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Post by steve on Apr 24, 2009 13:54:03 GMT
The following Nature paper suggests that it explains prehistoric climate quite well. Climate sensitivity constrained by CO2 concentrations over the past 420 million years Royer et al. Nature 2007 droyer.web.wesleyan.edu/climate_sensitivity.pdf
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Post by icefisher on Apr 24, 2009 15:18:38 GMT
The following Nature paper suggests that it explains prehistoric climate quite well. Indeed it does so very well but if and only if you don't have the mental capacity to distinguish between cause and effect.
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jtom
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Posts: 248
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Post by jtom on Apr 24, 2009 15:44:48 GMT
Either you are kidding or you don't understand the paper.
The don't use a CO2 model to try to explain past climates, they use past climates, assume that CO2 is the driver of T changes, and try to derive a value for delta T with respect to a doubling of CO2. They conclude that a doubling of CO2 would result in a 1.5 degree increase in T GIVEN THEIR INITIAL ASSUMPTIONS. It's a best fit analysis that averages over those periods when CO2 does not correlate with T.
You do realize, I hope, that this exact same modeling could be used to support a theory that a 1.5 degree increase in T would result in a doubling of the CO2? Perhaps a better conclusion since rise in CO2 seems to lag increase in T.
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jtom
Level 3 Rank
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Post by jtom on Apr 24, 2009 15:46:12 GMT
My reply above is directed to steve, not icefisher. Icefisher's post snuck in before I sent my reply.
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Post by curiousgeorge on Apr 24, 2009 17:07:55 GMT
This entire CO2 thing just doesn't compute for me. Co2 is what, .038% of the atmosphere. 385ppm. Take a million pingpong balls and paint 385 of them black. Stir them up in a really big bucket. Now try to find the black ones. Add a few more ( to simulate additional CO2 molecules). Still really hard to find. And even harder to make any claim regarding their effect on the remaining ~ 999,600 unpainted pingpong balls or the bucket. It just doesn't compute. Assigning the huge impact claimed by Gore and company to such a tiny fraction of the atmosphere just seems totally ridiculous to me. Laughable. Insane.
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Post by steve on Apr 24, 2009 17:07:57 GMT
jtom, before criticising my submission, you could consider offering evidence of your own to support your belief. Either you are kidding or you don't understand the paper. The don't use a CO2 model to try to explain past climates, they use past climates, assume that CO2 is the driver of T changes, and try to derive a value for delta T with respect to a doubling of CO2. They conclude that a doubling of CO2 would result in a 1.5 degree increase in T GIVEN THEIR INITIAL ASSUMPTIONS. It's a best fit analysis that averages over those periods when CO2 does not correlate with T. You do realize, I hope, that this exact same modeling could be used to support a theory that a 1.5 degree increase in T would result in a doubling of the CO2? Perhaps a better conclusion since rise in CO2 seems to lag increase in T. CO2 *is* a driver of climate change. I think apart from a very few, the question is to what degree it drives climate. The paper is using the relationship between CO2 rates of weathering rocks vs. temperature and CO2 levels. It is showing that if CO2 did not drive climate much (ie. low sensitivity) then unfeasibly high levels of CO2 would be required to explain the weathering rate.
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Post by steve on Apr 24, 2009 17:19:56 GMT
This entire CO2 thing just doesn't compute for me. Co2 is what, .038% of the atmosphere. 385ppm. Take a million pingpong balls and paint 385 of them black. Stir them up in a really big bucket. Now try to find the black ones. Add a few more ( to simulate additional CO2 molecules). Still really hard to find. And even harder to make any claim regarding their effect on the remaining ~ 999,999,600 unpainted pingpong balls or the bucket. It just doesn't compute. Assigning the huge impact claimed by Gore and company to such a tiny fraction of the atmosphere just seems totally ridiculous to me. Laughable. Insane. Curiousgeorge, many of the sceptics on this forum believe that this tiny amount of CO2 absorbs *all* the radiation available in its spectral range. Some even point out that this radiation is absorbed to extinction within a very few metres of the earth's surface (which is true). In other words, the infrared photons are very good at finding these ping pong balls. So I guess you're in complete disagreement with them! Perhaps if instead of a million ping-pong balls you rethought the experiment with a 100 thousand million million million million ping-pong balls, with 38.5 million million million million of them painted black. If you shot a laser through this bucket, what is the chance of hitting a black ping-pong ball. This equates to about 4km depth by 1 metre square of atmosphere I think (but it's friday evening)
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Post by curiousgeorge on Apr 24, 2009 18:33:27 GMT
I don't know enough about atmospheric science to disagree with anyone regarding radiation absorption, and the other fine points of it. I do understand the example you gave however, and I'll take your word for how it equates with reality without crunching the numbers myself. That said, it still seems ridiculous to argue that a few ppm increase in CO2 ping pong balls ( in the enlarged statistical universe that you described ) would cause the sort of apocalypse that is being argued for. So you increase the number of targets for the laser by a infinitesimal amount. So what. Not a big deal, statistically speaking.
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Post by poitsplace on Apr 24, 2009 19:54:45 GMT
I don't know enough about atmospheric science to disagree with anyone regarding radiation absorption, and the other fine points of it. I do understand the example you gave however, and I'll take your word for how it equates with reality without crunching the numbers myself. That said, it still seems ridiculous to argue that a few ppm increase in CO2 ping pong balls ( in the enlarged statistical universe that you described ) would cause the sort of apocalypse that is being argued for. So you increase the number of targets for the laser by a infinitesimal amount. So what. Not a big deal, statistically speaking. Socold and I actually agree loosely on the bare math for CO2 absorption. One BIG place we differ is that I like to point out that while the CO2 may be an "insulating blanket", it's not insulation the way you'd normally think of it. It only stops a certain percentage of the radiative spectrum but leaves huge gaps where energy is free to escape. Any time the energy trapped by CO2 manages to turn into actual heat...it immediately starts radiating away once again...and most of it pours out those gaps in the spectrum. Basically...CO2 is like an already thick blanket covering only 20-30% of your body. You'll hardly notice any extra insulation on that little strip because very little of your body's heat exits or enters through that little strip of insulation in the first place. BUT...make no mistake, we could do some serious damage to the earth if we put our minds to it. Look at the huge cloud covering asia. The only reason we don't have similar clouds covering europe and america is that we've put our collective foots down and said... No thanks, we'd rather pay a tiny bit more for power and actually be able to breathe. I'm all for that kind of thing. I think the vilifying of CO2 has made people lose sight of that though. People tend to get into this all-or-nothing mindset. In the end, there is no clean coal, oil, nuclear OR clean solar, wind, wave, tide, biofuel or hydroelectric power...they ALL leave junk laying around. They all cause pollution. They all screw with the environment in some way.
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Post by curiousgeorge on Apr 24, 2009 20:17:07 GMT
Good analogy. Thanks. And I agree regarding "normal" pollutants, having had several encounters with various really nasty ones in the last 60+ years. CO2, however, is not a pollutant just because the EPA says so. Hangin' a "Cow" sign on a horse does not magically cause the horse to become a cow. The EPA, Gore, et al are simply using the porridge argument (Goldilocks and the 3 bears) for political and personal gain at my expense. And that's where I get crazy.
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Post by magellan on Apr 25, 2009 1:23:52 GMT
People, all one needs do is compare mortality rates in 1900 and compare to 2009.
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Post by nautonnier on Apr 25, 2009 3:21:18 GMT
You will also note that the only 'natural forcing' is claimed to be TSI. There is no 'natural CO 2' shown which is far more than anthropogenic CO 2 and there is a total lack of water vapor from the diagram probably because it would dwarf every other forcing. Remember there is a huge amount of anthropogenic water vapor from all fossil fuels and all irrigation. This diagram is slanted to make politicians make decisions The solar forcing includes all components, TSI, UV, cosmic rays. The fact is that in spite of decades of looking for a solar effect on climate that differs from the very long term orbital cycles (1,000s of years) and the shorter term (9 to 13 years) variations in TSI, there hasn't been one discovered yet. The solar forcing assumes a baseline TSI of 1360 watts/meter squared so the forcing on the climate is from the small increase in TSI from the grand maximum of the past few decades. As we can see from the current (very long for most observed cycles) solar minimum, the TSI doesn't vary much, and so far, there hasn't been a huge increase in cloudiness (and cooling) predicted by the various cosmic ray hypothesis. The slightly cooler temperatures experienced in 2007 and 2008 were warmer than every year in the 20th century except for 1998. The CO2 forcing is for the increse in CO2 concentration over the pre-industrial (1850) measurement. In effect, it is assumed that the "natural CO2" concentration is 280 ppm, and the anthropogenic is the extra 100 ppm that we've put in the atmosphere since 1850. And keep in mind that even if we take drastic actions to curtail emissions, the concentration will increase by another 100 ppm within 50 years. Water vapor isn't included in the diagram, because it isn't a forcing. The diagram is only showing forcings. Water vapor will be (and has already been measured to be) a postive feedback, because as the temperature increases, the atmosphere will hold more water, which will increase the greenhouse effect. There are other positive feedbacks (melting ice reduces albedo, which means more sunlight is absorbed than reflected), however, no large negative feedbacks have been identified that could prevent the warming from the increased concentrations of greenhouse gases. While a large volcanic eruption could have a negative forcing for a few years, there really isn't another negative feedback that is going to save us from the coming warming. There is much paleoclimate evidence that when the atmosphere held more carbon dioxide, temperatures were warmer and sea levels were higher. There is no evidence of a negative feedback that stabilizes the global temperature. AGW Questionable Assumption 1" The solar forcing includes all components, TSI, UV, cosmic rays. The fact is that in spite of decades of looking for a solar effect on climate that differs from the very long term orbital cycles (1,000s of years) and the shorter term (9 to 13 years) variations in TSI, there hasn't been one discovered yet." Strange because such cyclic increases HAVE been identified in GCR there was quite a hoopla about it recently showing how the GCR variations even showed when an SSW event was happening. These variations have been plotted back for many years by looking at Be10. The paper by Nir Shaviv showed considerable response in Ocean Heat Flux due to the changes that there are in TSI. So I find your eagerness to write off the climate impact of TSI and other solar changes rather unscientific. Especially as even NASA is issuing statements saying that changes in the sun are likely to lead to a decade of cooling. AGW Questionable Assumption 2The CO2 forcing is for the increse in CO2 concentration over the pre-industrial (1850) measurement. In effect, it is assumed that the "natural CO2" concentration is 280 ppm, and the anthropogenic is the extra 100 ppm that we've put in the atmosphere since 1850. And keep in mind that even if we take drastic actions to curtail emissions, the concentration will increase by another 100 ppm within 50 years.
There are several assumptions here - but can you (or one of your compatriots) cite a 'peer reviewed' study that shows that all natural sources of CO2 have remained completely constant since pre-industrial times? (and that's actually 1750) I would expect to see error bars on the study too. There is considerable natural CO 2 as you are no doubt aware Plants have to ‘breathe’ to stay alive as well – “plant respiration releases 5 to 10 times as much carbon dioxide as fossil fuel burning” www.terradaily.com/reports/Of_Mice_Men_Trees_And_The_Global_Carbon_Cycle.html So all those 'deserts turned green and 'plant a tree' campaigns can lead to more CO 2. I am sure you have a study that shows that there has been no change since 1750 in these natural sources. (I am deliberately avoiding arguments over proxies and saturation) AGW Questionable Assumptions 3 and 4"Water vapor isn't included in the diagram, because it isn't a forcing. The diagram is only showing forcings. Water vapor will be (and has already been measured to be) a postive feedback, because as the temperature increases, the atmosphere will hold more water, which will increase the greenhouse effect. There are other positive feedbacks (melting ice reduces albedo, which means more sunlight is absorbed than reflected), however, no large negative feedbacks have been identified that could prevent the warming from the increased concentrations of greenhouse gases."I had this discussion about water vapor and forcing with Steve. You are in a small minority that does not consider water vapor a 'forcing'. Google "water vapor" OR "water vapour" forcing. You will be returned many many papers from AGW as well as realists all saying that water vapor provides a forcing. The real reason that it is left out is not due to your mis-assumption but rather because it would skew the entire graph as and in the process the CO 2 bar would become smaller than the current CH 4 bar and politicians would understand the importance of water vapor and the small effect of CO 2. Of course water does not STAY as vapor it condenses out (releasing stored heat) increasing convection and also raising the albedo. (You may have noticed this if you sunbathe and there is cloud between you and the sun that its cooler ?? - That's called a real world experiment with real data). There are studies being done using ERBE satellite measurements to quote one of them (note the use of the word 'forcing' ) : " 8. Discussion and conclusions It has been shown that individual deep convective cloud types observed in the Tropics have the potential to reduce strongly or to increase the net radiation in the Tropics. The visible optical depths of common convective cloud types in the upper tropical troposphere (310–180 mb) range from 1 to 60. In the near-equatorial convective Tropics over warm water, the net radiation at the top of these clouds varies from +123 to −16 W m−2, a range of more than 100 W m−2. The corresponding cloud net radiative forcings at the top of the atmosphere for these cloud types range from +20 to −119 W m−2. This great variation in net radiative effect arises mostly from the reflectivity of the clouds, which is primarily dependent on the water and/or ice content of the clouds." Tropical Convection and the Energy Balance at the Top of the Atmosphere; Dennis L. Hartmann, Leslie A. Moy, and Qiang Fu Journal of Climate; Article: pp. 4495–4511 Volume 14, Issue 24 (December 2001) The albedo issue with ice is over blown as most of the ice is at the poles and the angle of insolation is such that the albedo of ice and water is not significantly different. AGW Questionable Assumption 4" While a large volcanic eruption could have a negative forcing for a few years, there really isn't another negative feedback that is going to save us from the coming warming. There is much paleoclimate evidence that when the atmosphere held more carbon dioxide, temperatures were warmer and sea levels were higher. There is no evidence of a negative feedback that stabilizes the global temperature"I don't suppose you have read what you just wrote and realized the illogicality? If there is no negative feedback to stabilize the global temperature then Earth should be a sun-blasted rock like a hot Mars. There must be a negative feedback or once CO 2 causes the warming it would runaway. As the quote from AMS above said: "cloud net radiative forcings at the top of the atmosphere for these cloud types range from +20 to −119 W m−2 [/b]. This great variation in net radiative effect arises mostly from the reflectivity of the clouds, which is primarily dependent on the water and/or ice content of the clouds."[/i] Now minus 119W m −2 is quite a negative feedback - and it occurs when there is a lot of powerful convection - which is when the surface is warm and the atmosphere is humid and unstable. A classic negative feedback. Then of course there is the cold rain back to the surface cooling the surface and evaporating again to repeat the exercise. As I said in my initial post -there is a total lack of water vapor from that IPCC diagram probably because it would dwarf every other forcing. Remember there is a huge amount of anthropogenic water vapor from all fossil fuels and all irrigation. Probably more important - what is the accuracy of sets of GCM models built with your assumptions? The results would no doubt go straight into one of Al Gore's next epics.
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Post by donmartin on Apr 25, 2009 7:33:45 GMT
When you say that CO2 is a "driver" of climate change, I gather you are saying that the heat of the atmosphere increases in some way proportional to the quantity of CO2 in the atmosphere. In that case, Mars, which has an atmosphere comprised of 95% CO2, should have a warmer atmosphere than is recorded. I believe Hansen also is stumped by this issue. The atmosphere of Mars is less dense than that of the Earth, but not sufficiently less dense to account for the absence of a climate "driven" by CO2. And solar irradiation at a 6/10 ratio likewise does not account for the difference in atmospheric/surface heat of the planets.
Also, with reference to the ping pong metaphor, and given the Dalton/Rutherford atomic model, were a nucleus of an atom the size of a marble, the closest electron (the width of a hair) would be 2 miles distant from the nucleus. Pretty difficult to imagine anything colliding at that level. Or being "absorbed" for that matter. And how do you measure the number of photons in any given volume? If they exist.
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Post by steve on Apr 25, 2009 10:00:16 GMT
AGW Questionable Assumption 4" While a large volcanic eruption could have a negative forcing for a few years, there really isn't another negative feedback that is going to save us from the coming warming. There is much paleoclimate evidence that when the atmosphere held more carbon dioxide, temperatures were warmer and sea levels were higher. There is no evidence of a negative feedback that stabilizes the global temperature"I don't suppose you have read what you just wrote and realized the illogicality? If there is no negative feedback to stabilize the global temperature then Earth should be a sun-blasted rock like a hot Mars. There must be a negative feedback or once CO 2 causes the warming it would runaway. I want to question your logical analysis of what Ken said. I'm interested because I see this kind of obtuse analysis, or attempt to win an argument through flawed reducto absurdium a lot of times when debating with some sceptics. Ken referred to negative feedbacks that would "save us from the coming warming". In the context he's far more likely to be referring to warming in line with IPCC projections, rather than your fantasy runaway greenhouse effect. So is it fair to interpret him in this way just to try and win a debating point?
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Post by steve on Apr 25, 2009 10:08:57 GMT
When you say that CO2 is a "driver" of climate change, I gather you are saying that the heat of the atmosphere increases in some way proportional to the quantity of CO2 in the atmosphere. In that case, Mars, which has an atmosphere comprised of 95% CO2, should have a warmer atmosphere than is recorded. I believe Hansen also is stumped by this issue. The atmosphere of Mars is less dense than that of the Earth, but not sufficiently less dense to account for the absence of a climate "driven" by CO2. And solar irradiation at a 6/10 ratio likewise does not account for the difference in atmospheric/surface heat of the planets. What is your evidence for what you say about Mars (and Hansen). My rough calculation was that the greenhouse effect on Mars would raise its surface temperature about 10-20C (IIRC) if it behaved exactly as it did on earth. It's not clear whether we can calculate the expected greenhouse vs non-greenhouse temperatures on Mars, or accurately measure Mars temperatures to say whether this is so. And since Mars' atmosphere is much thinner there is less thermal inertia, so there is no reason to suggest that the greenhouse effect would be just the same. I was merely extending curiousgeorge's ping pong metaphor to be nearer reality so as to point out that maybe it might not be so hard to find a black ping pong ball if you sampled the right number of balls. The next step in the analogy would be to calculate the absorption cross sections for various wavelengths, which is what is done for HITRAN/MODTRAN databases that underlie the calculations, and show that this amount of CO2 does indeed absorb a lot of radiation.
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