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Riccardo at 00:21 AM on 12 February 2010Working out future sea level rise from the past
Berényi Péter, a possible mechanism for glacial termination has been described elsewhere in this site. -
Berényi Péter at 00:04 AM on 12 February 2010Working out future sea level rise from the past
Well, 125 ky ago axial tilt was close to its low value, somewhere around 22.5°, a degree smaller than today. If we take it into account, irradiation at North Pole summer solstice could not be substantially higher than present day Antarctic peaks. Still 7% higher than current arctic values, but is it enough to melt seventy million cubic kilometer of ice, then increase ocean temperature furher? At the tropics, where the bulk of ocean warming is done, neither eccentricity nor tilt has much effect. Are we missing something? -
Riccardo at 23:06 PM on 11 February 2010Why does CO2 lag temperature?
jisabi, read the part of the post after fig.2, it describes the mechanism of glacial termination with several links to relevant papers. In particular i'd suggest Caillon 2003. -
Berényi Péter at 23:05 PM on 11 February 2010Working out future sea level rise from the past
RSVP, Bern, SNRatio it turns out you are right and I am wrong. Sorry for that. I should have payed more attention, narrative with no math can be misleading. Areal velocity is "constant" indeed, as I have assumed, but only as long as orbit is not changed. With increased eccentricity, it should decrease. So. If A is area of orbital ellipse, T is orbital period, areal velocity is A/T. Let w be angular velocity, r distance to Sun. Instead of r^2w = const (1) (WRONG! in a sense) I should have written r^2w = A/T (2) For an ellipse with semimajor axis "a" and eccentricity "e" A = (1-e^2)^0.5a^2 (3) From (2) and (3) r^-2 = wT(1-e^2)^-0.5a^-2 (4) Since instananeous energy flux is proportional to r^-2, integrating (4) for an orbital cycle (from 0 to T) and dividing it by T gives average radiation power flux. P = 2Pi(1-e^2)^-0.5a^-2 (5) Solar input does depend on eccentricity after all, it is proportional to (1-e^2)^-0.5, so increases with decreasing eccentricity. For small values of e (1-e^2)^-0.5 ~ 1+e^2/2 (6) There is no first order dependence, that much is true. Present day value of e is 0.0167, 125 kyears ago it used to be somewhere around 0.04. Illinois State Museum Milankovitch Factors/Orbital Eccentricity http://www.museum.state.il.us/exhibits/ice_ages/eccentricity_graph.html If we assume "solar constant" (~1367 W/m^2) to be constant over such a timespan, it means a 226 mW additional average radiative "forcing" at TOA (Top of Atmosphere). Not much. Short term variations in solar constant are slightly larger than that. However, annual peak-to-peak irradiance variation due to eccentricity is proportional to 4e(1-e^2)^-2. It was 2.4 times more 125 ky ago than it is now. This year peak daily iradiance at the North Pole is 526.49 W/m^2 (on June 20-21) while it is 561.90 W/m^2 for South Pole (December 22). http://aom.giss.nasa.gov/srlocat.html Since at present perihelion occurs in early January, southern summer irradiation is considerably higher than its northern counterpart. With ancient eccentricity value and right phase of precession, peak daily irradiation at North Pole would be as high as 590 W/m^2 (12% higher than today). Of course axial tilt is also changing, making things a bit more complicated. Illinois State Museum Milankovitch Factors/Axial Tilt http://www.museum.state.il.us/exhibits/ice_ages/tilt_graph.html Anyway, enough to melt ice ferociously. On the other hand, polar winters must have got a lot more chilly back then, probably drier as well (just the opposite of what is observed in recent decades). I was also trying to deceive you (unintentionally, due to my usual hastiness) about the reasons behind constancy of semimajor axis. In fact, as we have seen, orbital angular momentum does change with changing eccentricity, even if there is no first order dependence. On the other hand, semimajor axis (which is inversely proportional to orbital energy and proportional to the two-third power of orbital period, irrespective of eccentricity) is fairly stable. For a different reason however than I was trying to push. It was worked out in late eighteenth century by Lagrange & Laplace. See link for details, amazing stuff. http://www.scholarpedia.org/article/Stability_of_the_solar_system -
SNRatio at 22:23 PM on 11 February 2010Working out future sea level rise from the past
I apologize for having contributed to mathematics as a broken language here. The intensity/eccentricity problem is easily solvable in closed form, I(e) = I(0)*(1+e^2/2)/(1-e^2)^2. Perhaps an interesting parameter is the summer half year intensity. For two eccentricities e1 and e2, the relation is approximately (pi+4e1)/(pi+4e2). The ca 0.2% variation in intensity between max and min e translates to 2-3 W/m^2 @max irradiation, average one fourth of that, as usual. -
jisabi at 22:05 PM on 11 February 2010Why does CO2 lag temperature?
I am looking for and I am having trouble finding a reasonable explanation for why during the onset of a glaciation sparked by milankovitch solar forcing declines that CO2 drops. I find quite a bit concerning the termination of glaciations and the lag of CO2 and I can get my head around that, but the CO2 drawdown is a bit more murky. Is it simply that you can dissolve more CO2 in the cooler water setup by the reduced solar input? This in turn further pushing the feedback loop towards further glaciation and greater CO2 uptake by the oceans? Perhaps my search is flawed, but I am not finding any peer reviewed articles that address this, any help would be much appreciated. -
RSVP at 19:04 PM on 11 February 2010Working out future sea level rise from the past
Bern "My point, though, was that eccentricity by itself does have some influence, when you integrate the energy input over an entire orbit. " I would think, especially if this effect is integrated over 100,000 years,... plus noting that fact that Northern Hemisphere winter coincides with perhelion, and that most dry land on the Earth is in the Northern Hemisphere, (which would imply a tendency for heat to store unevenly over time), and that ice ages more or less have 100,000 year cycle. Maybe Milankovich wasnt so far off the mark. -
Timothy Chase at 17:58 PM on 11 February 2010Could climate shifts be causing global warming?
Different Visions, Part II of II But somehow I don't think that is quite what you are interested in but rather science and the world we know. First of all, it isn't like AIRS is the only instrument we have for examining the world. We have been able to test the principles of radiation transfer in laboratories for over a century - including how they apply to carbon dioxide. We understand the physics underlying blackbody radiation, and that most substances absorb continuously, whereas for certain crystals, alloys, fine dusts and of course greenhouse gases will have well-defined absorption lines. This is what permits us to "fingerprint" them. Furthermore, the exact spectra of such substances have been extensively studied. The HiTran database contains over a million spectral lines. And as I pointed out earlier, we know that as you increase the partial pressure of greenhouse gases the spectral lines broaden -- so assuming you are able to identify a given spectral line as belonging to a particular gas you could presumably identify the partial pressure. Actually I believe temperature would complicate this, but only slightly. Might need one more spectral line. * Berényi Péter continued:The tricky part is to restrict the definition domain so as to make the transform invertible. It is done by constructing a model that does not allow for just any combination of state variables, but only a tiny subset, and if you are lucky, all states conforming to model would generate different radiation output.
Initially sounds like it could be a reasonable approach. Reminds me of a problem in the design of artificial intelligence -- specifically with respect to building a three dimensional model of the world based upon two or more two dimensional "representations." But in this context I believe it is mistaken. By Kirchoff's law we know that what radiation emit they will also absorb, so if the radiation escapes to space along a given absorption line that is saturated below a given altitude, then it must be escaping where saturation gives way to transparency, that is, where the gas ceases to be "opaque" to radiation at that particular frequency. This should be independent of the radiation being transmitted at that frequency in the lower layers of the atmosphere as all radiation will be absorbed at saturation, and the emission of radiation, assuming conditions of local thermodynamic equilibrium -- will be strictly dependent upon the intrinsic properties of the matter -- including its temperature. Consequently, given enough channels and enough unique absorption lines one could peel back the layers of the atmosphere like an onion. Given my analysis it would seem that there is no need for some sort of all-purpose model for computing one unique physical state that would produce the specific full spectrum. All you need are a certain set of well-chosen frequencies for the particular problem at hand. Not the ability to arrive at some unique distribution of all atmospheric constituents in an atmospheric column -- or more widely -- the atmosphere directly above the visible part of the globe itself. But as the atmosphere reaches atmospheric pressures of 20 mb or below non-local thermodynamic equilibrium conditions will begin to take over, and then the intensity of incident light, the angle of incidence and so on will begin to matter -- and it will be time to get out one's Einstein coefficients. And at that point I would presume it is a different ballgame. Advanced climate models incorporate non-local thermodynamic equilibrium radiation transfer theory, but that will be in terms of computing the spectra that a given physical situation gives rise to, not the physical cause of a given radiation signature. But once you start dealing with non-local thermodynamic equilibrium conditions the air is thin enought that it probably won't have that much of an effect upon the climate system. * Anyway, it might help to know that the Nasa JPL AIRS website doesn't simply have pretty pictures and movies. It explains in some detail what the AIRS instrument is and what it is capable of. Please see for example:AIRS uses cutting-edge infrared technology to create 3-dimensional maps of air and surface temperature, water vapor, and cloud properties. With 2378 spectral channels, AIRS has a spectral resolution more than 100 times greater than previous IR sounders and provides more accurate information on the vertical profiles of atmospheric temperature and moisture. AIRS can also measure trace greenhouse gases such as ozone, carbon monoxide, carbon dioxide, and methane. http://airs.jpl.nasa.gov/overview/overview/
It explains how AIRS works, calibrated and gives the specifications and the spectral ranges of the channels. It explains how it is used to improve weather forecasts, test and improve climate models (1, 2, 3, 4 and 5). It provides a portal for requesting data which is free and available to all, access to a database of the peer-reviewed papers that have made use of its products and a selection of those papers. However, if you want the data or documentation, you should probably try: Goddard Earth Sciences Data and Information Services Center http://disc.gsfc.nasa.gov/AIRS/ The data includes quality assurance sets. All data and documentation is free and open to the public. Incidentally, there are limits to what I can do. As should be clear at this point, my idea of aiming high was critiquing The Critique -- and nowadays I am a computer programmer. However, I am sure that they would appreciate someone taking a detailed look at their work. Particularly if they were to point out the flaws and offering suggestions on how things could be improved in a peer-reviewed paper. It is the only way things will improve, you know. Then again the scientists seem pretty happy with it at present. -
Timothy Chase at 17:56 PM on 11 February 2010Could climate shifts be causing global warming?
Different Visions, Part I of II Berényi Péter wrote in 45:As a first remark. I am not stressing the ontological bases of operationism, in fact I am a realist (in medieval sense). However, an exact description of operations to get values for certain quanities is indispensable for quality assurance & debugging purposes, especially in calibration and remote sensing.
Might help if you were to say which quantities. Don't you think? I mean, if you are interested in that some extremely detailed specificity it might help to be specific in terms of what you are looking for, eh? Then again, it might help me to see whether what you are proposing escapes my criticisms of Bridgman. * Berényi Péter continued:For example remote sensing of atmospheric water vapor by satellites at first sight requires the solution of the unsolvable. Given the spatio-temporal distribution of pressure, temperature, humidity, trace gases and all the other ingredients of some relevance, it is a straightforward(?) process to calculate radiance spectra at TOA. However, in practice it should be done the other way around. You first measure radiation, then look for a distribution of state variables that would produce the same radiation signature. Unfortunately the transformation is not reversible, that is, a multitude of distributions can produce the very same radiation.
Well, lets step back for a moment. This morning I went to the coffee shop. I could see where the sidwalk had been made wet by the drizzle in the air. I followed along the sidewalk just fine, turned the corners when I needed to, and recognized when the lights would permit me to cross the street. I was able to recognize all the items of food the coffee shop had available so that I could tell my wife on the cellphone, exhange money, then carry everything home -- navigating the stairs all the way up to the fifth floor. But I can only see three "channels" -- red, green and blue. Birds can see four "channels" - red, green, blue and another color in the ultraviolet range, although the exact wavelength differs from species to species. That color is visible to members of their own species but typically invisible to the birds of prey that hunt them. Rather than seeing a color wheel they see a color sphere. Mammals lost their color vision during the time of the dinosaurs. This was the result of living underground or coming out only at night -- and we only gradually reacquired it. Cats perhaps seeing red. All primates see no more than two -- other than humans which see three, -- well, most of us. But birds? Their ancestors typically remained above ground in broad daylight along with the rest of the dinosaurs. I have heard of a mantis shrimp as well. It is a crustacean, not actually a shrimp, but more closely related to crayfish I believe. They are the only animal that we know of that has hyperspectral vision -- with overlapping channels. They can see 11 or 12 different channels, depending upon the species -- with an additional four narrower channels due to filtering. Polarization? Horizontal, vertical, diagonal, anti-diagonal, clockwise and counterclockwise. Shallow-water hunters in an environment with reflected light and semitransparent prey. Beautiful animals. The AIRS instrument can see 2378 channels. It can see nearly 150 times as many channels as that of even the best mantis shrimp, 600 times that of birds and 800 times that of humans. Polarization? To within 5°, although maybe not as rich a world as what the mantis shrimp sees. Now when you state as I quoted above:You first measure radiation, then look for a distribution of state variables that would produce the same radiation signature. Unfortunately the transformation is not reversible, that is, a multitude of distributions can produce the very same radiation.
... this problem is as applicable to the vision of a human, bird or mantis shrimp as it is to the Atmospheric InfraRed Sounder -- only more so the fewer the channels that a given animal sees. And as such when you start speaking of all possible combinations of state variables (that is, in one sense or another, all possible physical worlds) that would produce a given radiation signature you are no longer dealing in science but philosophy, and if this is what interests you then I have two other papers that may be down your alley that we might discuss elsewhere: Doubting Descartes and, Something Revolutionary: On The Critique of Pure Reason -
Bern at 15:15 PM on 11 February 2010Skeptical Science now an iPhone app
Very nice! I'll add my voice to the "Android please" crowd. :-) There have been times when I really could have used a "ready reference" like this! -
SNRatio at 15:06 PM on 11 February 2010Working out future sea level rise from the past
I wonder if this may be the simplest way to estimate the effects of eccentricity e: Irradiation intensity is inversely proportional to angular momentum L=L(e), and from the orbit equation and the second law we get (integrating out) L(e)=a^2/T*L_integral where L_integral can be defined (R syntax) as follows: L_integral <- function(e=0){integrate(function(x){1/(1+e*cos(x))^2},0,2*pi)$value*(1-e*e)^2 } This is a decreasing function of e, therefore irradiation intensity will increase with increasing e. Please correct me if I am wrong! This gives about the same results as Bern got (his values in paranthesis): L_integral(0.0)/L_integral(0.058)=1.001686 (1.00181) L_integral(0.0)/L_integral(0.0167)=1.000139 (1.00017) It's not a strong effect, but it is definitely an effect. -
jeffgreen11 at 14:50 PM on 11 February 2010Skeptical Science now an iPhone app
I noticed that the app does not go sideways for easier veiwing. This would be a great thing to add. -
Doug Bostrom at 14:06 PM on 11 February 2010Skeptical Science now an iPhone app
I was first attracted to this site by John's concise explanations which are supported by loads of links to references and supporting materials. I've enjoyed reading here and getting pleasantly lost & distracted following links, quite apart from using SkS as a handy fountain of gob-stopping rebuttals. To that end, it might be fun (purely fun) to add a feature allowing you to shake or rotate the iPhone "Boggle" or "Magic 8 Ball" style, causing a randomly chosen article or blog post to appear. No practical benefit, really, just for grins. -
Jeff Freymueller at 11:45 AM on 11 February 2010Working out future sea level rise from the past
#76. "Well, it makes the study uncheckable. There are data for 2008 individual stations at the PSMSL site. If we do not know the subset used, we know nothing." Sorry, but that's nonsense. Many if not most (maybe all) of the continuous tide stations (which is what they used) are uniquely identifiable from the maps and the siting criteria they mention. If you can't get them all, then politely asking specific questions of the authors to sort out what you can't resolve on your own is what I would recommend. -
Bern at 10:52 AM on 11 February 2010Working out future sea level rise from the past
RE: Berényi Péter at 20:56 PM on 10 February, 2010 Ah, but I did divide it into segments of equal area. You assumed I divided the orbit by length, but I actually divided it by time. To be honest, I expected the higher eccentricities would result in *lower* annual average solar input, due to the longer time spent in the outer parts of the orbit. But in my reading I found that the semi-major axis of the orbit does not change, and, as I mentioned earlier, that means perihelion gets closer, more than counterbalancing the longer time at aphelion. Charlie A: yes, you're right, the phasing of the orbit with the seasons is critical too, as is precession & tilt, and these likely have a far greater effect than just the change in solar input due to eccentricity alone. My point, though, was that eccentricity by itself does have some influence, when you integrate the energy input over an entire orbit. -
MarkJohnson at 10:09 AM on 11 February 2010Skeptical Science now an iPhone app
Hi everyone, Mark from Shine Technologies here. Loving the feedback, keep it coming! Johnny_eh: we have submitted an update that will only require 3.0 and above. We can't go back any earlier than this due to what the application needs, but this should open it up to more people. The update (1.0.1) should be out within a week. -
Berényi Péter at 08:58 AM on 11 February 2010Working out future sea level rise from the past
Jeff Freymueller at 04:07 AM on 11 February, 2010: "They show the stations used in a series of figures, not a list" Well, it makes the study uncheckable. There are data for 2008 individual stations at the PSMSL site. If we do not know the subset used, we know nothing. http://www.pol.ac.uk/psmsl/psmsl_individual_stations.html -
moeyoldbold at 07:17 AM on 11 February 2010Skeptical Science now an iPhone app
THIS IS AWESOME! I LOVE IT! -
Andy Skuce at 06:37 AM on 11 February 2010Skeptical Science now an iPhone app
Thanks! Very slick interface and, of course, great content. -
Riccardo at 05:42 AM on 11 February 2010The role of stratospheric water vapor in global warming
Berényi Péter, check your maximum number of stations, it's different from the list of stations of the v2 dataset. -
Snertly at 05:37 AM on 11 February 2010Skeptical Science now an iPhone app
Looks ok, but there should be an option to replace the penguin with something more appropriate. For example a marionette figure who's strings sort of pop and jump each time the question button is hit. -
Doug Bostrom at 05:06 AM on 11 February 2010The role of stratospheric water vapor in global warming
Berényi Péter at 02:19 AM on 11 February, 2010 Here's a paper with a fairly comprehensive description of modern methods: Improvements to NOAA’s Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006) Older but with some digestive aids: An Overview of the Global Historical Climatology Network Temperature Database -
Doug Bostrom at 04:29 AM on 11 February 2010Skeptical Science now an iPhone app
Echoing Jack Kelly, a genius move. Portable improvement of any discussion of this topic. -
Jeff Freymueller at 04:18 AM on 11 February 2010Working out future sea level rise from the past
#69 thingadonta, I have no idea if there is a general relationship between swell size/height and phase of the moon, either regionally or globally. Sounds interesting, and possibly testable. I think there are some sea state measurements that are made by satellite, based on the scattering properties of the ocean surface (roughness, basically). But I don't know where one would go to find such data. -
Jeff Freymueller at 04:07 AM on 11 February 2010Working out future sea level rise from the past
#66 Berényi Péter: "Could you just copy-paste the list of tide gauge station identifiers used in the Church et al. (2004) calibration procedure along with a pointer to full sea level histories of those gauges?" They show the stations used in a series of figures, not a list. But I was able to get Church et al. (2004) for free from home, so I think you can get that paper (the later one requires a subscription). The 2004 paper is in Journal of Climate. As for the data, they got all the data from the Permanent Service for Mean Sea Level (http://www.pol.ac.uk/psmsl). I think their entire catalog is freely available. -
scatter at 03:54 AM on 11 February 2010Skeptical Science now an iPhone app
Nice one! I'll echo the request for an Android version. Check out http://isites.us for easy Android app dev -
jonny_eh at 03:06 AM on 11 February 2010Skeptical Science now an iPhone app
Awesome stuff. But why do you require firmware 3.1.2? I'm still on 3.0.1 because of some bugs I've encountered with the later firmware. Plus, there are still iPod Touch users on the 2.x firmware since it costs them $10 to upgrade.Response: The app has just been updated on iTunes with a new version 1.0 that works on firmware 3.0. Thanks for the feedback. -
Bodo at 03:00 AM on 11 February 2010Climate sensitivity is low
Hello! You could add that Schwartz updated and corrected (in some aspects) his analysis. He now claims that climate response time is 8.5 ± 2.5 years. According to this climate sensivity is 1.9 ± 1.0 K. http://www.ecd.bnl.gov/pubs/BNL-80226-2008-JA.pdf Thus his estimate of climate sensitivity now is at the lower bound of the IPCC range.Response: Thanks for the link, I wasn't aware of Schwartz' response and have updated the article accordingly. -
Berényi Péter at 02:57 AM on 11 February 2010Working out future sea level rise from the past
#70. RSVP "Kepler didnt have computer" He didn't have an electric toothbrush either. So what? -
Berényi Péter at 02:19 AM on 11 February 2010The role of stratospheric water vapor in global warming
#73. Riccardo at 09:47 AM on 10 February, 2010 "here is the graph" Wow. I still have to look into the details. Any idea why the number of surface stations in GHCN dropped so dramatically from its 1970 peak value of 9403 to a feeble 1137 in this year? Looks like 88% of the stations are lost. This is the smallest number in the last 120 years. $ wget http://www1.ncdc.noaa.gov/pub/data/ghcn/v2/v2.mean.Z $ gunzip -c v2.mean.Z | cut -c13-16 | sort | uniq -c -
Riccardo at 02:08 AM on 11 February 2010Working out future sea level rise from the past
thingadonta, here's a picture -
Riccardo at 02:03 AM on 11 February 2010Working out future sea level rise from the past
thingadonta, it's the combined effect of the moon and the sun. It has been know for millennia and anyone living by the sea is well aware of it. -
stbloomfield at 00:54 AM on 11 February 2010Skeptical Science now an iPhone app
Add me to the "Android please" group! -
RSVP at 00:31 AM on 11 February 2010Working out future sea level rise from the past
"Berényi Péter Don't do that, please. Sice J. Kepler (1609) the issue is settled." Kepler didnt have computer. Besides, even Kepler didnt say this, as he was only talking about conservation of angular momementum. -
thingadonta at 00:06 AM on 11 February 2010Skeptical Science now an iPhone app
I wonder if we will get the same from Anthony Watts and co, he keeps me well informed on snow levels at various climate conventions etc. -
pdt at 00:05 AM on 11 February 2010Skeptical Science now an iPhone app
Android version would be great! -
thingadonta at 00:01 AM on 11 February 2010Working out future sea level rise from the past
re#60: thanks Jeff, I was just wondering whether anybody had looked at it-ie the loading effect of rising sea levels. So it seems they have. It would have more bearing on eg flooded river deltas and such. Something else which is probably way off topic (I have always been interested in unusual oceanic features), various natives/locals/fisherman I have come across in the Indian Ocean are adamant that ocean swell size increases with the new moon. This assertion I have heard from areas separated by long distances and cultures. (They might also believe it increases at the full moon, but I havent heard it). I might just have dismissed this, excpet that they were usually right, at least in the short times I was there. Probably has nothing to do with changing sea levels (unless there is some sort of lunar-swell-tide relationship/cycle which has also changed over years/decades/centuries), but I doubt it. Just thought it was interesting. I have no real idea why they ?might be correct in their observation (?ocean current changes?, wind/swell energy combining with lunar tides??). -
Berényi Péter at 23:59 PM on 10 February 2010Working out future sea level rise from the past
#67. SNRatio Of course at least I. Newton (1687) is needed to handle the perturbation issue. The mathematical methods to treat effects of small orbital disturbances adequately took some time to develop even after that (a century or two) and with recent emergence of chaos theory, it is not finished yet. However, the case of eccentricity changes in Earth's orbit is simple. The main players are Jupiter & Saturn. Both have nearly circular orbit, Earth as well. Earth's orbit is also tiny compared to those of giant planets. Disturbances from forces other than radial cancel pretty well and radial forces do not change orbital angular momentum, so they leave orbital period alone. Q.E.D. -
Berényi Péter at 23:02 PM on 10 February 2010Could climate shifts be causing global warming?
Timothy, thank you for the long elaboration. However, it raises more questions than it answers. I would rather not overrun you with all of them in a sigle batch. If you would bear with me, I am going to serialize them. As a first remark. I am not stressing the ontological bases of operationism, in fact I am a realist (in medieval sense). However, an exact description of operations to get values for certain quanities is indispensable for quality assurance & debugging purposes, especially in calibration and remote sensing. http://en.wikipedia.org/wiki/Operational_definition For example remote sensing of atmospheric water vapor by satellites at first sight requires the solution of the unsolvable. Given the spatio-temporal distribution of pressure, temperature, humidity, trace gases and all the other ingredients of some relevance, it is a straightforward(?) process to calculate radiance spectra at TOA. However, in practice it should be done the other way around. You first measure radiation, then look for a distribution of state variables that would produce the same radiation signature. Unfortunately the transformation is not reversible, that is, a multitude of distributions can produce the very same radiation. The tricky part is to restrict the definition domain so as to make the transform invertible. It is done by constructing a model that does not allow for just any combination of state variables, but only a tiny subset, and if you are lucky, all states conforming to model would generate different radiation output. As you can see, a plethora of a priori assumptions go into choosing the particular model used to calculate atmospheric state backwards from radiance measurements. The question is what are the most important hidden assumptions behind model building for remote sensing purposes? How uniqueness is secured? To what extent "measured" (actually: calculated) values are dependent on model? -
Ned at 22:38 PM on 10 February 2010Skeptical Science now an iPhone app
That's fantastic, John. Thanks to you and to the people at Shine Technologies for doing this. Speaking of Tim Lambert and the debate ... someone could turn his global warming skeptic bingo game into an iPhone app. Then anyone with an iPhone could bring it to an event like the Lambert/Monckton debate and compete to see who gets the first "bingo". -
SNRatio at 22:25 PM on 10 February 2010Working out future sea level rise from the past
65 BP: You might be well advised to take the step further to Newton. Kepler settled the issue in a kinematical sense, not a dynamical - that was Newton's contribution. You are making the tacit assumption that wr^2 = L = const independent on eccentricity e. In the case of Earth, I guess we must assume the total energy E=T+V is approximately constant, e varying. Solving this equation for L, is it still independent on e? I haven't looked into that, but intuitively I would guess not. Using r=a/(1+e*cos(theta)), and integrating out theta from r^2w=L also seems to me to result in an expression for L dependent on e. But this is just some thoughts on the fly, I haven't looked into it. It seems to me that your argument shows that we can concentrate on L=L(e) to look at the total irradiation. You did not mention the variable albedo with a non-vertical axis of rotation, but if that is approximately a periodic function of angle, it should integrate to zero over a period, so that's probably ok. -
Konfacela at 22:04 PM on 10 February 2010Skeptical Science now an iPhone app
I've downloaded the app and would like to take this opportunity to thank John Cook for this brilliant website. I follow a number of climate blogs but this one is my favourite hands down - reliable, informative, supremely accessible and well-organised. Thanks a lot! About the app - brilliant spin-off, and I like the fact that they've kept the layout and the nice crisp graphics. I wish the app included a Facebook/Twitter Share button so I can let the world know I'm using it.Response: The Facebook/Twitter buttons are great ideas, we'll look to put this into the next version. Thanks for the suggestion! -
Jack_Kelly at 21:42 PM on 10 February 2010Skeptical Science now an iPhone app
Genius! I think this is a great move. Any chance of an Android version of the app too?!? Pretty please? Of course, I understand this project is a hobby rather than a dayjob so please don't think I'm nagging. SkepticalScience is a great resource.Response: We're exploring the idea of an Android version. Will post on this when I have news... -
Berényi Péter at 21:11 PM on 10 February 2010Working out future sea level rise from the past
#48 Jeff Freymueller at 12:17 PM on 10 February, 2010 "But you have to follow up the references. It is clear from the text that they followed the method of Church and White (2006), which in turn followed Church et al. (2004), which outlines the selection procedure" Of course I should have done that. Unfortunately I have a daytime job outside climate science and those papers are behind a paywall. I could arrange for a university proxy, but even that takes time. Could you just copy-paste the list of tide gauge station identifiers used in the Church et al. (2004) calibration procedure along with a pointer to full sea level histories of those gauges? -
Berényi Péter at 20:56 PM on 10 February 2010Working out future sea level rise from the past
Bern at 15:22 PM on 10 February, 2010: "I beg to differ" Don't do that, please. Sice J. Kepler (1609) the issue is settled. In your calculation you should not divide the orbital period up into 1000 equal-length segments, but segments for which enclosed area between radii connecting endpoints to center of Sun and the orbital segment itself is constant, i.e. one thousandth of area enclosed by orbit. Redo, enjoy. -
RSVP at 19:40 PM on 10 February 2010Working out future sea level rise from the past
Bern It looks like your calculations assume a static model. The Earth spends less time in those segments nearer the Sun, and more time in those segments farther from the Sun. -
RSVP at 19:37 PM on 10 February 2010Working out future sea level rise from the past
"Charlie A at 16:03 PM on 10 February, 2010 Bern and Berényi Péter" #61 It is clear that radiation intensity increases for the Earth as it gets closer to the Sun. It is also clear that the Earth's tangential velocity increases as it gets closer to the Sun, and that net radiative forcing is thereby compensated. That is very different from the idea that these two tendencies lead to perfect cancellation. I dont see this as being necessarily the case because I think of the characteristics of electromagnetics and gravity (not to mention drivers of the Earth's heat budget) as being independent. Perhaps, however the math proves me wrong. -
Doug Bostrom at 17:53 PM on 10 February 2010Sea level rise is exaggerated
Neil, I don't wish to be unkind to Dr. Mörner, just want to point out what he says elsewhere in that interview as a bit of a reality check. I'm not sure what exactly the situation with him is, but quite clearly this is wrong: "Always the same thing: In about 1970, the sea fell about 20 cm, for reasons involving probably evaporation or something. Not a change in volume or something like that- it was a rapid thing. The new level, which has been stable, has not changed in the last 35 years. You can trace it so very, very carefully. No rise at all is the answer there." Much of the rest of the piece consists of accusations of lies, coverups, falsifications, too much to be believable. It's actually pretty sad, and I say that with sincerity. Sometimes you need to look at a narrative in sum and ask yourself, how -likely- is this? If I'm confronted with one man's word against hundreds and there is coherent consistency between what those many say that is completely inconsistent with the beliefs of the lone individual, I'm afraid I'm not going to believe him. There are just too many eye-popping anecdotes in Dr. Mörner's story to hold water. -
Arno Arrak at 16:29 PM on 10 February 2010Sea level rise is exaggerated
I did not realize that you had posted a comment to my comment until now. I want to emphasize that factoring in water impoundment gives the true rate of sea level rise that would exist if no water were impounded. I don't know why you bring in the other curves especially since the slope, and hence the predicted rate or rise, is essentially the same. And none of this has any significance whatsoever on the fate of retreating ice sheets. That is a totally different issue and depends upon the causes of arctic warming. In the case of the Antarctic the West Antarctic ice sheet is melting because it is being undermined by warm water rising up from below in the Amundsen Sea. This is because prevailing winds are from land to sea and blow away the cold surface water which is then replaced by warmer Antarctic bottom water. It has collapsed before, most recently 1500 years ago, and may collapse again if this keeps up. In the Arctic we are now in the middle of more than a century long warming period that started abruptly at the start of the twentieth century. This abrupt beginning rules out any greenhouse effect as its cause and indicates that a rearrangement of North Atlantic current system that directed warm water to the north took place at the turn of the century. Since we know that the Gulf stream now brings warm water to the Arctic it is likely that it assumed its present northerly course at that time. It is futile to try to predict any of this from computer models using the old carbon dioxide global warming paradigm. They produce nothing but GIGO. -
Charlie A at 16:06 PM on 10 February 2010Working out future sea level rise from the past
The link to Kopp in the head post leads to a paywall. The full paper is freely available at http://www.princeton.edu/step/people/faculty/michael-oppenheimer/research/Kopp-et-al-%282009%29-Probabalistic-assessment-of-sea-level-during-the-last-interglacial-stage-.pdf
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