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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 102401 to 102450:

  1. The human fingerprint in the seasons
    55 (Humanity Rules), I don't see what you see. I went through the review, and while there are frequent references to the terms "winter", "summer" and "season", they almost all have to do with data studied being limited to a particular season (e.g. MWP winters), not comparisons between the two. The only reference to a specific difference in the seasons has to do with stratospheric wind patterns, and even these were inferred from model runs, not observations. I find nothing at all in the review to support your claim. Alternately, the review also says this:
    ...many of these solar-climate associations also seemed highly improbable simply on the basis of quantitative energetic considerations.
    and
    Recent estimates suggest a radiative forcing drift associated with solar irradiance changes of 0.017 Wm-2 per decade (see section 2). In comparison, the current rate of increase in trace greenhouse gas radiative forcing is about 0.30 Wm-2 per decade (Hofmann et al., 2008).
    So I'm not sure how anyone could make any observations on seasonal impacts of solar variations when there haven't been any.
  2. Stratospheric Cooling and Tropospheric Warming
    Hi All, I've tried to post an image but again I am not successful. Could someone take care of this for me and then show me the exact code used for this image. I was going to ask the question "The ozone layer is not at the top of the stratosphere so how does heating of the ozone layer cause the temperature to be the highest at the top?" But then I saw this image which shows the temperature increasing and then decreasing as you go up through the statosphere. This is what I would expect. That said, how is the stratosphere defined. Apparently it is not simply simply defined by a negative lapse rate! Bob
    Moderator Response: Fixed. See the help on posting images; you need an html tag: img src= "url" width=no more than 500 inside the usual lt and gt brackets.
  3. Stratospheric Cooling and Tropospheric Warming
    Bob, I actually think that once you sort it out, you can come up with a simple explanation. A lot of the complications can still be removed. The difficulty with anything like this lies primarily in removing relatively inconsequential complications. The reader probably does not need to know that the stratosphere is heated through UV and ozone creation, or what "optical thickness" means (that is a very confusing, obscure term that is meaningful to people that are familiar with it, but requires a paragraph just to explain, and so distracts and confuses the reader). Terms like "adiabatic lapse rate" and the 15 micron issue are similarly confusing details which do not really add anything to the heart of the explanation. A lot of things can be left out. Figuring what to leave out is the key to any simple model created for explanatory purposes, as you well know (and despite what the "it's not realistic" crowd moronically screams). The only factor that you really need to incorporate with what you have already written, IMO, is that energy is transferred at the molecular level via collision or emission/absorption, and in varying proportions depending on the density of the atmosphere. The main point is simply that energy can be absorbed one way but then surrendered in another, so that at equilibrium the total-radiation-in need not equal total-radiation-out in a particular band. As a result, the CO2 in the troposphere is more likely to absorb IR in that narrow CO2 band, but then passes it on through collisions to the abundant, non-emitting O2/N2, raising temperatures and somewhat "blocking" that band of radiation. Alternately, the CO2 in the more rarefied stratosphere is more often excited by collisions with the more abundant O2/N2, and emits the gained energy through radiation before it can pass it on through another collision. So CO2 prevents energy from escaping from the troposphere into the stratosphere in the CO2-IR bandwidth, and CO2 actively cools the stratosphere by emitting energy in the CO2-IR bandwidth. The only question left to clarify is relative amounts of these mechanisms (i.e. how much does stratospheric emission contribute to cooling, versus tropospheric "blocking"). I suspect that the latter is minor, at least as far as its influence on stratospheric temperatures (but I don't know).
  4. Renewable Baseload Energy
    Here are some more interesting links of actual projects/studies/companies in the field how to make renewable more reliable. - The first IEEE smart grid symposium - German company "energymeteo" - Australian company CSIRO - virtual power plant - RWE & Siemens effort: review article on VPP - VPP, microgrids, energy hubs: overview (semester thesis by R. Bühler from ETH Zürich, CH) To me it looks like the concept behind distributed energy production and virtual combination to be able to work on centralized offering for customers is gaining more and more attention and is leaving the concept/theory phase, entering in the demonstration/piloting phase around the globe.
  5. The human fingerprint in the seasons
    Alexandre to quote from the review linked by HumanityRules:
    There have been suggestions that 20th century global and hemispheric mean surface temperature variations are correlated to longer-term solar variations. Advanced statistical detection and attribution methodologies confirm that solar forcing contributed to the increase in global temperatures in the early part of the century but for the latter part of the 20th century they consistently find that using realistic variations, solar forcing played only a minor role in global warming, in agreement with the practically constant mean solar forcing since 1980.
    The passing of time doesn't apper to help the "it's the sun" supporters.
  6. 2009-2010 winter saw record cold spells
    #11: "The image @10 is somewhat misleading" Indeed. This thread is about winter 2009-2010; the photo date puts it in winter 2010-2011.
  7. Philippe Chantreau at 03:04 AM on 5 December 2010
    A basic overview of Antarctic ice
    "Since it appears to be statistically insignificant." I don't know how one can look at the data and come to that conclusion. Whatever analysis this assertion is based on is in error. The decline of global sea ice is statistically significant.
  8. Positive feedback means runaway warming
    #24: "I worry that our "clathrate gun" and associated ice age relics might be cocked and loaded, so to speak. " It is, as with many other questions of climate change, a question of rate of change. Thus we do not know if the loaded gun has birdshot or a deer slug. Archer 2007 is an excellent summary of methane hydrate and their climate change potential. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth’s radiation budget equivalent to a factor of 10 increase in atmospheric CO2. ... Fortunately, most of the hydrate reservoir seems insolated from the climate of the Earth’s surface, so that any melting response will take place on time scales of millennia or longer. Acoustic images of real-time methane releases as in this example are dramatic evidence that such melting is indeed occurring, albeit in isolated places. As summer Arctic sea ice continues to dwindle in the coming few years, 'science experiments' such as this will no doubt become more frequent and widespread. In my days in the offshore O&G exploration, hydrates were a well-known drilling hazard; punch a hole in one and you cause it to go unstable very quickly. These guys are going looking for them. Combine that plan with another series of avoidable mistakes such as those leading to the BP disaster and you have given your loaded gun to a bunch of drunk teenagers. Here is a long, but quite thorough 2008 Scripps Institute video on the subject.
  9. The human fingerprint in the seasons
    HumanityRules the two warming trends are both real and shown in the figure above. It's not clear to me why you say that the solar forcing influence on winter temperatures contradicts that the influence is larger in summer.
  10. 2009-2010 winter saw record cold spells
    The image @10 is somewhat misleading; note the "snow" in the English channel, North Sea and Irish Sea. The area where I live appears to be covered in snow, but there was none. Clouding the issue perhaps ? (Ouch, sorry)
  11. Positive feedback means runaway warming
    Re: Leland Palmer (24) Recent evidence supporting the clathrate gun hypothesis exists:
    "Evidence that massive quantities of methane gas have been released from the sea floor during past ice ages has been reported. The discovery supports the hypothesis that huge releases of ocean methane contributed to the rapid warmings of the Earth that have ended past ice ages."
    As reported in Reporting Climate Science .Com Free copy of the study available here. I agree with Ned in that, to the level of understanding we have currently, the possibility of a methane clathrate/hydrate release sufficient to trigger a hydrogen sulfide release and/or leading to a Venus-style runaway situation is remote. What is disturbing, however, is that such a possibility even exists. More disturbing is that future conditions may not be a good analog for anything in the paleo record other than the PETM. Without being able to establish an upper bound to the risk, we may find out that we we didn't know was more relevant than what we did. That should be of concern to all, as this is an experiment to be run once only. The Yooper
  12. Renewable Baseload Energy
    #344 I think there are many posts here contrasting what you said. More important: this thread is not about nuclear in any way. The question raised is the baseload capability of renewables, not the ability of nuclear to reduce CO2. Please.
  13. Renewable Baseload Energy
    What this thread shows is the reluctance of people to address co2 emmissions with the tech that is available and proven. Nuclear should be being built in the US. It is not to any scale. While the rest of the worlds large economies are building nuclear, the US languishes in debate. The stupidity of doing nothing but arguing is enough to make a grown man moan and groan with frustration.
  14. Positive feedback means runaway warming
    Wow, thanks for the quick and thoughtful response. Any thoughtful person would be thankful to be wrong about such a scenario, of course. The fact that we are coming out of an ice age, and starting from a cooler starting point might not save us from such a scenario, though. Our methane hydrate deposits are in equilibrium at ice age temperatures. The speed at which we are introducing CO2 is absolutely unprecedented, so far as I know. Also, the forcing from fossil fuel use is entirely non-random, unlike most past naturally occurring events. So, our methane hydrates could be particularly susceptible to disruption, and have had no chance to gradually lose methane, and have it safely oxidized into CO2 and sequestered via the rock weathering cycle over many thousands of years. Yes, there were warmer periods in the past, but we may have gotten to those warmer periods in a safer manner, more gradually, allowing harmless oxidation of methane at reasonable rates. The permafrost decay positive feedback is a similar concern. If this permafrost loses its frozen plant matter to decay into CO2 and methane gradually, there is no problem. If the accumulated frozen plant matter from thousands of years of ice age conditions decays within a century, though, this might add to warming in an unprecedented manner. The yedoma and thermokarst of Siberia are a similar concern. These ice age accumulations of methane and methane hydrate could also be susceptible to anomalously rapid dissociation. The PETM is worrisome, but the event that really worries me is the End Permian. As you point out, the PETM was nasty, but the End Permian mass extinction was the big one, extinguishing on the order of 90 percent of species existing at that time. Direct intrusion of the Siberian Traps volcanism into methane hydrate deposits may have been necessary to cause that one, but we don't know this for sure, so far as I know. So, I worry that our "clathrate gun" and associated ice age relics might be cocked and loaded, so to speak. Some things that might save us, as you point out, are the logarithmic nature of the greenhouse effects from the various greenhouse gases, and the diminishing returns positive feedback phenomenon. Also in favor of stability are the endothermic nature of methane hydrate dissociation, and the Planck radiation feedback. One thing that really worries me is the unpredictable nature of positive feedback phenomena. I frankly doubt the ability of anyone to predict the outcome of such a complex interlocked series of positive and negative feedbacks. If anyone could do it, it would be someone like Hansen- and Hansen is worried, too. Another thing that worries me is that estimates of the total quantity of methane hydrates differ by at least an order of magnitude. The sun is a couple of percent hotter than it was during the PETM, but several percent hotter than during the End Permian, I think. If we take the End Permian event, and add in a more rapid triggering event, a buildup of ice age methane hydrates, and a sun that is five percent or so hotter, what do we end up with?
  15. The human fingerprint in the seasons
    HumanityRules #55 Very well spotted. All that's needed now is to find a solar variation that would justify quantitatively the observed recent warming. Any links on this one? OTOH, I think there's plenty of evidence about another known forcing that has risen during the last half a century.
  16. 2009-2010 winter saw record cold spells
    Check out the cool satellite shot of snow blanketing the UK (from Science Daily).
  17. Renewable Baseload Energy
    Here is a more balanced and fact-based overview i found about how renewables are seen in Australia regarding baseload in the Parliamentary Library of the parliament of Australia.
  18. Stratospheric Cooling and Tropospheric Warming
    Tom, But more energy is coming into the earth than leaving. This applies to both the ground and deep space. My prevous remark regarding a distinction here was gratuitous. If we stabilized CO2 levels, this would continue for a few decades. Bob
  19. Renewable Baseload Energy
    My position on nuclear has shifted more negative due to Peter Langs postings. I am still agnostic since I know other people who think it is a good idea. If Peter's arguments are the best nuclear can do it is not worth much. I find Peter's posts to be riddled with inaccuracy and I now presume anything he says is factually incorrect unless another poster supports him. This thread and the "what should we do about renewables" thread both essentially devolved into Peter insulting everyone else after he came on. It is too bad, they were both good threads before Peter came on.
  20. Positive feedback means runaway warming
    Leland Palmer writes: How likely is all of this? You've written that very coherently, and it's not by any stretch of the imagination a "crackpot" scenario. But I would say it's very unlikely, even under a BAU emissions scenario. Lord knows I'm no expert on the PETM, but achieving that kind of CO2 pulse would seem to require burning more fossil carbon than would be projected even under an extreme scenario. And my understanding of the benthic methane hydrate issue is that it's likely to kick in only very slowly (on a global scale, ignoring local exceptions). The PETM was certainly nasty, and we wouldn't want to subject ourselves to anything like it. But it didn't lead to the kind of Venusian runaway warming you describe, despite involving much higher temperatures than AGW is likely to produce (remember that in addition to the large magnitude of the warming, the PETM was starting from a warmer point). Yes, the sun is hotter now, but the PETM-Holocene difference in TSI isn't that large (a couple of percent?). Perhaps most importantly, there have been other periods in the past (not just the PETM) when the planet was much hotter than today (think crocodiles and azolla blooms in the Arctic) and no Venusian runaway occurred. On very long timescales (tens of millions of years), the earth has been gradually cooling. We're going to be unwinding that process by at least a couple of degrees C in a geologically very short time ... but I think the dangers more involve disruption of our agricultural system, expensive and painful impacts from sea level rise, and loss of biodiversity (esp via ocean acidification). I don't think the Venusian runaway is remotely likely unless our descendants tried really hard to bring it about. (E.g., massive production and release of CFCs). Again, though, paleoclimate isn't really my area of expertise, so this is just one person's amateur understanding.
  21. The human fingerprint in the seasons
    44 Albatross So fingerprint = correlation? Is that all? Wow. Anyway I managed to get side tracked onto solar variance. There's a huge review of it here. http://www.agci.org/dB/PDFs/10S1_LGray_SolarInfluencesCLimate.pdf There are numerous references to a link between solar variance and winter warming trends which seem to contradict "If global warming was driven by the sun, we should see summer warming faster than winter.". It looks like observational based correlations of solar cycle variance are better at identifying a winter warming trend than one in summer. There's plenty of interesting points in that review to get both sides of the argument excited.
  22. Ocean acidification isn't serious
    Chris Shaker @17 Please search for 'Iron Fertilization' in this paper to see that iron is well recognized as a limiting factor in plankton growth Well aware of that thanks. Sorry, but "iron fertilization" is one of those ill-considered "engineering" ideas: Can ocean iron fertilization mitigate ocean acidification? " Here, using a global ocean carbon cycle model, we performed idealized ocean iron fertilization simulations to place an upper bound on the effect of iron fertilization on atmospheric CO2 and ocean acidification. Under the IPCC A2 CO2 emission scenario, at year 2100 the model simulates an atmospheric CO2 concentration of 965 ppm with the mean surface ocean pH 0.44 units less than its pre-industrial value of 8.18. A globally sustained ocean iron fertilization could not diminish CO2 concentrations below 833 ppm or reduce the mean surface ocean pH change to less than 0.38 units. This maximum of 0.06 unit mitigation in surface pH change by the end of this century is achieved at the cost of storing more anthropogenic CO2 in the ocean interior, furthering acidifying the deepocean. If the amount of net carbon storage in the deep ocean by iron fertilization produces an equivalent amount of emission credits, ocean iron fertilization further acidifies the deep ocean without conferring any chemical benefit to the surface ocean"
  23. Ocean acidification isn't serious
    Chris Shaker, You have so many misconceptions about the topic, it's difficult to know where to start. The advanced version of Ocean Acidification should be out by years end and hopefully that clears up some of your confusion. Coral reefs - long term monitoring is showing a rise in bleaching events and coral death. Both acidification and ocean warming negatively impact coral reefs. Again, this is a topic for a later post but some reading: Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005 Worst coral death strikes at SE Asia - 19 October 2010 "Many reefs are dead or dying across the Indian Ocean and into the Coral Triangle following a bleaching event that extends from the Seychelles in the west to Sulawesi and the Philippines in the east and include reefs in Sri Lanka, Burma, Thailand, Malaysia, Singapore, and many sites in western and eastern Indonesia. “It is certainly the worst coral die-off we have seen since 1998. It may prove to be the worst such event known to science,” says Dr Andrew Baird of the ARC Centre of Excellence for Coral Reef Studies and James Cook Universities. “So far around 80 percent of Acropora colonies and 50 per cent of colonies from other species have died since the outbreak began in May this year.”
  24. Stratospheric Cooling and Tropospheric Warming
    Bob, my discussions have covered the steady state. However, I am also not sure how important a distinction that is in the stratosphere in that, not lying next to any oceans, and being a rarified gass, the time interval between perturbation and adjustment to steady state would be quite short.
  25. Ocean acidification isn't serious
    There is also a Wiki on Iron Fertilization of the Ocean http://en.wikipedia.org/wiki/Iron_fertilization "Perhaps the most dramatic support for Martin's hypothesis was seen in the aftermath of the 1991 eruption of Mount Pinatubo in the Philippines.[citation needed] Environmental scientist Andrew Watson analyzed global data from that eruption and calculated that it deposited approximately 40,000 tons of iron dust into the oceans worldwide. This single fertilization event generated an easily observed global decline in atmospheric CO2 and a parallel pulsed increase in oxygen levels.[7]" Chris Shaker
  26. Ocean acidification isn't serious
    Please search for 'Iron Fertilization' in this paper to see that iron is well recognized as a limiting factor in plankton growth. They are talking about using Iron to cause plankton blooms to sequester CO2 and drop it down to the ocean floor http://www.cephbase.org/refdb/pdf/8122.pdf That paper also seems to show that mortality rates for some sea creatures, such as mollusks, increase with CO2. Chris Shaker
  27. Ocean acidification isn't serious
    The paper I referenced, showing plankton growth limited by iron was from Nature "We conclude that Fe deficiency is limiting phytoplankton growth in these major-nutrient-rich waters." http://www.nature.com/nature/journal/v331/n6154/abs/331341a0.html Chris Shaker
  28. Ocean acidification isn't serious
    Your link to a nature article does not appear to work http://www.nature.com/nature/journal/v466/n7306/abs/nature09268.html%3Cbr%20/%3E Did you notice the paper I referenced, showing plankton growth limited by iron? Chris Shaker
  29. Ocean acidification isn't serious
    Rob Painting: Did you read the paper I referenced, showing increased biomass in coral with increased CO2? Did you read the paper I referenced, showing increased plankton growth with increased CO2? Are you offering me any peer reviewed papers proving the opposite? No. Chris Shaker
  30. Ocean acidification isn't serious
    This paper leads one to believe that it is not as simple as the AGW believers want us to believe You're arguing a strawman there. Changes in seawater chemistry are anything but simple. Would we not expect the ocean equivalents of plants to also grow more as the CO2 increases as well, providing more food for sea life? No. Decreased carbonate concentrations in seawater, combined with acidification and ocean stratification affect the long-term viability of phytoplankton populations. For example: Global phytoplankton decline over the past century "Here we combine available ocean transparency measurements and in situ chlorophyll observations to estimate the time dependence of phytoplankton biomass at local, regional and global scales since 1899. We observe declines in eight out of ten ocean regions, and estimate a global rate of decline of ~1% of the global median per year. Our analyses further reveal interannual to decadal phytoplankton fluctuations superimposed on long-term trends.
  31. Ocean acidification isn't serious
    This paper leads one to believe that it is not as simple as the AGW believers want us to believe. Increased CO2 does seem to decrease CO3 in the lab, which is considered a limiting factor for coral growth. But, it also increases photosynthesis output, and actual coral growth in terms of biomass does not seem to suffer, and actually increases in some studies http://www.isse.ucar.edu/staff/kleypas/docs/PUBS/kleypas_langdon_icrs_2000.pdf More information http://scienceandpublicpolicy.org/images/stories/papers/originals/coral_co2_warming.pdf Are they trying to measure coral growth the wrong way when they concentrate on calcium carbonate measurements? Would we not expect the ocean equivalents of plants to also grow more as the CO2 increases as well, providing more food for sea life? Yes, plankton growth will be stimulated by increased CO2 levels, as long as other limiting factors do not come into play http://epic.awi.de/Publications/Tor2008b.pdf Another paper I scanned said that parts of the ocean are deficient in iron, which limits plankton growth http://www.nature.com/nature/journal/v331/n6154/abs/331341a0.html Plankton and algae will increase productivity as CO2 levels increase in seawater, they die, raining down on the sea floor, sinking more CO2. Chris Shaker
  32. Stratospheric Cooling and Tropospheric Warming
    Bob Guercio at 07:45 I think Tom and Spaceman have covered your questions as well as i could have(truth is, most of my posts on this thread have been "trying" to convey the mechanisms alluded to by the radiative exchanges in that paper.) And the existence of the tropopause itself, is pretty convincing evidence that this is the main phenomena responsible for stratospheric cooling/energy loss.
  33. Stratospheric Cooling and Tropospheric Warming
    Tom, Just one more point. Do your discussions here cover the transient state, the steady state or both. We are in the transient state now because more energy is reaching the earth's surface than that which is leaving. Let's assume that we miraculously stabilized atmospheric CO2 concentration today. The temperature of the earth will continue to rise until the output energy from the earth equals the input energy. That would be the steady state. I'm not talking about energy coming in and out from beyond the thermosphere. I'm talking about the ground. I meant my blog to be strictly for the steady state. Bob
  34. A basic overview of Antarctic ice
    Albatross at 09:42 AM on 4 December, 2010 Hi Bill, "Umm, no. I'm afraid that you seem to have completely missed the point of that statistical analysis exercise. Anyhow, the graph @89 is the net result of all the changes/processes and it is showing a distinct downward trend in global sea ice since about 2001." I looked at your post #74 and did not see the test of statistical significance applied to global sea ice Albatross. Since it appears to be statistically insignificant it probably either is or very close to it.
  35. Stratospheric Cooling and Tropospheric Warming
    It occured to me to use Ramathan and Dickson, 1999 and the version of MODTRAN at David Archer's website to better characterize the relative importance of the two effects we are discussing. Using Modtran with a lookdown altitude of 10 km on the 1976 US Standard Atmosphere, I determined the difference in outgoing radiation between an atmosphere with 375 ppm and one with 750 ppm of CO2 at approximately 3.25 w/m^2. From Ramathan and Dickson, the IR absorption by CO2 + H2O in the stratosphere is 19 w/m^2, and IR emission in the stratosphere is roughly 35 w/m^2 (Table 3); a difference of 16 w/m^2. Doubling CO2 will double both absorption and emission, to a first approximation, giving values of 38w/m^2 and 70w/m^2, and a difference of 32 w/m^2; making the net difference if there were no change in radiation from the troposphere 16 w/m^2. Introducing that change, the reduction in IR absorption will not excede the reduction in outgoing IR from the troposphere, and so will not excede 3.5 w/m^2. Subtracting that value from the stratospheric absorption, and then doubling for the increased CO2 concentration yields a minimum absorption of 31 w/m^2, and a net difference for doubling CO2 of (at most) 23w/m^2. Therefore the maximum cooling introduced to the stratosphere by shielding the stratosphere at some frequencies of IR is about 7 w/m^2, compared to a 16 w/m^2 from simply doubling the CO2 in the stratosphere. For comparison, the cooling introduced by redusing stratospheric ozone by 30% is about 5 w/m^2, or about 3 w/m^2 once we allow for reduced IR emissions by O3. I must emphasise that these are ballpark figures. However, we can reasonably conclude that the cooling of the stratosphere because of reduced IR emissions in the 15 micron band has a similar cooling effect to that of ozone reduction, and that the cooling effect of doubling stratospheric CO2 is 2 to 4 times as strong as that. Two additional points. First, it is evident that the as CO2 concentrations increase, the relative importance to the thermodynamics of the stratosphere of Ozone will decrease. This is quite apart from any changes in ozone concentration induced by temperature changes (which may be quite significant). Second, an additional important effect on stratospheric temperatures is albedo variations, with higher albedo resulting in higher stratospheric temperatures. This is a dominating effect following major tropical volcanoes, but probably less significant than other factors discussed here at other times. Finally, thankyou for the offer, Bob, but no thanks. I would much rather you got Gavin to review your rewritten blog. An expert is somebody who knows how to avoid fundamental errors. In this field, Gavin is an expert and I am not. So no matter how sound my reasoning appears to me, it is always possible I am overlooking something completely obvious.
  36. Stratospheric Cooling and Tropospheric Warming
    I'm not sure whether Science of Doom's website has been referenced yet on this thread but there are two articles in particular there that people here may find useful. I certainly did. Stratospheric Cooling Tropospheric Basics
  37. Positive feedback means runaway warming
    This is a very interesting and informative article, and I thank the author for it. Respectfully, however, I think that readers might jump to a false or questionable conclusion reading this article, because CO2 is only a piece of the climate change problem. What Hansen envisions, I think, in his runaway climate change scenario is a series interlinked positive feedback effects which in total might be sufficient to tip the earth into runaway warming. He very specifically mentions destabilization of the methane hydrates as part of his runaway scenario, for example. I can't speak for Hansen, but what I worry about is the scenario below. Increases in fossil fuel produced CO2 cause warming, which activates the following positive feedback processes: The Arctic sea ice/ albedo feedback. The permafrost decay feedback. The forest wildfire feedback. The ocean CO2 release feedback. The destabilization and release of methane from the shallowest methane hydrates including the Siberian yedoma and thermokarst. Atmospheric increases in water vapor. The combined effect of all of these processes destabilizes the oceanic methane hydrate deposits starting with the shallowest ones first. Most methane from this release ends up dissolved in the sea water, and oxidized into CO2. Increasing amounts are able to vent directly to the atmosphere through sudden releases. Destabilization of the hydrates also results in associated deposits of natural gas venting directly into the atmosphere. Most of this takes place in the Arctic, while the Antarctic continues almost intact. Due to the fact we are coming out of an ice age, large inventories of methane hydrates are available. As methane releases accelerate, concentrations of the hydroxyl radical in the atmosphere plummet, leading to longer residence times for methane in the atmosphere before it is oxidized into CO2, and increased warming as a result. About this time, CO2 based warming is approaching a first plateau, as this article predicts, due to diminishing positive feedback returns and saturated absorption bands. So, we get maybe 10 degrees C of temperature increase due to maybe 3000 ppm of atmospheric CO2. But methane impact on global heating has its own diminishing returns curve, and that curve is in its steepest part. Water vapor concentrations continue to increase, and the diminishing returns curve of water vapor is also near its steepest point at this time. The diminishing returns curve of CO2 is at a plateau. When the diminishing returns curve of methane and water vapor plateau, the earth is perhaps another twenty degrees C warmer, on top of the ten degrees C caused by CO2 alone. At this point many inland lakes lose their water to the atmosphere. Evaporation is greatly increased, from the landmasses. About this time, the oceans have heated enough to release most of the methane from hydrates. The oceans become anoxic, and hydrogen sulfide starts to evolve from the oceans, killing most land organisms. The hydroxyl radical has been overwhelmed, and atmospheric oxidation times for methane have become hundreds of years. The oceans begin to boil, and transfer their water into the atmosphere. Soon, most of the water in the oceans has transferred to the atmosphere. As ground temperatures increase, carbonate begins to convert to CO2. Plate tectonics, driven by the temperature difference between the mantle and the surface slows and stops. So the rock weathering cycle and subduction of carbon containing sediments also stops. Eventually, with all of the water, CO2, and methane in the atmosphere, the earth becomes another Venus, but hotter at first because we still have all of our water, while Venus has lost its water due to light induced dissociation of water into hydrogen and oxygen, and loss of the hydrogen into space, as happened on Venus. How likely is all of this? Well mass extinction events such as the Paleocene-Eocene thermal maximum have apparently taken us part way down this path, according to isotope ratio records. And the sun is hotter, now.
  38. Renewable Baseload Energy
    @Peter: I concur with others, here. You are the one who started with personal attacks, by suggesting that anyone who was in favor of renewables was an idiot. Seriously, you are a *terrible* salesman for nuclear energy. You have likely done more harm than good to your own cause - that alone should be reason for you to pause and reflect on what's the best way to sell nuclear to a hesitant public (hint: it's not what you're doing right now).
  39. Stratospheric Cooling and Tropospheric Warming
    In any case, my hat is off to you for wading through it all! Thank you but not just yet. I'll go through it tomorrow and I will probably understand it. It's still a little fuzzy but I'm pretty confident that I will get it. It's good that I posted the blog that I did. How else would I have fleshed this problem out. I think that now I understand Gavin's email to me. I'll repeat it here and comment: mostly right. You miss two key facts. First, all GHGs emit as well as absorb, and whether you will get warming or cooling in a region depends on the ratio of the change in absorption and the change in emittence. Second, the troposphere has many IR absorbers, the stratosphere only two (CO2 and O3 - everything else is minor). So the impact of CO2 above the tropopause is amplified. Otherwise you are spot on! Gavin See the first part. That is Gavin's short version of everything you guys have said. And then his comment that I was "spot on". I was "spot on" with that one mechanism but there is so much more to it. Thanks again but I really don't expect this thread to end just now. There's just too much to it and I'm sure that half the world is reading it and wants to understand it also. In the field of amateur climatolgy, my guess is that this is one of the most difficult concepts to grasp. I would like to have another go at writing a more comprehensive and accurate blog on this which is needed on the Internet. However, credit where credit is due and you guys have to be included. Please email me to discuss it further. robertguercio@optonline.net
  40. Spaceman Spiff at 15:11 PM on 4 December 2010
    Stratospheric Cooling and Tropospheric Warming
    Bob Guercio -- Another point of clarification. The 15 micron spectral feature I have been referring to in previous posts is the *very central-most spike* shown in this figure of transition probability of CO2 (for a particular value in temperature and pressure). Most of the CO2 spectral feature that you see in Archer's upwelling radiation spectrum of Earth, and that has been under discussion throughout this post, lies in the 13.5-17 micron region of the transition probability figure.
  41. Spaceman Spiff at 14:57 PM on 4 December 2010
    Stratospheric Cooling and Tropospheric Warming
    Bob Guercio -- If there is anything more that you'd like me to clarify, please ask. You left a few questions for me, but I think Tom Curtis might have answered most of them. Similar to Tom, I would say that the initial explanation was significantly incomplete. At the same time I am still uncertain whether all the important pieces have yet been identified. In any case, my hat is off to you for wading through it all!
  42. Renewable Baseload Energy
    Peter Lang - "Address your comments first to the scaremongers and renewable energy zealots who continually make their personal attacks to defend their beliefs, then I may take some notice" Oof. Peter, I suggest you go take a good look in a mirror. Counting posts, the majority of personal attacks in this thread come from you. After 2-3 exchanges you started posting you have done nothing but insult everyone else here. Even when (as I have) some have agreed with aspects of your postings. You may have excellent points in some particulars. But arrogant, insulting, and overall horrid behavior guarantee your input will be ignored. Sometimes the messenger overrides the message - you are succeeding in that. I only hope you are aiming to be tuned out.
  43. actually thoughtful at 14:36 PM on 4 December 2010
    Renewable Baseload Energy
    Quokka - would you pay $50 per month to eliminate global warming?
  44. Stratospheric Cooling and Tropospheric Warming
    Bob @122, everywhere where I say "atmosphere" in comment 120, you can substitute "stratosphere". It is not that atmosphere is wrong, so much, as that stratosphere is more specific. "The same radiation enters the stratosphere so I guess this means that twice as much energy would be taken out of the IR radiation since there are twice as many CO2 molecules to absorb it. Correct?" Yes. "I must ask you the same question that I asked Space Spiff. Are you saying that my mechanism is wrong or that it is one of several mechanisms and may not even be the dominant mechanism?" Essentially correct. Rather than saying it "... is not even the dominant mechanism", I would rather say it is probably not the dominant mechanism (from my understanding). Further, I think it is important to be aware that the mechanism you describe is only a cooling mechanism because the stratosphere is warmer than the upper troposphere. It is like playing boiling water (100 degrees C) through a fire hose onto some object. Is it a warming or a coolinig mechanism? That depends critically on whether the object you are drenching is a block of ice or several tonnes of red hot steel! Your mechanism is like reducing the temperature in the water in the hose by 10 degrees C. That will reduce the rate at which ice being drenched would warm, and increase the rate at which the red hot steel, being drenched, would cool. But I am unsure that calling it a cooling mechanism is informative.
  45. Renewable Baseload Energy
    $10,000 Electric Car? If Tata can pull this off with the capabilities mentioned at anything like this price, I would rate this as very good news indeed. This is a very good example of why electricity prices need to be kept as low as possible - to encourage migration from fossil fuels. With electricity prices two or three times higher, the running cost advantage of EV would be significantly eroded.
  46. Renewable Baseload Energy
    Peter Lang writes: [...] the scaremongers and renewable energy zealots who continually make their personal attacks [...] The lack of self-awareness here is simply mind-boggling.
  47. Renewable Baseload Energy
    Here is the IPCC AR4 assessment of CO2 emissions by electricity generation source, which we must assume was prepared by means of a comprehensive survey of the available authoritative literature.
  48. Renewable Baseload Energy
    PL #335 "Yea. Yea Yea Blah, blah, blah. Address your comments first to the scaremongers and renewable energy zealots who continually make their personal attacks to defend their beliefs, then I may take some notice. Otherwise I see it as simply the bias of the leanings of those who inhabit this site." I'd be inclined to take you more seriously if you didn't 1. Make the kneejerk accusation that everyone automatically opposes all of your ideas is clearly ideologically flawed. 2. That you'd actually answer the reasonable questions asked of you rather than either ignoring them, or making the accusations as in (1) Assuming that you do have some expertise in this area (and I have serious reservations that you have failed to challenge your own assupmptions properly, but it does appear that you posess important background knowledge about a large proportion of this topic), then it would be nice to be able to make use of them to understand the area properly, but the issues above render this impossible.
  49. Stratospheric Cooling and Tropospheric Warming
    As I'm putting the pieces together, I'm starting to think that this is a terribly difficult thing to explain simply!
  50. Stratospheric Cooling and Tropospheric Warming
    Bob, I don't know if this helps, but you seem to be thinking of the interactions as entirely a radiative story. In fact, it is a radiative/colissional story. Instead of: UVin + IRin = IRout, we have: UVin + IRin + Collisionalin = IRout + Collisionalout. Understood. In the stratosphere, for O3, UVin >> IRout > IRin; so O3 is a net absorber of radiation, with the excess energy being distributed to other components of the atmosphere by collission. You say atmosphere but I think you mean stratosphere. Am I correct? If this is the case, I think I understand. With CO2, IRout >> IRin, with UVin being zero. The energy defecit is drawn from the surrounding atmosphere by collisions. Again, I think you mean stratosphere? If we simply doubled the CO2 in the stratosphere, leaving that in the troposphere untouched, then initially IRout and IRin would double. The same radiation enters the stratosphere so I guess this means that twice as much energy would be taken out of the IR radiation since there are twice as many CO2 molecules to absorb it. Correct? Because IRout is larger than IRin, that results in a net energy deficit which the CO2 draws from colisional energy, in the process cooling the surrounding atmosphere until a new steady state is reached. Understood. If we instead doubled the tropospheric CO2, leaving the stratospheric CO2 untouched, that would reduce IRin, again creating an imbalance restored by local cooling of the atmosphere. stratosphere? If we do the actually possible, and double CO2 at both levels of the atmosphere, both factors will come into play. However, I believe, the first has the larger effect. More importantly, the second is a cooling effect only because IRout larger than, or equal to IRin. If IRin >> IRout, as would be the case in the absence of O3, then doubling both IRin and IRout would have a significant warming effect, more than sufficient to compensate for the small reduction of IR radiation from the troposphere in the 15 micron band. I think I understand. I must ask you the same question that I asked Space Spiff. Are you saying that my mechanism is wrong or that it is one of several mechanisms and may not even be the dominant mechanism? I want to thank both of you guys for helping me understand a very complex process. As I said to Spaceman, my brain hurts but it hurts more now. Bob

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