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Riccardo at 03:16 AM on 6 November 2009CO2 is not the only driver of climate
Gord, your examples of the need of a cooled detector are just guessing a reason when you don't know how it works. It has absolutely nothing to do with it. And about your "beloved" cancellation (sic) of light, this "cancellation" occurs at specific conditions and at particular points (or regions) in space, not everywhere. Also, you don't see that the effect is due to phase, which modulates the amplitude of the wave as function of time and space. You can not describe an energy flux this way becuase, in fact, it's not a wave. @WeatherRusty I know, there must be something pathological in me :D But i'm too curious to see how far a man who doesn't want to study and learn can go saying that the whole world is wrong. ;) -
Tom Dayton at 03:01 AM on 6 November 2009CO2 is not the only driver of climate
Gord wrote "There are no 'wave packets.'" Go to the HyperPhysics site that you trust so much, to the page on Blackbody Radiation. In that diagram, note the line connecting the Blackbody Radiation oval to the Stefan-Boltzmann Law oval. That connecting line says "summed over all wavelengths gives the." In other words, Blackbody Radiation... summed over all wavelengths gives the... Stefan-Boltzmann Law. The Stefan-Boltzmann Law is a merely a convenient summary description of the underlying, more fundamental, entities and behaviors. -
Gord at 02:38 AM on 6 November 2009CO2 is not the only driver of climate
WeatherRusty - re:your post#200 I wonder how many times I have to repeat, over and over again, these simple concepts. (see my many, many posts on interference that includes ACTUAL physics links) Here is one link that is so simple that a CHILD CAN UNDERSTAND! Cancellation of Light (This Bubble link is especially well done...even a child could understand it) http://www.exploratorium.edu/ronh/bubbles/bubble_colors.html ------------------------------------ I have repeated this at least 10 times now! What, exactly, don't you understand about interference and light cancellation ??? -
WeatherRusty at 02:22 AM on 6 November 2009CO2 is not the only driver of climate
I can't believe this attempt to educate Gord has continued on as it has. Not only does he dispute the reality of the greenhouse effect but he also claims quantum mechanics to be flawed in the most fundamental of ways. No discreet wave packets of light according to him? If a new wave pattern results from interference how is it we can detect discreet emitters of radiation such as distant stars? Leptons (photons) do not obey the Pauli Exclusion Principle. Information is not lost as a result of interfering waves, they pass right through each other. Downward "cooler" radiation is not canceled out by "warmer" radiation traveling in the opposite direction. The energy "waves" pass right through each other. Discreet emissions of electromagnetic radiation such as when an electron jumps energy levels within the Bohr model always propagate in all three spatial directions with no direction preferred just as a wave propagates outward in all directions when dropping a stone in water. The squiggle that represents the photon as shown in the model is just there to indicate emission, but the emission is actually as wave-particle duality. The model shows only the "particle" representation. -
Henry Pool at 01:41 AM on 6 November 2009How do we know CO2 is causing warming?
Ok, I have had some time now to study the most recent Palle et al report, I agree with the conclusion: "In the common period, earthshine, CERES along with ISCCP-FD data show a trendless albedo. However, preceding CERES, earthshine and ISCCP-FD reflectances show a significant increase before flattening and holding the increase. This implies a reduction in the net sunlight reaching earth...it is important to point out that the physical causes behind these decadal variations in albedo are still unknown, and that we just don't know yet whether we should expect the albedo changes observed during the modern period to persist into the future.." end quote. Well, if you go a few steps back (above) you will have noticed that I am pretty sure that the increase will hold because it is most probably due to a) an increase in CO2 b) an increase in ozone (due to elimination of CFC's) and c)greater shallow water reservoir surface areas due to human activities. Obviously as the weather was getting warmer more clouds are formed, which also helps to reflect more sunlight to space. The reflected sunlihgt is what makes earth cooler. So remember: water and carbon dioxide are like my mother and father. Make sure about the facts before you say anything bad about them/ I am not sure what you people are going to do or say in Copenhagen. I have done my job. -
dopeydoctorjohn at 01:37 AM on 6 November 2009There is no consensus
Birdbrainscan Thanks for your reply. The subject of my posts was the Doran study. Yes, looking at the bigger picture is something else I might have done, but, quite clearly, the subject of my posts was the Doran paper. Big pictures are made of little pictures. Pixels on your screen. Rods and cones on your retina. There's nothing inherently wrong in looking at one study. I don't doubt that the majority of scientists in this field agree with the current dominant paradigm. They always do, almost by definition (Kuhn). That's not my point, either. I read scientific journals every week (insofar as medicine is science) and I reflexly look for flaws in the research. This keeps my patients safe and well, and my practice successful. I stand by every material comment I made about the Doran paper, and you have not contradicted these observations. Is there a broad agreement amongst scientists that temperatures are rising? Clearly there is. Do some authoritative scientists disbelieve that catastrophe is at hand? Clearly some disbelieve. But either way the Doran study constitutes very poor evidence and does little to advance certainty about these questions beyond that which we have from other sources. It doesn't merit the space it occupies on this site. Surely there are better consensus papers around than this? But I did not, as you imply, take issue with their conclusion then seek to criticise their method. I took issue with their method. And I would happily tear apart a skeptic paper in the same way. The way researchers deal with non-response bias is well-established. You'll find it dealt with in any medical journal you care to open. (and doctors are busy people, too). I see no evidence of Doran dealing with this potential confounder. Which makes the research sloppy. And since a responder whose views are likely to concur with a researcher is more likely to answer a survey than a (potential) responder whose views are likely to disagree with a researcher, exploring non-response bias might have turned up evidence Doran might not have wanted. But nothing in post 173 suggests an accusation of fraud. I could as easily assert that accusing me of accusing Doran, at this point, of fraud, is itself "way out of line". Do you have comment about 174-176? Can I take it then that these observations re the Doran study go unchallenged? Do you have comment about the substance of 177-179, aside from their temperature? before asking me to just turn away from this research and look at other research? Aside from exhorting me to chill out and avert my eyes, do these observations re the Doran study remain unchallenged? In my field I read a lot of junk science. I don't like being bullshitted. Well intentioned or not, Doran is misleading in comparing the scientists and the public on the one graph when they were not asked the same question. No matter how noble the cause, sloppy or disingenuine work is not justified and is ultimately self-defeating. Machiavelli's methods have no place in science. -
Riccardo at 01:14 AM on 6 November 2009CO2 is not the only driver of climate
Gord, just to add fuel to the fire, there's one more thing you don't understand, the reason why an IR detector is cooled. The dector can work at room temperature, it is cooled only to have a better the signal to noise ratio. Clearly you're talking of things you don't know. -
PeterPan at 00:11 AM on 6 November 2009The albedo effect
So albedo has had an effect on global temperatures - mostly a cooling effect on long term trends
But, after showing Pallé 2004 (Fig. 2), I don't see any new long term trend; only recent trends (since 2000). The update in Palle 2008 (fig. 2a, p. 32) still shows an overall decreasing long-term trend in albedo (and therefore a warming effect), isn't it? In fact, Pallé 2005 compared earthshine with other data sets and says that 1985-2000 trend would range "from 2–3 W/m2 [Wielicki et al., 2002; Pinker et al., 2005] to 6–7 W/m2 [Palle´ et al., 2004; Wild et al., 2005]" (paragraph [20]). *I've also seen that Pallé replied to the comment by Bender suggesting that the earthshine could be considered global (paragraph [3]). -
clayco at 23:21 PM on 5 November 2009ACRIM vs PMOD, the rematch
@ Peter Pan http://pielkeclimatesci.wordpress.com/2009/08/03/nicola-scafetta-comments-on-solar-trends-and-global-warming-by-benestad-and-schmidt/ "Benestad and Schmidt apparently do not know that since 1978 Lean 1995 as well as Lean 2000 do not differ significantly from PMOD because PMOD was build (by altering the published TSI satellite data) by using Lean 1995 and Lean 2000 as guides. Moreover, we also merge the Lean data with ACRIM since 1978 to obtain an alternative scenario, as it is evident in all our papers. The discontinuity problem addressed by Benestad and Schmidt in merging two independent sequences (Lean’s proxy model and the ACRIM) is not an issue because it is not possible to avoid it given the fact that there are no TSI satellite data before 1978." Nicola Scafetta -
chris at 23:08 PM on 5 November 2009The albedo effect
re #5: RSVP, "nighttime Earth" means nighttime on Earth!. Click on the convenient link to Palle 2004 that John very thoughtfully added to the legend to Figure 2 in his summary. You'll find that Earthshine, the "ghostly glow of the dark portion of the lunar disk", is measured from the Big Bear Solar Observatory in Big Bear City in California during four hours of darkness at night. The paper contains a simple description of the measurement of Earthshine by comparing the brightness of the earth-lit Moon to that of the sun-lit Moon... -
chris at 22:55 PM on 5 November 2009The albedo effect
re #4 RSVP: (i) Note that there isn't much uncertainty over the radiative forcing resulting from doubling of atmospheric CO2. The uncertainty lies in the climate response to this forcing, and this uncertainty applies to any source of forcing. So it is entirely appropriate to compare the forcing of any given phenomenon (e.g. albedo), to the pertinent and rather well characterised forcing arising from doubling atmospheric CO2. And remember that the generation of "controversy" is not necesssarily a representation of scientific understanding based on evidence, and we should really seek light on these subjects rather than heat.... ....and so, the fact that some people believe the greenhouse effect is a "myth", is no reason to wallow in ignorance ourselves! (iii) Yes a change in albedo can be considered a forcing, since it represents a change in solar radiation that "participates" in the energy balance that defines a particular climate (temperature) state. Of course it may also be a feedback (sea and land ice response to forcings), but it is convenient to consider it's contribution as a forcing (in the manner that Palle et al do), when considering the temporal variation in energy balance (i.e a "lumped" forcing). However!...note that we have to very careful with albedo, since the source of the albedo change complicates a direct assignment of a forcing (as Palle et al. 2008 discuss [*]). So an albedo change resulting from a change in cloud coverage, doesn't necesarily equate to a negative forcing, since clouds also reduce the radiative dissipation of thermal energy to space. [*] E. Pallé et al (2006) Can Earth's Albedo and Surface Temperatures Increase Together? Eos Trans. AGU, 87(4), doi:10.1029/2006EO040002 -
Gord at 22:37 PM on 5 November 2009CO2 is not the only driver of climate
Tom Dayton - re:your post#189 and #190 (Second attempt to get this posted, without deletion) Here is the Stefan-Boltzmann Law again: P/A = BC*T^4 (watts/m^2) http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/stefan.html Clearly, if T is greater than absolute zero an Electromagnetic Field is produced....continuously. There are no "wave packets". ---------------------------------- Why don't you produce ANY AGW paper that says the Sun's radiation, Earth Radiation or Atmosphere Radiation is in "wave packets"? -
Gord at 22:35 PM on 5 November 2009CO2 is not the only driver of climate
Tom Dayton - re:your post #187 (Second attempt to get this posted, without deletion) You said... "That is incorrect. One of the greatest advances in the history of human knowledge was the 20th century realization that "the energy in electromagnetic waves could only be released in 'packets' of energy." Not continuously. Not hypothetically. In the real world. By all objects." A Photon is released by an atom dropping in energy state....that can be considered to be a Packet of Energy. Multiple atoms releasing multiple photons on a continuous basis will produce a continuous release of Photon Energy. A Photon does not propagate on it's own....the Photon Energy is CARRIED by and Electromagnetic Field having a frequency and wavelength. (EM Fields are NOT PACKETS) Maybe you should have also quoted these statements from the same link: "In physics, a photon is an elementary particle, the quantum of the ELECTROMAGNETIC FIELD and the basic "unit" of light and all other forms of ELECTROMAGNETIC RADIATION. It is also the force CARRIER for the electromagnetic force. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances" "Like all elementary particles, photons are governed by quantum mechanics and will exhibit wave-particle duality – they exhibit properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit WAVE INTERFERENCE, but also act as a particle giving a definite result when quantitative mass is measured." "It also accounted for anomalous observations, including the properties of BLACK BODY RADIATION, that other physicists, most notably Max Planck, had sought to explain using semiclassical models, in which light is still described by Maxwell's equations, but the material objects that emit and absorb light are quantized." ---------------------------- Heat Radiation Radiation is heat transfer by the emission of electromagnetic waves which CARRY energy away from the emitting object. For ordinary temperatures (less than red hot"), the radiation is in the infrared region of the electromagnetic spectrum. The relationship governing radiation from hot objects is called the Stefan-Boltzmann law: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c2 --- Properties of electromagnetic waves "An electromagnetic wave, although it CARRIES no mass, does CARRY energy." "A more common way to handle the energy is to look at how much energy is CARRIED by the wave from one place to another." http://physics.bu.edu/~duffy/PY106/EMWaves.html --- Heat flux "Heat flux or thermal flux, sometimes also referred to as heat flux density or heat flow rate intensity is a flow of energy per unit of area per unit of time. In SI units, it is measured in [W·m-2]. It has both a direction and a magnitude so it is a vectorial quantity." http://en.wikipedia.org/wiki/Heat_flux ----------------------------------------------- All bodies that have a temperature will produce an Electromagnetic Field (and carry Photon Energy)...continuously. Black body Planck's Law, Wein's Law and the Stefan-Boltzmann Law will determine the frequencies (a probability function) and magnitude (w/m^2) of the Electromagnetic Fields produced by the body temperature. http://en.wikipedia.org/wiki/Black_body Here is the Stefan-Boltzmann Law again: P/A = BC*T^4 (watts/m^2) http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/stefan.html Clearly, if T is greater than absolute zero an Electromagnetic Field is produced....continuously. Your statement.... "There exist in the real universe, objects that are so cold that they emit wave packets so infrequently that occasionally a wave packet from one object travels all the way to the other object without encountering a wave packet coming the other way." ....is a violation of the Stefan-Boltzmann Law, Planck's Law, Wein's Law and all Electromagnetic Physics! ------------------------------------- PS: Does the Sun blink "on and off" due to "packets" or does it produce continuous waves? -
Gord at 22:30 PM on 5 November 2009CO2 is not the only driver of climate
Re: Measurements of Back Radiation. (First try to get this posted was deleted) All direct measurements of Back Radiation use instruments that have their IR detectors cooled far below the -20 deg average atmosphere temperature. The cooled IR detectors make the direct measurements possible, just like the 2nd Law states. I have already posted this along with Instrument specifications in my Post #16. Isn't it funny that these same "scientists" (who absolutely know that these instruments use cooled IR detectors to make their direct Back Radiation possible) then claim that the Back Radiation will heat a warmer Earth? Isn't it funny that these same "scientists" claim that the Back Radiation (324 w/m^2 being absobed by a warmer Earth) EXCEEDS the Solar Energy (168 w/m^2) energy reaching the Earth's surface but never, ever say that we should harness this Phantom Back Radiation as a clean energy source? Isn't it funny that these same "scientists" know that IR Back Radiation (available Day and Night) can be concentrated at the focal point of a parabolic mirror (Solar Oven) never ever mention that Solar Ovens don't produce any warming when pointed at the colder atmosphere Day or Night? There are numerous Mega-Watt Solar Power installations that use parabolic mirrors to boil water which is then used to produce power. Funny how these installation don't produce any power from Back Radiation at night? There are probably hundreds of thousands of Solar Ovens used in 3rd World countries to boil water and cook food. Funny how these installation don't produce any power from Back Radiation at night? Isn't funny that these "scientists" never mention the actual measurements done by the Physics Dept. at Brigham Young University where they use Parabolic Mirror Solar Ovens to freeze water when the Ovens are pointed at the colder atmosphere, Day and Night? (just like the 2nd Law says will happen). Isn't funny how so many people believe that Back Radiation can HEAT A WARMER EARTH when it can't even heat an ounce of water even when the Back Radiation should be concentrated at the Solar Oven's focal point. -
Gord at 21:55 PM on 5 November 2009CO2 is not the only driver of climate
Tom Dayton - re:your post#188 They really managed to get just about everything wrong. "...a much larger fraction of long-wave radiation from the surface of the earth is absorbed or reflected in the atmosphere instead of being radiated away, by greenhouse gases, namely water vapor, carbon dioxide and methane" All objects that "absorb" energy HAS to "radiate" the same amount. (Conservation of Energy) ---------- "Since the emissivity (weighted more in the longer wavelengths where the Earth radiates) is reduced more than than the absorptivity (weighted more in the shorter wavelengths of the Sun's radiation), the equilibrium temperature is higher than the simple black-body calculation estimates, not lower. As a result, the Earth's actual average surface temperature is about 288 K, rather than 279 K." Gee, the Sun was the ONLY energy source in the calculation of the 279 K temp. The Atmosphere and the Earth are NOT ENERGY SOURCES, so how did the Earth manage to jump in temperature to 288 K ???? They CREATED energy. Typical. -
Gord at 21:50 PM on 5 November 2009CO2 is not the only driver of climate
Re:Interference When waves interfere they produce a NEW WAVE. If the waves that produce the interference are continuous the NEW WAVE will be continuous. If you do any measurement, all you can measure is the NEW WAVE. Example: A radiates 100 w/m^2 UP. B radiates 100 w/m^2 DOWN. A and B are close, no field losses. Between A and B the Field is 0 w/m^2. Any measurement done will give 0 w/m^2. Without knowlege that A and B exist, no measurement can be done between A and B to prove they exist. Interference (wave propagation) "In physics, interference is the addition (superposition) of two or more waves that results in a NEW WAVE pattern." There is even an animation of continuous waves creating a continouous Interference pattern that produces a NEW WAVE that is CONTINUOUS! http://en.wikipedia.org/wiki/Interference_(wave_propagation) Cancellation of Light (This Bubble link is especially well done...even a child could understand it) http://www.exploratorium.edu/ronh/bubbles/bubble_colors.html -
Gord at 21:47 PM on 5 November 2009CO2 is not the only driver of climate
RSVP - re:your post#184 Yes, there are exceptions where the atmosphere is warmer than the Earth's surface but these cases are by no means the norm. Heat energy, in these rare cases, will flow from a warmer atmosphere to a cooler Earth. Global Warming from the atmosphere, of course is impossible because it would require an average atmospheric temperature to be higher than the Earth surface average temp. -
PeterPan at 20:36 PM on 5 November 2009ACRIM vs PMOD, the rematch
Loads of thanks, chris & Riccardo!! Your answers have been very quick, clear and helpful! :) Thanks! -
RSVP at 20:12 PM on 5 November 2009The albedo effect
"This is sunlight reflected from the Earth and then reflected from the Moon back to the nighttime Earth." When the Moon is "new" in our sky, the Earth is shining its brightest on the Moon. When the Moon is "full", in the Moons "sky", the Earth is very dark except for maybe a detectable glow of urban sprawl. Light coming from the Moon is reflecting from the Sun. What is meant here by the "nighttime" Earth? -
RSVP at 20:07 PM on 5 November 2009The albedo effect
Article begins with... "A change of just 1% to the Earth's albedo has a radiative effect of 3.4 Wm-2, comparable to the forcing from a doubling of CO2." Is it conceivably possible to discuss a subject without including some reference to CO2? Hasnt enough controversy around this subject indicated that it isnt the most convenient standard for comparison? 1) First because as we have seen in previous comments, for some, the greenhouse effect might be a complete myth. 2) Even if it is real, your own articles indicate quite a bit of variability for how much forcing could be associated with a doubling of CO2. 3) Even though you are dealing here with "albedo" as an independent variable, it is dependent on atmospheric radiative absorption. You even explain this here, and yet it is then used as one more independent forcing factor. Conceptually, it would seem that "albedo" per se is not a forcing in its own right, but only a measurement. For instance, the reflective properities of objects on the earth's surface determine radiative forcing. The color of paint for instance is the object of forcing, not the measurement obtained.Response: The term 'doubling of CO2' is a convention - we could just as easily say 3.7 Wm-2 but it just doesn't roll off the tongue as smoothly. To answer the possibility of greenhouse effect being a myth, the enhanced greenhouse effect has been confirmed by multiple independent lines of empirical observations. If you're genuinely interested in the science of global warming, I strongly recommend you read the following papers:- Philipona 2004 (surface measurements confirming increased downward longwave radiation)
- Evans 2006 - analyses high resolution spectral data, quantitatively attributed the increase in downward radiation at specific wavelengths to each of several anthropogenic gases.
- Harries 2001, Griggs 2004, Chen 2007 all compare satellite measurements of outgoing infrared radiation to find less radiation escaping at CO2 absorption wavelengths.
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Tom Dayton at 16:25 PM on 5 November 2009CO2 is not the only driver of climate
Someone on this thread pointed out to Gord that wave packets (photons) passing from sky to ground, even if they do interact with wave packets going from ground to sky, do their interference thing while they share the same space but do not destroy any of their energy, and after passing each other simply carry on to hit the ground and sky, respectively. (Sorry for not crediting that someone, but I can't find that bit. One example that is close to that phrasing was a recent comment by Riccardo. Here are some places for more explanation of that: PhysLink.com: "This interference pattern is akin to ripples on water that approach each other, form an interference pattern of peaks and troughs and then continue on their way." A longer explanation is at MadSciNetwork -
Albatross at 16:19 PM on 5 November 2009Working out climate sensitivity
Thanks Riccardo! -
Alberta Clipper at 16:14 PM on 5 November 2009How do we know CO2 is causing warming?
Two areas on earth at the same latitude, both have the same maximum daytime temperature of 32C. At night, in one area the temperature drops out 17 degrees, to a minimum of 15C, the other area the temperature only drops out 5 degrees to a minimum of 28C. Both areas are at the same altitude, there is also no measurable wind through the 24 hour period. The reason for the different drop-out rates... water vapour. The area with the largest drop-out is a desert. The other area is a very humid climate. In Meteorology, the area with the large drop-out is described as "heat energy is rapidly lost to outer space". I don't buy the influence of the small 0.028% to 0.038% (280 ppm to 380 ppm) of CO2 in the atmosphere, as having a major effect, as stated ad-infinitum everywhere.Response: The enhanced greenhouse effect from CO2 has been confirmed by empirical observations as shown above. You're correct that water vapor is the most dominant greenhouse gas. Water vapour is also the dominant positive feedback in our climate system and amplifies any CO2 warming. Positive feedback is why climate is so sensitive to CO2 warming. -
Tom Dayton at 15:49 PM on 5 November 2009CO2 is not the only driver of climate
Gord, now let's extend the emission of thermal energy as wave packets (photons) from two very cold objects to the Earth's surface and atmosphere. Both surface and atmosphere comprise a riot of wildly heterogeneous bits of mass of various shapes, sizes, temperatures, and many other attributes. All those bits individually emit photons. The overall effect is a riot of photons in all manner of directions, having all manner of frequencies, in all manner of phases and timings. There is no single continuous wave of radiation from the surface, nor one from the atmosphere. Your model is incorrect. -
David Horton at 13:27 PM on 5 November 2009High CO2 in the past, Part 2
"350 ppm is what we should be targeting (of course, that's a political impossibility" - if the good guys say this it helps to make it a self-fulfilling prophecy. Since the denialists don't believe any kind of target is necessary, it is incumbent on us to push for the "scientific ideal" which is now even lower than 350, in fact down to 280 or so. That way, if politics is the art of compromise, a compromise between no target and 280ppm might give a result of, say, 400ppm, which we might be able to live with. A compromise between "350 is politically impossible so let's accept, say, 450" and no target is, perhaps, 550ppm or worse which we certainly can't live with. -
Riccardo at 10:50 AM on 5 November 2009ACRIM vs PMOD, the rematch
One thing to add to chris comment. The trick to artificially pump solar sensitivity in the model is to use a "slow" time constant as short as possible and similar to the solar cycle, 8-12 yr in the paper. Where does this number come from? Is it realistic? The number comes from Schwartz 2007 JGR 112, D24S05 which has been shown to grossly underestimate it (Foster et al 2008 JGR 113, D15102). Also, it looks quite unrealistic given that it represent the time it takes to the climate system to reach equilibrium. -
chris at 09:35 AM on 5 November 2009ACRIM vs PMOD, the rematch
PeterPan, Scafetta, in the paper you link to uses (in my opinion) a sleight of hand based on false premises to come up with an extraordinaly high climate sensitivity to solar forcing, to arrive at the ("up to 65%") value that you reproduce. He analyses different Empirical Solar Signature ("ESS") parameterizations (ESS1 and ESS2) to attempt to match the solar variability to climate (temperature)variability. He finds that according to his ESS1 parameterization (fast climate response to solar forcing and thus small climate sensitivity to solar forcing), the solar variation cannot account for preindustrial temperature variation (he seemingly considers "preindustrial" to mean pre-1900), and therefore choses a model (ESS2) with a slow response time and very large temperature response to solar forcing. His error is one shared by a couple of the dull selection of papers he cites, namely he makes an a priori assumption that all "pre-industrial" temperature variation is solar-induced, and thus he has to swell the solar contribution to attempt to match this. This is obvously wrong. It's quite well characterised that some of the warming from the LA to 1900 warming was due to reducrion of volcanic (negative) forcing (say 0.l oC) and the change in CO2 concentration from pre-industrial levels (around 276 at the LIA) to 1900 (~300 ppm) should give around 0.35 oC warming at equilibrium within the middle of the range of climate sensitivity (3 oC of warming per doubling of CO2). Let's say that 0.25 oC of this was realized by 1900. So we expect that around 0.35 oC of the warming from the bottom of the LIA to 1900 was volcanic/greenhouse-induced. The Moberg temperature reconstruction that Scafetta "fits" to (see Scafetta's Figure 6), gives around 0.35 oC of warming from the bottom of the LIA to 1900. So there isn't any need to "pump up" the climate response to solar variability to ludicrous proportions in an attempt to "fit" solar variability to a particular temperature reconstruction, and the solar contribution to temperature variability determined by proper solar scientists (Lean, Frolich, Solanki, Lockwood etc) is likely to be correct (e.g. perhaps 0.10 C warming Maunder Minimum (MM) to 1900 or 0.2 oC MM to 1950)... -
PeterPan at 08:38 AM on 5 November 2009ACRIM vs PMOD, the rematch
Thanks again for a very informative post. New studies go on confirming that PMOD seems more reliable. Anyway, I had also read elsewhere that the temperature difference between using ACRIM or PMOD would be very little, that's why I still wonder how Scafetta gets that 65 % (mentioned by clayco) if ACRIM was used (?): "Since 1980 the solar contribution to climate change is uncertain because of the severe uncertainty of the total solar irradiance satellite composites. The sun may have caused from a slight cooling, if PMOD TSI composite is used, to a significant warming (up to 65% of the total observed warming) if ACRIM, or other TSI composites are used" http://www.fel.duke.edu/~scafetta/pdf/Scafetta-JASP_1_2009.pdf Do you know any paper or blog post where it's been addressed? Thnks! -
Tom Dayton at 08:14 AM on 5 November 2009CO2 is not the only driver of climate
Gord, have you noticed that even the Wikipedia entry for the Stefan-Boltzmann law (Temperature of the Earth section) explains the atmospheric greenhouse effect without saying that it violates the second law of thermodynamics? -
chris at 07:55 AM on 5 November 2009The albedo effect
re #1: Steve, the confusion lies largely in the papers of Palle et al from which the figures above are taken. For example, Palle et al (2004) are simply not clear about the anomaly values in their Figure 3 (Figure 2 above). I can't see from their paper what the reference albedo is from which the values (0.02 etc.) are anomalies with respect to. Yes the W/m2 axis should really be reversed as you suggest (Palle et al (2004)'s mistake!). On Pinatubo: There doesn't seem to be much of an effect on albedo. Palle et al (2004) suggest this isn't surprising:The albedos for the years after the eruption of Mt. Pinatubo (1991–1992) are among the largest; however, the increase is just comparable with interannual variability. The lack of a sharp rise is not unexpected, however, because Pinatubo's increased contribution of stratospheric aerosols is not accounted for by any of the ISCCP parameters used.
Presumably the ISCCP data is optimised for characterising clouds from which albedo effect are determined. I wonder whether an essential difference between the properties of volcanic aerosols (scatter incident light) and clouds (reflect incident light) might be responsible for the apparent absence of Pinatubo on apparent albedo??? -
chris at 06:56 AM on 5 November 2009CO2 has been higher in the past
re #29; Disclaimed There's a decent amount of recent research/reviews on the subject of CO2 levels and extinctions. Here's a selection of papers/reviews that address this. It might be about a year out of date, and I wrote this in a slightly different context elsewhere....I had a quick look at the literature earlier, and didn't find anything that substantially adds to this. The major extinction events of the past 300 million years are generally associated with rapid onset and long term warming events, and tectonic processes are considered the most likely causes of the rise in greenhouse gases and warming associated with these (especially massive flood basalt events; e.g. the Serbian Traps at the end-Permian extinction; the Deccan Traps at the end-Cretaceous extinction; the tectonic events resulting in plate boundary separation and opening up of the N Atlantic at the Paleo-Eocene Thermal Maximum) Major extinctions are associated with long lived perturbation of the climate system and the atmosphere. For example the early Jurassic extinction is associated with events (greenhouse gas induced warming) lasting 200,000 years Svensen H et al (2007) Hydrothermal venting of greenhouse gases triggering Early Jurassic global warming Earth Planetary Sci Lett 256 554-566 Abstract: The climate change in the Toarcian (Early Jurassic) was characterized by a major perturbation of the global carbon cycle. The event lasted for approximately 200,000 years and was manifested by a global warming of similar to 6 degrees C, anoxic conditions in the oceans, and extinction of marine species. The triggering mechanisms for the perturbation and environmental change are however strongly debated. Here, we present evidence for a rapid formation and transport of greenhouse gases from the deep sedimentary reservoirs in the Karoo Basin, South Africa....... likewise comprehensive analyses of the coincidence of major tectonic events, and resulting elevation of greenhouse gas levels, are associated with several of the major extinctions of the last 300 million years. Note that CO2 isn't the only player. Methane is implicated in several of these events (see especially the PETM below) and sulphurous oxides and their effects on ocean acidity and oxygen content are also implicated: Wignall P (2005) The link between large igneous province eruptions and mass extinctions Elements 1, 293-297 Abstract: In the past 300 million years, there has been a near-perfect association between extinction events and the eruption of large igneous provinces, but proving the nature of the causal links is far from resolved. The associated environmental changes often include global warming and the development of widespread oxygen-poor conditions in the oceans. This implicates a role for volcanic CO2 emissions, but other perturbations of the global carbon cycle, such as release of methane from gas hydrate reservoirs or shut-down of photosynthesis in the oceans, are probably required to achieve severe green-house warming. The best links between extinction and eruption are seen in the interval from 300 to 150 Ma. With the exception of the Deccan Trap eruptions (65 Ma), the emplacement of younger volcanic provinces has been generally associated with significant environmental changes but little or no increase in extinction rates above background levels. R. J. Twitchett (2006) The palaeoclimatology, palaeoecology and palaeoenvironmental analysis of mass extinction events Palaeogeog., Palaeoclimatol., Palaeoecol. 232, 190-213 concluding paragraph: "Mass extinction studies have enjoyed a surge in scientific interest of the past 30 years that shows no sign of abating. Recent areas of particular interest include the palaeoecological study of biotic crises, and analyses of patterns of post-extinction recovery. There is good evidence of rapid climate change affecting all of the major extinction events, while the ability of extraterrestrial impact to cause extinction remains debatable. There is growing evidence that food shortage and suppression of primary productivity, lasting several hundred thousand years, may be a proximate cause of many past extinction events. Selective extinction of suspension feeders and the prevalence of dwarfed organisms in the aftermath are palaeoecological consequences of these changes. The association with rapid global warming shows that study of mass extinction events is not just an esoteric intellectual exercise, but may have implications for the present day." Notice that greenhouse environments are associated with the very delayed (millions of years) recovery of biota following thse extinctions; Fraiser ML et al. (2007) Elevated atmospheric CO2 and the delayed biotic recovery from the end-Permian mass extinction Palaeogeog. Palaeoclim. Paleoecol. 252, 164-175 Abstract: Excessive CO2 in the Earth ocean-atmosphere system may have been a significant factor in causing the end-Permian mass extinction. CO2 injected into the atmosphere by the Siberian Traps has been postulated as a major factor leading to the end-Permian mass extinction by facilitating global warming, widespread ocean stratification, and development of anoxic, euxinic and CO2-rich deep waters. A broad incursion of this toxic deep water into the surface ocean may have caused this mass extinction. Although previous studies of the role of excessive CO2 have focused on these "bottom-up" effects emanating from the deep ocean, "top-down" effects of increasing atmosphere CO2 concentrations on ocean-surface waters and biota have not previously been explored. Passive diffusion of atmospheric CO2 into ocean-surface waters decreases the pH and CaCO3 saturation state of seawater, causing a physiological and biocalcification crisis for many marine invertebrates. While both "bottom-up" and "top-down" mechanisms may have contributed to the relatively short-term biotic devastation of the end-Permian mass extinction, such a "top-down" physiological and biocalcification crisis would have had long-term effects and might have contributed to the protracted 5- to 6-million-year-long delay in biotic recovery following this mass extinction. Earth's Modern marine biota may experience similar "top-down" CO2 stresses if anthropogenic input of atmosphere/ocean CO2 continues to rise. The lesser extinction associated with the Paleo-Eocene-Thermal Maximum (PETM) 55 MYA is probably the best characterised (not surprisingly since it's the most recent!) example of massive tectonic processes (the opening up of the N. Atlantic as the plates seperated) associated with enhanced atmospheric greenhouse gases, ocean acidification etc.: M. Storey et al. (2007)Paleocene-Eocene Thermal Maximum and the Opening of the Northeast Atlantic Science 316, 587 - 589 abstract: The Paleocene-Eocene thermal maximum (PETM) has been attributed to a sudden release of carbon dioxide and/or methane. 40Ar/39Ar age determinations show that the Danish Ash-17 deposit, which overlies the PETM by about 450,000 years in the Atlantic, and the Skraenterne Formation Tuff, representing the end of 1 ± 0.5 million years of massive volcanism in East Greenland, are coeval. The relative age of Danish Ash-17 thus places the PETM onset after the beginning of massive flood basalt volcanism at 56.1 ± 0.4 million years ago but within error of the estimated continental breakup time of 55.5 ± 0.3 million years ago, marked by the eruption of mid-ocean ridge basalt–like flows. These correlations support the view that the PETM was triggered by greenhouse gas release during magma interaction with basin-filling carbon-rich sedimentary rocks proximal to the embryonic plate boundary between Greenland and Europe. And even the end-Cretaceous extinction (that did for the dinosaurs) seems to have had at least a significant component from massive flood basalt events (that resulted in the Deccan Traps in what is now India). In fact there is increasing evidence that the impact that resulted in the Chicxulub crater in the Yucatan post-dates the onset of the extinction by several 100,000's of years, and the extinction is associated with global warming (including a sudden contribution from the impact into limestone-rich deposits that vapourized massive amounts of carbonate (limestone) back into CO2): Keller G (2005) Impacts, volcanism and mass extinction: random coincidence or cause and effect? Austral. J. Earth Sci 52 725-757. Abstract: Large impacts are credited with the most devastating mass extinctions in Earth's history and the Cretaceous - Tertiary (K/T) boundary impact is the strongest and sole direct support for this view. A review of the five largest Phanerozoic mass extinctions provides no support that impacts with craters up to 180 km in diameter caused significant species extinctions. This includes the 170 km-diameter Chicxulub impact crater regarded as 0.3 million years older than the K/T mass extinction. A second, larger impact event may have been the ultimate cause of this mass extinction, as suggested by a global iridium anomaly at the K/T boundary, but no crater has been found to date. The current crater database suggests that multiple impacts, for example comet showers, were the norm, rather than the exception, during the Late Eocene, K/T transition, latest Triassic and the Devonian-Carboniferous transition, but did not cause significant species extinctions. Whether multiple impacts substantially contributed to greenhouse worming and associated environmental stresses is yet to be demonstrated. From the current database, it must be concluded that no known Phanerozoic impacts, including the Chicxulub impact (but excluding the K/T impact) caused mass extinctions or even significant. species extinctions. The K/T mass extinction may have been caused by the coincidence of a very large impact ( > 250 km) upon a highly stressed biotic environment as a result of volcanism. The consistent association of large magmatic provinces (large igneous provinces and continental flood-basalt provinces) with all but one (end-Ordovician) of the five major Phanerozoic mass extinctions suggests that volcanism played a major role. Faunal and geochemical evidence from the end-Permian, end-Devonian, end-Cretaceous and Triassic/Jurassic transition suggests that the biotic stress was due to a lethal combination of tectonically induced hydrothermal and volcanic processes, leading to eutrophication in the oceans, global warming, sea-level transgression and ocean anoxia. It must be concluded that major magmatic events and their long-term environmental consequences are major contributors, though not the sole causes of mass extinctions. Sudden mass extinctions, such as at the K/T boundary, may require the coincidence of major volcanism and a very large Impact. Beerling DJ et al. (2002) An atmospheric pCO(2) reconstruction across the Cretaceous-Tertiary boundary from leaf megafossils Proc. Natl. Acad. Sci. USA 99 (12): 7836-7840 Abstract: The end-Cretaceous mass extinctions, 65 million years ago, profoundly influenced the course of biotic evolution. These extinctions coincided with a major extraterrestrial impact event and massive volcanism in India. Determining the relative importance of each event as a driver of environmental and biotic change across the Cretaceous-Tertiary boundary (KTB) crucially depends on constraining the mass of CO2 injected into the atmospheric carbon reservoir. Using the inverse relationship between atmospheric CO2 and the stomatal index of land plant leaves, we reconstruct Late Cretaceous-Early Tertiary atmospheric CO2 concentration (pCO(2)) levels with special emphasis on providing a pCO(2) estimate directly above the KTB. Our record shows stable Late Cretaceous/ Early Tertiary background pCO(2) levels of 350-500 ppm by volume, but with a marked increase to at least 2,300 ppm by volume within 10,000 years of the KTB. Numerical simulations with a global biogeochemical carbon cycle model indicate that CO2 outgassing during the eruption of the Deccan Trap basalts fails to fully account for the inferred pCO(2) increase. Instead, we calculate that the postboundary pCO(2) rise is most consistent with the instantaneous transfer of approximate to 4,600 Gt C from the lithic to the atmospheric reservoir by a large extraterrestrial bolide impact. A resultant climatic forcing of +12 W(.)m(-2) would have been sufficient to warm the Earth's surface by approximate to7.5degreesC, in the absence of counter forcing by sulfate aerosols. This finding reinforces previous evidence for major climatic warming after the KTB impact and implies that severe and abrupt global warming during the earliest Paleocene was an important factor in biotic extinction at the KTB. Note that there may be some question over the absolute concentrations of atmospheric CO2 calculated using the plant stomatal frequency index. Note also that since these processes all occurred in the deep past, we obviously don't know exactly all the contributions to all the extinctions. However the associations between tectonic/mantle plume breaching/flood basalt eruptions/global warming and extinctions are increasingly supported by the evidence. -
Riccardo at 06:27 AM on 5 November 2009Working out climate sensitivity
Albatross, there might be problems with how Lindzen managed the ERBE data. The ERBE team recommends to analyze data at 36 (or multiples of 36) days intervals due to drifting of the satellite. Lindzen and Choi apperently didn't follow the advice. Dr. Roy Spencer, not an AGW supporter for sure, repeated the analysis and found significantly smaller feedback parameter. So probably it is Lindzen and Choi's estimate "way off the mark". -
Usmar at 05:48 AM on 5 November 2009Empirical evidence that humans are causing global warming
I believe if you are going to talk about humans creating CO2 we should also look at the large human CO2 sink ... crops. Looking at easy to find crop data for the US and the world; it is easy to calculate that the carbon we put into the atmosphere (based on your 29 gigaton CO2) is (27% Carbon) 7.8 gigatons of Carbon. Just looking at world wheat production, 21.8 gigatons of Carbon is taken out of the atmosphere (based on ~40% carbon in whole plant and the plant weighing ~100 times the seeds harvested). Heck even if the plant weighs 50X more than the seeds harvested that 10 gigatons of carbon from the atmosphere. What if you added in all the other human planted food crops? bet you come up with the fact that we have taken much more CO2 out of the atmosphere than we ever created by 10,000X. No something else is at play with the increase in temperature we are seeing .... -
Tony Noerpel at 05:24 AM on 5 November 2009The albedo effect
Hi John The first paragraph below "albedo trends since 2000" refers to figure 1 but should refer to figure 2. The % shown in Figure 2 and 3 do not appear to match. Anyway, like Steve L. I'm a little confused. Thanks TonyResponse: Apologies for the Figure 1/2 confusion - I was shuffling things around while drafting this post and failed to update that reference. Now fixed.
The % shown in Figure 2 and 3 are the same. In Figure 2, Palle uses fractions. In Figure 3, he uses percentages. Eg - 0.01 = 1%. -
Tom Dayton at 04:59 AM on 5 November 2009CO2 is not the only driver of climate
Gord, you wrote "In the real world, ALL objects above absolute zero will radiate continuously and Interference will also be continuous." That is incorrect. One of the greatest advances in the history of human knowledge was the 20th century realization that "the energy in electromagnetic waves could only be released in 'packets' of energy." Not continuously. Not hypothetically. In the real world. By all objects. The increase in frequency of radiation from increasing the temperature of an object does not mean there is a single, continuous wave whose frequency increases as the temperature increases. Instead, all objects always emit a gaggle of discrete wave packets (photons), each of those individual photons having a single frequency/wavelength. Some of those photons have a high frequency and some have a low frequency. Increasing the temperature of an object causes it to emit, among its gaggle of photons, a greater percentage of the higher frequency photons and a lower percentage of the lower frequency photons. That's why Wikipedia's entry on Thermal Radiation says "The emitted wave frequency of the black body thermal radiation is described by a probability distribution depending only on temperature." "Probability distribution" describes the membership of the gaggle of photons. If you randomly grab one photon out of the gaggle, it will have a particular, definite frequency. Most likely that frequency will be the frequency that is at the peak of the probability distribution. If you grab multiple photons from the gaggle, some of them will have high frequencies and some will have low frequencies. If you plot the number of photons (on the y axis) having a given frequency or wavelength (on the x axis) you will see a distribution that approaches the shape of that theoretical probability distribution as the size of your sample grows. The Properties section explains "Thermal radiation, even at a single temperature, occurs at a wide range of frequencies. How much of each frequency is given by Planck's law of radiation... The main frequency (or color) of the emitted radiation increases as the temperature increases... The total amount of radiation, of all frequencies, goes up very fast as the temperature rises." So my previous example is correct. There exist in the real universe, objects that are so cold that they emit wave packets so infrequently that occasionally a wave packet from one object travels all the way to the other object without encountering a wave packet coming the other way. That happens both from the warmer object to the colder object, and from the colder object to the hotter object. That violates your (Gord's) model of continuous waves emanating continuously from both objects. That means your model of summing/interfering is false in that case. Which means your interpretation of the second law of thermodynamics is false in that case. The second law of thermodynamics is not wrong. Your interpretation of it is. That animation of wave packet emission that I keep linking to, also can be found by Googling "physlet Illustration: emission in the bohr model". -
Steve L at 03:02 AM on 5 November 2009High CO2 in the past, Part 2
Riccardo, agreed -- that is the general approach taken. -
Steve L at 02:57 AM on 5 November 2009The albedo effect
Hi John, I get the overall message, but I was tripped up at Fig 2. First, the anomaly axis can't be in %, can it, if a change in 1% = 3.4 W/m2 (the figure shows a change of .01% = 3.4 W/m2)? More semantically, shouldn't the W/m2 axis be reversed, such that higher albedo represents a negative forcing? Finally, in your description of the figure, you mention Pinatubo's large effect in 1991, but I can't see it in either data set shown in your Figure 2. Am I misinterpreting the figure?Response: Which way the Y-axis should go is really a po-tay-to/po-tah-to issue. But yes, it might have been less confusing if they put negative numbers on the W/m2 axis. I will update the caption of Figure 2 and 3 to clarify this.
In Figure 2, the albedo calculated from ISCCP satellite data is not without its own problems. A Real Climate analysis sums it up thus: "The earthshine-trained ISCCP reconstruction of the albedo is a purely statistical parameter that has little physical meaning as it does not account for the non-linear relations between cloud and surface properties and planetary albedo and does not include aerosol related albedo changes such as associated with Mt. Pinatubo, or human emissions of sulfates for instance."
I mainly displayed Figure 2 because this is the graph that seems to pop up everywhere - it seemed important to show that it is now defunct. Unfortunately, it may have sown more confusion than clarified. -
Riccardo at 22:31 PM on 4 November 2009CO2 is not the only driver of climate
I think there is a misinterpretation of interference hanging around. For the principle of superimposition at any point the resulting wave is simply the sum of the single waves. It can also be zero, but this does not mean that the waves somehow "disappeared". Immagine two identical plane waves propogating in opposite directions and 180° out of phase. The resulting amplitude is zero everywhere but the two waves are still there. Indeed, if you put a mirror anywhere between the two sources you can deflect the waves. In our case it means that the IR flux from the atmosphere travels towards and actually reaches the earth surface. The earth still emits according to its temperature, but the net flux is reduced. -
Philippe Chantreau at 21:45 PM on 4 November 2009CO2 is not the only driver of climate
There is a number of papers that present measurements of downwelling IR radiation. This link shows the composition of sunlight. http://en.wikipedia.org/wiki/File:MODIS_ATM_solar_irradiance.jpg. It looks like it's lacking at the wave lengths of GH gases Nevertheless IR at these wave lengths does reach the surface, as measured in numnerous studies. This book is interesting. The measurements presented by Liou show that the downward IR flux increases with decreasing altitude, indicating an atmospheric source. Dunno if that link will work, the book is: An Introduction to Atmospheric Radiation by Kuo-Nan Liou. http://books.google.com/books?id=6xUpdPOPLckC&pg=PA164&lpg=PA164&dq=measured+downward+IR&source=bl&ots=NnPMfJXhPy&sig=sRrO6GTGgT_ckcTmdAumr-_9zww&hl=en&ei=p0vxSpX4C4uuswO5jOn4AQ&sa=X&oi=book_result&ct=result&resnum=5&ved=0CBgQ6AEwBA#v=onepage&q=measured%20downward%20IR&f=false This paper also shows measurements of both solar flux and total IR downward flux. http://www.arm.gov/publications/proceedings/conf08/extended_abs/hinkelman_lm.pdf We have already discussed the Evans (2006) paper, also presenting spectroscopic measurements. http://ams.confex.com/ams/Annual2006/techprogram/paper_100737.htm This is from a quick search, there likely is a lot more out there. So actual measurements of downward IR flux at the wave numbers of greenhouse gases are readily available. To the extent that this is IR radiation, I will consider it satisfies 2) of Gord's post 162 and also contradicts his assertion above that all actual measurements show that the atmosphere does not radiate IR back to the surface. It's been measured for quite some time, there are papers from the 60's treating of it. -
chris at 20:47 PM on 4 November 2009CO2 has been higher in the past
In case anyone is wondering why I launched into a description of my understanding of the relationships between CO2 levels and ice sheet dynamics/sea levels in the Miocene and now, it was in response to a question posed by Mizimi in what was then post #33, asking why if CO2 levels are approaching levels observed 15 million years ago, why aren't sea levels much higher now (as then). However Mizimi's post disappeared shortly after I posted mine! -
RSVP at 20:45 PM on 4 November 2009CO2 is not the only driver of climate
Aside from the global "average", which is normally warmer, air or the surface? I would say surface except for maybe snow on a sunny day, and maybe air vs water in the some circumstances. (just musing) Gord If I may ask a question... are you aware of any exceptions outside of the average temps you cite?. In which case I am just wondering if you would allow greenhouse warming in these specific cases... -
Gord at 19:35 PM on 4 November 2009CO2 is not the only driver of climate
shawnhet - re:your post#178 The closest is #3. "GG absorb and emit infrared energy, but this has no effect on the temperature of the Earth's surface." ------------------------------ There is a distinct difference between Greenhouse Gases and the Greenhouse Effect. Greenhouse gases in the atmosphere will absorb IR energy and heat up, but they only heat up to an average of -20 deg C and the Earth has an average temp of +15 deg C. The Greenhouse Effect says that the -20 deg C atmosphere will heat the warmer Earth. The infrared energy from the colder atmosphere cannot reach let alone heat a warmer Earth. This is proven by the violation of several Laws of Science and ALL actual measurements. -
Gord at 19:34 PM on 4 November 2009CO2 is not the only driver of climate
Tom Dayton - re:your post #179 The animation/simulation in your link does not work. ----------------- You said... "Radiation is discrete, not continuous, at this low level of analysis." Exactly, therefore it is not applicable. In the real world, ALL objects above absolute zero will radiate continuously and Interference will also be continuous. -
Riccardo at 19:24 PM on 4 November 2009High CO2 in the past, Part 2
Steve L, concerning time resolution, it should be noted that there are ice cores with annual or sub-annual resolution for the last 100 thousands years (GISP2 and NGRIP ice cores in Greenland). The resolution gets worst going back in time but at least from the onset of the ice ages cycles it stays below a few centuries or less, depending on the specific site. But anyway, the real problem with this skeptic argument is physics. What should be the plausible mechnism for a rapid emission of CO2 of the order of a few decades? And also, to not be detected the CO2 must be reabsorbed by the climate system in a few decades as well, while we know, instead, that it stays in the atmosphere much longer. Here we notice a general attitude of the skeptics, immagine a mechanism which can not be ruled out a priori but that is far from being plausible. The trick is that in this way the burden of the proof stays upon "AGW theorists". It's far easier to immagine a weird hypotesis than prove it's unplausible or plain wrong. -
Philippe Chantreau at 18:58 PM on 4 November 2009CO2 is not the only driver of climate
I'm still considering all the implications of this, and it really does not seem to make sense. It would imply that a radiant barrier is impossible. Yet radiant barriers are used from homes to spacecrafts. -
Steve L at 10:21 AM on 4 November 2009High CO2 in the past, Part 2
I thought another of the things that a skeptic might target is the lack of temporal resolution in general. I wonder how much CO2 has changed naturally in the past on a short timescale (over a couple of hundred or 1000 years). This is an inelegant excuse for me to expand on John's digression. I find the taxonomy of skeptic arguments interesting for a couple of reasons. First, relating to what I just wrote, there's only one or two entries for anthropogenic CO2 being insignificant relative to other CO2. I would be curious to know more about periods of rapid CO2 change in the past (or maybe more information about how solidly we know CO2 hasn't changed as quickly as it is currently changing). The other thing I find interesting about the taxonomy is that there are three groups, but "Warming isn't bad" is very unpopulated relative to the others. And another category ("It's too late to stop it") doesn't exist at all. I am curious about the implications for both categories of argument of short- vs long-term contextual information from paleo studies. It seems to me that those skeptical of the need to act should be demanding short term temporal resolution in these and other historical reconstructions.Response: Be aware that the skeptic arguments sorted by taxonomy is by no means comprehensive. There are probably around 100 skeptic arguments I have yet to add to the list. Time being the issue, I've prioritised them by popularity - next on my to-do list is always the skeptic argument that has been used the most. I also tend to focus on science based arguments - arguments like "people are making money from global warming" or "Al Gore is a hypocrite" add no real value to this website.
If I get the time, I would like to expand on studies of CO2 in the past as they only serve to confirm the influence CO2 has on climate. -
Albatross at 08:42 AM on 4 November 2009Working out climate sensitivity
Could someone please explain to me why the Lindzen and Choi paper makes a vague reference to the climate sensitivity of doubling CO2 being 0.5 C? This seems to be inconsistent with the warming (over 0.7 C) that has already been observed with "only" ~390 ppmv of CO2. Does the CO2 sensitivity implicitly include the net impact of all feedbacks arising once the warming is initiated? That is, it is not only a metric of the response arising solely to CO2, but rather of the integrated response of the entire climate system (oceans, atmosphere, cryposhere) to doubling CO2. Thanks in advance. If the latter, then Lindzen and Choi's estimate seems way off the mark. Thanks in advance. -
chris at 06:46 AM on 4 November 2009CO2 has been higher in the past
Actually, my scenario isn't quite right, since there was significant Antarctic ice already by around 33 MYA and I think that the threshold for a fully-ice-free world is considered to be more like 700-750 ppm. Otherwise, the main points apply - it took an awful long time for extensive ice to form and major ice sheet expansion including Greenland ice only occurred later in the Miocene when CO2 levels dropped to Holocene levels. Even though we're approaching (or may have passed in the case of Greenland) thresholds for major ice sheet melt and sea level rise, we have only just done so, and the melt response is (hopefully) slow... -
Philippe Chantreau at 06:32 AM on 4 November 2009CO2 is not the only driver of climate
Well you did not really answer my questions in 149 either. I have no problem waiting for that until I read more through the response to G&T that was sent to IJMPB. I do have other things to do too. -
chris at 06:27 AM on 4 November 2009CO2 has been higher in the past
re #33 It’s likely a matter of time scales and the direction of the evolution of the climate in response to long lived changes in radiative forcing. You can think about it from both cooling (then) and warming (now) directions: (i) The Miocene, moving forward in time: 25 million years ago (MYA), the Earth was warm and there were no major ice sheets. Atmospheric CO2 levels were 600 ppm and higher, a level that was incompatible with the formation of major stable ice sheets. CO2 levels dropped slowly (thought to be the result of enhanced weathering [1] due possibly to movement of India and the Deccan Trapps into the equatorial humid belt with a resulting slow excess in the rate of CO2 removal from the atmosphere over many millions of years, relative to atmospheric influx [2]). (ii) The threshold for ice sheet growth seems to be around 500 ppm during this period, likely simlar to the current threshold. From around 15 MYA to 10 MYA CO2 levels fluctuated below and above this threshold with Antarctic ice forming somewhat and waning [3]. Going from warm, ice-free world to a CO2 level dropping to 500 ppm and a bit below, ice formation and extensive build up would be slow, a situation supported by a negligible ice albedo going in the cooling direction from an ice-free world. Simply due to the fact that ice sheet growth was very slow under these conditions, sea levels remained much higher then than now even as CO2 levels were dropping below the threshold for ice sheet formation. It was really only as a result of the further drop in CO2 levels around 13 MYA and again around 11 MYA, that extensive ice sheet formation occurred and sea levels dropped towards present day levels. (iii) Now consider the situation in reverse. The CO2 levels are rising and the threshold is being crossed in a warming direction. We’ve raised CO2 levels towards the 500 ppm threshold for a ridiculously short period of time (a few decades!) in the geological context, and the ice sheet response is (we hope!) slow. A world with extensive ice sheets takes (we hope) an awful long time to come to a new equilibrium with respect to a new enhanced forcing. The albedo effect from land ice probably results in significant hysteresis in the system, such that it’s more difficult to lose ice in a warming scenario, and more difficult to form ice in a cooling scenario. [1] Wan SM et al. (2009) Extreme weathering/erosion during the Miocene Climatic Optimum: Evidence from sediment record in the South China Sea Geophys. Res. Lett. 36 Art. # L19706 http://www.agu.org/pubs/crossref/2009/2009GL040279.shtml [2] D. V. Kent and G. Muttoni Equatorial convergence of India and early Cenozoic climate trends PNAS 2008 105:16065-16070 http://www.pnas.org/content/105/42/16065.abstract?sid=4e6a6e83-8034-4eef-b0a2-865623be72e1 [3] W. M. Kürschner et al. (2008) The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of terrestrial ecosystems. PNAS 105, 449-454 http://www.pnas.org/content/105/2/449.abstract Those are all likely to be considerations relevant to the relationships between CO2 levels, temperatures, and climate, ice sheet and sea level responses over very long periods.
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