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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 88001 to 88050:

  1. Clouds provide negative feedback
    KR (RE: 66), "Cause => Effect CO2 is a cause, changing (primarly and from anthropogenic actions) independent of temperature, while water vapor and clouds respond promptly to temperature and don't change on their own, and are hence amplifying effects of temperature change." I think the confusion here lies somewhere in between the definition of 'forcing' and that there are many other things in the climate system, other than anthropogenic CO2 (and GHGs), that are changing and subsequently inducing new 'forcings' independent of temperature. As just one example, take the fluctuations of Arctic and Antarctic sea ice extents, which we know are largely driven by factors other than temperature (wind patterns, ocean currents, etc,). Yes, anthropogenic CO2 'forcing' is a cause and not an effect of temperature, but even without anthropogenic CO2, the climate is frequently perturbed by new 'forcings' - not all of which are due to temperature changes, yet the globally averaged temperature remains very, very stable.
  2. Clouds provide negative feedback
    RW1,
    In short, the cloud feedback is huge.
    You love to exaggerate things. The cloud feedback is important, not huge. It's more important if it is neutral or negative, but you've shown no evidence other than that you think common sense says so, while hundreds of climate scientists think otherwise. But even if you proved clouds to be a weak negative feedback, it would reduce sensitivity to anywhere from 1.9 to 3.4 (versus 3 to 4.5), given that 3 is the current best estimate, but also at the low end of the range. Even 1.9 is very, very bad, especially since we're currently taking no action to avoid it. But first you need to submit some evidence beyond your "plain, everyman logic" to prove that clouds are even a neutral feedback, let alone negative. And that evidence has to contradict all of this evidence to the contrary. I'm afraid a sensitivity below 3˚C is very, very unlikely.
    But what causes the temperature to drop and the water vapor to be removed from the atmosphere if water vapor is the primary amplifier of warming?
    This question is evidence that you don't understand how things work. You need to go study more. If this were the case, the planet would never, ever cool, no matter what.
    ...but I don't see how CO2's effect is fundamentally different than water vapor..
    Because water vapor will increase or decrease in the atmosphere fairly quickly in response to temperature. Raise the temperature, raise the water vapor. Lower the temperature, lower the water vapor. CO2, on the other hand, will stay in the atmosphere for hundreds of years, even if, for example, a large volcanic eruption temporarily lowers temperatures.
    ...why would the response to water vapor warming in the system be any different than warming caused by CO2?
    There's no difference in the warming. What is different is that the CO2 won't drop out of the atmosphere when the temperature drops (for instance, during the winter).
    Why would the same forces that modulate or control water vapor's radiative forcing, not modulate and control CO2's radiative forcing?
    There are no such forces for either. This isn't a human designed system with controls and balances. It's nature, and it's (fortunately) got a simple balance to it, and one that should be very hard to shove, but we've found a way to do it. The point is not how each one (water vapor vs. CO2) affects temperature. The point is that water vapor content is itself affected by temperature on short time scales, while CO2 is only affected on very, very long time scales. And, in fact, there is a positive CO2 feedback (such as outgassing from the ocean) that will, in the long term, increase CO2 levels even further.
  3. CO2 limits will harm the economy
    I think Gilles should try reading the post he's commenting on here, as it refutes every claim he made. Just as one example, try reading the Impact on Gasoline Prices section.
  4. Clouds provide negative feedback
    scaddenp (RE: 69), "The atmosphere has a temperature gradient. At a certain height, water condenses out. CO2 does not." I know. "Note that in our current AGW-world, CO2 is not a feedback." Agreed.
  5. Clouds provide negative feedback
    The atmosphere has a temperature gradient. At a certain height, water condenses out. CO2 does not. Maximum water content in atmosphere is temperature-dependent. Maximum CO2 is not. Note that in our current AGW-world, CO2 is not a feedback. The mechanisms are too slow to have produced much GHG feedback yet.
  6. Clouds provide negative feedback
    Sphaerica (RE: 58), "Yes, because water vapor responds quickly to changes in temperature. There's nothing anyone or anything can do to inject water vapor into the atmosphere and keep it there. The temperature will drop, and the water vapor will condense and things will return to normal." But what causes the temperature to drop and the water vapor to be removed from the atmosphere if water vapor is the primary amplifier of warming? "This is not the case with CO2, whether it is added anthropogenically or geologically. No matter how it gets there, once it does get there, it stays there for a very long time and it's effect forces the climate to follow suit." Yes, but I don't see how CO2's effect is fundamentally different than water vapor, especially if water vapor is the primary amplifier of warming (CO2 induced or otherwise). In other words, why would the response to water vapor warming in the system be any different than warming caused by CO2? Why would the same forces that modulate or control water vapor's radiative forcing, not modulate and control CO2's radiative forcing? The surface has no way of distinguishing where the radiative 'forcing' originated from - water vapor or CO2. All the surface 'knows' is its total energy flux, as it determines the surface temperature.
  7. Clouds provide negative feedback
    RW1 - clouds are not forcing because unless you have something like GCR changing clouds, there is no way to produce a long term change in cloud cover without something else being responsible for changing the temperature. If your vision of reality is right, then you would have world with no change to GHG, solar, or aerosols, going through climate change (ie a long term change in radiative balance). Now plenty of that kind of internal variability in short time scales - weather. But no evidence whatsoever of any such change on long term.
  8. CO2 limits will harm the economy
    Now for the *real* impacts of carbon pricing : http://www.foxbusiness.com/markets/2011/04/11/oil-prices-inflation-pose-risk-global-economy-imf/ http://www.nytimes.com/2011/04/19/business/global/19euro.html http://blogs.reuters.com/james-pethokoukis/2011/04/18/the-politics-of-sps-u-s-debt-warning/ = recession, unbearable debts, economic crisis. That's the real world.
    Moderator Response: [DB] Please demonstrate the relevance of a link by providing some context showing why its relevant to the thread at hand. Otherwise, you're merely vomiting forth newspaper links (in this case) with no demonstration that you've actually read the post you're commenting on. Future posts lacking such context will receive moderation. FYI: as in the real world of astrophysics, peer-reviewed science publications carry the most weight, don't they?
  9. Clouds provide negative feedback
    RW1 - At the risk of repeating myself: Cause => Effect CO2 is a cause, changing (primarly and from anthropogenic actions) independent of temperature, while water vapor and clouds respond promptly to temperature and don't change on their own, and are hence amplifying effects of temperature change. Water vapor and clouds change in response to temperature. If you have any evidence supporting water vapor or cloud changes independent of temperature, I suggest you publish it. Nobody else has found any such evidence - I will (I believe correctly) take assertions to that effect as just wishful thinking without such evidence.
  10. Clouds provide negative feedback
    muoncounter (RE: 62), "I thought there was agreement that water vapor doesn't stay in the atmosphere that long." It doesn't, but it also doesn't take 40 years for changes in water vapor concentration to effect changes in temperature. For example, a sunny humid day is generally warmer than a sunny dry day, all other things being equal. "Ah, we've come full circle, as you've said that before: It's also inline with the sensitivity only being about 0.6 C" That was assuming only half of the 3.7 W/m^2 from 2xCO2 is incident on the surface. For the purposes of this discussion and elsewhere here, I've accepted that the full 3.7 W/m^2 affects the surface (at least for now).
  11. Clouds provide negative feedback
    KR (RE: 59), "Not just claiming that, but stating that with plenty of evidence. CO2 has been changing due to anthropogenic emissions, while water vapor and clouds have been changing strictly due to temperature changes." Not necessarily strictly temperature changes, but even so, I don't see how that excludes them from being a 'forcing'. Do water vapor changes not also cause temperature changes? Do cloud changes not also cause temperature changes? Surely they do.
  12. Clouds provide negative feedback
    RW1#62: "why doesn't it take 40 years for the forcing of water vapor in the atmosphere" I thought there was agreement that water vapor doesn't stay in the atmosphere that long. I don't know how things are where you live, but I wipe a lot of that water vapor off my car windows every morning. #61: "the average sensitivity could easily come down to 1 C or less." Ah, we've come full circle, as you've said that before: It's also inline with the sensitivity only being about 0.6 C . Of course, the temperature record doesn't support that contention, as we've already seen 0.8C with far less than a doubling of CO2.
  13. Muller Misinformation #4: Time to Act
    Moderators, I have just noticed that I accidentally included the wrong link in my post above. The first link should be to The economic impacts of carbon thread: http://www.skepticalscience.com/argument.php?a=36#48902 I would greatly appreciate your fixing the hyperlink.
    Moderator Response: [mc] Done! Beat the Yooper to it for once.
  14. Clouds provide negative feedback
    muoncounter (RE: 60), "The time it takes to double CO2 through anthropogenic input has nothing to do with the time it takes for the forcing of CO2 already in the atmosphere to increase temperature, which is, of course, already in progress. I don't understand how you mixed up the two. See the 40 year lag thread I linked earlier for discussion of this." Sorry for the misunderstanding, but my question then is why doesn't it take 40 years for the forcing of water vapor in the atmosphere to increase (and decrease) temperature?
  15. More Carbon Dioxide is not necessarily good for plants.
    Stephen Baines - I wholeheartedly agree. Johnd appears focused on technological seed/breed development to escape these consequences ("However with the will, technology will help over come some this also."), although he has put forward no actual data to support this - the FACE results appear to be exploring what is within the range of existing plant variants, rather than demonstrating that selective breeding can produce superplants. There does appear to be a small yield effect with increased CO2 for some species (wheat, yes, soybeans, no), fighting with decreased nutritional value, much larger hydrological changes and heat stress, with an end result of at best little change in productivity, but a more likely decrease thereof.
  16. CO2 effect is saturated
    novandilcosid @87, the claim I was responding to is quite specific:
    "There are some other interesting aspects: The atmospheric window is almost constant, the conduction is almost constant, so the heat transport from the surface into the atmosphere is almost a constant whatever the surface temperature. What happens as the temperature rises is that the Net radiation (surface radiation less radiation through the window less back radiation) DECREASES and this balances the increase in water vapour condensation."
    So according to you for any two temperatures T1 and T2, e1sT14-W-Rback1+E1+C1=e2sT24-W-Rback2+E2+C2, where T stands for temperature, W for energy escaping through the atmospheric window, R for back radiation, E for evaporative energy transport (latent heat), C for conduction, e for the emissivity, and s for the Stefan-Boltzman constant. I can allow (as indicated in the notation) that energy escaping the atmospheric window is near constant for small changes in temperature with no changes in GHG concentrations. However, all other factors are variable with temperature. Specifically, you insist that an increase in temperature will result in an increase evaporation. But increased evaporation reduces soil moisture content, thus reducing the emissivity of the soil (factor 1). It also increases the emissivity of the lowest portion of the atmosphere, thus reducing the altitude of emission (factor 2), and at the same time reduces the lapse rate which increases the temperature at any given altitude (factor 3). Factor's (2) and (3) combine to increase back radiation. (The increased humidity will also decreases the size of the atmospheric window, but we will neglect that.) Increasing temperatures also increases wind speed globally, thus increasing conductive heat transfer by increasing the rate of turn over of the layer of atmosphere in immediate contact with the surface (factor 4). Increased humidity will also increase conductive transfer because of the high heat capacity of water vapour. So, you have at least four hetergenious factors you need to juggle to gain your equality, and only one term (W) which can be eliminated from the equation. The proof that change in net surface radiation equals the negative change in net evaporative transfer, therefore does not follow, and is highly implausible.
  17. Clouds provide negative feedback
    Sphaerica (RE: 57), "What is your point about clouds again? Now that you've proven that they are a strong positive feedback, why are we discussing them?" Because if a lot of the enhanced warming comes from positive cloud feedback, and the cloud feedback is NOT really positive - but negative (even slightly negative), it is going to reduce the projected amount of warming significantly. The IPCC even says that if the cloud feedback is neutral, it would reduce the average sensitivity to 1.9 C instead of 3 C. That's a reduction of over half of the enhanced warming. If the cloud feedback was even moderately negative, the average sensitivity could easily come down to 1 C or less. In short, the cloud feedback is huge.
  18. Stephen Baines at 13:02 PM on 20 April 2011
    More Carbon Dioxide is not necessarily good for plants.
    I'm with Marcus. Johnd, your characterization of the arc of this debate bears no resemblance to what I have observed, although I suspect we fly in different circles. Biogeochemical models have built in CO2 fertilization in response to increasing CO2 since the 80's, with different responses for C-3 and C-4 plants. The FACE experiments were designed to parameterize those models under a range of conditions, and to test for acclimation and ecosystem level knock-on effects. What really came out of the FACE experiments though was how variable plants were in this respect, and how tricky it is to generalize about responses more specific than photosynthesis. In the end, the effects of CO2 (0-50%, depending on plant) are small and variable compared to responses to precipitation. Why? Well, there is a ceiling to the CO2 effect, it is fully realized for only some species under very specific circumstances (high nutrients, high water, high light). The effect is even less notable for net ecosystem productivity. Water limitation, by contrast is a hard limit for plants, and is very hard to overcome technologically without consequences (ask the people in the Owens "River" Valley!). Variation in precip results in 2 orders of magnitude variation in primary production between ecosystems. That trumps CO2 as a limiting factor every time. Expansion of arid zones will not be compensated on a global level by CO2 fertilization. Seeing how we've dealt so far with famine induced by precipitation in Africa, I'm also not as optimistic about application of technology or of the political will to address the problem in places where rich people don't tread.
  19. Clouds provide negative feedback
    RW1#54: "I don't understand the question." Well, you stated "Anthropogenic CO2 forcing is very gradual," I asked how you to substantiate this; you responded that "it's claimed to take about 100 years to double CO2." The time it takes to double CO2 through anthropogenic input has nothing to do with the time it takes for the forcing of CO2 already in the atmosphere to increase temperature, which is, of course, already in progress. I don't understand how you mixed up the two. See the 40 year lag thread I linked earlier for discussion of this.
  20. Clouds provide negative feedback
    RW1 - "If water vapor is not a 'forcing' in the climate system, then how can CO2 be a 'forcing'? Are you claiming that increased water vapor in the atmosphere is not a 'forcing', but increased CO2 is a 'forcing'?" Not just claiming that, but stating that with plenty of evidence. CO2 has been changing due to anthropogenic emissions, while water vapor and clouds have been changing strictly due to temperature changes. This is part of the grand scheme of Cause -> Effect, RSVP; CO2 (due to our actions) is a recent cause of climate change, water vapor and clouds respond as an effect.
  21. Muller Misinformation #4: Time to Act
    #39 Trouble is, the natural habitats of the lesser spotted wood lice appear to be the Coalition party room, the Australian union movement, Corporate board rooms, and every climate change thread in every blog in the world.
  22. Clouds provide negative feedback
    56, RW1,
    ...but increased CO2 is a 'forcing'?
    Yes, because water vapor responds quickly to changes in temperature. There's nothing anyone or anything can do to inject water vapor into the atmosphere and keep it there. The temperature will drop, and the water vapor will condense and things will return to normal. This is not the case with CO2, whether it is added anthropogenically or geologically. No matter how it gets there, once it does get there, it stays there for a very long time and it's effect forces the climate to follow suit.
  23. Clouds provide negative feedback
    52, RW1, Clouds come in ahead of albedo, and behind water vapor. I'm still not quite sure how you turn this into "A very large amount (if not most) of the enhanced warming" but I'll concede the point. Clouds are an important positive feedback in the models (but not "most"). So what's your point? 53, RW1,
    The only true 'forcing' of the climate system is the Sun.
    No. If anything, solar output is the single strongest constant in the entire system. Changes in CO2 concentrations in the atmosphere are almost certainly the primary driver as far as total change. They are tied to every major climate swing in some way, and global temperature closely tracks CO2 concentrations. Albedo is probably the primary driver as far as getting the ball rolling (and that can come from orbital forcings or aerosols -- volcanism). Water vapor and clouds are fast acting feedbacks that do not force anything on their own. But we're drifting. What is your point about clouds again? Now that you've proven that they are a strong positive feedback, why are we discussing them?
  24. Clouds provide negative feedback
    KR (RE: 51), If water vapor is not a 'forcing' in the climate system, then how can CO2 be a 'forcing'? Are you claiming that increased water vapor in the atmosphere is not a 'forcing', but increased CO2 is a 'forcing'? This is the problem. They are both 'forcings' in the way you're using the term. The main difference is water vapor acts on much shorter time scales, but it is still a 'forcing' none the less.
  25. Clouds provide negative feedback
    See the IPCC report for formal definition of forcing, but it is basically something can change the radiative balance independent of temperature. Only a change in forcing can change climate. The forcing in the system are solar, GHGs (which can also be a feedback, but are a forcing if changed independently of temperature -eg by release of fossil fuel), and aerosols. On a larger time scale, changes in continent distribution and in the nature of the biosphere can alter albedo so that it is also a forcing.
  26. Clouds provide negative feedback
    muoncounter (RE: 50), "Huh? What does that have to do with the rate at which CO2 radiative forcing increases global temperature?" I don't understand the question. Is 100 years not a significantly slower rate than hours to days?
  27. Muller Misinformation #4: Time to Act
    funglestrumpet: it does matter what's causing the warming, because the actions that must be taken are very different. If humans are causing the warming by emissions of greenhouse gases, then the obvious & most urgent action is to reduce or eliminate GHG emissions. If, on the other hand, it were all down to natural causes, then our most immediate priority would be to prepare human civilisation for the coming climate changes. The best science out there tells us that it's more than 95% likely that it's the former, not the latter, so the prudent course would be to reduce GHG emissions as quickly as possible. From a risk management point of view, I think the response to the recent events at Fukushima Dai-ichi tell the story. What's the chances of a magnitude 9 earthquake and a 14 metre tsunami hitting a nuclear power plant in it's operating life? I'd wager those odds are less than 1-in-20, even in Japan, and yet nuclear plants all around the world are scrambling to make sure they're prepared for far more unlikely eventualities. On the other hand, we've got a higher than 19-in-20 chance of climate disruption with associated human cost and massive economic losses (measured in the tens or even hundreds of trillions), and we have crowds of deniers running around shouting that we don't need to do anything, because there's too much uncertainty. Just to stray off-topic (mods, feel free to delete this last para!) - I'm starting to get quite amused how Gilles seems to post on every single thread, no matter what the topic, a comment about how we supposedly have no alternative to continuing use of fossil fuels, despite people pointing out such alternatives to him many, many times in the past. I agree entirely with the mod position: do not feed the troll. But I also agree with Tom Curtis' suggestion that trolling comments be deleted and replaced with a link to the appropriate page for that discussion. Otherwise, the trolling has achieved it's objective of diverting the reader's attention from the topic at hand, and that seriously detracts from the much more valuable discussions that appear in the comments here.
  28. Clouds provide negative feedback
    KR (RE: 51), "From your link: "In AOGCMs, the water vapour feedback constitutes by far the strongest feedback" - followed by the lapse rate, and then surface albedo and clouds." Are you not actually reading the whole section? This not what it says (or implies). The surface albedo is the smallest feedback - closer to a third of the average cloud feedback (0.26 W m-2 °C–1 vs. 0.69 W m–2 °C–1 for clouds). The water vapor feedback is directly tied to and offset by the lapse rate feedback (1.80 W m-2 °C–1 vs. -0.84 W m-2 °C–1 for the lapse rate). " 'Water vapor and clouds act on time scales of hours to days.' Absolutely. Which why they are strictly feedbacks, not forcings." Define specifically what you mean by a 'forcing'? The only true 'forcing' of the climate system is the Sun. All the other components, such as water vapor, clouds, and precipitation, are really just responding directly or indirectly to the Sun's forcing, the net effect of all of which dictate the equilibrium surface temperature. "They cannot stay out of balance long enough to affect any other feedbacks on their own." Why not? What's keeping them from staying "out of balance"?
  29. CO2 effect is saturated
    DB, if you have been given worse in that sense, I am truly mortified.
    Moderator Response:

    [DB] Some days you're the windshield, some days you're the bug. But you can always do this afterwards:

  30. Clouds provide negative feedback
    Sphaerica (RE 48), "Water vapor does not equal clouds." I never claimed that it did. "Again, no, clouds come in a distant fourth, at best, behind H2O feedbacks (water vapor), CO2 feedbacks, and albedo feedbacks." Not according the latest IPCC report, which says: "The water vapour feedback is, however, closely related to the lapse rate feedback (see above), and the two combined result in a feedback parameter of approximately 1 W m–2 °C–1, corresponding to an amplification of the basic temperature response by approximately 50%. The surface albedo feedback amplifies the basic response by about 10%, and the cloud feedback does so by 10 to 50% depending on the GCM." Clouds can be up to 50%, where as surface albedo is only about 10%.
  31. Clouds provide negative feedback
    RW1 - Re: your claim that "A very large amount (if not most) of the enhanced warming from the climate models comes from positive cloud feedback." From your link: "In AOGCMs, the water vapour feedback constitutes by far the strongest feedback" - followed by the lapse rate, and then surface albedo and clouds. "Water vapor and clouds act on time scales of hours to days." Absolutely. Which why they are strictly feedbacks, not forcings. They cannot stay out of balance long enough to affect any other feedbacks on their own.
  32. Clouds provide negative feedback
    RW1#:46 "it's claimed to take about 100 years to double CO2." Huh? What does that have to do with the rate at which CO2 radiative forcing increases global temperature?
  33. Clouds provide negative feedback
    40, RW1,
    I don't see how this is so. Anthropogenic CO2 forcing is very gradual, taking decades and centuries. Water vapor and clouds act on time scales of hours to days.
    Normal climate change takes millenia. The 0.3˚C swings in global temperature that have been normal for the past two thousand years are not climate change. And clouds have nothing to do with anything. Please begin providing evidence instead of mere assertions.
  34. Clouds provide negative feedback
    40, RW1,
    Actually, when the planet cools (or is cooling), there is more going out than coming in for a while...
    When the planet cools, it radiates less, not more.
    The point is the equilibrium global surface temperature from year to year fluctuates very, very little. This has nothing to do with energy always needing to being conserved.
    No, it doesn't, but it also has nothing to do with clouds. It has to do with the fact that the only mechanism for actual cooling the planet is to either reflect or radiate heat, and the only mechanism for warming is to trap heat. As such, the planet has a fairly stable climate because very little will naturally change the chemical balance of the atmosphere or the albedo of the surface except over very, very long time frames. None of this says that clouds have to be some powerful control knob that keeps everything mellow. The planet stays where it is because it is very, very hard to shift it out of balance (as evidenced by the small changes in climate despite large changes in orbital forcings, except for that perfect case that initiates or terminates an interglacial). You can't say that clouds must be a mitigating factor because you figure they must be. You're going to need much stronger evidence than that.
  35. CO2 effect is saturated
    My apologies to the moderators - I really am giving you a lot of trouble of late.
    Moderator Response: [DB] I've been given worse.
  36. Clouds provide negative feedback
    40, RW1,
    "In AOGCMs, the water vapour feedback constitutes by far the strongest feedback..."
    Water vapor does not equal clouds. The two are very distinct and different. Water vapor involves a GHG effect which is stronger than that of CO2, and is listed in my feedbacks (as H2O).
    The bottom line is a lot of the enhanced warming comes from positive cloud feedback.
    Again, no, clouds come in a distant fourth, at best, behind H2O feedbacks (water vapor), CO2 feedbacks, and albedo feedbacks.
  37. Clouds provide negative feedback
    muoncounter (RE 44), " 'CO2 forcing is very gradual, taking decades and centuries.' Centuries? How do you know that?" Because it's claimed to take about 100 years to double CO2.
  38. CO2 effect is saturated
    novandilcosid @92, I will not dispute the claim that the majority of emissions to space in the range 630 to 710 cm^-1 come from the stratosphere. (I am not agreeing, I am just not disputing.) Certainly it comes from high enough that, as shown in 82 and 86 above, that increasing CO2 concentrations make no difference to the amount of radiation escaping from the troposphere at those wave numbers, which is all that is relevant to this discussion. But those same figures above clearly show that there is a substantial reduction in radiation to leaving the troposphere outside those that range, but between 500 and 850 cm^-1. While you ignore that substantial reduction, your theories are irrelevant. Therefore you need to either accept the values indicated above, in which case we can proceed, or you need to calculate the change in tropospheric radiation at those wave numbers for yourself and show the basis of your dispute with the scientists.
    Moderator Response: [DB] Fixed missing bold closing tag.
  39. CO2 effect is saturated
    novan, I believe I misread your original energy balance comment so you can disregard my subsequent post. I'm not sure what point you're trying to make with post 87 though. I would rather suggest you stick to the topic at hand (CO2 effect saturation and GHG physics) in order to keep your argument clear.
  40. More Carbon Dioxide is not necessarily good for plants.
    villabolo#173: "making deserts and other types of dry land grow." Dry land burns really well. "This is a situation of historic proportions," said Victoria Koenig, public information officer with the Texas Forest Service, in a phone interview with AccuWeather.com Tuesday. "The fuels are so dry. The winds are astronomical. The behavior of the winds is a perplexing situation. It's never been like this before."
  41. Clouds provide negative feedback
    (RE: my #2), "Clouds cover 2/3rds of the surface, so 341 W/m^2 x 0.67 = 228 W/m^2 average incident on the clouds. 79 W/m^2 divided by 228 W/m^2 = 0.34 average reflectivity of clouds. 1/3rd of the surface is cloudless, so 341 W/m^2 x 0.33 = 113 W/m^2 average incident on the cloudless surface. 23 W/m^2 divided by 113 W/m^2 = 0.20 average reflectivity of the cloudless surface. 0.34 - 0.20 = 0.14. 341 W/m^2 x 0.14 = 48 W/m^2 loss for each additional m^2 of cloud cover." There is slight error in this calculation, which I would like to correct for the record. The average reflectivity of clouds is actually about 0.35 (not 0.34), which corresponds to about 51 W/m^2 loss for each additional m^2 of cloud cover instead of 48 W/m^2, resulting in a net loss about 12 W/m^2 instead of 10 W/m^2.
  42. Announcing Shaping Tomorrow's World
    Looks interesting - as much as I find climate science to be fascinating (sometimes in a slow-moving-train-wreck way...), as an engineer I find solutions to the problems even more fascinating. I'll be bookmarking that for sure!
  43. More Carbon Dioxide is not necessarily good for plants.
    Gentlemen; this discussion has been beaten to death. I understand that my illustrations and video, which take up a large segment of my post, concern the productivity of plants under higher CO2 levels. However, it is not the most important issue in a world which would have as low as 500 ppm of CO2. The issue in point #5 is: "5. The worse problem, by far, is that increasing CO2 will increase temperatures throughout the Earth; making deserts and other types of dry land grow. While deserts increase in size, other eco-zones, whether tropical, forest or grassland will try to migrate towards the poles. However, soil conditions will not necessarily favor their growth even at optimum temperatures. This will seriously decrease the amount of land useful for agriculture." (Last sentence recently added.) Of course, we're quite aware of the counter-arguments, made on this thread, concerning "losers and winners". What we should be discussing is whether or not the losers will far exceed the winners. I offer two points in counter-rebuttal to the implicit assumption of this "losers and winners" argument, that the outcome would somehow balance each other. 1. How much land taken out of commission, or substantially reduced in growing ability, will there be by an increase in aridity. This compared to any theoretical increase in abundance in food crops. 2. I believe this has been mentioned before on this thread. What would be the effects of mass migrations and invasions of those lands with 'enhanced productivity' compared to any benefits to the 'blessed' lands or its inhabitants? In my opinion, this would be an effect equaling or, more likely surpassing, any actual benefits; let alone deficits. I will add an illustration to my desertification point for the purpose of emphasizing its importance. I'll also be adding another brief point concerning AGW caused human migration and invasion. In any case, it's time to switch subjects; PLEASE.
  44. More Carbon Dioxide is not necessarily good for plants.
    Wow John D, you still don't get it, do you? The whole *point* of this thread is to show that the impacts of future global warming go well beyond the simplistic "CO2 = more biomass" mantra spouted by the Denialists. No one that I know of here has questioned that, under the right circumstances, enriching the CO2 content of the atmosphere will lead to some increase in *total* plant biomass (not necessarily seed/fruit)-at least in the short to medium term. However, the thing you & your ilk still refuse to accept is that, outside of a controlled environment, an enriched CO2 atmosphere will have a number of negative effects on crop yields-from the impacts of pests & disease, to the impacts of global warming on the activity of Rubisco Activase, to the effects of changed hydrology (droughts & floods). The combined effects of these negatives will almost certainly be enough to offset the straight yield increases garnered from eCO2-especially after acclimation sets in. Now *yes*, maybe some of these negatives can be overcome through the development of new farming techniques-at least in the First World. Of course these measures won't come cheap, & will either send many farmers to the wall or significantly increase the cost of staple food items. Of course, the attitude of you & your ilk is that this is a perfectly good price to pay-so long as the interests of the fossil fuel industry aren't hurt. The rest of us, however, think that it would be much more cost-effective to *not* perform massive experiments on our atmosphere & climatic systems.
  45. A Flanner in the Works for Snow and Ice
    Ken Lambert @87, Just one last time: Taking the data on historical sea ice extent I listed the summer sea ice extent from 1979 to 2008 (the limit of the data). I then took the difference between the 1979 extent and that of each year, and used it to calculate the difference in summer incoming energy flux between that year and 1979. From this, I determined both the average over the period, and the cumulative total for the period, but by summing the values, and by multiplying the mean by 30. The results: Mean difference between 1979 and target year: 0.445 million km^2 Mean additional energy flux compared to 1979: 3.37*10^20 Joules cumulative additional energy flux compared to 1979: 1.01*10^22 Joules Mean additional energy flux for the 2004-2008 mean compared to to 1979: 1.39*10^21 Joules cumulative additional energy flux for the 2004-2008 mean compared to 1979: 6.97*10^21 Joules. Very clearly from your calculation, the value you determine in the quoted section of 87 is the cumulative additional energy in ice melt over the period 1979-2010. That is comparable to the cumulative additional energy flux compared to 1979, or 1.01*10^22 Joules. In contrast, the 1.51*10^21 Joule figure I calculated is comparable to the Mean additional energy flux for the 2004-2008 mean compared to to 1979, or 1.39*10^21 Joules. It differs slightly because it is calculated for an approximate average of the years 2006-2010 rather than 2004-2010, and also because it is compared to an approximate average of 1979-2003 (which has slightly more ice than 1979 itself). I do not know how I could possibly be clearer than I have been in this post. Therefore if you persist with the absurdity that the difference in energy flux over a season is the difference in energy flux over 32 years, there is no further basis for debate between us.
  46. Clouds provide negative feedback
    RW1#43: "CO2 forcing is very gradual, taking decades and centuries." Centuries? How do you know that? See the thread 40 Year Delay, which suggests that the thermal inertia of the oceans results in a lag to full warming from CO2 forcing on the order of 40 years.
  47. novandilcosid at 10:25 AM on 20 April 2011
    CO2 effect is saturated
    Tom Curtis wrote at #82: "It is odd that novan concentrates his discussion on the 650 wave number. It is well known that at that wave number, CO2 absorption is at its peak, and that as a result the majority of CO2 emissions to space at that wavenumber come from the stratosphere." Actually my calculations were not for the Wavenumber 670 region (indisputably stratospheric) but used the table values for wavenumber 650. [There are two ways to interpret this table, as it lists absorption rates through different gas depths at 50 wavenumber intervals. So either the table value is a spot measurement, or it is an average across the 50 wavenumber band centred on the tabled value. Either way it does not invalidate the conclusions.] I took a standard line and decremented it iteratively using the amplitude at each frequency as an attenuation factor, checking at each iteration for the total remaining power. In this way I was able to replicate the table absorptions at STP. I then had the number of iterations per atmcm of CO2. I then repeated the exercise at altitude, altering the shape of the absorption line (it gets peakier but narrower with altitude) to see what happens. I found that at wavenumber 650 (not 670) the emissions to space are mostly from the stratosphere. Emissions from the troposphere are not totally extinct but are only a small fraction of the spacebound photons in that band. We should not lose sight of the fact that over 10% of the atmosphere lies ABOVE the Tropopause (8% in the region 35N to 35S, 20% at higher latitudes). In the strong emission/absorption CO2 band from wavenumbers 625 to 725 most emissions are coming from above the Tropopause.
  48. novandilcosid at 10:02 AM on 20 April 2011
    CO2 effect is saturated
    e's claims at #90 above are erroneous. His second equation should read: Change in Back Radiation = Change in Surface Radiation + Change in Evaporation. The Surface Balance equation can be rewritten: Absorbed Solar = Net Surface radiation into the atmosphere + Net Surface Radiation through the window to space + Convection + Evaporated water (latent heat). Writing this in terms of change, and making the (only slightly wrong) assumptions that changes to Absorbed Solar, Conduction and Net Surface Radiation through the window to space are zero, then yes indeed Net Surface radiation into the atmosphere = -Evaporated water (latent heat). This is another way of saying two things: 1. The energy transported from the surface always equals the insolation. Unless the solar constant or the albedo change, the energy from the surface is a constant. 2. As the Greenhouse tightens we expect the back-radiation to increase at a greater rate than the surface radiation: the radiative balance between the atmosphere and the surface narrows. At a perfect greenhouse, the retransmission of energy from the GHGs would be from the first layer of molecules - no temperature difference, perfect black body so total balance. The relative increase in back radiation allows the surface temperature to rise. This rise increases the evaporation rate in such a way that the relative increase in back radiation balances the increased evaporation. Note that the heat transport into the atmosphere from the surface is approximately Conduction one fifth Net Radiation one fifth Evaporation three fifths If the temperature increases, evaporation goes up and net radiation goes down. The rate at which evaporation increases with temperature is in dispute - essentially it is unkown. Measurement suggests 5% per DegC. The modellers use 2.5% or less. Additionally relative humidity is often taken to be constant. Measurement suggests that this may be abrave assumption.
  49. Muller Misinformation #4: Time to Act
    "I think he's just inflating uncertainty in the style of Judith Curry." The uncertainty argument gets flipped on it's head, and in this instance especially. It is our uncertainty surrounding sensitivity and aerosols and UHI (which, I believe he is looking at differently than others) that make the statement about 'having time' so wrongheaded. His study is merely another thermometer, has no attribution modelling, AFAIK, and doesn't really speak to how each degree of temperature rise changes the planet, or each W/m2 of forcing changes the energy that drives the atmospheric systems or how heat effects the hydrological cycle, etc. Those are the realities that we will be dealing with, not numbers on a stick. Our policy time table will be set by real-life effects because policy is about real people, what we value, and how willing we are to put what we value at risk.
  50. Clouds provide negative feedback
    KR (RE: 35), "And don't forget the speed of change of anthropogenic forcings, primarily CO2. Which is changing faster than any of the other forcings, in fact faster than all the other forcings are changing combined." I don't see how this is so. Anthropogenic CO2 forcing is very gradual, taking decades and centuries. Water vapor and clouds act on time scales of hours to days.

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