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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 75351 to 75400:

  1. Climate Denial Video #6: Past climate change
    Ok, I will try and stay away from any epistemological statements. I am curious though and from what I can gather, you are saying that the physics of a GHG MUST always result in warming, but there could be counter scenarios that will itself counteract the resulting warming. Am I on point?
    Moderator Response: [Dikran Marsupial] It is unhelpful to discuss scientific issues in absolute terms (e.g. MUST, certain, always) as if someone is being ultra-pedantic it introduces the opportunity for evasion of the substantive topics via quibbling. Thus I wouldn't say that GHG MUST always result in warming, but I would say that there is no credible evidence or physical theory to suggest that GHGs wont always result in warming. This is mostly because the theories that suggest strong negative feedback and hence low climate sensitivity are generally unable to explain paleoclimatic events (unlike theories that suggest climate sensitivities considered plausible by mainstream scientific opinion).
  2. Climate Denial Video #6: Past climate change
    Hmm...so no amount of negative feedback will alter this result? [epistemological digression snipped]
    Moderator Response: [Dikran Marsupial] No, of course not, however climatology is based on physics, if someone wants to claim that negative feedback will prevent CO2 from causing warming then (i) they need to provide physics that support negative feedback of that magnitude (ii) be able to explain events from paleoclimate that pretty much rule out that degree of negative feedback.

    No more discussion of epistemology on this thread; it is unnecessary for a discussion of the science at the level appropriate for a forum of this nature. You need to understand the science before epistemological issues are worth discussing.
  3. Santer et al. Catch Christy Exaggerating
    Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature.
    I've heard this number a number of times, but never managed to track down a source. So recently I tried working it out for myself, learning the statistics from some of Tamino's old posts on ARMA and autocorrelation, as well as Lucia, Science of Doom and Kelly's climate charts and graphs. The standard deviation of the residual noise in the HADCRUT record after fitting a linear trend (1975-2010 as Tamino or 1913-1944 as per Lucia) is a little over 0.1C. Several different methods seem to give estimates of the effective number of parameters as ~1/6 of the number of months. So the standard error on the OLS trend needs scaling up by ~2.5x. So, having made that correction, how many years of data do you need for 2σβ to be less than 0.017C/yr? About 11, on average. (And using the same method I agree with Phil Jones that warming since 1995 becomes significant only when you include the 2010 data, so I don't think I'm doing anything badly wrong.) So I'm itching to find out what Santer has done. Am I asking the wrong question? Should I be looking at the number of years required for the trend to be statistically significant more that 95% of the time? 95% significance 95% of the time? It would be nice to never have to answer another 11 year trend again. But - it's AGU paywalled. Sigh.
  4. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    You can also add the condition, I think, that the proportion of cloud condensation nuclei produced by Galactic cosmic rays is significantly greater than from other sources.
  5. Antarctica is gaining ice
    The idea that ozone depletion is responsible for the increase in Antarctic sea ice had a cold bucket of water thrown on it. See Has the ozone hole contributed to increased Antarctic sea ice extent? Sigmond & Fyfe, 2011.
    In this study we consider the impact of stratospheric ozone depletion on Antarctic sea ice extent using a climate model forced with observed stratospheric ozone depletion from 1979 to 2005. Contrary to expectations, our model simulates a year‐round decrease in Antarctic sea ice due to stratospheric ozone depletion.
    "Circulation changes, in part due to ozone depletion, are responsible for the increase in Antarctic sea ice," would seem more correct.
  6. Climate Denial Video #6: Past climate change
    Btw, inserting thermal inertia and lag feedback is not neutral. If these can be accounted for in a climate models for long time spans, you can certainly take them out. Ok, so we dont, or can't know, for a 1 year time frame. How about 5 years, 10 or 50? Is it possible to find a quantified relationship between the CO2 ppmv and temperature. I am trying to determine if a designated amount of CO2 directly correlates to a rise in temperature and can be expressed as a truth value. Think of the syllogism below. 1) Humans increase CO2 levels in the atmosphere. 2) Increased CO2 levels raise global temperatures. 3) Therefore, humans contribute to global warming. If there is a direct relationship to CO2 and temperature this syllogism would be valid. If this can be falsified, then the syllogism will not hold, or the correlation between CO2 and temperature MAY not be a truth value.
    Moderator Response: [Dikran Marsupial] The direct effect of CO2 radiative forcing on equilibrium temperatures is about 1 degree C per doubling. This is not contested, even by skeptic scientists such as Pat Michaels and Roy Spencer. This there is a direct relationship between CO2 and temperature and it is directly falsifiable. Thus the syllogism is valid. Poppers' theory of falsification does not require that the falsification should be possible within a particular timescale, so equilibrium sensitivity is perfectly adequate for "scientific acceptability"; please lets not have yet another thread devolve into pointless irrelevant epistemological discussions.
  7. CO2 is just a trace gas
    Paulie200, I posted the link merely to point out that IR reaches the sky. Your post didn't give the proportion of photons absorbed in the minimal path that you calculated (I assume it's close to zero) or the proportion absorbed over 17 km. I don't know if it is small or large, but the IR satellite (typically inverted color) implies it is on the large side if the earth shows up as black. Sorry that I implied your calculation was wrong, but I was wondering about the significance of the shortest path calculation.
  8. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Agnostic, et. al., The following paper shows recent data correlating the different cloud clusters with temperature. While the paper may be a difficult read for some, it shows the warming effect of cirrus clouds, and the cooling effect of low-level clouds. The discussion and conclusion are easier for the non-expert to understand. http://www.atmos-chem-phys.org/10/6435/2010/acp-10-6435-2010.pdf One should note that this paper was an attempt to correlate clouds with temperature increase only. Other factors influencing clouds were not examined, and acknowledgement that they could exceed the temperature influence. I hope this answers your question, and I fully understand that some people are trying to prove a large positive or negative cloud feedback.
  9. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    The fact that 2010 tied 2005 for the warmest year on record despite the deepest solar minimum in more than a century should put a rather sizeable dent in Svensmarks theory.
  10. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    To add to CBDunkerson's comment at #20, Jonathon and Agnostic should remember that the climate skeptics wish to show a significant negative feedback through clouds. They want such a feedback so that the observed positive feedbacks (ice-albedo, water vapour etc) won't drive us to a large warming through CO2. That way, they can accept the radiative physics without accepting CO2 driving significant warming. Unfortunately, palaeoclimate already tells us that the response of the Earth is a net positive feedback (e.g. Knutti and Hegerl 2008), most likely around 3C per doubling CO2. Palaeoclimate already includes clouds (obviously), so significant negative cloud feedback is a bit of a non-starter from the off! To pinch the quote Albatross used (which Camburn still hasn't responded to): "Why would anthropogenic CO2 now be the first forcing that doesn’t engage net positive feedbacks?" Dr. John Nielsen-Gammon
  11. Other planets are warming
    Isn't there a much simpler way to rebut this argument. All these other planets are devoid of life , looking at the Solar System should remind us that the 'goldilocks zone' where life is possible is very narrow. Comparing dead planets to the Earth is less than persuasive because these other planets have incredibly hostile environments. Also isnt this argument a (logical)fallacy ? 'Correlation is not causation' springs to mind
  12. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Jonathan#19: "clouds remain the largest uncertainty in climate science." Maybe so. But this is no longer uncertain: In 41 years of cosmic ray data, only 35 possible events of CR decrease -> less clouds -> short term warming were observed. Fewer than one event per year. If the GCR crowd expects anyone to buy in to this mechanism, is that all there is to show? It would be interesting to compile a timetable of when even these few events occurred and see just how much global warming (or is it cooling?) is due to these ephemera. Or is it chimera? A fitting question to pose to the keeper of the uncertainty monster.
  13. IPCC is alarmist
    lancelot, so far as I can tell the "climate tipping point" quotation is the wording of the people who wrote the Wikipedia article rather than Pachauri or Hansen. It is not shown in quotation marks in the article, and does not appear in the link cited as the source. Thus, if you are accusing the IPCC of "crying wolf" with the 'tipping point' comment... it didn't come from either of the two scientists you are apparently conflating (improperly IMO) with the IPCC reports. Also note that there ought to be a difference between the carefully reviewed work of thousands of scientists from around the world in the IPCC reports and things Rajendra Pachauri happened to say off the cuff. You accuse the IPCC of losing credibility for promoting a target limit of 350 ppm... but that target does not appear in the IPCC reports. I also note that you give absolutely NO reason for believing that Hansen's 350 ppm limit is 'wrong'. You just take that as a given and then fault the IPCC for "crying wolf"... even though they didn't.
  14. Dikran Marsupial at 21:24 PM on 13 September 2011
    IPCC is alarmist
    lancelot It is dissapointing that so soon after writing that replies should be "objective rather than emotive" you are already using emotive rhetorical terms, such as suggesting the IPCC are apparently "'crying wolf'", when in fact they are doing no such thing and the confusion lies at your end, as I have already pointed out. Passing 350ppm DOES NOT imply that we should have already observed the tipping point to which the quote alludes. The quote refers to a stabilisation value for carbon dioxide, it refers to a long term objective, and hence the dangers it seeks to avoid are likewise long term. Not observing those tipping points on passing 385ppm does not mean that the danger has passed and the tipping point wont happen because of action we have already taken (unless we do something about it - such as stabilise at 350ppm). If you truly are in the position where you must "make financial decisions on allocation of public resources" then you are under an obligation to either understand the science more fully, or obtain trustworthy expert opinion. If you are going to accuse the IPCC of "crying wolf" based on a misunderstanding of the science then it is not surprising that you have a difficulty on your hands as you are dismissing the trustworthy experts without developing a basic understanding of the science.
  15. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Agnostic, essentially your point about clouds having both positive and negative feedback effects amounts to a fifth requirement for the list in the article above... it would have to be shown that the hypothetical (i.e. contrary to actual observations) decrease in cloud cover was having a significant net warming effect... which, again, is not consistent with the results of previous studies. Basically, requirements 1, 2, 4, and (newly stated) 5 for GCRs to be causing global warming are all contradicted by the available evidence. Items 3.2 and 3.3 are uncertain. However, given that ALL of these things would have to be true for the 'GCR induced warming' hypothesis to hold up... it already doesn't. The details of cloud formation and climate impacts are extremely complicated issues which will likely take decades of further study to work out to a high degree of accuracy... which is likely why 'skeptics' keep coming back to this issue; 'You cannot prove every detail of how clouds interact with the climate... therefor they could be causing the observed warming'. The first part of that statement is true, but the second is false. We don't know how gravity works either... but we can measure its effects closely enough to put bounds on its behavior. Ditto for GCRs and clouds. We can determine the possible range of their impact on the climate from observations and thus rule them out as a significant factor even without knowing all the details.
  16. IPCC is alarmist
    Adelady hello - I did give the full quote. You gave part of it. You omitted: '350 ppmv is a 'Safe upper limit... in order to avoid a "climate tipping point" There is no additional qualification to that statement such as give by dana1981. The consensus view here seems to be that there is no misquote. If that is correct, it worries me. 350 as a 'stable state' level is indeed very ambitious. In view of the ongoing rate of development in China, India and the rest of the developing world, it is also, I think, totally unrealistic. We are heading for at least 450 ppmv, possibly 500 ppmv. To get back to a stable level of 350 will take a very, very long time. And I am yet to be convinced that it is necessary. But my main point is that by apparently 'crying wolf' too often, the IPCC loses public credibility.
  17. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Agnostic, While both effects will result from increased cloud cover, the general thought is that more sunlight will be blocked, leading to cooling. Data indicates that cloud cover was less during the 1990s, correlating with the increasing temperatures. The types of clouds also play a role; higher, cirrus clouds are very ineffective reflecters of sunlight, but will block escaping radiation from Earth. Conversely, low cloud cover blocks more sunlight from reaching the Earth's surface. Large, thunderclouds move heat via convection from the Earth's surface up through the troposphere. The final word has not been reached regarding the full effects of cloud cover. Some scientists maintain that the effects are local, and insignificant globally. Others claim that the increased temperatures led to the observed decrease in cloud cover. Still others, like Svensmark, claim that the decreased cloud cover was responsible for the rising temperatures. For these reasons, clouds remain the largest uncertainty in climate science.
  18. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Agnostic it depends on the type of clouds. Very crudely, low level cumuliform (convective) clouds tend to result in cooling while thin stratiform clouds in warming. You're right that GCR would result in cooling only if they increase low level clouds.
  19. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Arkadiusz Semczyszak "Even if the GCR cause significant changes in cloud cover or GCR has other influences on climate - they are small or very small. It's true. " This is, I think, is the central point, a small but not very significant influence of the sun has been detected in the last 60 years. Whatever may be found on the capability of GCR to nucleate aerosols, let alone cloud condensation nuclei, we may safely conclude empirically that the effect must be small. The microphysics of clouds is a very interesting topic well worth studying. I'm sure it will contribute to our understanding of the climate in general and of clouds and precipitations in particular. What we can already say, though, is that it will not change significantly our current views on AGW.
  20. Climate Communication: Making Science Heard and Understood
    Great work! The question I always ask myself when thinking about science communication is this: "Who are your target audience?" I guess in your case there isn't a single answer. The audience is highly segmented, and different segments presumably require very different communication strategies. Do you have a model of your target audiences, with strategies to communicate to them? Do you have suggestions on how lay people can help out? FWIW what I'm doing at the moment is as follows: - I engage primarily in incidental discussion on forums primarily devoted to other topics, such as religion or board games. News forums are too hot for me. Maybe they are too hot for effective communication in general. - I try and respond to attacks on the science as if they were genuine interested queries - naively overlooking attacks and just picking one or two technical points to talk about. - I try to think of my audience not as the person I am responding to, but as the lurker reading the thread. Having the last word or winning points are irrelevent. Being perceived as the more reasoned and better informed party is much more effective. So far, that seems to be working better for me. No doubt different strategies work for other people. In particular, humour is a powerful tool and allows you to be far more direct, but it's not my forte.
  21. Dikran Marsupial at 19:27 PM on 13 September 2011
    There is no consensus
    Dana69 wrote: "It is necessary for me to see and examine the arguments of both sides of the fence, and I then make up my own mind, based on these arguments." well quite, that is what we should all do. Have you read the IPCC WG1 report (or at least used it to check whether claims are true)? However Dana69 then wrote: "I am pretty sure that current climate models underestimate the role of the sun in climate variability and overestimate the role of greenhouse gases and aerosols." I suspect that you have not done enough reading to have a balanced view on this one. Please go to "Its the sun" and give a list of the sources for and against on which you base your opinion and then give an explanation of why you think the models do not sufficiently account for the role of the sun. I will happily discuss this with you if you can show that you have followed the procedure you have set out in the first quote. As for Rip van Scientist, he wouldn't defend any position until he had had a chance to get up to date with the science (fortunately the IPCC has produced a report which sets out the mainstream scientific position, the NIPCC have similarly produced a report setting out the contrarian view). He (being a scientist) would then base his arguments on the science. The importance of a concensus is not of any relevance to the scientists, who are capable of grasping the scientific arguments. Its importance is for the rest of us who can't accurately weigh the scientific arguments becase we don't have the necessary background. Then like seeking second (and third, and fourth and ... n-1th and nth) opinons for a medical problem, the fact that a strong majority recommend a particular course of treatment is a fairly reliable indication that it would be a wise course of action. Good science generates broad (but never complete) concensus, not the other way round.
  22. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Does an increase in cloud cover result in global cooling by blocking sunlight from reaching the earth’s surface, or global warming by reflecting more infra red radiation back to the earths surface? Surely that conundrum needs to be definitively settled before we argue the merits of claims about cosmic rays on cloud formation?
  23. Climate Denial Video #6: Past climate change
    One year is almost a no-feedback scenario, barely enough time to get water vapour operating. On that basis, I guess, with 0.3 per doubling, then you would need 3 doublings for 1 degree rise. Of course, 10 years after that... Timeframe matters because of both thermal inertia and lag in feedback response which have time range from few years to hundreds of years. (eg the albedo feedback from melting ice is limited by physics of melting).
  24. Mythic Reasoning about Climate Uncertainty
    Muoncounter @71, Re the Cury and Webster paper-- WTH? This is now what "skeptics" are peddling as science? I agree with SkyWatcher, another epic fail for Curry-- I thought her "Italian flag" analogy was so bad that it would be impossible to beat, now we have a "monster" analogy, I was wrong. I tried to read the paper, but I couldn't, just too bad. Very sad that such a poor paper is appearing in a respected journal like BAMS.
  25. Just Deserts: Winning the 2011 Eureka Prize
    Bill @39 Well how about that. I stand corrected. You learn something new every day.
  26. Mythic Reasoning about Climate Uncertainty
    #71: Curry's resorting to hand-waving and wild speculation I see. Has she never read a real science paper? Quantifying uncertainty is a crucial step in presenting results, while failing to quantify uncertainty is the hallmark of a variety of recent failed skeptic papers, such as Spencer and Braswell. Epic fail from the Curry.
  27. There is no consensus
    ... or does Rip Van Physicist (assuming his 40-year coma has not had too many ill effects) actually go and read some of the key papers and get to grips with the overwhelming nature of the evidence, rather than basing it on somebody else's survey-based opinion? I'm also interested to hear where solar activity has been underestimated and CO2 been overestimated.
  28. There is no consensus
    Dana69, Being skeptical is certainly the right approach, but giving equal weight to all arguments is not. You will find that there is a very clear correct answer to almost every issue in climate science, no matter how much doubt certain people attempt to sow. A lot of people will lead you astray with seemingly sensible but incomplete analyses (such as your chemist friend's discussion of how CO2 warms the atmosphere). To begin with you will very quickly learn that (a) it absolutely is not the sun and (b) there is absolutely no question that the rise in CO2 is 100% the result of human activity, and the majority of it is from burning fossil fuels. I would also point out that argument from authority itself is not a fallacy. The fallacy occurs when the authority is not qualified in the area in question, or when the point is expected to be taken as 100% true because of the authority's position. But it is perfectly valid and common to use the position of an actual, qualified authority when one is not and cannot become completely educated in a matter themselves. As with much of science, very little is ever taken as 100% true, but much like the consensus discussed on this thread, for all intents and purposes the probability of truth must govern reason. It's simply not logical to say "it seems almost certain that what I'm doing will kill me, but it's not 100% certain, so I'm going to go ahead and ignore the risks." BTW, did you ever see the response I posted on this comment on the CO2 trace gas thread to your chemist friend's mistakes concerning the ability of greenhouse gases to warm the atmosphere?
  29. Climate Denial Video #6: Past climate change
    All things being neutral, 1 year time frame.
    Moderator Response: [Dikran Marsupial] A one year time frame is not very sensible in a discussion of climate. The thermal inertia of the oceans means that a very large change in forcing would be required for an immediate (one year) change of global temperatures of one degree, which would result in a truly catastrophic change in equilibrium temperature once all the warming had been realised. As a result I doubt anyone has performed a model run or calculation that gives a direct answer to the question. I'd be mildy interested in the answer though if anyone has.
  30. Mythic Reasoning about Climate Uncertainty
    Gag. The uncertainty monster is in press. Our fearless mythologist addresses the following important issues: Monster hiding. Uncertainty hiding or the “never admit error” strategy can be motivated by a political agenda or because of fear that uncertain science will be judged as poor science by the outside world. Apart from the ethical issues of monster hiding, the monster may be too big to hide and uncertainty hiding enrages the monster. And I thought that was the hallmark of the deniersphere. Monster exorcism. The uncertainty monster exorcist focuses on reducing the uncertainty through advocating for more research. This is as opposed to those scientists advocating less research. Monster simplification. Monster simplifiers attempt to transform the monster by subjectively quantifying and simplifying the assessment of uncertainty. Monster simplification is formalized in the IPCC AR3 and AR4 by guidelines for characterizing uncertainty in a consensus approach consisting of expert judgment. We get it, consensus = bad. When we hear that 9 out of 10 doctors agree, it must be that one brave holdout, Dr. Nick, who is correct. After all, he's got a degree. Did no one write a real paper for this month's Bulletin?
    Response:

    [DB] As you point out, this guy would have been a worthy candidate, had he been real.

  31. There is no consensus
    dana69#437: "a physicist that has been in a coma for the last 40 years." I suspect there are a few of those around. However, the flip side of your question is equally valid. Does Rip Van Physicist side with the dissenting 3%? Or does he infer that there must be an enormous weight of evidence behind the opinions of the 97%?
  32. Climate Denial Video #6: Past climate change
    Dana 69 - Q"How much CO2 ppmv is needed to raise global temperature 1 degree Celsius?" A. Less than humans have emitted so far. Since the Industrial Revolution the Earth has warmed 0.8°C, but we are already committed to a further 0.6°C because of 'warming in the pipeline' - primarily the lagged response of ocean warming. In fact some land areas of the Earth are already committed to extreme warm temperatures because of the CO2 humans have released through fossil fuel burning. (coincidentally I'm writing up a blog post on this very point)
  33. There is no consensus
    Dana69 - based on the questions you are asking, sitting down with the IPCC AR4 would be a good first step. Know what the published science is and then take it from there. I'm looking forward to you presenting evidence for science underestimating the sun. Perhaps you should look at Benestad & Schmidt 2009 found.
  34. There is no consensus
    SO it seems fair to say that there are arguments for both sides of the equation. To be sure about my skepticism: It is necessary for me to see and examine the arguments of both sides of the fence, and I then make up my own mind, based on these arguments. I am pretty sure that current climate models underestimate the role of the sun in climate variability and overestimate the role of greenhouse gases and aerosols. But I am as sure that the increase of CO2 in the atmosphere since the start of the industrial revolution is mainly from the use of fossil fuels. Appealing to authority that there is 97% consensus is a fallacy. Quick thought experiment. Lets say your a physicist that has been in a coma for the last 40 years. You wake up to the current world and the first headline you see is the shrinking arctic ice. Someone walks by and states how could anyone doubt that man is not destroying our world with CO2. You ask the person what she means and she says that 97% of all scientists claim there is a consensus regarding AGW. Would this physicist run around and defend the point by claiming 97% consensus? If his mother asked him about the proof, is his quack, consensus, consensus enough?
    Response:

    [DB] "It is necessary for me to see and examine the arguments of both sides of the fence, and I then make up my own mind, based on these arguments."

    Try starting here and reading up on all of the argument rebuttals that interest you.

    "I am pretty sure that current climate models underestimate the role of the sun in climate variability and overestimate the role of greenhouse gases and aerosols."

    Is that based on anything scientific or...?

  35. There is no consensus
    Dana69 @11:39 AM, 13 September, no. Over the course of the 20th century natural phenomenon have contributed slightly to the warming. However, over the last 30 years, natural forcings alone would have resulted in a slight global cooling. On the other hand, anthropogenic global warming would have been much stronger without the effect of human emitted aerosols which cool the Earth and have countered as much as half of the overall warming trend, and in some periods (eg 1950 to 1970) have almost completely countered the warming trend.
  36. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Camburn#2: "studying, with validity, the link between GCR and climate." Validity? I wonder. An FD occurs in response to a solar coronal mass ejection. The influx of charged particles enhances magnetic shielding of the earth, resulting in a lowered CR flux at the ground (hence the counter-intuitive decrease following a solar 'storm'). The typical FD has a sharp onset and an exponentially decaying tail lasting a few days. Your linked paper (Dragic et al 2011) shows a measurable effect for only FDs with at least 7% decrease from prior background. That cuts the population down enormously, as weaker FDs are much more frequent. The authors have a dataset running 41 years (1954-95); there are a grand total of 35 7% FDs in that period. If this is what is causing clouds to form, there isn't even 1 cosmic ray induced cloudy episode per year! It gets better. From the paper: We have decided to avoid the direct use of cloudiness data in the analysis of CR-cloud connection and replace it with a different, well defined physical quantity: diurnal variation of surface air temperature (DTR), which should be inversely correlated with cloud cover. The rationale for this is the following: if cloudiness is high in the daytime, more sunlight is reflected back to space and the daily temperature maximum is lowered; in the nighttime, less infrared radiation from the earth surface is emitted into outer space and the daily temperature minimum is increased. Therefore - more clouds means lower DTR. So we're not even talking 'cosmic rays cause clouds' anymore. Here's the new mechanism: 'A decrease in cosmic rays causes a temperature change that might or might not result from fewer clouds.' However, when the authors broaden their sample to include 5% FDs, the DTR increase disappears; hardly a robust result. But it is not necessarily true that this 'mechanism' works the other way: Does higher DTR only mean fewer clouds? Figures in the paper show that 3-4 days after onset, DTR peaks on the order of 0.5C difference. Why does the peak in DTR occur as the FD is declining or quite possibly over? Does it take that long for the cosmic-ray cloud connection to stop making clouds? Is there going to be some sort of mystery lag between FD onset and DTR increase? Or are there other causes for these short-term DTR increases? With studies like this posing as evidence, the cosmic ray-climate connection looks weaker than ever. That splitting sound you just heard? Another nail bent.
  37. There is no consensus
    The topic of this thread it states: "97% of climate experts agree humans are causing global warming." Is this saying that without any man contributing CO2 the globe would not be warming?
  38. Climate Denial Video #6: Past climate change
    I have a question: How much CO2 ppmv is needed to raise global temperature 1 degree Celsius?
    Response:

    [DB] Under what timeframe?  Are other forcings and feedbacks being held to zero?  How about aerosol emissions?  The answer...depends.

    Unless you are reading the Tucson Citizen.  Giddyyap.

  39. Dessler Demolishes Three Crucial 'Skeptic' Myths
    Camburn @45, that is an odd response by you. You are on record as saying, "Spencer is not the only one who shows that the 20 fold is .....a large large stretch to say the least." Note, the ellipsis is your original not very subtle attempt to imply some suitable ad hominen should be included, but it turns out on the most detailed analysis to date that 20 to 1 is a very good estimate, and that Spencer's 2.2 depends on assuming (at best) an unrealistically shallow mixed layer, and on the very dubious switch to three monthly (seasonal) data. Given that he claimed to be using 100 meter data, the apparent use of 25 meter data is very damning. Unable to defend your original assessment of Dessler 2011 (and Spencer and Braswell 2011), you resort to distraction by drawing attention to Bart's blog comment analysis. Others have justly drawn attention to the discordance between your apparent extreme skepticism of peer reviewed papers and your credulity towards "blog comment science". I would rather address Bart's analysis directly, specifically, the claim that:
    "“The approximate period of the ENSO cycle is around 5 years.” I’m not talking about a cycle time, though. I am talking about the time it takes for clouds to react to temperature changes. That is, if you increase global temperature by 1 degC (and could hold it there), within 4.88 years, you will be 1-exp(-1) = 63% of the way to creating an opposing 9.5 to 10 W/m^2 reduction in insolation. The unit step response is plotted here."
    For clarity of discussion, here is the step response plot referred to: So let's put this into perspective. "Bart", an unknown commentator on a blog performs a statistical analysis which purports to show, without any physical mechanism, and on just 10 years data, that the climate response to a doubling of CO2 will be to reduce temperatures by approximately 1.5 degrees C. Oddly, you do not find this highly suspect, but rather "an excellent analysis". Without going into technical detail like Nick Stokes, I find this claim simply incredible, ie, not possible to be believed. A negative feedback of such strength would either force the Earth into a Snowball state within 50 years if it only cools; or if it is a negative feedback on warming as well, would force the climate into wild multiple degree oscillations in mean global temperature on decadal timescales. What is more, I cannot help noticing that his data (10 years) is to short to determine if the response he is detecting is cyclical or not. Given that, the apparently coincident timing with regard to the average return interval of ENSO events, and more compellingly to me, a half solar cycle, is highly suspect. To the extent that he is detecting anything, it seems far more likely that he is detecting a residual response to cyclical (Solar Cycle) or quasi-cyclical (ENSO) events. He provides no analysis rebutting that possibility.
  40. Just Deserts: Winning the 2011 Eureka Prize
    cynicus: yes, that's the sense I meant 'one-sided' - the vast majority (almost all) of the evidence points to global warming being real, driven by human GHG emissions, and a serious problem. Talking about the range of possibilities that you mentioned is just hand-waving - particularly when all of those possibilities are bad, and only the degree is different. Even the low end will have nasty repercussions, the most likely values will be disastrous, and I really, really hope the actual values don't lie in the upper part of the range...
  41. CO2 is just a trace gas
    Eric @ 96, I really don't comprehend why you want to send me on a fishing expedition for what you want to say, but I did read the little brief on IR satellite images. Interesting, but perhaps you got the wrong link? Or maybe I'm missing something? I'm open minded, just let me know how my admittedly simple exercise in first approximations is wrong, then point me to the correcting information.
  42. CO2 is just a trace gas
    Sphaerica @ 97: OK, that is a bit confusing What I was trying to do, in keeping with the spirit of the original post, was to come up with some simple example of why "trace" does not mean insignificant. A 6.8 meter "layer" of CO2 sounds a little more significant than 0.039% for those who don't easily grasp numbers. But I can't say 'layer', because the science sticklers here might make me do the calculations to bring it all to a uniform pressure and then calculate the optical depth of the layer, not to mention explaining the quantum mechanics of absorption and all the other physics ;) So I chose path length. 390 pmm CO2/1,000,000 ppm Atmosphere, is a ratio. The 'ppm' cancels. (I rounded to 400ppm because we'll be there soon enough.) Consider a cylindrical volume of any diameter straight up through the troposphere. By the Ideal Gas Law all gases occupy about the same volume at a given temp and pressure. For any given diameter, the volume of the cylinder times the percent concentration of a gas component, gives the volume of that gas. The cylinder is uniform, and CO2 is well mixed, so the ratio of CO2, times the length of the cylinder, ALSO gives the effective length that a photon must transit of that particular component were it all in one place (Albeit at different pressures and temperatures along the path.) What I was trying to say is that yes 0.039% of something doesn't seem like much. But if that something is large, like a layer of atmosphere 17 km thick, it's actually a lot more than it first appears. (I'm not a PhD, but I do get to use IR instruments on occasion, it doesn't take a whole lot of CO2 to make the instrument useless for measurements in and near the CO2 absorption band because of how effective an absorber it is.)
  43. Climate Denial Video #6: Past climate change
    I like it, but it could benefit from including the critical graph--the one that shows how drastically current CO2 levels are off the previous charts.
    Response:

    [DB] You mean like this one?

    CO2

  44. IPCC is alarmist
    Hang on lancelot. The full quote reads "What is happening, and what is likely to happen, convinces me that the world must be really ambitious and very determined at moving toward a 350 target." He said it in 2009. The CO2 concentration was already blowing past 380ppm. The 350ppm target is really very, very ambitious because it requires us not to just cut emissions, but to reduce concentrations. I don't know what kind of policy/financial work you do. But if someone comes to you with a proposal to quarry, crush and distribute dusts & gravels of CO2 absorbing rocks, do the world a favour and set them to work.
  45. Just Deserts: Winning the 2011 Eureka Prize
    Congratulations! There was never doubt in my mind that John and SkS are in the class of their own. It is about time that someone noticed and more awards will certainly follow.
  46. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Camburn, #1 Given theres no discernable trend in cosmic rays over the last 60 years, any link to climate must indicate that the climate is incredibly sensative, wouldnt you say?
  47. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Dana: It would help readability if you were to enlarge Figure 1.
    Response:

    [DB] Now thumbnailed; click on it for larger 1050x454 native resolution.

  48. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    ThingsBreak also has an excellent overview of the scientific literature, well worth the read (Camburn and fellow "skeptics" I'm looking at you). Some quotes from the ThingsBreak piece: "Basically, what’s actually been demonstrated by Kirkby, et al. isn’t at odds with the IPCC. What is at odds with the IPCC hasn’t been demonstrated by Kirkby, et al. And the claims by Svensmark, Shaviv, and other ‘GCRs drive climate’ proponents have been debunked at pretty much every step of the way. GCRs may have some influence on cloud behavior, but they’re not responsible for significant climatic changes now or in the geologic past." "After the initial furor of “skeptic” blog-spinning dies down, cosmic rays will probably find themselves falling out of favor once again. But there’s no such thing as too debunked when it comes to myths about climate change, and there’s little chance this will be the last time cosmic rays will be trotted out to claim that we don’t need to reduce greenhouse gas emissions.' But I understand that 'skeptics' and those in denial about AGW have to continue to fabricate debate and uncertainty, it is what they do. Readers, don't fall for their misinformation and distortion and cherry-picking.
  49. Extreme Flooding In 2010-2011 Lowers Global Sea Level
    Hot of the press... "New evidence of sea-level oscillations during a warm period that started about 125,000 years ago raises the possibility of a similar scenario if the planet continues its more recent warming trend, says a research team led by the Woods Hole Oceanographic Institution (WHOI)." Source: "Sea Levels Much Less Stable Than Earlier Believed, New Coral Dating Method Suggests'" Science Daily, Sep 12, 2011 To access this article, click here.
  50. Just Deserts: Winning the 2011 Eureka Prize
    Congratulations to everyone here at SkS but particularly John. In the beginning it was John, popping in at other sites and spreading the word (and links). Nice vision John and great follow through.

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