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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 76151 to 76200:

  1. Dikran Marsupial at 05:48 AM on 30 August 2011
    CO2 is just a trace gas
    SocialBlunder The total number of CO2 moleclues above our head is closely related to the percentage. The mass of atmospheric carbon (not CO2) in Pg is 2.127 times the the concentration expressed in ppm. I'm sure you could work out the number of molecule from that, Avogadros constant, the radius of the Earth and a two atomic weights. However the point of the article is that you can't tell whether something is significant just by looking at the amount of it lying around, and often the units in which something is measured can give a misleading impression. The single figure that is most worth knowing is 1 degree C, which (ignoring feedbacks) is the direct effect on equilibrium global temperatures of a doubling of CO2. If CO2 is only 0.039% of the atmosphere, it only needs to be 0.078% of the atmosphere to raise global temps by 1 degree C (all things being otherwise equal). If 0.039% isn't much then it won't take much to double it - the "skeptics" can't have it both ways! ;o)
  2. CO2 is just a trace gas
    H2SO4 cannot induce nucleation mediated by GCR: too low concentration in atmosphere: 200pptv (!) in the lower troposphere. ;-) ;-) http://www.agu.org/pubs/crossref/2001/2001JD000605.shtml
  3. CO2 is just a trace gas
    If "The total number of CO2 molecules above our heads in the atmosphere is more important than their percentage in the atmosphere", being able to compare the ppm, tons, and temperature shift would be helpful. In Hansen's Earth's Energy Imbalance and Implications there is a tempting description of "An equation for climate forcing as a function of CO2 amount is given in Table 1 of Hansen et al. (2000)." I was not able to find the 2000 paper.
    Response:

    [DB] Try here:

    http://pubs.giss.nasa.gov/docs/2000/2000_Hansen_etal_2.pdf

    Hansen 2000_Table1

  4. Mythic Reasoning about Climate Uncertainty
    Eric the Red, I find your claims overconfident and not supported by the evidence, as indication by your lack of support for any of your statements. "Solar activity was high" No. Solar activity trended downward. Solar Trends "volcanic activity was low" No. A monthly and latitudinally varying volcanic forcing dataset in simulations of 20th century climate "ENSO cycles yielded stronger and more frequent EL Ninos" There is such an ENSO/SOI trend during the covered period, but as we know from various ENSO-adjusted analysis, it has a limited effect on long-term trends. "The IPCC tried to diminish these effects, resulting in higher warming attributed to CO2 rise. " If they "diminished" the volcanic effect, there would be, if anything, less attribution to human causes. Nothing, however, was "diminshed".
  5. Mythic Reasoning about Climate Uncertainty
    "Now Judith seems predominantly concerned her about the "motivated reasoning" of what she calls the "climate establishment." " Maybe I am off base here but if you read Dr Curry's commentary the verbiage sounds familiar. Not familiar as in 'others in her camp have said the same thing' (although true), but familiar in the sense that the same kinds of misuse of syntax and dismissal of data are common in the 'soft sciences'. Now those 'soft sciences' (polysci, sociology, economics) have, to a large degree, been undone by postmodern philosophy. The latter seems to boil down to 'my opinion equals your data, because all your data must be inherently biased'. I often wonder if the widespread adoption of postmodern philosophies in our universities has not had some terrible unintended consequences.
  6. It's not bad
    Joseph#126: "qualified with the word "may" as in global warming "may do this bad thing"." Quick and easy answer to that: look at the vicious criticism that comes out whenever a climate scientist makes a specific statement. But a better answer is simply that climate change is about trends, not specific events. You can say 'this is the observed trend; if that continues, here's what can or may happen.' "This suggests that even though the science about the cause of global warming may be settled, the science about its predictions is far from that." What is the 'science of predictions'? "And this in turn puts a big question mark on the importance of this issue in light of its economic cost." Absolutely not. The costs need to be studied as risk-adjusted expected values, which include both most likely and worst case scenarios. The cost of mitigation (reacting after the fact) is almost always far greater than the cost of prevention (or some form adaptation). Consider, for an obvious example, the cost of boarding up and leaving town in advance of a hurricane vs. the risk of loss of life and property damage if you do nothing. On some occasions, you leave town only to find that the storm goes elsewhere, but on another you may have saved your life. If you are not considering the worst case, you make bad decisions. That's basically what we are doing when we say 'the science isn't settled' and therefore 'do nothing.' If we can take action now to reduce the probability of occurrence of the worst case, then we are way ahead in the long run.
  7. Mythic Reasoning about Climate Uncertainty
    Eric the Red - Would you care to support any of the statements in your post? Natural forcings alone over the last 150 years should have resulted in a slight decrease in temperature, as opposed to the observed 0.8C temperature rise with our contributions. "I feel that the IPCC statements definitely lead to overconfidence, and they went out of their way to minimize other causes in the AR4 report." Are you accusing the IPCC of deception in this statement? They went through the evidence quite thoroughly - and that evidence supports the quite conservative (with many underestimates, in fact) statements the IPCC made.
  8. It's not bad
    Joseph, Quite impressive analysis for someone who has only been reading this site for a few days. The incluson of the word "may" is usually a reference to the uncertainty of an event, or the lack of data to back up an assertation. For instance, there are those who claim that global warming will lead to more and stronger hurricanses; others fewer, but stronger; some more frequent, but weaker; and others fewer and weaker. The qualifiers often occur in areas of disagreement.
  9. It's not bad
    I am new to this blog but I find this to be very informative, and as a result of reading through it the last few days I have already changed my opinion on this issue, having been solidly in the "global warming is just a natural cycle" camp, to believing that it is actually caused by human activity. Having said that I am not convinced that global warming is actually bad for humans. It does seem to me by reading many other posts/articles that your postings are biased towards the negative side. For example most articles I read suggest that warming will actually increase water supply for agriculture as a whole because of ocean evaporation/rainfall. But your posting concentrates on drought driven by heat and seems to downplay the potential increase in water supply from added rainfall. Also almost all your potential negatives (and to be fair your positives as well), are qualified with the word "may" as in global warming "may do this bad thing". This suggests that even though the science about the cause of global warming may be settled, the science about its predictions is far from that. And this in turn puts a big question mark on the importance of this issue in light of its economic cost.
    Response:

    [DB] "most articles I read suggest that warming will actually increase water supply for agriculture as a whole because of ocean evaporation/rainfall"

    Then I would suggest reading this post then for starters:

    The Dai After Tomorrow

  10. Mythic Reasoning about Climate Uncertainty
    NewYorkJ I feel that the IPCC statements definitely lead to overconfidence, ( -Snip- ). Whose best estimate has natural contributions being negative? Solar activity was high, ENSO cycles yielded stronger and more frequent EL Ninos, and volcanic activity was low. ( -Snip- ).
    Response:

    [DB] Intimations of fraud and scientific misconduct deleted.

    Please note that posting comments here at SkS is a privilege, not a right.  This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

    Moderating this site is a tiresome chore, particularly when commentators repeatedly submit offensive, off-topic posts or intentionally misleading comments and graphics or simply make things up. We really appreciate people's cooperation in abiding by the Comments Policy, which is largely responsible for the quality of this site.
     
    Finally, please understand that moderation policies are not open for discussion.  If you find yourself incapable of abiding by these common set of rules that everyone else observes, then a change of venues is in the offing.

    Please take the time to review the policy, again, and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter, as no further warnings shall be given.

  11. CO2 is just a trace gas
    200 mg of arsenic is considered fatal, so 3 ppm is a fatal dose.
  12. Temp record is unreliable
    224, econ101lab, You are advised to eliminate the following sorts of offensive falsehoods and snarky implications from future comments if you wish to learn and be guided, rather than to make a splash and warp other people into matching your own flavor of I-read-it-somewhere-and-I-believe-it-until-you-prove-otherwise:
    • I have a tough time getting my arms around the "settled science" position
    • when two thirds of the planet isn't observed
    • one of the most significant variables isn't even modeled or clearly understood (clouds and cloud formation)
    • smacks of intellectual hubris
    • are there other untracked or unobservable variables of which I am unaware?
    All of this was in your opening paragraph, before you asked perfectly valid questions, but also laced them with a litany of misinformation and misunderstandings about temperature measurements on which your own confusion was based. In the future, if you don't know, simply ask. Don't broadcast an offensive and ignorant position, and use your comment to litter the world with even more misinformation of your own. If your goal is to learn, then learn. If your goal is to pontificate on things you don't understand, then expect a fair amount of blow-back here.
  13. Republican Presidential Candidates vs. Climate Science
    “House Republicans are planning votes for almost every week this fall in an effort to repeal environmental and labor requirements on business that they say have hampered job growth.” Source: “House GOP revs up a repeal, reduce and rein-in agenda for the fall,” Washington Post, Aug 29, 2011 To access the entire article, click here
  14. Republican Presidential Candidates vs. Climate Science
    "Jon Huntsman Jr., a former Utah governor and ambassador to China, isn’t a serious contender for the Republican presidential nomination. And that’s too bad, because Mr. Hunstman has been willing to say the unsayable about the G.O.P. — namely, that it is becoming the 'anti-science party.' This is an enormously important development. And it should terrify us." Source: "Republicans Against Science," Op-ed by Paul Krugman, NY Times, Nov 28, 2011
  15. Temp record is unreliable
    @ econ101lab Aside from using the Search function, there are several ways to get the most out of SkS: 1. By Argument # 2. By Popularity 3. By Taxonomy (my favorite) 4. By Chronological Posting These will find most of the 4,000+ blog posts here at SkS. As always, if/when questions arise on a particular thread, feel free to post those questions there (or on another more appropriate thread) and someone will get back to you. Regular participants here follow the Recent Comments thread, so any new comments posted will be noticed regardless of the thread that they are posted on. Happy Hunting!
  16. Mythic Reasoning about Climate Uncertainty
    How can anyone seriously claim conservative IPCC statements lead to overconfidence as claimed in the conclusion? They go out of their way to highlight uncertainty. I haven't seen any attribution study that can assign 50% or more of the warming of the last 50 years to the net of natural causes, yet the IPCC leaves that open to a 10% chance. Then there's the best estimate that natural contribution has been nil or even a little negative. Also take a look at statements from Dr. Andrew Lacis. Lacis at NASA on Role of CO2 in Warming Also see: More Curried Leftovers
  17. Temp record is unreliable
    econ101ab @223, it is very late here, and I am very tired, so I will only respond to your second point tonight. Essentially, you are ignoring the fact that the temperature calculations are for temperature anomalies rather than for absolute temperatures. An extrapolation of absolute temperatures would be absurd for exactly the reasons you give. The temperature anomaly, essentially the absolute temperature minus the mean temperature over some period, will not be so affected. Specifically, if it is an unusually warm day at Palm Springs, it will probably be an unusually warm day at Big Bear Lake as well. The difference in their anomalies on any day will be small even though the difference in their absolute temperature on every day is large. This is explained in greater detail in On Averages and Anomalies Part 1. (Link give by KR in 219 above.)
  18. Temp record is unreliable
    Philippe, you question my sources. What do you think I am doing here? Rather than snarky comments about my motives, I appreciate the willingness of KR, Tom, and DB to show me how the site works and give me a start on how to find information. Geez, lighten up.
    Moderator Response: You'll find less "snarkiness" in responses to you if you refrain from writing so stridently and confidently before you have read up on the rudiments. Folks here have a hair trigger for such behavior because it happens so often. Your failure to understand the really, really fundamental fact that temperature anomalies are used, is exactly such a case.
  19. Tar Sands Impact on Climate Change
    "Einstein said to think and not act is a crime," James Hansen tells SolveClimate News. "If we understand the situation, we must try to make it clear." Source: "NASA's Hansen Explains Decision to Join Keystone Pipeline Protests" by Elizabeth McGowan, SolveClimate News, Aug 29, 2011. To access this informative and timely article, click here.
  20. Temp record is unreliable
    Tom, I will read your recommendation re: Ned's article. I fully accept your observation of the tenuous nature of macro economics as accurate due to the long time spans needed for observation and the virtually infinite and unobservable micro variables which can cumulatively affect the macro picture. This is why I have a tough time getting my arms around the "settled science" position. I'm not trying to be difficult but when two thirds of the planet isn't observed (either water temp or air temp over water) and one of the most significant variables isn't even modeled or clearly understood (clouds and cloud formation), the certainty smacks of intellectual hubris. As a non-climatologist, are there other untracked or unobservable variables of which I am unaware? Again, not trying to be a butt here. While I think Keynes and Galbraith were wrong based on the observable record and Friedman on the money, others dispute that looking at the exact same historical record (of course perhaps taking different micro impacts into account). OK, I've begun doing the reading suggested by KR (thank you again KR). I used the search function, unsuccessfully, to try and find previous posts for a few questions I have. My questions are regarding temperature records and how they're calculated. I ask the questions because I do not understand so please take them in that vein. First, wouldn't the cumulative error in a cell or block that is extrapolated vs observed, quickly make the data from that cell meaningless and affect the long term results more the longer it was used? Particularly if it was in close proximity to the central station and hence had a greater weighting? Second, Mr. Tamblyn does an excellent job laying this out for a non-climatologist. I understand the teleconnection concept and it makes sense as long as the station extrapolations take place from similar altitudes. I can think of numerous locations where I have been personally, where locations 50-60 miles apart might vary 50-60 degrees F. Palm Springs vs Big Bear Lake in California during the winter is an excellent example. I have played golf in the morning in 80 degrees in PS and then gone to the top of the tram where there's snow on the ground and the temp is in the 20's. If Big Bear were to be extrapolated from either LA or Palm Springs (both about 60 miles away) they would have significant weight due to proximity but no relevance. And is his contention that the Andes and coastal Peru have the same weather systems passing over accurate? The Andes are much higher than the San Gabriel Mtn's and the SGM's actually stop weather from the coast from moving inland. Meaning that one location (LA) has totally different weather from one 90 miles away (PS) precisely due to a geographical feature. Western and eastern Colorado create a similar situation. As do the Ngorongoro Crater and the Serengeti (went both places this summer, put it on your bucket list!) I looked at the gridded map and can see numerous places globally where this could logically happen. I see how it can be adjusted for if there are only occasional lapses in observed temp, but how is it adjusted when there is no station? Satellite? Thank you. Back to my homework.
  21. Mythic Reasoning about Climate Uncertainty
    "Crisis of confidence, perhaps" I question just who is having this "crisis of confidence." I think that Judith is projecting her own "crisis" onto the larger public without evidence to support her speculation. That projection is fueled by the general vibe among her "denizens," who seem to be similarly affected. When I see what I consider to be overextrapolation, I tend to wonder about the very same sort of "motivated reasoning" that used to concern Judith with respect to the reasoning of "skeptics," predominantly. Now Judith seems predominantly concerned her about the "motivated reasoning" of what she calls the "climate establishment." What motivates that change in the focus of Judith's scrutiny?
  22. SkS Weekly Digest #13
    Grand Poopah is no doubt the title my wife & I will be giving Mini-Composer once he's born.
  23. Climate Sensitivity: Feedbacks Anyone?
    16, Eric the Red,
    Although the sea ice has been present for 5000 years, it has been anything but constant.
    I do not agree with this statement. Do you have any citations to support this assertion? Can you quantify the variability that you conjecture has occurred?
    Moderator Response:

    [DB] EtR must be acknowledging the unprecedented loss of Arctic Sea Ice ongoing in today's time (unprecedented over the past 5,000 years)...

  24. ConCERN Trolling on Cosmic Rays, Clouds, and Climate Change
    This bit on Nigel Calder's blog has the 'it's cosmic rays' folks shouting, 'we told you so!' Calder apparently has dramatized the sequence of events in one experimental run to great success. I've interspersed a few questions that seem unanswered in his rendition.
    In an early-morning experimental run at CERN, starting at 03.45, ultraviolet light began making sulphuric acid molecules in the chamber, while a strong electric field cleansed the air of ions. It also tended to remove molecular clusters made in the neutral environment (n) but some of these accumulated at a low rate.

    Q1: That electric field also acts as shielding. Why are any molecular clusters accumulating in a shielded chamber with no particle beam input?

    As soon as the electric field was switched off at 04.33, natural cosmic rays (gcr) raining down through the roof of the experimental hall in Geneva helped to build clusters at a higher rate.

    Q2: Most cosmic ray workers would interpret 'natural cosmic rays' as the background flux of muons produced by atmospheric interactions with the solar wind (usually referred to as solar cosmic rays). How do they automatically identify this background as GCRs? And what sort of electric field shielded the chamber from muons (negatively charged) with energies on the order of GeVs?

    How do we know they were contributing? Because when, at 04.58, CLOUD simulated stronger cosmic rays with a beam of charged pion particles (ch) from the accelerator, the rate of cluster production became faster still.

    Q3: 'Stronger' in this context must mean higher energy. The original experimental design called for a pion beam on the order of 600 MeV, no 'stronger' than the background muons. Further, charged pions decay quickly to muons. What does this utterly critical statement mean? Are they actually investigating solar cosmic rays and not GCRs? Are they now saying that solar cosmic ray muons cause cloud nucleation as well? The mechanism for Be10 production requires higher energies, usually in the form of GCR-induced protons. It was the link to paleo abundances of Be10 that kicked off the whole GCR-climate link in the first place. Calder's dam on which global warming is said to break has some leaks.

    Moderator Response: [muoncounter] CLOUD Project design sheets called for 3.5 GeV positive pion beam. A separate experiment in Denmark used 580 MeV.
  25. Mythic Reasoning about Climate Uncertainty
    Joshua#16: "she believes "Climategate" created a "crises"" That's a great observation, although it strikes me as an extreme overreaction to events. Crisis of confidence, perhaps; crisis in the observation and understanding of the science, no. I have to wonder how the 'denizens' would react to the conclusions of the 2006 paper. Conflict with their core beliefs (greenhouse warming is real? Does not compute!) is not tolerated.
  26. SkS Weekly Digest #13
    @Mark Harrignton #1: Thanks for the positive feedback. I'll forward your request that SkS create a "Toon Gallery" to our Grand Poopah, John Cook.
    Moderator Response: [Dikran Marsupial] I think "poobah" was the word you were looking for! ;o)
  27. SkS Weekly Digest #13
    Sad and funny at the same time.
  28. Mythic Reasoning about Climate Uncertainty
    Re: #14 I've been reading Judith's blog quite a bit lately - and from what I've seen, her change in perspective is at least correlated to her interpretation of "Climategate." Judith has indicated that she believes "Climategate" created a "crises" in climate science - in the view of the public in general (although, interestingly, from what I've seen has yet to quantify the data that underlies her certainty about the impact of "Climategate"). My interpretation is that her view of a larger reaction to "Climategate" is more a projection (of her own reaction) - as she has stated often that "Climategate" deeply affected her own approach to the "climate community." I am sympathetic to Judith's concerns about the impact of motivated reasoning and confirmation bias in the debate about climate change; those basic psychological phenomena are fundamental attributes of the reasoning of people (scientists or otherwise) engaged in debate about controversial topics. Unfortunately, from what I've seen, ironically Judith fails to consistently apply similar scrutiny to her own reasoning processes, the reasoning of her "denizens," or the reasoning of other players in the "skeptical" blogosphere. Judith was concerned about phenomena such as "motivated reasoning" both before and after "Climategate" (even if the terminology she used to describe those phenomena evolved over time). I think that the dramatic shift in her own conclusions about the science of climate change, the related political context, and the reasoning process of people that she disagrees with, clearly lies in a shift in the "motivations” behind her own reasoning. I’m not suggesting anything particularly nefarious there; without knowing her personally it would be impossible for me to assess what lies at the root of her motivations. I think that it is “unscientific” for anyone to base conclusions about someones motivations based purely on speculation (although I will note that Judith seems unconcerned with the constant drone of many of her "denizens" attributing nefarious motivations to pretty much anyone who thinks that global warming is 90% likely to be anthropogenic). However, something fundamental changed with respect to what Judith is motivated to prove in her view of the climate change debate. As to whether “Climategate” or something else lies at the root of her shift in motivations may be a chicken/egg enigma – but perhaps the answer to that riddle could be found in “laying bare the underlying causal chain and potential approach to verification” evidenced in her reasoning process."
  29. Climate Ethics: What Can Science Tell Us?
    Thanks Rob for the post and link to the Li paper.
  30. Extreme weather isn't caused by global warming
    Adelady, I wholeheartedly agree. AGW does not directly cause these events, but can affect the impact due to warmer temperatures and higher humidity.
  31. Climate Sensitivity: Feedbacks Anyone?
    Ice-albedo feedbacks should be included in fast-feedback sensitivity as the absorption / reflection of solar radiation is immediate. There is some indication that the high latitude albedo effects are more localized than the ice-albedo feedbacks associated with continental ice, as witnessed by local temperature changes. I agree with Sphaerica (a rarity) about the 5000 vs 7000 year distinction about the Arctic sea ice. Although the sea ice has been present for 5000 years, it has been anything but constant. (DB, I think you are confusing sea ice extent with sea ice anamoly in your Antarctic graphic). Vegetative albedo feedbacks are slow and highly variable by comparison, and when combined with the absorption feedback results in a net negative.
    Response:

    [DB] You may want to check the link...both are down.  Just sayin'.

    SH Sea Ice

  32. Climate Ethics: What Can Science Tell Us?
    24, Rob Painting, Thanks!
  33. SkS Weekly Digest #13
    I love these "toons of the week". Moderators may we please have a link to all of them like there is to the graphics?? The graphics are powerful ways of communicating the message of the science but the toons are, sometimes, an even more powerful and quite "disarming" way to rebut the denialists without the aggravation and confrontation that frequently ensues.
  34. Mythic Reasoning about Climate Uncertainty
    muoncounter, Dr. Curry isn't the only scientist who's scientific philosophy has changed dramatically from straightforward participation in the scientific effort to politicized (one assumes) support of science mirepresentation. The psychology associated with these transitions is rather fascinating. Craig Loehle provides another example: 20-odd years ago Loehle felt so strongly against attempts at political interference in science, and particularly the efforts at "fraud-hunting" and "auditing" that he wrote a letter to Nature on the subject. some excerpts [see Nature (1989) 338, p. 370]:
    "There is a danger in the controversy over fraud in science of merging the concepts of fraud and error. The call for an audit of scientific papers for error is a symptom of this trend. Fraud such as fabricating data or publishing the work of other's as one's own is of course serious, particularly when it involves assessment of drugs and other medical treatments whwre lives are at stake. But error is an inevitable part of science. The fundamental point is being missed in the current debate...."
    and towards the end:
    "Who will review the error hunters? Who is qualified to punish whom?"
    And yet Loehle spends time on a blog where the sort of "auditing" that he decried all those years ago is used to bully and harass scientists. Googling "Craig Loehle fraud", uncovers many examples of his (scientifically pretty dismal) work being used to bolster the efforts of those bellowing "fraud" against science. Dr. Loehle seems to think this is now acceptable.
  35. Climate Sensitivity: The Skeptic Endgame
    @Gilles, #38 Concerning the amount of carbon still available in fossil fuels... I agree that there is much less accessible carbon in the world than commonly assumed. Some IPCC scenarios may well overstate the possible emissions. Still, I once calculated how much fossil carbon there is, based on studies by the Energy Watch Group (EWG) (http://www.energywatchgroup.org/) and found that together with the other CO2 sources (e.g. land use change, cattle), there is still easily enough Carbon in the ground to ruin the planet. To determine this, I researched the "carbon emission limit" that will keep us on the "safe" side. According to [Meinshausen et al. 2009] this is 1000 billion tons of CO2 equivalent between 2000 and 2050. They estimate that 25% of this are already emitted, so there remain 750 billion tons (Gt). Of this, about 40% come from other sources than fossil fuel burning: land use change, cattle, paddy fields, nitrogen dioxyde fertilizers etc. So there remain 450 billions tons CO2 to come from fossil fuel burning. To normalize these to pure carbon equivalent for easier comparison with fuel carbon content, I divide by 3.67 (the molecular weight ratio between 2 oxygen atoms and one carbon atom) and get ~123 Gt/C as the upper limit to what we can still emit from fossil fuels. Now comes a little eyeballing stunt: Looking at the respective coal and oil production curves from the EWG studies (and researching for the natural gas ones elsewhere) and multiplying the readings for 2025 and 2050 by approximate carbon content and summing these numbers, I come up with possible emissions of 7.403 Gt/C in 2025 and 5.421 Gt/C in 2050. Now even if I multiplied the lower number for 2050 with the remaining years up to 2050 (38), I get emissions of ~206 Gt/C - far above the limit. Of course, fossil fuel scarcity will not force us to drop to this 2050 level tomorrow - in a "peak fossils" scenario, production will follow a nice right-side-of-a-bell-curve trajectory, so actual accumulated emissions could be much higher than 200 Gt/C - shooting this planet to hell. Oh, and by the way... [Meinshausen et al. 2009] give a probability of 25% that 1000 Gt/CO2 until 2050 will *still* produce warming above the magic "safe" limit of 2°. Would you use an airplane with 25% probability to crash? No? And we are talking about a whole planet here, not just an airplane!
  36. Climate Sensitivity: Feedbacks Anyone?
    Ice-albedo feedback due to sea ice and snow cover is　(in principle) included in fast-feedback sensitivity or "Charney sensitivity". Ice-albedo feedback due to continental ice sheets and albedo feedback due to vegetation are considered as slow feedbacks.
  37. Dikran Marsupial at 17:41 PM on 29 August 2011
    Settled Science - Humans are Raising CO2 Levels
    Skeptical Wombat If Salby's answer to your question were to be "if the Industrial Revolution had not occurred then CO2 levels would still have gone up by 95% of the amount by which they did increase" he would be very wrong. I suspect what Salby meant was that if you look at the additional CO2 that has been added since the industrial revolution, then only 5% of those molecules will be of directly anthropogenic origin. This is basically true and completely consistent with the cause of the rise being 100% anthropogenic. I know that sounds rather counterintuituve, but it is true. The reason that only about 5% of the molecules are of directly anthropogenic origin is that there is a vast exchange flux that each year exchanges about 20% of atmospheric CO2 with CO2 from the surface oceans or from terestrial biosphere. However this is a straight exchange and hence doesn't alter the atmospheric CO2 levels, but it does mean that anthropogenic CO2 is replaced by "natural" CO2. The action of the exchange flux has confused many, especially leading to the "residence time" argument discussed on another thread. This is well known to those who study the carbon cycle. I am currently writing an advanced version of the "residence time" rebuttal, and it will include a simple model that explains the 5% figure (and I'll include an analogy for those that don't like differential equations). BTW, the sinks and sources are not undiscovered; the figures given in the IPCC WG1 report are consistent with an anthropogenic cause of the rise and there being only a small fraction of anthropogenic CO2 comprising the excess.
  38. Extreme weather isn't caused by global warming
    "I suppose what I am getting at at what stage can we start safely matching extreme weather events to AGW?" One thing you can do is look at the average increase in humidity due to raised temperatures. When we say that there's 4% more moisture aloft than before, you can get hold of the weather service's measurements of precipitation leading to floods and other damage. Then do some calculations with and without that 4%. What height would the floodwater have reached if there had been x% less water flowing into the system? The big issue here of course is that 4% is the global average increase. Choosing - let alone justifying - a more suitable number for a specific time and place is much harder. But this sort of calculation can be illustrative if not definitive. Without a 4% increase in humidity, floodwaters may only have reached 2 streets from the riverbank rather than the ... distance they did. Not terribly scientific, but may provoke thought. And much more useful for real life. AGW may not cause certain events directly, but it can worsen the impact of those that do occur.
  39. Climate Ethics: What Can Science Tell Us?
    Scadden P @ 20 & Dan Bailey (moderator comment) @ 15 - There has been a dramatic increase in ENSO severity during the last century. See Gergis & Fowler (2006) "Although extreme events are seen throughout the 478-year reconstruction, 43% of the extreme ENSO events noted since A.D. 1525 occur during the 20th century, with an obvious bias towards enhanced El Nino conditions in recent decades. Of the total number of extreme event years reconstructed, 30% of all reconstructed ENSO event years occur post-1940 alone suggesting that recent ENSO variability appears anomalous in the context of the past five centuries." The frequency and intensity of ENSO appears to be tied to the mean state of the tropical Pacific. When equatorial waters in the central and eastern Pacific are warm, frequency and intensity are increased. When cooler, activity diminishes, although there can be huge swings in intensity during these cooler periods. See Li (2011) As far as future projections are concerned, that's unsettled for now. Climate models seem split on whether we'll see an increase/decrease in ENSO activity. See Vecchi & Wittenburg (2009) and Collins (2010)
  40. Mythic Reasoning about Climate Uncertainty
    muoncounter: that is indeed extraordinary. I wonder if Curry offers extraordinary evidence to explain her change of mind on global warming? If not, then it certainly leaves one wondering as to how & why someone can so completely change their public statements on an issue. As you've suggested, in politics it's all too common, and driven by a motivation to gain or retain elected office. Elsewhere, the motivation is generally ideological, religious, or financial (or a combination thereof).
  41. Climate Sensitivity: Feedbacks Anyone?
    Excellent article. Contrarians often comfort themselves with by suggesting that climate sensitivity is about 1C per doubling and that you can only get to higher sensitivities through "hypothesised positive feedbacks". They don't appreciate the physical reality of the feedbacks, and that they are not only real, present and active today, but also absolutely necessary to explain past climate change. You cannot explain climate with negative net feedbacks. Ice-albedo feedback seems a very appropriate topic as we head below 5 million sq km IJIS extent in Arctic for only the 4th time, which is the 4th time in 5 years. Late summer Arctic sea ice volume is also desperately low, and with futher reduction, extent loss is certain and so will be a further increase in the albedo feedback.
  42. Extreme weather isn't caused by global warming
    "I suppose what I am getting at at what stage can we start safely matching extreme weather events to AGW?" Doing this scientifically requires matching observations of weather to predictions from the climate models. As I understand it, only really disruptions to the hydrological cycle (drought and extreme precipitation events) are settled science within the predictions. Hurricanes are not. AR4 discussed extreme precipitation events but there was not really a long enough record to be making strong statements. Droughts will wax and wane in cycles but the pattern of drought is consistent with predictions. I dont believe you can link any single weather event to AGW - only trends in frequency and/or intensity.
  43. Climate Ethics: What Can Science Tell Us?
    This discussion belongs here. I have commented there.
  44. Climate Ethics: What Can Science Tell Us?
    So is it safe to work on the principle that at the moment the indications are that the ENSO may be more intense but not neccessarily more frequent? Also it seems that ENSO is claimed to be the driver of intense weather events in eastern North America and Africa. Is that true? I suppose what I am getting at at what stage can we start safely matching extreme weather events to AGW?
  45. Climate Sensitivity: Feedbacks Anyone?
    12, Camburn, Your own link belies your statement, and you provide no other supporting links. Michael Sweet said (correctly):
    For the last 5,000 years (or more) the Arctic sea ice has been a constant ice sheet over most of the Arctic Ocean.
    Your link said:
    ”The climate in the northern regions has never been milder since the last Ice Age than it was about 6000-7000 years ago. We still don’t know whether the Arctic Ocean was completely ice free, but there was more open water in the area north of Greenland than there is today,” says Astrid Lyså, a geologist and researcher at the Geological Survey of Norway (NGU).
    See the difference? 5,000 years versus 6,000-7,000? Coincidentally, temperatures have been dropping for the last 7,000 years, which marked the Holocene Climactic Optimum, when temperatures were approximately roughly equal to what they are today. So evidence that the Arctic had less ice 7,000 years ago is further evidence of current warming, what that warming will do, and the fact that warming above and beyond that will have unheard of effects. It's all consistent... all except your personal interpretation of it, that is.
  46. Sceptical Wombat at 12:48 PM on 29 August 2011
    Settled Science - Humans are Raising CO2 Levels
    The question I would ask Salby is what he means by saying that anthropogenic emissions only account or 5% of the increase in CO2. Presumably he means that if the Industrial Revolution had not occurred then CO2 levels would still have gone up by 95% of the amount by which they did increase. That leaves the question of where the CO2 we emitted has gone and where the increase in CO2 we observe came from. If we assume that 97.5% of the CO2 we emitted has been soaked up by negative feed back we must assume that the same would be true of the CO2 from the natural source that is responsible for the observed increase. In other words there is an as yet undiscovered source which is emitting 19 times as much as we are emitting and an undiscovered sink which increases proportionately to increases in CO2 in the atmosphere and is currently absorbing a 19.5 times the amount we are emitting. That looks like a very big source and a very big sink - should be easy to find.
  47. Climate Sensitivity: Feedbacks Anyone?
    michael sweet@4: Your point about Arctic Ice is not correct. Study of north shores of Greenland Paleo study of Greenland North Beach Holland also had a very extensive study on Arctic Ice, but it seems the url to the paper is no longer viable. There are also paleo studies of bow head whales that dispute that the Arctic Ice has been stable for the past 7,000 years. In fact, it has flucuated dramatically.
  48. Climate Ethics: What Can Science Tell Us?
    Sphaerica@18: While this paper (ENSO-Scale Variability in the Eocene Greenhouse Recorded by Fossil Bivalves and Wood from Antarctic) doesn't seem to say anything about the intensity of ENSO, it does seem to indicate that the frequency will be unchanged by warming temperatures. Also a blurb here.
  49. Climate Ethics: What Can Science Tell Us?
    Also, Boer et al 2004. "Three streams of evidence, namely simulations with coupled models, feedback analysis in the tropical Pacific, and observation-based paleoclimate reconstructions, all support the expectation of a future mean El Nin˜o-like temperature response to the positive radiative forcing resulting from a continued increase in atmospheric greenhouse gas concentrations." However, a multi-model study van Oldenborgh et al 2005 isnt so definite, and Guilyardi 2005 concluded "There are no clear indications of an El Nino frequency change with increased GHG." This seems to be repeated in later papers. I would say this is still unsettled science unless someone has some newer evidence.
    Moderator Response: [mc] fixed closing link tag
  50. Climate Ethics: What Can Science Tell Us?
    Sphaerica#16: "unable to find any papers (yet) that explicitly say that climate change will affect (increase) ENSO events." An oldie-but-a-goodie: Timmermann 1999 Increased El Nino frequency in a climate model forced by future greenhouse warming The tropical Pacific climate system is thus predicted to undergo strong changes if emissions of greenhouse gases continue to increase. The climatic effects will be threefold. First, the mean climate in the tropical Pacific region will change towards a state corresponding to present-day El Nino conditions. It is therefore likely that events typical of El Nino will also become more frequent. Second, a stronger interannual variability will be superimposed on the changes in the mean state, so year-to-year variations may become more extreme under enhanced greenhouse conditions. Third, the interannual variability will be more strongly skewed, with strong cold events (relative to the warmer mean state) becoming more frequent. That last one sounds like a description of the last couple of winters.

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