Recent Comments

Prev  2481  2482  2483  2484  2485  2486  2487  2488  2489  2490  2491  2492  2493  2494  2495  2496  Next

Comments 124401 to 124450:

124401. thingadonta at 10:15 AM on 12 February 2010
        Is CO2 a pollutant?
        "The net result from increasing CO2 are severe negative impacts on our environment and the living conditions of future humanity." I agree with the general view that if most climate scientists are right, the net effects of c02 will be very negative. However, the issue here is a general philosphical one. By labelling and demonising something natural and essential to life as a 'pollutant', is a dangerous and misleading policy. It creates a dogmatic, one-sided political perspective. As David Haughton points out, you could also call water a 'pollutant' using this sort of labelling. If too much is ingested in the lungs, one drowns, it can form hurricanes which kill thousands of people, it can form tsunami waves that kill thousands, etc etc, so should we call 'water' a pollutant and form policies against it? Of course not. It is misleading and dangerous to do such a thing, regardless of its overall net positive or negative effects. Labelling C02 a pollutant may achieve political goals, but at the expense of also creating a dogmatic perspective. What this sort of general policy does to the mind (as also with Plato and with his concept of a Republic run by an elite-he never asked what such an arrangemnet does to the mind of those involved), is that is creates systematic bias and extremism. It is the same kind of problem with eg demonising dissent, dissent of course can be very wrong, but it can also have value, but the demonisation of dissent as a general policy is what is wrong. I'm sorry, but it is just another case of 'lumping' which is a general philosophical issue that some people have a valid disagreement with.
124402. Berényi Péter at 09:49 AM on 12 February 2010
        Is CO2 a pollutant?
        Posted by John Cook at 22:54 PM (main article): "as the oceans absorb CO2 from the atmosphere, it leads to acidification that affects many marine ecosystems" Seawater is nowhere near to being acidic, not even neutral. It is alkaline. No conceivable CO2 levels could turn it into an acid. Acidification is a misnomer, designed to conjure scare up. The process can honestly be described as dealkalinification, at best. All the surface waters of the world are carbonate-saturated. The lysocline, where calcium carbonate solubility starts to increase sharply is somewhere around 3700 m. The CCD (Carbonate Compensation Depth), below which no limestone deposition occurs is at 4200-5000 m. It didn't change much during glacial periods, when atmospheric CO2 levels are supposed to be considerably lower than today. Kinda enigma, see: Glacial/interglacial variations in atmospheric carbon dioxide (review article) Daniel M. Sigman & Edward A. Boyle http://www.up.ethz.ch/education/biogeochem_cycles/reading_list/sigman_nat_00.pdf With water warming, lysocline goes down, not up. If all else fails, we can put some limestone into oceans to balance CO2. There are several million gigatons of it in crust, a tiny little percentage would suffice.
124403. angliss at 08:32 AM on 12 February 2010
        Is CO2 a pollutant?
        Thank you for the explanation, RSVP. That's what I thought you probably were going for, but I wanted to be sure before I attempted to respond with a scientific rebuttal. However, CBDunkerson has already made the very points I would have made and I feel no need to reiterate his points. Ed Seedhouse - I think you meant carbon dioxide, not carbon monoxide.
124404. Doug Bostrom at 08:30 AM on 12 February 2010
        Is CO2 a pollutant?
        David Horton at 08:05 AM on 12 February, 2010 David, I get what you're saying, but the analogy with water from a tsunami or other natural event really does not work. I even disagree with our host when he says: "How we choose to define the word 'pollutant' is a play in semantics." The CO2 in question here is an effluent from human activities. Our C02 emissions are an outcome of our engineered products, something we now realize is a serious imperfection. As another example, C0 is found naturally occurring in the atmosphere yet we have spent a lot of money improving our motor vehicle engineering so that we do not emit too much C0. We do not accept that because C0 is a naturally occurring atmospheric constituent that we may ignore the C0 we produce as a byproduct of our activities. EPA's job is going to be explaining that simple fact, but the job of explanation is going to be very difficult given the call to confusion they'll be facing from industry.
124405. David Horton at 08:05 AM on 12 February 2010
        Is CO2 a pollutant?
        Thanks for putting in this topic John. It is one of those pieces of semantic nonsense (how many CO2 molecules could you fit on the head of a pin?) that are trotted out by deniers as if discovering some new universal truth hitherto covered up by the secret scientific brotherhood. On a practical level my understanding is that the American EPA, and possibly other countries are in the same position, can only regulate to reduce "pollutants" in air soil and water. It was never envisaged when such bodies were being established that CO2 would be become the most important issue of all and need controlling. The simplest thing would be to rewrite legislation to say "control pollutants AND CO2" and that would get us away from semantic games. I mean clearly CO2 isn't a pollutant in the classical sense. Nor is water. And yet water, after a flood, or a landslide, or a tsunami, damages human environments as much as any chemical released from factory or oil tanker. So too much water, too quickly, in the wrong place at the wrong time, is a damaging agent in the same way that pollutants from an oil tanker crash, or a factory fire, are damaging agents. It is all reminiscent of the old debate about what is a "weed". Definitions usually break down at some point and we are usually left with just the idea that a weed is a plant growing rapidly in the wrong place. So perhaps it would be helpful to refer to CO2 as a chemical weed rather than a pollutant. That might stop the deniers dancing on the heads of pins.
124406. Dennis at 07:52 AM on 12 February 2010
        Is CO2 a pollutant?
        Alexandre writes: "Anything can be a pollutant, in the wrong concentration." This is a good way to look at it, and an excellent analogy is to think of drugs and other medications. In the correct dosage, a drug can save your life. But too much of it can kill you. Same with CO2
124407. From Peru at 07:14 AM on 12 February 2010
        Is CO2 a pollutant?
        CO2 is toxic to subwater organisms, because the following reaction occurs: CO2(ac)+H20(l)=H2CO3(ac) H2CO3(ac)= H+(ac) + HCO3-(ac) Yes, seawater has a natural pH buffer thanks to all the salts there(the so-called alkalinity), but the quantity of CO2 we emit is so big that this buffer is overwhelmed. In consecuence, oceanic pH has dropped 0,1 pH units from pre-industrial times(pH used to be 8,2. now is 8,1). This is equal to roughly 30% increase in acidity!(don't forget that pH is a logarithmic scale). More acidic water means that shelled creatures like corals, pteropods, diatoms, etc, will lose their shells and die. This alone is more than enough to consider CO2 a pollutant, even if we ignore global warming!
124408. Doug Bostrom at 06:53 AM on 12 February 2010
        Is CO2 a pollutant?
        RSVP at 05:21 AM on 12 February, 2010 For chronic exposure, even lower. Some folks become symptomatic at less than 2,500ppm after a relatively brief time, but if we were to somehow hit that we'd all be cooked anyway.
124409. CBDunkerson at 06:45 AM on 12 February 2010
        Is CO2 a pollutant?
        RSVP, it is true that the atmosphere of Mars is 95% carbon dioxide... but the mass of the Martian atmosphere is only 0.5% that of Earth. Further, Mars does not have any significant component of water vapor in its atmosphere. That, combined with Mars getting about 43% as much sunlight is responsible for its cold temperatures. The high percentage of CO2 in the Martian atmosphere DOES provide a greenhouse effect. Just not enough to overcome the low amount of sunlight and lack of much more potent water vapor greenhouse warming.
124410. CBDunkerson at 06:29 AM on 12 February 2010
        Is CO2 a pollutant?
        Anything which causes damage to an ecosystem when it grows too concentrated is a pollutant. Thus we have "light pollution" and "noise pollution" despite light and sound being 'naturally occurring' and generally harmless things. Early in the planet's history "oxygen pollution" wiped out alot of species. A single molecule of CO2, or just about any other substance, is not going to noticeably harm the environment in any way... but 80,000 ppm CO2 would kill off most life on the planet. Thus, somewhere between those extremes CO2 logically MUST be considered to become a pollutant. It is a measured fact that increased CO2 emissions have changed the pH of the shallows of the world's oceans. This change has clearly had an adverse impact on species living there. Thus, human CO2 emissions have become a pollutant for the ecosystems of the upper portions of the world's oceans. Likewise, rising global temperatures have been linked to the increasing atmospheric carbon dioxide level... and those rising temperatures are having adverse impacts on countless ecosystems all over the world. Thus, atmospheric CO2 has reached levels where it has become a pollutant for many parts of the planet. Granted, there are many other areas which have suffered no significant adverse impacts from increasing CO2 levels yet. However, since CO2 released in one part of the planet can mix throughout the atmosphere in a matter of mere months this means that release of CO2 anywhere on the planet is contributing to the harm in areas being polluted by it... similar to acid rain from sulfur dioxide (another naturally occurring substance which only becomes a pollutant at high concentrations) appearing far removed from the emissions source.
124411. RSVP at 06:16 AM on 12 February 2010
        Is CO2 a pollutant?
        "angliss at 05:35 AM on 12 February, 2010 RSVP - I don't see what the point of your Mars atmosphere comment was. Can you clarify your purpose with that comment?" While I believe there is such a thing as thermal environmental pollution, I am personally not convinced (yet) that anthropogenic CO2 is the main cause of global warming. One way to look at this is by comparing the situation on Mars, which happens to also have a 24 hr day, and an atmosphere of pure CO2 that is just about the same as would exist on the Earth if all other gases from our atmosphere were removed (which is the point of explaining my calculations). On Mars, the average temperature is down around -40C. And yes, I am aware that Mars only gets about half the sunshine as the Earth, however, shouldnt all that CO2 be keeping the plantet a little warmer?
124412. Ed Seedhouse at 06:13 AM on 12 February 2010
        Is CO2 a pollutant?
        Venus, too, like Mars, has an atmosphere of nearly pure carbon monoxide. Yet it, unlike Mars, is hellishly hot. RSVP, do you suppose, that, just maybe, distance from the sun has some slight influence here?
124413. CoalGeologist at 05:46 AM on 12 February 2010
        Is CO2 a pollutant?
        As with so many other aspects of the climate change debate, the question of whether CO2 should be regarded as a pollutant has become more an issue of politics and ideology than of science. An interesting analysis and discussion can be found in the United States Supreme Court decision in Massachusetts et al. v. EPA et al.: http://www.law.cornell.edu/supct/pdf/05-1120P.ZO At the time, the U.S. Environmental Protection Agency, acting on behalf of the Bush Administration, declined to regard CO2 as a pollutant that could potentially be regulated under the Clean Air Act. The Supreme Court split 5-4, along ideological lines. See p. 26 for discussion of the term "pollutant". The political nature of this dispute is further evident in that the plaintiffs included 11 (2004) "Blue States" plus one Red State (New Mexico), while the EPA was joined by 9 (2004) "Red States" plus one Blue State (Michigan, capital of the auto industry!).
124414. angliss at 05:35 AM on 12 February 2010
        Is CO2 a pollutant?
        RSVP - I don't see what the point of your Mars atmosphere comment was. Can you clarify your purpose with that comment? CoalGeologist - as you point out, "pollutant" also depends on source. An example I like to use is fixed nitrogen. It's a vital soil nutrient - but becomes a pollutant when there's too much of it spread on fields and the excess flows down the Mississippi and into the Gulf of Mexico, where it fuels algae blooms and a massive dead zone.
124415. carrot eater at 05:32 AM on 12 February 2010
        Is CO2 a pollutant?
        This entire discussion is missing the required context. People may differ on how they use the word 'pollutant', but in the US the issue goes back to this Supreme Court case: http://en.wikipedia.org/wiki/Massachusetts_v._Environmental_Protection_Agency The Supreme Court found that CO2 qualifies as a pollutant, as defined by the Clean Air Act. Regardless of whether you want to use the word 'pollutant' or not, increased CO2 levels have adverse effects which qualify them for regulation under the Clean Air Act.
124416. John Russell at 05:24 AM on 12 February 2010
        Is CO2 a pollutant?
        In many posts on many websites, deniers try constantly to make the people concerned about human impact on the climate admit that they think of CO2 as a pollutant (which is of course why John addressed the question here). Their reasons then become clear when, with denier's glee, they come back with, "...but it's necessary to support life on Earth!" It's just another of the many carefully rehearsed tricks that deniers use against those with a shaky understanding of the causes of climate change, in order to undermine their trust in the findings of climate scientists. Unfortunately at the moment the science of the 'blindingly obvious*' used by deniers seems to be winning the battle for public opinion. *'blindingly obvious' is the phrase used by arch-denier Lord Monckton to describe the evidence against AGW.
124417. RSVP at 05:21 AM on 12 February 2010
        Is CO2 a pollutant?
        CO2 can actually be toxic to humans at or above 50,000 ppm. See link: http://www.inspectapedia.com/hazmat/CO2gashaz.htm
124418. CoalGeologist at 05:21 AM on 12 February 2010
        Is CO2 a pollutant?
        Part of the ambiguity in the term "pollutant" is that a distinction needs to be made between the [quantity of] CO2 represented by the flat part of the curve above versus the incremental CO2 introduced as a by-product of human activity ("anthropogenic CO2"): same molecule, different origin. We encounter an analogous (intentional?!) ambiguity when skeptics use the term "global warming" to describe all warming that has occurred: a) since the last glacial maximum (~22,000 years before present) or b) since the LIA. It is not simply CO2 but A-CO2 that is interpreted to be driving anthropogenic warming (AGW), and thus is acting as a "pollutant". The other potential ambiguity is that the harmful impact of A-CO2 needs to be measured relative to the "status quo", which refers specifically to the climate and environment that has existed for the several thousand years prior to human impact on climate. This is a "blink of an eye", geologically. During the time period preceding the curve shown depicted above, both CO2 and temperature varied substantially in response to natural drivers. This partly explains why many geologists see climate change in different context.
124419. Berényi Péter at 03:37 AM on 12 February 2010
        Could climate shifts be causing global warming?
        #47 Timothy Chase at 17:58 PM on 11 February, 2010: "Initially sounds like it could be a reasonable approach" It is _actually_ the approach they are using to reconstruct upper/mid troposphere relative humidity distributions using AIRS spectra. The algorithm IS dependent on the (rather complicated) ECMWF global atmospheric model. European Centre for Medium-Range Weather Forecasts ECMWF general circulation model (TL799L91) It is not just philosophy, but a hard fact of life. Have a look at this recent presentation: Applications of Satellite Water Vapor Retrievals to Climate Studies Ming-Dah Chou Department of Atmospheric Sciences National Central University Presentation at the Research Center for Environmental Changes, Academia Sinica, February 3, 2010. http://www.rcec.sinica.edu.tw/Seminar%20files/Presentation%20files/100203(Dr.%20Edward%20Cook)Satellite%20Water%20Vapor%20Retrievals.pdf From "Concluding Remarks": - Global distributions of water vapor can be best derived from Satellite observations. - However, satellite retrievals of water vapor in the upper and lower troposphere encounter inherent difficulties, and the satellite-retrieved water vapor in these important regions is not reliable. So. The question still stands. To what extent "measured" (actually: calculated) values are dependent on model? For the general idea, still used in AIRS reconstructions see: High resolution observations of free tropospheric humidity from METEOSAT over the Indian Ocean. R´emy Roca, H´el`ene Brogniez, Laurence Picon and Michel Desbois Laboratoire de M´et´eorologie Dynamique, CNRS, Palaiseau, France MEGHA-TROPIQUES 2nd Scientific Workshop, 2-6 July 2001, Paris, France. --- At another site, another time I would happily discuss the intricacies of phylosophy. However, it looks a bit off-topic here. As for the multitude of spectral channels. Some women are tetrachromats. I don't think they can grasp reality more accurately than anyone else. Myopic girls could do worse. Anyway, image processing skills of the soul are not understood. On the other hand, things in science are supposed to be understandable. As for doubting Descartes, consider the following tiny piece: 1. If a subphrase of a phrase does not make sense, the entire phrase is senseless. 2. Senselessness is preserved by negation. 3. The negation of "I think (therefore) I am" is "I am not (therefore) I don't think". 4. The phrase "I am not" does not make sense Therefore: Chartesian philosophy is based on nonsense. Google for it. http://www.google.com/#hl=en&q=%22I+am+not%22 --- AIRS fact sheet
124420. LauraM at 01:47 AM on 12 February 2010
        Is CO2 a pollutant?
        Republican Rep. Mike Noel (Utah): "Are you stating on record that CO2 is a pollutant? Are you saying that CO2, carbon dioxide, is a pollutant, are you saying that?” Professor Joseph Andrade: "I'm saying that carbon dioxide has a unique molecular structure which absorbs infrared radiation, and that that is in part responsible for the effects that you're concerned with, Representative Gibson is concerned with, and Representative ...." Noel: "I want to get this on the record, ok? Are you saying that we have to rid the planet of carbon dioxide?" Andrade: "Of course not!" Noel: "It's not a pollutant then, it's not going to kill you. It's not going to kill plants. Is that correct? I also have a degree too, professor. So I want to get this straight. Is it a pollutant?" (The conversation becomes a verbal skirmish, and the committee chairman breaks it up.) Noel: "I'm sorry, I'm sorry ... It got out of hand."
124421. foram at 01:39 AM on 12 February 2010
        Is CO2 a pollutant?
        Argh, typo. Should just say "acidification is a decrease in pH". Relatively small changes in pH are associated with significant alterations to ocean carbonate chemistry, which affects the ability of calcifying organisms (such as corals) to build their skeletons
124422. foram at 01:33 AM on 12 February 2010
        Is CO2 a pollutant?
        Westwell, a acidification is a decrease in pH. Nobody is suggesting the oceans will become acidic! You could take a look here (http://royalsociety.org/Ocean-acidification-due-to-increasing-atmospheric-carbon-dioxide/) if you are genuinely interested in learning about the issue.
124423. Lou Grinzo at 01:27 AM on 12 February 2010
        Is CO2 a pollutant?
        I think a key factor here is timing. We tend to think of something being a pollutant or poison if it has an immediate negative effect, as someone mentioned above. I think this is a precarious view, though. When we're talking about a substance that hangs around in the atmosphere (at least the portion not absorbed by the oceans, plants, etc.) for a very long time and can therefore build up over decades and centuries to a dangerous level, I would say that still qualifies as a pollutant. As for the "too much of anything is bad" idea--of course that's true, but if we consistently apply that guideline it leaves us doing nothing about any pollutant. The only rational approach is to distinguish between critical and non-critical levels of substances. If we call the damaging levels of something a pollutant, regardless of its source *e.g. sulfurous emissions from volcanoes), then I think that's fine. Westwell: Oceans don't acidify because of CO2 absorbed from the atmosphere? Really?
124424. RSVP at 01:17 AM on 12 February 2010
        Is CO2 a pollutant?
        Using figures from the graph, one can estimate the comparable height of a pure CO2 Earth atmosphere removing all other gases. For intance, if you assume an air atmosphere 20 km high, with a concentration of 0.0274 CO2 (how it used to be), you would have a CO2 atmosphere of 5.5 meters covering the Earth. If you assume 0.0387 vppm, that pure CO2 atmosphere grows to 7.8 meters. Assuming continual doubling, to 0.0774, you get 15.5 meters. If you dont like 20 km and wish to consider a higher atmosphere of 40 km for instance, then these results simply get multipled in linear fashion, so that at worst, you get roughly around 30 meters of pure CO2 covering the Earth. Ironically, that basically describes the atmosphere of Mars, which has a composition of nearly pure CO2. http://www.daviddarling.info/encyclopedia/M/Marsatmos.html ... and Mars is a very cold place. PS I derived these figures assuming the Earth as a perfect sphere, using the formula for calculating the volume of a sphere and applying it to an assumed Earth radius of 6378.1 km. No rocket science required, but I did use a computer spreadsheet.
124425. Ani at 01:14 AM on 12 February 2010
        Is CO2 a pollutant?
        Yes it is semantics. But playing politics is something we do everyday, wether at work, school, internet, etc. It seems like in the USA and UK we do it for sport. But the bottom line is we have to move foward so it doesnt matter if you call it klem kaditlehopper as long as something gets done
124426. Westwell at 00:58 AM on 12 February 2010
        Is CO2 a pollutant?
        Re:"as the oceans absorb CO2 from the atmosphere, it leads to acidification that affects many marine ecosystems." This is not true. The oceans are buffered and the acidification does not rise from increased absorption of CO2.
124427. Berényi Péter at 00:56 AM on 12 February 2010
        Is CO2 a pollutant?
        I would reserve the term "pollutant" to stuff that 1. has got an immediate, direct harmful effect to human health and/or to quality of local environment in a way that substantially decreases property value 2. can be traced back to individual polluters, actual deed and the damage done being provable at court None of these conditions hold for carbon dioxide. If CO2 is "pollutant" what term would you reserve for e.g. dioxin, the stuff involved in the Union Carbide disaster, Bhopal, India, 1984? Thousands perished. http://lists.essential.org/dioxin-l/msg01318.html There should be a difference in legislation and multilateral treaties regarding the two kind of substances, otherwise not even overt criminals can be brought to justice. Cases like that can never be cured by taxation, virtual bonds, persuation & speeches. Also, humans do breathe out CO2, a substantial amount of it (up to 300 kg/year/person, ~2 Gt/year for mankind). If polluting is declared a criminal act (as it should have) and human breath is a pollutant, then it follows the very act of breathing should be punished. Each living person is amenable to law, judge included. Forget freedom, establish breathing permits ("breathing is not a right, it is a privilege"). More likely this policy would meet some resistance. It could bring down all legislation against "pollutants" and evil/irresponsible guys involved in the act of "polluting" (i.e. killing/robbing people). Collateral damage of the most undesirable kind. Invent another term, please.
124428. Tony O at 00:46 AM on 12 February 2010
        Is CO2 a pollutant?
        Got to agree with Alexandre. Somewhere along the way we have forgotten the concept of enough.
124429. Alexandre at 00:34 AM on 12 February 2010
        Is CO2 a pollutant?
        Anything can be a pollutant, in the wrong concentration. Even if it´s a naturally occurring substance. Take any substance that´s part of a biological cycle, vary it significantly and voila! You get undesirable consequences. Double Oxygen, anyone?
124430. Riccardo at 00:21 AM on 12 February 2010
        Working out future sea level rise from the past
        Berényi Péter, a possible mechanism for glacial termination has been described elsewhere in this site.
124431. Berényi Péter at 00:04 AM on 12 February 2010
        Working 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?
124432. Riccardo at 23:06 PM on 11 February 2010
        Why 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.
124433. Berényi Péter at 23:05 PM on 11 February 2010
        Working 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
124434. SNRatio at 22:23 PM on 11 February 2010
        Working 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.
124435. jisabi at 22:05 PM on 11 February 2010
        Why 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.
124436. RSVP at 19:04 PM on 11 February 2010
        Working 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.
124437. Timothy Chase at 17:58 PM on 11 February 2010
        Could 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.
124438. Timothy Chase at 17:56 PM on 11 February 2010
        Could 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
124439. Bern at 15:15 PM on 11 February 2010
        Skeptical 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!
124440. SNRatio at 15:06 PM on 11 February 2010
        Working 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.
124441. jeffgreen11 at 14:50 PM on 11 February 2010
        Skeptical 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.
124442. Doug Bostrom at 14:06 PM on 11 February 2010
        Skeptical 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.
124443. Jeff Freymueller at 11:45 AM on 11 February 2010
        Working 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.
124444. Bern at 10:52 AM on 11 February 2010
        Working 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.
124445. MarkJohnson at 10:09 AM on 11 February 2010
        Skeptical 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.
124446. Berényi Péter at 08:58 AM on 11 February 2010
        Working 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
124447. moeyoldbold at 07:17 AM on 11 February 2010
        Skeptical Science now an iPhone app
        THIS IS AWESOME! I LOVE IT!
124448. Andy Skuce at 06:37 AM on 11 February 2010
        Skeptical Science now an iPhone app
        Thanks! Very slick interface and, of course, great content.
124449. Riccardo at 05:42 AM on 11 February 2010
        The 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.
124450. Snertly at 05:37 AM on 11 February 2010
        Skeptical 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.

Prev  2481  2482  2483  2484  2485  2486  2487  2488  2489  2490  2491  2492  2493  2494  2495  2496  Next