arkadiusz Semczyszak at 01:07 AM on 28 November 2008
        Volcanoes emit more CO2 than humans
        John Cook said: “There are two skeptic approachs to volcanoes: high volcanic activity causes global warming and/or low volcanic activity causes global warming” - I say: “two skeptic approachs to volcanoes”, don’t excluded… „On the contrary, relatively frequent volcanic activity in the late 20th century may have masked some of the warming caused by CO2.” - I think - it’s not “all” right… 1.In IV report IPCC, chapter 2, p. 194, is Fig. 2.18 - distinctly differ from John’s Fig whit volcanic - optical depth… 2. In this IV report on p. 195-6 is writing about “chemical destruction of stratospheric ozone”. Here is, in references, one interesting position: Tabazadeh at al, 2002… I remind You, what Tabazadeh was said then - in 2002 y: "Both the 1982 El Chichon and 1991 Mt. Pinatubo eruptions were sulfur-rich [not only S, but else Cl2 ,B(OH)3,NH3,CH4, Cl, F by metals compounds] , producing volcanic clouds that lasted a number of years in the stratosphere," "A 'volcanic ozone hole' is likely to occur over the Arctic within the next 30 years, [!!!]" “Between about 15 and 25 kilometers (9 to 16 miles) in altitude, volcanic Arctic clouds could increase springtime ozone loss over the Arctic by as much as 70 percent, according to Drdla” (http://www.spaceflightnow.com/news/n0203/05volcano/ and http://www.gsfc.nasa.gov/topstory/2002/20020304volcano.html) The annually production anthropogenic CFC = 750,000 T pure Cl, = one week by Mount Erebus productions…, at the all a World volcanoes, have a annually production 36,000,000 T Cl… Results about It , is visible here http://www.esrl.noaa.gov/gmd/dv/spo_oz/SP_Dobson_Oct15-31_2007_mod1.gif, and of stratosphere temperature in: http://www.atmosphere.mpg.de/media/archive/1385.jpg, Robert A. Ashworth in papers: CFC Destruction of Ozone - Major Cause of Recent Global Warming! (2008; http://omsriram.com/GlobalWarming.htm - all paper is very interesting) say: “The loss of ozone allowed more UV light to pass through the stratosphere at a sufficient rate to warm the lower troposphere plus 8-3/4" of the earth by 0.48 o C (1966 to 1998).” IPCC said: global anthropogenic GHG effects in this period = ~ 0,5 dg. C, Ashworth said: “anthropogenic emissions of chlorofluorocarbons”, it’s the reason it… …I say: volcanic S, Cl, F - emissions, dear Mrs. Ashworth… I propose else this image: http://www.leif.org/research/Erl70.png. It’s worth seeing.
130671. Dan Pangburn at 15:59 PM on 27 November 2008
        Models are unreliable
        Post #75 was a repeat of the statement in #69 that followed the statement quoted in #76. It is unclear why you did not appear to notice this before and now do not seem to be able to see the difference between the two statements.
130672. Quietman at 05:52 AM on 27 November 2008
        It's not bad
        Can Carbon Dioxide Be A Good Thing? Physicist Explains Benefits Of Carbon Dioxide June 1, 2007 — A physicist from Colorado State University and his colleagues from the North American Carbon Program (NACP) have discerned and confirmed the unforeseen advantages of rising carbon dioxide levels. Through the processes of photosynthesis and respiration, scientists have been able to elucidate why plants are growing more rapidly than they are dying. The NACP is employing methods, such as the use of cell phone and aircraft towers to monitor and retrieve carbon data for their continuing study.
130673. Mizimi at 04:34 AM on 27 November 2008
        Human CO2 is a tiny % of CO2 emissions
        A thermostat 'cycles' around a predetermined temp within defined limits; design limitations normally restrict this to 2C. So, for example, a simple heating system will show a more or less sinusoidal curve around the setpoint with an offset of around 2C. This curve can be limited by the use of predictive electronics, but not completely negated. Electronic and compressed air temperature controllers modulate continuously as the detected temp fluctuates and provide closer control, BUT still show a sinusoidal fluctuation around the set point even though much lower than a conventional thermostat (industrial standards of around 0.5C). There is no equilibrium. Semantics is about the meaning of words; once you start to misuse words then communication is degraded. Better to invent a new word than to misuse an existing one..and science is historically pretty good at inventing new ones.
130674. Quietman at 04:25 AM on 27 November 2008
        It's the ocean
        chris Compare the charts of "hot spots" to a good map of the ocean floor such as Nat. Geo. maps. Also see post 115 in the volcano thread.
130675. Mizimi at 04:14 AM on 27 November 2008
        It's Urban Heat Island effect
        According to WikiP the land surface area of the earth is 148,939,100 sqkm and the total area of deserts (not chocolate flavoured desserts) bigger than 50,000 sqkm amounts to 31,678,000 sqkm...about 21%. This however includes Antartica which if you remove from the list reduces the total to 17,849,000 sqkm.....more than 10% of the earth's land area and that only includes those over 50,000 sqkm. Googling 'African deserts' gives 25% of Africa is listed as desert....hardly tiny.
130676. Douglas Watts at 10:44 AM on 26 November 2008
        Evaporating the water vapor argument
        Thank you, Chris. Mizimi's little docudrama is telling because its humor depends on the listener being scientifically illiterate or willing to make oneself temporarily illiterate for the sake of an ideology.
130677. chris at 09:35 AM on 26 November 2008
        Models are unreliable
        Come on Dan. You provided your own answer to that illogical mantra in your first paragraph of your post #69: [Dan ".....a temperature down trend is insufficient to prove that net positive feedback does not exist. My bad to have overlooked this before."] You were right in your post #69. Why change your mind again??
130678. chris at 09:24 AM on 26 November 2008
        It's the sun
        Not really WA What errors and corrections in the GISS record? There have been some truly trivial errors. Science doesn't proceed without errors. When these are identified they are corrected..it's not really a big deal oddly in your last paragraph, you contend that the satellite record is consistent with the hypothesis that there is no positive feedback. But in fact you are quite wrong. The satellite record is consistent with surface warming as a result of enhanced greenhouse warming of the atmosphere. The predicted enhancement of troposheric water vapour has been identified (see post #173 above). How could you have come to a completely incorrect notion of the satellite record? Probably because one or two less than honest scientists (Roy Spencer is one) have repeatedly made massively profound errors during the last nearly two decades of "analysis" of this data. And although their errors have been repeatedly corrected in the scientific literature, Spencer has taken to presenting falsehoods and misrepresentations directly to the public on dodgy website and suchlike. That's what I found astonishing about your viewpoint. On this and other threads you embrace embarrasingly erroneous nonsense (The Scotese paleotemperature/paleoCO2 sketch; a German schoolteachers pathetic misrepresentation of early CO2 measurements; hearsay notions about satellite measurements)...and yet you make dull attempts to trash the pukka science. If you have evidence that "we have ice ages with high CO2 and warm eons with low CO2", why not show us? If you've evidence that "The satellite record is to an even greater extent consistent with the hypothesis that there is no positive feeedback due to increased CO2", why not show us? If you've evidence that (the satellite record) "is also consistent with the hypothesis that human activities have no measurable effect on world temperature", why not show us? We want to see your evidence Wondering Aloud. We're skeptical of individuals that embrace errant and obvious nonsense and yet attempt to downplay pukka science. We're not concerned with proof. We're interested in the science and therefore we want to see your evidence.
130679. Wondering Aloud at 05:56 AM on 26 November 2008
        It's the sun
        Chris Re:218 This is a splinter in your neighbors eye issue if I have ever seen one. Especially in light of the errors and corrections in the GISS record. Is it your contention that it is incompetance in that case or bias? Ice core samples show that the warming happens first, our host claims a natural delay accounts for this. I think having a reversed order of cause and effect should give anyone pause, and let's not fool ourselves that is what we have there. It most certainly does not support the correlation you claim. Unless you would also contend that I ate too much junk food because I had gained weight. As to the more distant past while very uncertian I don't see how anyone could get anything like a correlation from what is there, we have ice ages with high CO2 and warm eons with low CO2. The satellite record is to an even greater extent consistent with the hypothesis that there is no positive feeedback due to increased CO2. In fact it is also consistent with the hypothesis that human activities have no measurable effect on world temperature. I think I am saying that isn't really much of a proof.
130680. Quietman at 05:28 AM on 26 November 2008
        Volcanoes emit more CO2 than humans
        This article Prehistoric Climate Can Help Forecast Future Changes ScienceDaily (Nov. 25, 2008, includes an interesting graphic. The "hot spot" anomalies in ocean temperatures are all very geologically active areas of volcanism/plate tectonics. While the article itself is worth reading, it's the illustration that stands out.
130681. Dan Pangburn at 17:08 PM on 25 November 2008
        Models are unreliable
        During the last and previous glacial periods the temperature changed from an uptrend to a down trend with the atmospheric carbon dioxide level higher during the down trend than it had been during the uptrend. That could not happen if there was significant net positive feedback and proves that significant net positive feedback does not exist. Without the imposition of substantial net positive feedback the GCMs do not predict significant global warming.
130682. chris at 10:29 AM on 25 November 2008
        Water vapor is the most powerful greenhouse gas
        Not really Mizimi: (i) The CDIAC is exactly about anthropogenic greenhouse gases. That's why they reference them with respect to pre 1750 levels (zero for the CFC's but not for CO2, methane, ozone, and nitrous oxide). (ii) both sites (EPA and CDIAC) don't include water vapour because they are considering anthropogenic greenhouse gas forcings. The EPA site has a specific section about water vapour. As they state (and we've already established this point in numerous posts above on this thread), human activities aren't believed to directly affect water vapour concentrations (it's not a forcing, it's a feedback), but the warmer atmosphere from anthropogenic greenhouse gases results in a water vapour feedback that amplifies the anthropogenic forcing from enhanced greenhouse gas concentrations. That's all very straightforward and easy to understand. (iii) Otherwise your numerology is suspect. In fact it's not possible to partition greenhouse effect contributions from the individual greenhouse gases in the manner that you have done, since the greenhouse gases don't act independently, especially when water vapour is considered. removing CO2 from the atmosphere results in a very large cooling, since a significant part of the water vapour contribution arises as a feedback to CO2-induced warming, and if you remove the CO2 you remove a lot of the water. Do you see why that makes a linear, discrete "partitioning" of the greenhouse effect to individual components inaccessible to simple-minded arithmetic? In fact this issue has been dealt with many times through the use of modelling of the effects of removing various components of the atmosphere. An early example is: Ramanathan V, Coakley JA (1978) Climate Modeling Through Radiative-Convective Models. Rev. Geophys. 16, 465-489. For example if you remove CO2 from the atmosphere the greenhouse effect is reduced by 9% and if you remove water vapour it's reduced by 36%. But if you removee CO2 and water vapour it's reduced by more than 45% (the sum of the two). Likewise if you remove everything but CO2, 26% of the longwave IR is still absorbed in the atmosphere. So if one wanted to put numbers to the contribution of CO2, it's somewhere between 9-26% of the greenhouse effect.... If you find Ramanathan and Coakley heavy going, Wikipedia has a goodish account: http://en.wikipedia.org/wiki/Greenhouse_effect#Water_vapour_effects
130683. chris at 09:43 AM on 25 November 2008
        Models are unreliable
        Re #70 I wouldn't really say that's a modelling error Quietman. Have a read of the original article in Nature Geosciences. A very small amount of carbon from inefficient burning of fossil fuels (that isn't captured in catalytic converters!), or from forest fires under oxygen-deficiency, or from people that use inefficient wood-burning stoves in the less-developed world, may be retained in the soil for long periods, and thus the amount released into the atmosphere may be reduced somewhat. Remember that no one expects the GCM models to be perfect. We know that they're not. That's not really the point of modelling. We know already from basic atmospheric physics and from numerous studies of the real world that the Earth responds to enhanced greenhouse gases with a warming somewhere of the order of 3 oC per doubling of atmospheric CO2. That's completely independent of models. The models help us to predict the spatial distribution of this warming, its effects under different emission scenarios and such like. As new information is obtained about contributions and their paramaterization, so the models are iteratively improved. So the work just published in Nature Geoscience will be explored further no doubt, and when it's sufficiently characterized/parameterized will be incorporated into the models... ..that's how science works!
130684. chris at 09:29 AM on 25 November 2008
        Models are unreliable
        Re #69 Dan O.K., so you've finally come round to the truism that a downtrend in temperature is not proof that a net positive feedback doesn't exist, after all. So everyone else but you wasn't wrong! Your bad indeed. But we got there in the end... Your second paragraph is illogical. We all know that the Earth's equilibrium temperature response has a logarithmic relationship to the atmospheric CO2 concentration. Arrhenius had worked that out already over 100 years ago. Your third and fourth paragraphs are nonsense too. Why go to a non-science magazine created with the intention (as the Editor admits) of misrepresenting the science on power industry-related matters? We've already seen (see posts #54 and #58) that "articles" in that magazine on climate-related matters are dodgy. Not surprisingly, the author of that article has got it wrong. There are lots of errors: (i) absorption of EM radiation doesn't "take place close to the surface". Photons can travel vast distances before being "absorbed". It depends on the absorbtivity/transmisivity of the medium through which the photons pass. (ii) If one considers longwave IR emitted from the Earth's surface, the wavelength/energy of the emitted wavelength has to be considered, since the absorption coefficient (k) is inversely related to the wavelength of the absorption band. The transmisivity, t, (absorbtivity = 1-transmisivity) of a column of air = t = e^(-k*p*l) where k is the absorption coefficient, p is the partial pressure and l is the path length. since the absorption coefficients for the absorption bands of the greenhouse gases are known[1], we can calculate the pathlength required to effectively absorb all of the radiation (at that energy/wavelength). For 99% absorption, the pathlength of the 4-5 micron absorption band of CO2 is 625 metres at current atmospheric CO2 concentrations and for the ~14-20 micron absorption band, CO2 at 385 ppm is still unsaturated at 7,800 metres of altitude. likewise for the 12-20 micron infrared absorption band of water at 0.4%, water vapour is still absorbing at 1,700 metres. (iii) in other words at current atmospheric greenhouse gas concentrations, the absorption bands aren't saturated, and enhancement of the concentration of greenhouse gases, particularly at higher altitudes [see (iv)], is effective in trapping more of the longwave IR emitted from the Earth's surface. (iv) In any case, the altitude of absorption of IR emitted from the Earth’s surface isn’t that important. A key element of the greenhouse effect is the altitude of emission of longwave IR into space. This has to happen for radiative balance between incoming radiation and outward radiation. You’ve actually given a clue to an important consideration unwittingly in the very first statement of your post: [Dan “bad boy” Pangbourn: “Radiated energy (from all surfaces, including earths) varies as the fourth power of absolute temperature”] Exactly so. As greenhouse gases are added to the Earth’s atmosphere, the radiation of IR into space is suppressed at any altitude (especially altitudes far from the Earth’s surface). So the radiation emitted to space from (say) 5 km is suppressed by enhanced CO2 concentrations, and so the altitude of mean radiation to space is increased. Since an increased altitude in the troposphere is at a lower temperature, the efficiency of radiation to space is decreased (as you said yourself). What’s the effect of this? The troposphere must warm in order to restore radiative balance. Since the surface and troposphere are strongly coupled, the warming of the troposphere is transmitted to the earth’s surface (and vice versa) [2]. (v) The article in the anti-science journal that you linked to makes three more errors that relate to ignoring real world measurements. These are: (i) on page 1044 your ill-informed author states: “It would be expected that more CO2 would have a greater effect on atmospheric warming at higher altitudes, but that seems not to be occurring in spite of the predictions of most GCMs”. But as we’ve seen already on this thread, the tropsopheric warming is quite consistent with GCMs (see my posts #60 and #66, where this exact issue is addressed). (ii) on page 1045 your ill-informed author states: “The GCMs take feedbacks into account, such as the supposed positive feedback from extra warming caused by the radiation by extra water vapour”. Yes, exactly. In line with the enhanced tropsopheric warming caused by enhanced [CO2], the troposphere is accumulating extra water vapour rather in line with predictions [3-7]. According to your ill-informed author this shouldn’t be happening since adding extra greenhouse gases isn’t (according to him) supposed to make the troposphere warmer! (iii) and overall your ill-informed author neglects to state that we can measure in the real world, not only the longwave radiation transmitted down to the Earth’s surface from the troposphere (which shouldn't be happening according to your ill-informed author), but the enhancement of this radiation due to the enhanced greenhouse gas concentrations of the last 30 years (which also shouldn't be happening according to yuor ill-informed author), or the reduction in this radiation outwards to space [8-12] ---------------------------------------- [1] this has been known for decades. See e.g RM Goody and GD Robinson (1951) Quart. J. Roy. Meteor. Soc. 77, 153 [2] Shine, KP (1995) Spectrochimica Acta A 51, 1393-4. [3] Santer BD et al. (2007) Identification of human-induced changes in atmospheric moisture content. Proc. Natl. Acad. Sci. USA 104, 15248-15253 [4] Soden BJ, et al (2005) The radiative signature of upper tropospheric moistening. Science 310, 841-844. [5] Buehler SA (2008) An upper tropospheric humidity data set from operational satellite microwave data. J. Geophys. Res. 113, art #D14110 [6] Brogniez H and Pierrehumbert RT (2007) Intercomparison of tropical tropospheric humidity in GCMs with AMSU-B water vapor data. Geophys. Res. Lett. 34, art #L17912 [7] Gettelman A and Fu, Q. (2008) Observed and simulated upper-tropospheric water vapor feedback. J. Climate 21, 3282-3289 [8] Harries JE et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997. Nature 410, 335-337. [9] Worden HM et al. (2008) Satellite measurements of the clear-sky greenhouse effect from tropospheric ozone. Nature Geoscience 1, 305-8. [10] Philipona R et al (2004) Radiative forcing - measured at Earth's surface corroborate the increasing greenhouse effect. Geophys. Res. Lett. 31, art # L03202. [11] Wild M et al. (2008) Decadal changes in surface radiative fluxes and their role in global climate change Adv. Global Change Res. 33 , 155-167. [12] Philipona R et al (2005) Anthropogenic greenhouse forcing and strong water vapor feedback increase temperature in Europe Geophys. Res. Lett. 32, art # L19809. etc. etc. etc. etc……
130685. Mizimi at 09:11 AM on 25 November 2008
        Water vapor is the most powerful greenhouse gas
        Try: http://yosemite.epa.gov/oar/globalwarming.nsf/UniqueKeyLookup/SHSU5BUM9T/$File/ghg_gwp.pdf which gives warming potentials; (and they acknowledge WV is a GG and address their tables to 'selected' GG's) and: http://cdiac.esd.ornl.gov/pns/current_ghg.html (which doesn't acknowledge WV...and their data is NOT just AGG's........unless you deem we are responsible for all the pre-1750 gases ???) If you check the math from table 2 in the EPA site ( which can be checked against the DOE site) CO2 accounts for ~72% of GG warming EXCLUDING WV. CH4 about 7% and N2O 19%, the rest is CFC's etc. Now factor in WV at 95% (topend) and CO2 is responsible for 72% of 5%...3.6% of the total, or 1.19C Take the lowend 90% WV and you get 7.2% of the total or 2.38C Now run the increases due to man's contributions alone and you will get the numbers I quoted in #29
130686. Quietman at 09:10 AM on 25 November 2008
        Misinterpreting a retraction of rising sea level predictions
        chris forget it, the damn graph was drawn backwards.
130687. Quietman at 09:05 AM on 25 November 2008
        Misinterpreting a retraction of rising sea level predictions
        The wording I used is misleading and I did not realize how it would be taken. The high points decline slightly but the lower end is constantly getting warmer, ie. instead of saying it's getting warmer I should have said its not getting as cold. Just follow the trend line of the coldest points to see what I meant.
130688. chris at 05:47 AM on 25 November 2008
        Water vapor is the most powerful greenhouse gas
        I have checked them out. Your numbers are nonsense and don't come from the DOE or from the IPCC. The data on Greenhouse Gas concentrations from the US government CDIAC refer to anthropogenic greenhouse gas and so don't include water vapour. Is that what you're on about? e.g. http://cdiac.esd.ornl.gov/pns/current_ghg.html But we don't really know what you're talking about unless you give us a link to the data that you cut 'n pasted those weird numbers from.
130689. Quietman at 04:20 AM on 25 November 2008
        Volcanoes emit more CO2 than humans
        More on Tectonic activity and poor instruments: "On May 12, 2008, at 2:28 p.m., China's Szechwan province changed forever. In the space of 90 seconds, an earthquake equivalent to 1,200 H-bombs pulverized the earth's crust for more than 280 kilometers. Entire cities disappeared and eight million homes were swallowed up. This resulted in 70,000 deaths and 20,000 missing." "According to ShaoCheng this tragedy could have been avoided. "There hasn't been one earthquake in Szechwan province for 300 years. Chinese authorities thought the fault was dead," he says. The problem is that China relied on GPS data, which showed movements of 2 mm per year in certain areas when in reality the shifts were much bigger. "GPS is high-tech, but do we really know how to interpret its data?," he questions." Ref: Can China's Future Earthquakes Be Predicted? ScienceDaily (Nov. 24, 2008)
130690. Mizimi at 05:57 AM on 24 November 2008
        Water vapor is the most powerful greenhouse gas
        The numbers are not cut and pasted but taken from the sites mentioned. Check them out yourself. The DOE site does not include WV in their GG listing so I take that as ignoring its effect as a GG. The 95% WV quoted is the 'high' side figure from various sites; the 'low' side figure generally quoted is 90% from other sources and one can rerun the sums using the 90% if desired. The rest is simple maths. I included WV in the calcs for obvious reasons.
130691. Patrick 027 at 15:48 PM on 23 November 2008
        Arctic sea ice melt - natural or man-made?
        Now I'm getting ahead of myself, but I wonder if maybe the longer-term trend in AO/NAM might be somehow related to changes in meridional momentum transport - if the residual mean meridional circulation (forced by EP fluxes) isn't changing, this doens't necessarily mean the gradient in zonal momentum that it crosses is not changing. Also - it seems odd to use this to describe a climate CHANGE - it is more obviously applicable to short term weather - but, as there is enhanced warming of the Arctic ocean and high latitudes particularly in winter relative to lower latitudes, this would tend to produce a 'thermal low' in the absence of everything else - and that would tend to pull air poleward at the surface (relative to whereever it goes otherwise) and push air equatorward at mid and high levels (relative to whereever it goes otherwise) and the coriolis effect would increase westerly winds at the surface - but while reducing them aloft; okay, that didn't work, but there could be more to it than that - maybe - I don't know...
130692. Patrick 027 at 15:41 PM on 23 November 2008
        Arctic sea ice melt - natural or man-made?
        After wrapping up Rossby wave basics, I'll get back to AO/NAM (I've found one source which suggested that changes in planetary wave propagation caused by AGW could account for some of the multi-decadal trend in AO/NAM (NAM(1); however I found one paper which argues that while shorter variations of AO/NAM are linked to planetary wave flux changes, the longer-term trend doesn't seem to be so linked. (NAM(2)) Interestingly I think they focussed on a time of year when ozone depletion wouldn't be a direct factor (radiative heating/cooling), but also I'm not sure if solar changes could also be ruled out at least as far as being a direct influence via radiative heating/cooling of the polar stratosphere at the time the AO changes occur. I'm not clear on whether AGW would directly radiatively cool the lower winter polar stratosphere more than the lower winter mid-latitude stratosphere, although that seems to be the trend... Then again there's also gravity waves - did the paper include gravity waves? - no, I don't think it did... anyway, that's coming up...
130693. Patrick 027 at 15:16 PM on 23 November 2008
        Arctic sea ice melt - natural or man-made?
        I've decided not to go into 'absolute momentum' unless specifically asked. The other point I was going to make was that vorticity is proportional to an angular momentum per unit mass per unit area (for circular motion at radius r, counterclockwise tangential speed v (at all points on the circle, or averaged), the angular momentum per unit mass is v*r, the circulation is v*(2*pi*r), and the area-average enclosed vorticity is the circulation divided by enclosed area, v*(2*pi*r)/(pi*r^2) = 2*v/r. Notice that v/r is the angular frequency, and the vorticity is twice the angular frequency. f is equal to twice the planetary angular frequency times the sine of the latitude, and including f, the absolute angular momentum per unit mass is v*r + 1/2*f*r^2; multiplying by 2*pi and dividing by area to get absolute vorticity, the result is 2*v/r + f, where 2*v/r is the relative vorticity. Angular momentum can also be defined for any parcel of air relative to some other parcel or point - it is then less precisely related to the vorticity in the space between. On a small scale, an intrinsic absolute angular momentum may be conserved whenever potential vorticity is conserved (when absolute vorticity is inversely proportional to an area defined by material lines), but angular momentum defined relative to any point is not necessarily conserved following the air under the same conditions. However, there is still a conservation of angular momentum that applies, where air that loses or gains this angular momentum must be exchanging angular momentum with some other air or the Earth itself. Angular momentum can be defined relative to the Earth's axis, in which case it is (per unit mass) equal to: R*cos(latitude) * [ u + OMEGA*R*cos(latitude) ] where R is the radius of the Earth (so R*cos(latitude) is the radius of a latitude circle), OMEGA is the angular frequency of Earth's rotation, u is the zonal wind (relative to the Earth) and OMEGA*R*cos(latitude) is the speed of the surface of the Earth itself in the zonal direction. Generally, on average, Westerly (eastward) angular momentum is lost from the Earth below the atmosphere by friction (and any form drag) acting on tropical trade winds, which then transport that angular momentum upward and poleward in the Hadley cell. Eddy fluxes of angular momentum transport it farther poleward and bring it downward. The Earth gets it back from friction and form drag acting on westerly winds at mid-to-high latitudes. Because the torque of the winds acting on the Earth at any one latitude belt is proportional to the wind stress times the area times the radius of the latitude circle, one or more of the following is necessary for long-term balance - stronger surface mid/high latitude westerlies than low-latitude easterlies, a greater area of mid/high latitude westerlies than low-latitude easterlies, or a greater effective drag acting on mid/high latitude westelies than low-latitude easterlies. I'm not sure if the properties of Rossby waves would tend to create the third condition if all else was equal, but the distribution of mountain ranges would have an effect. This has consequencies for how a steady-state Hadley cell would be sustained in the absence of eddies. Rather than a surface low at the equator and high at the poles with surface easterlies everywhere in between, there would be weaker polar highs or perhaps slight polar lows with midlatitude highs; the high-latitude winds would westerly with a westerly ageostrophic component (supplied from downward transport of momentum, enough to overcome friction even if around a polar low pressure) so that the coriolis force would accelerate the winds equatorward. If there were not a zero net torque, the atmosphere would continually sping up or slow down so as to change the torque until balance were achieved.
130694. Quietman at 06:24 AM on 23 November 2008
        Models are unreliable
        chris disregard that - I misread your statement. I was referring to the last 10 years while you referred to the entire length of the last PDO.
130695. Quietman at 06:22 AM on 23 November 2008
        Models are unreliable
        chris Just a small point re: "3. These (NASA GISS, Hadcrut, NOAA) show long warming trends from the mid 1970's through to the present." In reality only GISS actually shows a slight increase, the others are actually slightly negetive.
130696. LarianLeQuella at 06:16 AM on 23 November 2008
        Other planets are warming
        I suggest that people who think that the sun is responsible, and cite warming on other planets become familiar with the Inverse Square Law. ;)
130697. LarianLeQuella at 06:15 AM on 23 November 2008
        Climate change on Mars
        I suggest that people who think that the sun is responsible, and cite warming on other planets become familiar with the Inverse Square Law. ;)
130698. Quietman at 06:01 AM on 23 November 2008
        Models are unreliable
        Just another modelling error: Global Warming Predictions Are Overestimated, Suggests Study On Black Carbon ScienceDaily (Nov. 19, 2008) — A detailed analysis of black carbon -- the residue of burned organic matter -- in computer climate models suggests that those models may be overestimating global warming predictions.
130699. Dan Pangburn at 17:29 PM on 22 November 2008
        Models are unreliable
        Radiated energy (from all surfaces, including earths) varies as the fourth power of absolute temperature so a temperature down trend is insufficient to prove that net positive feedback does not exist. My bad to have overlooked this before. However, review of temperature during the last and previous glacial periods reveals that the temperature changed from an uptrend to a down trend with the atmospheric carbon dioxide level higher during the down trend than it had been during the uptrend. That could not happen if atmospheric carbon dioxide level increase was a significant driver of average global temperature increase. The present atmospheric carbon dioxide level is somewhat higher than it was during the glacial periods. As Carbon dioxide level increases, each additional increment has less influence than the previous increment. This effect is appropriately called saturation. Thus increased atmospheric carbon dioxide now is even less able to influence temperature than it was during the last glacial period when temperature increasing trend changed to a decreasing trend. The conclusion from all this is that the current rising atmospheric carbon dioxide did not have a significant influence on any temperature rise including the temperature rise from the mid 1970s until about a decade ago and will never be a significant factor in temperature increase. Contrary to Chris’ assertion which was “The major predictor of Anthropogenic Global Warming is our understanding of the greenhouse effect …” the discovery long ago that carbon dioxide and water vapor absorb certain wavelengths of infrared radiation does not mandate that human activity has caused the planet to get significantly warmer. It is pretty widely known that the infrared absorption, mainly by water vapor, helps make the planet have the nominal temperature that it does. It is less widely known that the absorption takes place close to the emitting surface (half within 24 meters as calculated from Barrett’s paper at http://www.warwickhughes.com/papers/barrett_ee05.pdf , others calculate even closer). Adding carbon dioxide to the atmosphere results in the infrared radiation being absorbed a bit closer to the emitting surface. The atoms that absorb the infrared radiation energy nearly all immediately share it by thermal conduction with the much more abundant adjacent atoms that are transparent to infrared radiation. That, for the most part, is what warms the air. The shared energy is then carried up by convection currents. Existing GCMs are unable to objectively account for this natural convection so the process is imposed on the models with a contrived parameterization. Contrary to one of many of Chris’ erroneous assertions, that I have stated that “I am right and everyone else is wrong”, I share the perception with over 31,000 other scientists and engineers at http://www.petitionproject.org/ that human release of carbon dioxide will not cause catastrophic global warming. These scientists and engineers gain nothing for this declaration while the 2500 or so alarmist climatologists must make dire predictions for the government grants to continue.
130700. Patrick 027 at 15:29 PM on 21 November 2008
        Arctic sea ice melt - natural or man-made?
        "the geostrophic wind is non-divergent in isobaric (and also isentropic, I believe) coordinates - the convergent motion may be ageostrophic, and if so, the coriolis force on it is not balanced by the pressure gradient force. This means the coriolis force itself exerts a torque about a center on ageostrophic motions " ... Just to be clear, though - that was just to illustrate one major process; Solving the momentum equations for vorticity yields the more general result that absolute vorticity (RV + f) remains inversely proportional to a horizontal area or the horizontal projection of an isobaric (or isentropic) area enclosed by material lines, which shrinks or grows by horizontal convergence or divergence, respectively, when (the horizontal component of) absolute angular momentum is conserved, which is true, except for: 1. friction or mixing, 2. nonzero solenoidal term (not applicable to isobaric or isentropic coordinates), 3. nonzero tilting/twisting (horizontal variations in vertical momentum transport, which is generally small for larger scale motions and is zero for adiabatic motion in isentropic coordinates), and with the approximation that 4. the coriolis effect acting on vertical motion and causing vertical acceleration is neglible (which is true even for rapid motions in thunderstorms, because with rapid vertical motion, the air (following the air) has to start and stop within a time frame much shorter than the Earth's rotation period, given atmospheric dimensions). 5. the 'curvature terms' are neglible (which is true) - the curvature terms account for the curvature of the Earth; for x,y,z coordinates defined everywhere locally, with x being east, y being north, z being up - moving around involves accelerations of that coordinate system itself; for example, two great circle routes that are not identical inevitably intersect, so in order for two air parcels to remain on parallel trajectories for long distances, there must be some horizontal acceleration on at least one of them... etc. - but that is a small effect. Sometimes factors which absolutely must be included for understanding longer term processes, such as radiative heating and friction, can actually be ignored without losing a basic understanding of some processes that happen over short-enough periods of time.

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