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Post by ron on Feb 11, 2009 2:03:37 GMT
That's clouds. I was talking convection, which is frequently, but not always connected with clouds. And storms.
Those big super cyclones caused by AGW which churn up the hot waters, lofting "super" heated moisture into the atmosphere and move all that heat up 30,000+ feet. You know, the ones that completely cover the Gulf of Mexico, or completely churn up the Pacific...
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Post by steve on Feb 11, 2009 12:20:19 GMT
Don't they list solar activity in that chart??? I gotta go look at it again. It includes total solar irradiance. It is included! It's just that for the purposes of looking at the impact with regard to warming, it's called a "feedback" not a "forcing". It doesn't really matter what it's called does it, as long as it's taken into account. Basically the idea is that things that are externally/independently changed such as CO2, solar, aerosols, are "forcings". The changes result warming/cooling which has secondary impacts which are "feedbacks". There's nothing dogmatic about it. It's a practical matter. Forcings are called forcings because they are given as absolute numbers. Feedbacks are usually called feedbacks because they are provided as a function of the forcing. Eg. for Nautonnier's paper, they're specifically looking at the radiative impact of clouds, and talk about "forcing" because they are thinking about the scenario of when the clouds are there vs when they are not. If they were thinking about *changes* in the clouds as a result of outside influence they might refer to the outside influence as a forcing and the *change* in the radiative forcing as a feedback. The feedback would then be expressed as a function of the forcing. eg "a forcing of X amount of sulphates causes a feedback of 2X W/m^2 due to tropical cloud changes".
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Post by tallbloke on Feb 11, 2009 13:54:23 GMT
It would be nice if in addition to having a go at me, people would also have a go at the obviously faulty saturation argument. Or please win your Nobel prize by constructing an earth-like atmosphere that cannot be influenced by the instantaneous doubling of a gas that strongly absorbs infrared. How about one where temperatures increased by the doubling of an infrared absorbing trace gas are offset by the concomitant increase of another gas which overlaps the trace gas' absorption bands and forms clouds which reduce insolation? Ever heard of negative feedbacks Steve? the earthshine project's data indicates cloud levels increased globally from from it's inception in late 1998 to 2000 and have stayed at elevated levels since. I await my nobel prize.
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Post by tallbloke on Feb 11, 2009 14:00:29 GMT
Basically the idea is that things that are externally/independently changed such as CO2, solar, aerosols, are "forcings". The changes result warming/cooling which has secondary impacts which are "feedbacks". There's nothing dogmatic about it. It's a practical matter. Forcings are called forcings because they are given as absolute numbers. Feedbacks are usually called feedbacks because they are provided as a function of the forcing. But Steve, co2 levels are a function of temperature, and rises in temperature always precede rises in co2 levels. Therefore, using your own logic, co2 is a feedback, not a forcing.
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Post by steve on Feb 11, 2009 16:32:17 GMT
It would be nice if in addition to having a go at me, people would also have a go at the obviously faulty saturation argument. Or please win your Nobel prize by constructing an earth-like atmosphere that cannot be influenced by the instantaneous doubling of a gas that strongly absorbs infrared. How about one where temperatures increased by the doubling of an infrared absorbing trace gas are offset by the concomitant increase of another gas which overlaps the trace gas' absorption bands and forms clouds which reduce insolation? Ever heard of negative feedbacks Steve? the earthshine project's data indicates cloud levels increased globally from from it's inception in late 1998 to 2000 and have stayed at elevated levels since. I await my nobel prize. Negative feedbacks is one thing. Wrong arguments based on saturation are another. Prior to it occurring, what are the expectations that feedbacks from clouds and water vapour will be negative. But then we have examples where the the climate has apparently exhibited the effects of strong positive feedbacks (ice age cycles, cooling and drying of the atmosphere following Pinatubo). Finally, (only finally) it is difficult to construct a physically and observationally realistic model (checked against both weather and climate) that shows negative feedbacks. That's why I say it's not a dogmatic choice. It's about having an easy way of categorising and understanding the impacts. Even when we talk about anthropogenic CO2 being a "forcing" we are already looking only at the net increase in atmospheric concentrations that are caused by the CO2 and ignoring the excess CO2 that gets absorbed by the oceans and plants. We don't talk about a positive forcing of 300ppm CO2 minus a negative forcing of the 200ppm of excess CO2 absorbed by the ocean. So when you next hear that "climate scientists ignore water vapour, the biggest greenhouse gas" then you should know they don't ignore it. They just call it a feedback instead of a forcing.
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Post by tallbloke on Feb 11, 2009 17:22:15 GMT
But then we have examples where the the climate has apparently exhibited the effects of strong positive feedbacks (ice age cycles, cooling and drying of the atmosphere following Pinatubo). Not sure if I get you here, but cooling and drying implies less cloud which would be a 'negative feedback' allowing more insolation thus resisting the cooling would it not? That's why I say it's not a dogmatic choice. It's about having an easy way of categorising and understanding the impacts. Even when we talk about anthropogenic CO2 being a "forcing" we are already looking only at the net increase in atmospheric concentrations that are caused by the CO2 Increases in co2 are caused by the co2? Huh?? So when you next hear that "climate scientists ignore water vapour, the biggest greenhouse gas" then you should know they don't ignore it. They just call it a feedback instead of a forcing. Still seems misleading to me. Anyway, we know the modellers don't ignore water vapour. They just overestimate the co2 feedback in relation to it and expect it to be where it isn't.
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Post by nautonnier on Feb 12, 2009 2:31:13 GMT
Steve, Your explanation is simple - but does not appear to fit with the climatology usage - but perhaps I am being mislead by the Journal of Climatology... VOL. 17, NO. 19 Journal of Climate - 1 OCTOBER 2004; q 2004 American Meteorological Society 3661 - LETTERS On the Use of Cloud Forcing to Estimate Cloud Feedback ABSTRACT Uncertainty in cloud feedback is the leading cause of discrepancy in model predictions of climate change. The use of observed or model-simulated radiative fluxes to diagnose the effect of clouds on climate sensitivity requires an accurate understanding of the distinction between a change in cloud radiative forcing and a cloud feedback. This study compares simulations from different versions of the GFDL Atmospheric Model 2 (AM2) that have widely varying strengths of cloud feedback to illustrate the differences between the two and highlight the potential for changes in cloud radiative forcing to be misinterpreted.www.gfdl.noaa.gov/reference/bibliography/2004/bjs0402.pdfA quick Google also showed many other 'Cloud radiative forcing' papers. Lack of precise terminology makes it difficult - I have quotes of clouds in the tropics with negative radiative forcings in the 100WM -2. Seems that the terms forcing and feedback are being used interchangeably in some papers, in your way in others and in yet another way in the cite above.
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Post by steve on Feb 12, 2009 13:48:33 GMT
tallbloke,
In the above I meant that the CO2 *emissions* were causing the net rise in CO2.
If the level of water vapour in the atmosphere reduces because of cooling, then this reduces the greenhouse effect caused by the water vapour. The effect on clouds is more complex and less certain, but there is no good evidence that cloud changes will balance the changes to the greenhouse effect, and *reasonable* evidence that the relative effect due to changes in clouds is small.
PS. I'll have a look at the paper nautonnier linked a bit later. Other papers by Soden are what I currently base my understanding about water vapour feedbacks on.
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Post by tallbloke on Feb 12, 2009 15:33:52 GMT
tallbloke, In the above I meant that the CO2 *emissions* were causing the net rise in CO2. If the level of water vapour in the atmosphere reduces because of cooling, then this reduces the greenhouse effect caused by the water vapour. The effect on clouds is more complex and less certain, but there is no good evidence that cloud changes will balance the changes to the greenhouse effect, and *reasonable* evidence that the relative effect due to changes in clouds is small. PS. I'll have a look at the paper nautonnier linked a bit later. Other papers by Soden are what I currently base my understanding about water vapour feedbacks on. The best estimate I've seen is that a 1% drop in cloud cover will allow about 2W/m^2 of insolation through. The earthshine project estimates cloud cover increased by around 2% between late 1998 and 2000, and has remained roughly at that level since. This would cause a ~4w/m^2 drop in insolation. If the increase in cloud cover is over important bits of ocean, the implications for ENSO etc could be quite profound.
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Post by steve on Feb 12, 2009 16:24:09 GMT
tallbloke, In the above I meant that the CO2 *emissions* were causing the net rise in CO2. If the level of water vapour in the atmosphere reduces because of cooling, then this reduces the greenhouse effect caused by the water vapour. The effect on clouds is more complex and less certain, but there is no good evidence that cloud changes will balance the changes to the greenhouse effect, and *reasonable* evidence that the relative effect due to changes in clouds is small. PS. I'll have a look at the paper nautonnier linked a bit later. Other papers by Soden are what I currently base my understanding about water vapour feedbacks on. The best estimate I've seen is that a 1% drop in cloud cover will allow about 2W/m^2 of insolation through. The earthshine project estimates cloud cover increased by around 2% between late 1998 and 2000, and has remained roughly at that level since. This would cause a ~4w/m^2 drop in insolation. If the increase in cloud cover is over important bits of ocean, the implications for ENSO etc could be quite profound. So that apparently sudden cloud change could be corroborative evidence matching up with the claim that climate scientists make, that natural variability has been working in opposition to the CO2 warming. If whatever caused the clouds to increase so suddenly now causes the clouds to decrease then we'll get extra warming.
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Post by tallbloke on Feb 12, 2009 16:35:46 GMT
The best estimate I've seen is that a 1% drop in cloud cover will allow about 2W/m^2 of insolation through. The earthshine project estimates cloud cover increased by around 2% between late 1998 and 2000, and has remained roughly at that level since. This would cause a ~4w/m^2 drop in insolation. If the increase in cloud cover is over important bits of ocean, the implications for ENSO etc could be quite profound. So that apparently sudden cloud change could be corroborative evidence matching up with the claim that climate scientists make, that natural variability has been working in opposition to the CO2 warming. If whatever caused the clouds to increase so suddenly now causes the clouds to decrease then we'll get extra warming. I suspect it's not so simple. If there are longer term cycles at play bringing temps down, the barely-existent co2 forcing isn't going to help much. As the temperature record shows, there seem to be cycles of ~11, 60 and 170 years which have all just topped out. So even if cloud cover does diminish, earth may well still cool further.
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Post by ron on Feb 12, 2009 17:44:47 GMT
So that apparently sudden cloud change could be corroborative evidence matching up with the claim that climate scientists make, that natural variability has been working in opposition to the CO2 warming. If whatever caused the clouds to increase so suddenly now causes the clouds to decrease then we'll get extra warming. TRUE! Of course it could also be that the increased warmth from the el nino caused the extra clouds, which would make an el nino a net cooling event. Who knows. Not me. Not our scientists or computer models either, I fear.
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Post by steve on Feb 12, 2009 18:24:57 GMT
So no compelling refutation of AGW theory. Just *possibilities* of cycles "topping out", El Niño cooling theories, negative cloud feedbacks and spurious arguments about saturation.
Karl Popper's not pooping the AGW party just yet.
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Post by ron on Feb 12, 2009 18:50:22 GMT
So no compelling AGW theory, either.
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Post by nautonnier on Feb 13, 2009 21:34:16 GMT
So no compelling refutation of AGW theory. Just *possibilities* of cycles "topping out", El Niño cooling theories, negative cloud feedbacks and spurious arguments about saturation. Karl Popper's not pooping the AGW party just yet. The AGW theory _used_ to be: ** CO 2 concentrations in the atmosphere are rising faster due to human activities. ** Although CO 2 itself only absorbs at most 8.5% of outgoing IR this is sufficient to raise the temperature by a small amount.** The small rise in temperature due to CO 2 will initiate an increase in evaporation of water and this will lead to tropospheric warming especially in hotspots in the tropics at medium / high levels. ** Clouds may form but overall they have a net effect of zero as any daytime shading is balanced by night time warming** Therefore the overall effect is that the Earth's radiation budget is unbalanced and the planet will warm. ** This 'Green House Effect' is such that it 'overwhelms all other natural forcings' This logical edifice was fine in the last decades of the twentieth century. Counter to this now we have: ** CO 2 concentrations in the atmosphere are rising faster due to human activities. This is perhaps true but CO2 is a trace gas with vanishingly small amounts in the atmosphere and the actual amount put out by human activity is dwarfed by that put out by nature. ** Although CO 2 itself only absorbs at most 8.5% of outgoing IR this is sufficient to raise the temperature by a small amount. True a small amount is probable - but no-one can quantify the actual amount in the real world. There are formulae that are used for lab experiments and models but it cannot be and has not been verified empirically in the real world.** The small rise in temperature due to CO 2 will initiate an increase in evaporation of water and this will lead to tropospheric warming especially in hotspots in the tropics at medium / high levels. This appears to be incorrect, The hotspots hypothesized are not there and no-one can tell whether there is even increased water vapor due solely to the hypothesized CO2 radiative forcing in the real atmosphere.** Clouds may form but overall they have a net effect of zero as any daytime shading is balanced by night time warming The effect of clouds is still unverified. There are some papers from ERBE satellite research that show that in some cases clouds in the tropics can be strongly NEGATIVE forcings - more than --100WM-2 in some cases. The potential impact of cloud shading and negative forcing can be orders of magnitude greater than any other radiative forcing effect** Therefore the overall effect is that the Earth's radiation budget is unbalanced and the planet will warm. Although said it is only weather the planet has COOLED surely this cannot be possible unless something inside or outside the system has changed that is MORE EFFECTIVE at changing the radiation budget than CO2** This 'Green House Effect' is such that it 'overwhelms all other natural forcings' From the previous statement Although said it is only weather the planet has COOLED surely this cannot be possible unless something inside or outside the system has changed that is MORE EFFECTIVE at changing the radiation budget than CO2As far as I can see, the Earth warmed erratically with perturbations from the occasional volcanism during the last 20 years of the twentieth century. However, we then entered a longer term plateau and then a few years drop. This does not fit with 'GHG overwhelming all other natural forcings'. 'Weather' is far shorter term than 3 or 4 years. What we can say is that warming has stopped for a period of years and the CO 2 caused warming hypothesis has no explanation for it. Indeed the normal 'explanation' is to draw a 'trend line' longer than 10 years and claim that the 'trend' is still up. Unfortunately, that is not what the CO 2/AGW hypothesis says. It is that CO 2 will unbalance the Earth's radiation budget to such an extent that it overwhelms all natural forcings. It has to say that or the warming at the end of the twentieth century could be a natural forcing. As an analogy the foot is hard down on the accelerator and the car is slowing down - not running roughly (weather) - it is slowing down and something must be causing it to decelerate that has more effect than the accelerator pedal. Yes the car is still going faster than it was 30 seconds ago so I could claim I have an accelerating trend - but I would start sounding like a used car salesman. If this deceleration continues then I have to doubt that the engine is actually is responding to the accelerator at all. That is where I and others are with the CO 2 causes global warming climate change - its like saying the accelerator causes the deceleration. And the more the AGW proponents keep returning to the weeds of the formulae or claiming that there is still an upward trend if 10+ years are taken into account, rather than addressing the issue of the actual cooling, the more they sound like used car salesmen. Take it back to the workshop and cure that accelerator and we might consider buying the car.
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