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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 111051 to 111100:

  1. Is climate science settled? Especially the important parts?
    thingadonta wrote : "Climate scientists are not going to fool skeptics with this possible recent revival of an old-age trick-denying and using uncertainty in the Earth's climate and weather as a means to social control. A completely opposite way of looking at it (the skeptical one, by the way), is that you should actually never 'cast aside' one's 'doubt of climate science'; such is the road to ideology, blind faith, and false certainty as a means to social power and control. The Aztecs and Mayans discovered it, and now 21str century ‘scientists’ have discovered it (but not the sceptical ones)." These are very skewed comments(politically and scientifically), which reveal a lot more about you and your beliefs than about global warming itself. Politically, you seem to see "social power and control" as an inherent desire of scientists and others involved with research into global warming. Apart from the "skeptics", of course - whoever they might be and however you define them, beyond your belief that anyone who doesn't like or accept global warming must, by default, be a skeptic. That would seem to include everyone from Monckton to Lindzen, and every position from 'It's all a UN, secret government conspiracy' to 'The Greenhouse theory is false' to 'Maybe the effects won't be quite so serious as some suggest'. All skeptics/skeptical but few worthy of being taken seriously. With regards to the science, you have no answers or rebuttal and can only denigrate and belittle what you define as 'scientists', who are, again, all those apart from the "skeptical" ones you like. Again, they are undefined by you and so, presumably, run the gamut from Gerlich/Tscheuschner to Singer to Lindzen. They you would no doubt call scientists without the qualifying quote marks; the rest you smear by association. I find that reprehensible and snide but you are somehow allowed to make such assertions without ever backing up your beliefs. Shameful but very revealing of your motivations, beliefs and lack of serious credibility.
  2. How we know an ice age isn't just around the corner
    Anne-Marie Blackburn at 19:20 PM, I agree, CO2 don't drop for no reason. Just as the seasonal variation doesn't vary for no reason either. The nett global variation is greater than the total estimated human emissions, and when measured regionally the annual variations can be up to about 50ppm, but more often around 20ppm, well in excess of human emission levels, so the capacity to absorb higher levels is available if the right conditions are in place. These variations whilst large by comparison to the human emissions are small compared to the total land and ocean emissions which are about 27 times human emissions. Thus only a very small variation in the natural processes is required to make a significant difference to the nett gain or loss of CO2 from the atmosphere.
  3. Plain english rebuttal to 'Global warming isn't happening' argument
    Good post. I like the summary of the bullet points. It is too bad you have to summarize so much interesting data. In number 4 why is the stratosphere an exception? The stratosphere is a separate part of the atmosphere than the troposphere. The troposphere is predicted to warm and the stratosphere is predicted to cool. Both have been measured and are warming/cooling as predicted.
  4. How we know an ice age isn't just around the corner
    GC @ 48 - "I see plenty of evidence to suggest that CO2 is not a major climate driver." I gotta disagree GC, the link between CO2 and global temperature goes back a long way. The last 400,000 years. 650, 000 years. 800,000 years. However if yours is a version of the CO2 lags temperature argument, see here Why does CO2 lag temperature? And it's only a forcing this time around, not a feedback, because of human greenhouse gas emissions.
  5. Is climate science settled? Especially the important parts?
    Thingadonta @8 Jacob Bronowksi was very clear in his conclusions about human history in his infamous 'Ascent of Man' series and book; if history teaches us anything, its that humans should never be too sure of themselves. Ahh, the truth is out - Climate change deniers are not human ! Perhaps they are alien beings from a hot planet planning to invade us... :-)
  6. Sea level rise: the broader picture
    DW #70 Before we get into repetition please have a look at this topic from May this year: http://www.skepticalscience.com/news.php?p=2&t=78&&n=202 Note my posts #24, #30, #60, #67 - particularly #67 I came across Dr Trenberth's paper as a result of the Climategate 'travesty' emails, and have a passing familiarity with it since late 2009. If 'the missing heat' is way down deep it got there very quickly by an unknown process DW, so don't hold your breath waiting for it to burst forth.
  7. Is climate science settled? Especially the important parts?
    @thingadonta #8 To summarize your viewpoint: you can never be sure about anything. Indeed. You can never be sure that tomorrow the laws of thermodynamics will still apply or that the sun will still rise in the east. Indeed. And you cannot eliminate this uncertainty by doing irrational things like sacrificing people. Indeed. You then suggest that this is the same as what climate scientists try to do: to take away the uncertainty with irrational hocus-pocus. That’s where you’re wrong. No science is ever completely settled. Science strives to minimize the uncertainty but a 100% certainty is not achievable. Nevertheless, in the past this hasn’t stopped us from using the laws of thermodynamics to construct cars and power plants, using the laws of electromagnetism to build cellphones, using the laws of mechanics to launch space ships. I never heard anyone demanding that the science should be settled for a 100% before using this knowledge. If we had waited, we would still be living in caves. Using the knowledge you have to your best advantage (taking into account the uncertainty that still exists) is not irrational. It is the best we can do. We don’t know absolutely everything about climate science. We know enough to act. That’s the message climate scientists try to get across.
  8. The surprising result when you compare bad weather stations to good stations
    michael sweet @ 65 Scientists have nothing to lose if they present real data limiting adjustments only to what needs adjusting to ensure we're comparing apples with apples. I would feel far more comfortable with data showing wider divergence between well and poorly sited stations. I have no investment in the direction of the divergences. For example, if poorly sited stations in some (or even many) instances showed cooler trends (a counterintuitive result given the assumptions underpinning the surface stations project), I would happily accept this. I have no problem with all the data showing a warming trend. However, the data are so exquisitely consistent over extended periods as to seem improbable and thus implausible. Data measurement is never so utterly robust as to yield zero anomalies between a range of measurements over many years. I would liken the outcome to tossing and coin and finding it lands neither heads nor tails but stood vertically on its rim - an improbable but nevertheless possible outcome. As I've pointed out before, I may have misunderstood the derivation of the data set and if so would be very happy to stand corrected. Part of the problem lies with what I suspect is your assumption that I have raised the issue in order to push a sceptical agenda.
  9. How we know an ice age isn't just around the corner
    JohnD, You know what the natural processes are that remove CO2 from the atmosphere. You even commented on it. As the post makes clear, ocean uptake of CO2 has profound consequences of its own; natural processes are not necessarily benign. Nor is it guaranteed to continue as it has done in the past
  10. Is climate science settled? Especially the important parts?
    jbowers: you nailed the deniers position very well: the science isn't settled, unless it's their science.
  11. Anne-Marie Blackburn at 19:20 PM on 5 September 2010
    How we know an ice age isn't just around the corner
    johnd, you would need evidence that in the absence of human emissions of CO2 natural processes would be removing 2ppm CO2. Before the Industrial Revolution, the system was more or less at equilibrium - natural processes weren't removing more CO2 than they were emitting. They are now only removing half of the additional CO2 humans are emitting, i.e. the CO2 which has disrupted the equilibrium. So why would you think that CO2 would be removed at similar rate without human emissions? CO2 levels don't just drop for no reason - they are usually a feedback process.
  12. Quantifying the human contribution to global warming
    Chris Colose @ 21 - A Matter of Humidity Sherwood & Dessler 2009. "Thus, although there continues to be some uncertainty about its exact magnitude, the water vapor feedback is virtually certain to be strongly positive, with most evidence supporting a magnitude of 1.5 to 2.0 W/m2/K, sufficient to roughly double the warming that would otherwise occur. To date, observational records are too short to pin down the exact size of the water vapor feedback in response to long-term warming from anthropogenic greenhouse gases. However, it seems unlikely that the water vapor feedback in response to long-term warming would behave differently from that observed in response to shorter-time scale climate variations. There remain many uncertainties in our simulations of the climate, but evidence for the water vapor feedback—and the large future climate warming it implies—is now strong."
  13. Is climate science settled? Especially the important parts?
    Okay, see how the title says the science isn't settled, the plastic sceptics say the alarmists say it is settled, yet Monckton says it is settled as well... It's ironic. Maybe I should have been explicit about it, but I'd have thought my stating that I agree with MattJ would have helped you figure that one out. Try the link I posted to Citizen's Challenge.
  14. Is climate science settled? Especially the important parts?
    J Bowers I hope you are being fectitious, quoting Monckton. If not, are you questioning the validity of science agreed on by 97% of climate scientists and virtually every major scientific organization in the world, and then offering Monckton as proof they are all wrong? You must be kidding. I'm sure a journalist with no science background, who claims to have invented cures for all kinds of diseases, and who tells you the earth is cooling and then tells you, the warming is due to something other than greenhouse gases, and then tells you not to worry because global warming will be benficial, is a better source than all those scientists.
  15. New presentation debunking Monckton's critique of IPCC predictions
    Roy Latham @ 7 - "The trend for the last century is around the lower bound of the IPCC predictions." Doesn't make sense. The IPCC hasn't been around for a century.
  16. Climate change: Water vapor makes for a wet argument
    scaddenp at 14:39 PM, Phil, it is not really a critical path chart which would show the sequence of events, such a chart probably doesn't exist such is the complexity of the processes. However the question this chart immediately raises is that as evaporation requires an input of energy, how can IR radiation provide this. The chart shows a value of 390 for surface radiation and 324 for back radiation. Clearly there is a nett deficit of about 66 where an excess would required if energy was to be put into the evaporation process. From the chart it appears the process relies on incoming solar energy to provide the energy that not only drives the evaporation and other consumers of energy but to make up the nett loss in IR radiation. IR radiation can only enter the system after solar radiation has already transferred it's energy to the surface including the water that covers 2/3 of the surface. Immediately the solar radiation ceases, the losses of IR increase rapidly leaving even less energy to contribute to evaporation, even if there was excess available in the first place.
  17. New presentation debunking Monckton's critique of IPCC predictions
    The refutation of Monckton is, in essence, that the range of IPCC predictions is so broad as to include global warming so slight as to pose no serious problem, all the way to predictions that global warming is a dire problem. So when one wants to validate the IPCC one takes the data as being within the lower bound -- that global warming is not a problem -- validation. However, when one argues that global warming is a serious problem, one takes the midpoint or higher of the predictions. The trend for the last century is around the lower bound of the IPCC predictions. Skeptics argue that the relatively low rate of warming that started after the Little Ice Age was the trend likely to continue. That is denounced by crisis advocates as too low, but it is now supported as being within the range of model predictions. The refutation of Monckton asserts that nothing much can be said from seven years of data or even fifteen years. Why is that? Crisis advocates say that there is no solar activity going on, no ocean cycles, no paucity of volcanic activity -- that there is nothing to presently account for climate change other than CO2. Skeptics claim, by contrast, that climate is complex, with CO2 being one of many factors, and without all the factors being well modeled. Predictions that just about anything could happen supports the skeptics, not climate crisis.
  18. How we know an ice age isn't just around the corner
    scaddenp at 14:25 PM, I am looking for some explanation as to why it would not be so. Only about half of the current emissions are estimated to remain in the atmosphere, so the other half are being absorbed by natural processes which indicates that those processes are not that slow. In addition the seasonal fluctuations indicate that the capacity to absorb extra CO2 are in excess of the total anthropogenic emissions and further indicates that natural processes may have the capability of being a number of times faster.
  19. Climate change: Water vapor makes for a wet argument
    Johnd, firstly, forget clouds etc - you MEASURE the radiation coming from the atmosphere (not the sun), that is warming the sea. However you slice the cake, you have more radiation warming the sea with GHG than without them. And for equal windspeed, waves etc. warmer water will result in more evaporation than cooler water. The chart which shows all the energy interactions from from Trenberth & Kiehl. Latent heat etc. that you keep asking about. I would recommend the Science of Doom series Earth Energy Budget for the gory detail.
  20. How we know an ice age isn't just around the corner
    Re: Joe Blog (46) and GC (47) "Full-blown glaciation with high GHG level" A more robust discussion of this issue can be found here. The post, reader comments and the NOTES section give valuable insights on this. The Yooper
  21. How we know an ice age isn't just around the corner
    JohnD - are you under the impression that CO2 would be dropping by the amount it currently sequesters of current emissions even we were werent emitting? Net CO2 losses from natural processes is extremely slow and obviously completely overwhelmed by human emissions as CO2 is rising.
  22. Is climate science settled? Especially the important parts?
    Thingadonta, there is a qualitative difference between science and the "exploitation of uncertainties" you describe, and for once I'd like to see you actually admit that you're capable of learning (being a skeptic is pointless otherwise). It would make many here much more willing to be patient with you. In addition to what James Wight has said, understand that science--unlike any of the other practices you mentioned--is completely open about what it doesn't know. That is, in fact, the opposite of those historical 'exploitations'. The rich and powerful sought (and still seek) to control what is known and unknown by hiding their uncertainty behind a convenient "truth." Once truth is claimed, science has stopped. But you keep looking for certainty. I suggest you find a church, because you won't get it in science. You will, however, get people who are willing to act on a certain level of probability. There is a high probability that AGW is occurring. That probability, according to the people who have dedicated their lives to studying climate (and who definitely wish they were wrong, for a number of reasons), is much higher than any other scenario for the near future. Given the evidence, and looking at the math, I agree. Certainty in science doesn't mean the discovery of absolute truth; it means reaching the point of willingness to act. With climate change, I'm there. With C-section vs. natural birth for twins, I'm still not sure, and I only have a few months to figure it out and may not even then, but I'll be forced to act. Something tells me that even if we get 10 C warming in the next 20 years, you'll still be like, "It has to be something else. Couldn't possibly be AGW." I've asked this of others: what would be convincing evidence of AGW? What would it look like to you? Btw, you do manage to actually act, don't you? Even in the midst of the storm of uncertainty and doubt that is your life?
  23. Quantifying the human contribution to global warming
    Eric, this is a good question, and a lot of popular accounts of the water vapor feedback get this wrong. I'm trying to work on more posts on feedbacks on my own site and possibly for guest contributions to others to clarify such matters. First of all, C-C only provides an upper bound on the water vapor content in a given parcel of air at some temperature. It is therefore reasonable to assume that if the vapor pressure reaches or exceeds the saturation vapor pressure, you will get condensation. However, C-C does not, in itself, tell you how water vapor will change as the climate warms. Secondly, just because warmer air has a greater capacity to "hold" more water vapor, it is not at all self-evident that it will. It is like saying that a larger bucket will hold more water than a small one, neglecting how leaky either one of them is. However, if relative humidity (the percentage of vapor the air is actually holding relative to saturation) stays roughly constant, then the C-C relation is a great starting point for describing the fractional change in vapor content per unit warming (and like CO2, it's the fractional change rather than the absolute change which is important for the radiative transfer). And to the extent relative humidity is conserved in the large scale, as wasexpected going back to at least Manabe and Wetherald in the '60's water vapor must provide a strong positive feedback. There are solid energetic constraints for why relative humidity should remain roughly conserved in the lower atmosphere, but these arguments do not hold a lot of weight in the upper free atmosphere, and it is higher up where air is cold and where water vapor has the strongest contribution to feedback (the lower level air is more important though for precipitation responses). There are several physically plausible mechanisms for getting a negative water vapor feedback. The Held and Soden (2000) review paper on water vapor feedback provides some examples. Before the IRIS cloud hypothesis, Lindzen's idea in the early 1990's was that the mean detrainment altitude of deep convection will be both higher and cooler in a warmer climate. The water vapor deposited into the free atmosphere depends on the saturation vapor pressure at the temperature of cloud detrainment, and so this would in principle lead to less vapor left behind at higher altitudes. There is not really a theoretical basis (as far as I know) as to why this should be wrong, but like IRIS, there was really no supporting evidence for this. Many observational-based approaches and more sophisticated GCM's have evolved, and responses to ENSO, Pinatubo, and satellite observations show that models are pretty much getting things right. The Dessler and Sherwood paper in Science last year describes the evidence rather well. Furthermore, the developed thinking now is that the water vapor feedback is controlled by the large-scale dynamics and the saturation specific humidity in the outflow regions of tropical deep convective systems, and is not particularly sensitive to the detailed microphysics (e.g., Sherwood and Meyer 2006).
  24. How we know an ice age isn't just around the corner
    Anne-Marie Blackburn (#40), I was nodding in agreement with your post until the end. I quote: "On top of that, we're seeing a rise in global temperatures when natural factors should be leading to a slight cooling. This strongly suggests that greenhouse gases are overwhelming the impact of other factors." CO2 concentrations in the atmosphere are rising and will continue to do so unless the burning of fossils fuels is sharply reduced. I think we are in agreement on this. I suspect that we also agree that the Earth has been warming since 1850 (it is so important to choose the right start date). When it comes to attributing how much of the recent warming results from CO2 concentrations and how much from other causes, we may disagree. I see plenty of evidence to suggest that CO2 is not a major climate driver. If you do not share my opinion I look forward to hearing your views.
  25. Is climate science settled? Especially the important parts?
    Thingadonta You say " Most of the history of the world has been about exploiting uncertainties for power". Like the oil companies / corporates regarding climate change for example?
  26. How we know an ice age isn't just around the corner
    Joe Blog (#46), Thanks for your comment. Let's hope that somebody will take the trouble to enlighten us.
  27. Is climate science settled? Especially the important parts?
    jdsykes, the burden of proof is always on the proponent, not the skeptic. However, the proponents of AGW have well and truly met the burden of proof; otherwise the scientific community would not be convinced. Some of the evidence that convinced scientists is discussed here and here. thingadonta, did you actually read my post? I wrote: “Science comes to tentative conclusions based on the balance of evidence. The more independent lines of evidence are found to support a scientific theory, the closer it is likely to be to the truth.” This is very different to the way that religions arrive at conclusions. Religious “truth” is based on authority and revelation and myths, whereas AGW is based on scientific evidence. Religious dogma is usually asserted to be absolutely certain, regardless of what empirical evidence might say. Scientific conclusions are not dogmatic; for example, the IPCC acknowledges there is a possibility that global warming is not anthropogenic. AGW is not a religion.
  28. Urban Heat Islands: serious problem or holiday destination for skeptics?
    BP #37 Actually I've revised my opinion somewhat here. Your failure to do the basic statistical tests to assess the validity of your regression is either an example of incompetence (i.e. you don't know how to do it and you won't admit it), or that you are afraid that doing the correct tests will show that your model is not valid (or that you have done this, and do not want to show the results), in which case it's not an example of incompetence, but of scientific fraud. Strong words, and I know that superficially it seems counter to the site's comments policy. However, this is in response to a clearly inadequate analysis of data presented on this site. BP's only options are to allow these charges to go unchallenged and thus demonstrate that one of the above is true, do the F test and correlation test himself and publish it here, and/or to release his raw data to allow someone who knows how to do it to do it for him.
  29. Quantifying the human contribution to global warming
    How does the C-C relation govern upper tropospheric water vapor? Isn't is governed by convection, cloud formation and other local factors? It seems like we are presupposing that the local variations are all somehow averaged out and the C-C relation holds on average. But it only holds for some (possibly changing) percentage of the upper troposphere and in the rest there is greater and lesser water vapor depending on local conditions.
  30. Is climate science settled? Especially the important parts?
    I live with uncertainty routinely, and so do you. I pay my insurance, I do up my seatbelt, I wear sunscreen, I had children, I buy garden plants. I do not understand these problems with certainty and / or uncertainty. We are living beings surrounded by other living things as well as lots of other people. This is all uncertain, and crossing the road is risky - but I manage this by obeying road rules and keeping my eyes open, as I'm sure you do. My "doubt" about climate science is the same as most people's. Don't know the size or the direction of the uncertainties. But not knowing the timing or the extent of possible storm damage to my house doesn't stop me from paying the insurance premium.
  31. How we know an ice age isn't just around the corner
    gallopingcamel at 15:32 Well for the earth to go into a full blown glaciation with a high GHG level, would mean it must be through increased albedo reducing SW, through which ever mechanism(from the hypothesis you stated, to greatly increased particulates from volcanism, or impact, biological? etc) One of those interesting questions we may never be able to answer with full confidence. But i for one dont know ;-)
  32. Climate change: Water vapor makes for a wet argument
    scaddenp at 08:56 AM, forgetting about clouds for a moment that also trap IR radiation over about 2/3rds of the earths surface, water also covers about 2/3rds of the earths surface. Thus one would expect that if longwave radiation is a factor of any significance in increasing evaporation than perhaps 2/3rds of that radiation is a result of the initial absorption of solar shortwave radiation by the water suggesting that for at least 2/3rd of any IR driven evaporation it is a case of the water heating itself by the heat already dissipated. Perhaps if could provide a critical path chart or flow chart that would assist in conveying how this circular flow of energy all fits into place.
  33. Is climate science settled? Especially the important parts?
    "Just because some details are still not well understood should not cast into doubt our understanding of the big picture: humans are causing global warming." One can look at this from another angle-the skeptical one (since this site is supposed to be about skepticism). Most of the history of the world has been about exploiting uncertainties for power. Nations go to war based on it. Religions and ideologies arise from the fear of it, and totalitarian regimes attempt to wipe it from the face of the earth. Exploiting uncertanties in climate is nothing new to the 20-21st centuries. Most of the ancient religions stumbled on the idea that you can exploit the fear and uncertainties regarding projected climate/weather (floods, droughts etc) for power. Why do you think humans were ever sacrified to a Sun God?. It is essentially about replacing uncertainty of future climate with a false certainty about future climate, whilst at the same time eliminating dissent -either real dissedents or simply 'potential' dissedents- by a formalised ritual tradition. Sound too extreme? Thousands of people per year were sacrificed in Central and South America (notably-in areas prone to climate swings and El Nino-La Nina) to serve a political structure based on fear and uncertainty surrounding climate. Spanish conquistadors found 100's of thousands of skulls sacrificed simply for the sake of exploiting fear of climate and climate projections, and to eliminate dissent, and doubt, of a political system built on false climate certainties. In the common case of sacrificing young female virgins, this also served the purposes of male patriarchy, but it was ultimately and largely for reasons of personal and class-based power. Nothing more. Climate scientists are not going to fool skeptics with this possible recent revival of an old-age trick-denying and using uncertainty in the Earth's climate and weather as a means to social control. A completely opposite way of looking at it (the skeptical one, by the way), is that you should actually never 'cast aside' one's 'doubt of climate science'; such is the road to ideology, blind faith, and false certainty as a means to social power and control. The Aztecs and Mayans discovered it, and now 21str century ‘scientists’ have discovered it (but not the sceptical ones). If you think this view is extreme, take a look at human history, or ask anyone who has actually ived under a totalitarian regime. They don’t take their scepticism lightly. Jacob Bronowksi was very clear in his conclusions about human history in his infamous 'Ascent of Man' series and book; if history teaches us anything, its that humans should never be too sure of themselves.
  34. How we know an ice age isn't just around the corner
    Anne-Marie Blackburn at 08:22 AM, you are missing the distinction, natural processes are removing half of the estimated anthropogenic emissions so it can't be said that one is overwhelming the other, each is only winning half the battle. It could be argued that CO2 levels would be falling by 2ppm each year in the absence of any anthropogenic emissions, so the 4ppm added annually is equally overwhelmed if a term such as overwhelmed is to be used at all. The nett global gain in CO2 concentration is less than the range in nett global seasonal fluctuation, and in turn the seasonal fluctuation in various regions in both hemispheres indicate values many times that of the annual emissions. This indicates that under normal seasonal conditions regionally there is a large capacity for natural processes to sequester many times more CO2 than what is being currently emitted. Thus understanding what drives those natural processes is vitally important especially given such natural processes also release about 30 times the CO2 into the atmosphere to that of anthropogenic emissions. If the processes are driven primarily by external factors related perhaps to solar emissions that may indicate what measures can be taken as counter measures. However if the processes are driven by other human related factors then perhaps action may be more effectively directed there. Given the relative magnitude of natural processes versus fossil fuel related emissions, a very little change in the natural processes, whether releasing or absorbing, whether driven by natural forces or by human action, would have perhaps greater impact than the huge change necessary to reduce emissions. At the end of the day it may be that if temperatures that rise as a result of increased emissions, the seasonal growth that already has a significant influence on the annual nett gain may accelerate to balance the emissions with overall nett positive benefits. However unfortunately the current understanding of all the processes involved is far from complete but studies that at least compare plant growth under deprived, ambient and enriched conditions are continually extending the current understanding of at least one aspect of the natural processes.
  35. The surprising result when you compare bad weather stations to good stations
    Chriscanaris, So you say that because all the data indicates a rise in temperature that suggests to you that there is a problem? Maybe the temperature was carefully recorded for years at many places and the result is real!! The uniformity of the data suggests to me that it is a robust result. The scientists lose either way. If there were problems with the data you would claim we should ignore it because of the problems. When the data is consistent you complain it cannot be trusted because it is too uniform. Heads you win tails I lose!!! What would you be happy with?
  36. Urban Heat Islands: serious problem or holiday destination for skeptics?
    BP: Since you claim that the UHI is proportional to population, the temperature trends in rural areas in the US where population has declined should show a decline in temperature. Many rural areas in the US have population declines over the past thirty years. Show three that show declines in their temperature trends. Urban and rural stations show the SAME trend in temperature increase. This shows that the temperature is increasing. Your claim for a logarithmic increase for population change made without any mechanism or data is simply an unsupported claim. You need to get some valid data or stop wasting our time. Your claims have become more and more shrill recently, while your data has declined in quality. Consider if you want to continue on this path.
  37. Quantifying the human contribution to global warming
    There's been some interesting questions and a few off-target remarks here, which touch on several topics. Hopefully I can provide some focus below. The radiative forcing for a change in CO2 is highly dependent on the the temperature structure of the atmosphere, cloud cover, and water vapor. You can boil down the physics to a simple statement about forcing going like the logarithm of concentration, but this cannot be derived (or the 5.35 W/m2 coefficient) without spectrally resolved calculations. This is in part because the other gases/clouds "steal" some of the radiation that would otherwise. In fact, the power of a specific greenhouse gas is maximized when it is acting by itself and does not need to compete with the spectral overlap by other constituents. This is discussed in an in press paper by Schmidt et al 2010 which attempts to partition the total greenhouse effect by contribution to individual gases, and I discuss it here. What's more, the logarithmic dependence breaks down under situations not too far from modern-day Earth-like conditions, such as at the very high CO2 concentrations thought to exist at the termination of a snowball planet. To touch on RSVP's point in 9, he is correct that there is still some uncertainty in the forcing for a doubling of CO2 (The central value is 3.7 W/m2, though with a range of about +/- 0.3 W/m2, see Forster and Taylor, 2006 depending on method used) but becomes much larger for different atmospheres (like past Mars or early Earth). The vertical temperature profile is also relevant because the greenhouse effect requires some sort of lapse rate to allow colder atmosphere aloft to radiate to space at a temperature colder than the surface. Even though the concentration of CO2 is pretty uniform over the globe, the forcing does have some variation over the planet due to changed tropopause location and lapse rate effects. The solar radiation of course does matter for the greenhouse effect to be relevant at all (and even the shortwave absorption by water vapor and CO2 is not completely zero, though much smaller than the longwave part). If the Earth had no incoming sunlight, the greenhouse effect would not support any temperature higher than the 'cosmic background' temperature, although it would take the planet a bit longer to cool off to that point than a planet where you turned off the sun and had no atmosphere at all. This is obviously quite removed from reality though and Dima is correct that the small variations in solar radiation do not matter for the CO2 greenhouse effect. In fact, the true no-feedback sensitivity parameter (in the article, 0.27 K/(W/m2))is also dependent on the finite absorption of the atmosphere, and so becomes more on the order of about 0.3 to 0.31 K/(W/m2). This so-called Planck feedback response is pretty robust across various models; see for example Table 1 in Soden and Held, 2006 [PDF]). This table gives an estimate of the magnitude of the Planck feedback amongst various models (you need to take one divided by these numbers to be consistent with my units). Water vapor acts to enhance this sensitivity by making a plot of the outgoing longwave radiation vs. temperature more linear than the T^4 dependence that a blackbody has. This enhances the sensitivty by a factor of about two, to the extent that the upper tropospheric moisture content scales with the Clausius-Clapeyron relation. To humanity rules (#11), the vapor content should go up nearly exponential with T, but the absorptivity goes up nearly like the logarithm (though not as nicely as CO2, and some have argued more of a square root dependence), so the feedback of water vapor as T increases should be somewhat linear. See my article on feedbacks here for more. Also keep in mind that the typical sensitivity-forcing equations in this article apply only at equilibrium and the timescale to reach equilibrium depends on the climate sensitivity, so the "heating in the pipeline" becomes larger as sensitivity increases. To HumanityRules (#11 regarding the natural oscillations)-- I don't think anyone argues that the polar regions are highly variable and exhibit significant amounts of influence from ocean circulation. In particular, windiness and advection is a large part for estimating year to year 'minimum' in sea ice extent, but the preconditioning of ice loss (not just extent but thickness) is clearly due to albedo feedback which is in part related to rising temperatures, and these temperatures are rising almost everywhere on the globe, it's not a redistribution, so this is a signature of external forcing. Just from the abstract, the Chylek paper uses detrended data to see a see-saw effect, so it's unclear to me how you can make statements about the trend from this (but I have not looked at the whole paper and cannot for some time), but the abstract itself says that natural variability in the Arctic as well as the trend are both at play here. Finally, the canonical 2 to 4.5 C estimate of equilibrium temperature change per doubling of CO2 (and the feedback parameter lambda itself) does encompass water vapor feedbacks but also the other effects (lapse rate, clouds, ice-albedo) required to get the full range.
  38. Climate change: Water vapor makes for a wet argument
    johnd - heating the water to cause evaporation can be done by short-wave AND long wave. That is why radiation from GHGs matter. I am perfectly ready to accept that without solar radiation coming in then you dont get any IR going out. The point is that the GHG re-radiate outgoing IR back to the surface causing more warming of the water. A careful statement of your alternative theory would be appreciated.
  39. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    I think it is....NOAA intensity-or-frequency
  40. Is climate science settled? Especially the important parts?
    One interesting resource on the "when did we know CO2 was bad" topic is the 1965 report to US President Johnson. The appendix that refers to CO2 is: http://bit.ly/dvbtRN (That's a link to a PDF in a public folder in my DropBox account.)
  41. Anne-Marie Blackburn at 08:22 AM on 5 September 2010
    How we know an ice age isn't just around the corner
    johnd, I said that greenhouse gases were overwhelming the impact of other factors, which in context meant that their warming impact was greater than the cooling impact expected from other, natural factors. With regards to natural processes, I don't agree with you. If natural processes were overwhelming CO2 emissions, we'd see no increase or even a decrease in CO2 levels. But CO2 levels are rising, which means CO2 emissions from human activities are overwhelming the ability of natural processes to remove this additional CO2.
  42. How we know an ice age isn't just around the corner
    Anne-Marie Blackburn at 07:55 AM, yes, the alternative scenario is no anthropogenic emissions. Only then could a baseline be established for where natural processes would be heading. At the moment natural processes sequester about half of anthropogenic emissions so it is not valid to claim that the emissions are overwhelming the natural processes, as they, the natural processes are equally overwhelming the anthropogenic emissions.
  43. Anne-Marie Blackburn at 07:55 AM on 5 September 2010
    How we know an ice age isn't just around the corner
    johnd, I'm not sure I understand your point - what is the alternative scenario in this case? I have pointed out in my original post that natural factors would in all likelihood have led to global cooling, though the overall forcing would probably not have been strong enough to cause a new glacial period. Isn't this the alternative scenario you mention? Also I should mention that this is the basic explanation for this rebuttal - you can read a more detailed explanation here.
  44. Empirically observed fingerprints of anthropogenic global warming
    Dana, Good job. This is a nice and useful post in general, though I would be careful (for this and future posts that Skeptical Science does) not to oversell some of these points and equate ‘consistency’ with a ‘fingerprint.’ Consistencies do not always lead to any explanatory or predictive power, and this could very well be the case with the simulations of the time evolution of global mean temperature anomalies. The solid agreement between model simulations of temperature change (e.g., the Meehl graph) and observations is curious given the strong uncertainties in radiative forcing which ranges from ~0.6 to 2.4 W/m2) (see AR4 Figure 2.20), feedbacks, ocean heat content uptake, and the model ensemble members themselves (e.g., Schwartz et al 2007 Nature commentary; Knutti 2008, GRL). Indeed, the models probably do not sample the full range of uncertainty which is in part owing to the neglect of aerosol indirect effects or possible anti-correlations across the models between forcing and sensitivity, and more detailed inclusion of aerosol physics could very well lead to inconsistencies in model-observations. This should not be surprising or problematic, since formal attribution is about spatio-temporal patterns rather than the agreement in model-observation time series of temperature change. This can be done even after subtracting off the global mean temperature anomaly or ‘tuning’ the amplitudes of a perturbation (since we don’t know the sensitivity). For instance, we would generally expect the response to a volcanic eruption to occur after the eruption. In space, we might expect the response to short-lived aerosols to be focused over areas with large changes in sulphate emissions. These patterns should be pretty robust because they are very strongly constrained by the basic characteristics of the forcings and the climate system. As another example, the increase in downward infrared radiation to the surface is not necessarily unique to increased greenhouse gases, nor is it necessarily inevitable that more CO2 should directly make the atmosphere a better emitter to the surface. This would be the case if the boundary layer was moist enough to already radiate close to a black body at its temperature, which is nearly the case in the tropics. The CO2 still makes it warmer by reducing the outgoing flow of radiation and the increased temperature of the troposphere increases all the energy fluxes into the surface (the sun could do this too), not just the radiative fluxes. Water vapor really complicates getting a clean CO2 spectrum of downwelling radiation, and the best place to do this would probably be a clear night in the Antarctic winter, but this is not too relevant to the enhanced greenhouse effect anyway. I don’t see how Philipona et al (2004) really understood this at the time. Chris
  45. Is climate science settled? Especially the important parts?
    Colorado Bob at 00:23 AM on 5 September, 2010 Thanks for that link. The various GRACE estimates of mass loss are known to disagree (sometimes by significant factors) due to the relatively short time series, and this paper looking at GIA correction is actually in line with other recent GPS based work. However all trend estimates show unquestionable significant mass loss and acceleration of loss. Better absolute estimates of this loss are important for the sea level budget, but do not change the mean sea level rise measurements.
  46. Carbon dioxide equivalents
    Daniel Bailey at 06:27 AM, I also appeal to the moderators to allow reply to posts that have previously introduced a line of discussion and have been allowed to remain. I made a general response regarding how logging permanently removes large amounts of essential nutrients thereby depleting the nutrient reservoir within the soil. You made mention of the "remnants of the once mighty forests that stood here (the stumps of which measure up to 8 feet across)" which you indicated as being having been logged out. Mighty forests cannot grow without the nutrients firstly being available in the soil, there is only so much that can be absorbed out of thin air. If you could estimate the quality and quantity of timber that was removed from the forests, it would be easy to arrive at a reasonable estimate of what amount of nutrients the soil had available originally, but not once the timber was removed, thereby allowing some comparison of soil nutritional levels before and after.
    Moderator Response: Please instead post your comment on a relevant thread, and on this thread post a comment saying you have replied over there, with a link to your specific comment. You can get the link to your comment by right clicking on its date-time stamp and choosing the resulting menu item Copy Link Location.
  47. How we know an ice age isn't just around the corner
    Anne-Marie Blackburn at 20:32 PM, given that about half the anthropogenic carbon emitted is sequestered by natural means it can also be claimed natural processes are as equally influential in determining the nett result. As to which is prevailing can only be judged by considering what the situation would be without the anthropogenic emissions. Would natural processes have continued to reduce CO2 levels leading to global cooling? Making an case supporting one scenario is biased unless the alternative is recognised and quantified.
  48. It's the sun
    thanks, after reading up on it and starting to understand the basics im pretty much sold on the CO2 and greenhouse gas as the prime candidates.. only problem is, it seems so many people want to blame it on something that wont hit their profit margins, not to mention all the media and blog sensationalism pushing the general consensun to the point of denial. Anyhow, thank you very much for taking the time to reply to my posts. I also found this link to be a source of great information : http://www.metoffice.gov.uk/climatechange/ However I cant help but feel that a very real problem is being used as an excuse to keep energy company shareholders happy - charge more for less - after all... its saving the world lol
  49. Hurricanes And Climate Change: Boy Is This Science Not Settled!
    @Berényi Péter: Why are you drawing a linear trend line on your graphs? They clearly do not represent linear processes. One could argue for a multi-decadal signal in your 25-year averaging, and probably in your 10-year averaging. On what basis did you choose your averaging periods? If you want to do something interesting, integrate your data over each solar cycle and express the results in terms of energy released. BTW, what does "Annual Sum of Saffir-Simpson Category" mean? For 2004 there were 9 hurricanes in the Atlantic giving an annual sum of Saffir-Simpson categories of 27, well above the range of your scale.
  50. Carbon dioxide equivalents
    A plea to our moderator and John Cook for forbearance, in that we are straying perilously off-topic on this thread. But a claim was made that I feel needs to be justified with a source: Re: johnd (19)
    "The soils would not always have been poor, especially if it could grow giant trees... good soil can suddenly become poor soil."
    What source do you reference that shows the soils in Northern Michigan and Wisconsin were ever good? Soils in this area not under cultivation already tend to have 1-12" of acidic loess overlaying either sand dunes or bedrock. Shorter growing seasons relative to warmer, more southerly climes have meant narrow, more densely packed tree growth rings than is typically found. As a result, the forests here take a long time to achieve maximal height and spread of canopy. Compare this to soils farther south in Ohio, Indiana and Illinois, where loessal drift is often measured in thousands of feet. Coupled with a warmer, longer growing season, forests there achieve greater heights and canopy spreads yielding much greater boardfeet yields when harvested. Even hardwoods. Unless you have more direct experience in the soil types and forests of this area than I, please cite your sources which offer testimony different from what my own direct, personal lifelong experience shows? Michigan background info the same for Wisconsin Not trying to be argumentative here. But this is really not a subject I'm willing to debate, nor is this a proper venue for anything other than science-based discussions and sharing of learnings. So please, share the learnings. The Yooper
    Moderator Response: It's better to post a comment on a relevant thread and then on this thread post a link to that comment.

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