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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 75101 to 75150:

  1. Dikran Marsupial at 22:03 PM on 14 September 2011
    IPCC is alarmist
    lancelot wrote: "In general: Do you think 350ppmv is a realistic global target? If so, when do you think it might be achievable? " This is pretty off-topic for this article, if you want to discuss it in detail, please find a more appropriate thread. From a scientific perspective, the natural environment is currently taking about 1.6GtC per year out of the atmosphere. 40ppmv is about 19GtC, so it would take the natural environment at least 12 years to get back down to 350ppm if we cut emissions to zero today. That gives an approximate lower time limit. So of course it is achievable, however I am rather cynical about those in public office and those that elect them. Both are generally too focussed on short term self-interest to act for the long term good of us all. Thus 450ppmv is a more realistic stabilisation point (the politics being the limiting factor not the science), and we will have to put up with the consequences, which will generally be worst in those parts of the world least capabale of adapting and who generally will have been least responsible for creating the problem.
  2. Dikran Marsupial at 21:48 PM on 14 September 2011
    IPCC is alarmist
    lancelot wrote: "I am quite familiar with the science. " Very clearly this is not the case, otherwise you would not have seen any contradiction in the idea that 350ppm is a "safe" stabilisation concentration yet not having observed a "tipping point" given that we had already past that level. The reason there is no contradiction has already been explained to you, and yet you have not accepted it, nor refuted it. This is not encouraging. A more realistic safe upper limit argument would be to say that the safe upper limit for dietary intake would be 2500 calories per day. However if on one day you eat 4000 calories at a banquet, the fact you didn't have a heart attack or stroke on that day does not mean that 2500 calories is not the long term safe upper limit. The 350ppm is a safe LONG TERM stabilisation figure, not a limit on the safe SHORT TERM transient concentration. If you think it is just that the Wikipedia article is badly worded, why are you discussing it here, rather than at Wikipedia (I suspect the chaps at Wikipedia would point out the error in your position much as I have)?
  3. IPCC is alarmist
    Dikran and CBD, hello. I am quite familiar with the science. I did not 'improperly conflate' RKP and J Hansen with IPCC. Wikipedia does. Don't shoot the messenger! RKP, in his highly public position, should not say things 'off the cuff'. No-one in such a position should. How is whether the figure appears in IPCC reports relevant to the impact of public statements made 'off the cuff'? Have you heard of the 'Media'? CBDunkerson you wrote: "the 'tipping point' comment... it didn't come from either of the two scientists" I didnt say that it did. The Wiki article appears to. Safe upper limit: If an engineer says that 100 lbs per sq ft is a safe upper limit for loading an elevator, he means exactly that. He does not mean that is a limit 'just in case' someone were to walk in carrying another 100 or 200 lbs or whatever. He means it the safe upper limit as would be generally understood in any other field I can think of. If it is not that sort of limit in climate science, what exactly is it? - this seems to be turning into a game of words. I have simply pointed out how the Wiki quote could be (mis)understood by the average reader. Take that up with Wikipedia perhaps? In general: Do you think 350ppmv is a realistic global target? If so, when do you think it might be achievable?
  4. Santer et al. Catch Christy Exaggerating
    Thanks for the pointer, CTG! I'll give it a good look, and maybe get a reprint of Santer too. If it turns out to be useful I'll try and write it all up as a resource.
  5. CO2 limits will harm the economy
    Well this site mostly deals with the science. Climate Progress is one place to discuss the political solutions.
  6. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Research into the climatic impacts of solar cycle variability is certainly worth pursuing. Its just a whole different kettle of fish to suggest that this can meaningfully translate into impacts on climate trends! Thats the point. Its a Cycle! And the important thing to remember is that Solar cycles produce a range of changing phenomena, not just GCR levels on the Earth. Assuming that any solar cycle influence on climate is mainly due to one possible impact of only one of these phenomena changes is unreasonable. Particularly when that is based on studies of correlations only. Off the top of my head here is a list of potential or real influences that the solar cycle 'could' have on climate variability. - Overall solar energy flux from the sun varies a fraction of a percent over the solar cycle. This is well known - Higher energy parts of the solar spectrum, UV and up vary by more than this - 1 to 2% over the cycle. Since UV is absorbed preferentially in the stratosphere, this could have an impact. Also UV is actually involved in the creation of Ozone in the stratosphere. And research in recent years has suggested that the Ozone hole over the Antarctic is having an observable impact on Antarctic weather, resulting in the continent becoming more isolated from weather systems in the rest of the world. - Methane conversion to H2O and CO2 happens mainly in the stratosphere an depends on the availabilty of OH radicals. UV changes could impact on this reaction pathway. - One major source of aerosols that are known to impact on clouds, sulphates, is phytoplankton in the ocean. Changes in TSI and/or UV levels could impact on the rate of aerosol formation by the plankton. - Changes in Solar wind and the magnetosphere don't just impact GCR's, they could impact weather in the Ionosphere for example. - Similarly changes in the degree to which the Earth is shielded from solar influences, solar wind etc could also impact on rates of deposition of interplanetary dust etc onto the Earth. As this falls through the atmosphere it could impact on cloud formation. - Fluctuations in GCR's are also thought to possibly impact on charge separation in clouds. The tops and bottoms of clouds have a significant charge separation and fluctuations in this could impact cloud optical properties and precipitation rates. This pathway of GCR's impacting on the charge searation of existing clouds seems to need fewer hard steps to have an impact than Svensmark's hypothesis. - Then their is Svensmark's theory which is plausible as a possible minor contributory mechanism, but implausible as a substantial or dominant mechanism. Are none, some, all of these mechanisms possible (as well as others we haven't thought of). Yep. Are they proven? No. Hence broad research is worth while. But it is research into cyclical variability, not underlying trend because we know that the cycles involved are too short to explain the observed trends.
  7. Hockey stick is broken
    It would also by nice if you provided a link back to your sources. You are aware of various non-tree ring proxy reconstructions as well?
  8. Renewable energy is too expensive
    Very balanced view on Renewables. Often supporters of Renewables overlook the production costs at present. With increased efficiency and improved materials,solar energy will be cheaper in the coming years especially CSP. Dr.A.Jagadeesh Nellore(AP),India Wind Energy Expert E-mail: anumakonda.jagadeesh@gmail.com
  9. CO2 limits will harm the economy
    Two things: 1. I have a very high level of confidence in climate models, and am not the least but skeptical about AGW. You folks do a bang-up job of demolishing every quibble put into your path. Forgive me if I do not have the same confidence in economic models ... all the whizziest of the math whiz kids out of MIT didn't go into climate science when they could make ten times as much working on Wall Street, and not a one of them managed to predict our current economic debacle. 2. So far, I haven't seen a single mention of just how much good any of the proposed laws would do in terms of reducing the effects of global warming ... to me, a furry-minded layman, they all seemed much too little, and much too late. I would love to see comment on this. P.S. I realize politics are verboten on this thread (although that seems to be subject to considerable wiggle room). What bothers me most of all is that real live scientists are winning the arguments here, and on sites like it, but losing dismally outside them ... the 3% of GW skeptics seem to have swayed more than half the population with garbage arguments. I think we really do need to take a somewhat different approach to the problem if any public action is to be taken.
  10. Hockey stick is broken
    Roh234 - the world has moved on from 1998, but Mc Intyre hasn't. The rebuttal to future hockey sticks remark is amusing, but in all seriousness the evidence is overwhelming that present temperatures surpass that of the Medieval Warm(ish) Period. For starters: 1. Glaciers were advancing in North America during the MWP. See SkS post: Icing the Medieval Warm Period 2. The North American cordillera snowpack was much heavier during the MWP - indicating that it was colder back then. See: The Unusual Nature of Recent Snowpack Declines in the North American Cordillera - Pederson (2011) 3. Atmospheric circulation patterns match the paleoclimate proxies - See SkS post: The Medieval Warm(ish) Period in Pictures 4. Paleoclimate reconstruction below:
  11. It's Urban Heat Island effect
    Roh234 - read the Intermediate version. Noone doubts that urban heat island exists - thats why the effect is removed by comparisons with rural stations in the global records.
  12. There is no consensus
    77/79 is a 97% out of 0.77% of climate scientists. I assume we are using the Doran study. A 30% turn-out may be typical in internet polls but 70% of views are not here. 70% is too large. I'm not claiming that the 70% are skeptics but when 70% don't show up it is not legiminate. And in the Oreskes report he took a poll in 'refered journals'. There has been rejection of skeptic papers in the journal as it 'goes againt the consensus'.
    Response:

    [DB] As a new participant here, please take the time to acquaint yourself with the Comments Policy.  Posting comments here at SkS is a privilege, not a right. 

    Please take the time to review the policy and ensure future comments are in full compliance with it.  Thanks for your understanding and compliance in this matter.

  13. It's Urban Heat Island effect
    Counties in Calafornia have shown evidence of the heat island effect. (-Snip-)
    Response:

    [DB] Posting just a graphic (please restrict widths to 450 pixels or less) without demonstrating the significance of it helps no one.  And therefore proves nothing.

  14. Climategate CRU emails suggest conspiracy
    I got a 60 page report with ove 228 points of legiminate criticism (with propoer citation) why the trial and questioning may be fuzzy. http://thegwpf.org/images/stories/gwpf-reports/Climategate-Inquiries.pdf
    Response:

    [DB] If you want to be taken seriously, dispensing denialist literature with a sweeping hand-wave does you no favors.

    A focus on the science is best.

  15. Hockey stick is broken
    Hey I'm new to this fourm but Steven McIntyre has got a rebuttal to his rebuttal and a rebuttal to any new hockey sticks. here is a reconstruction showing Briffa's exclusion of data and what it really is supposed to be. From the Keigwin 1996 study. I will debate the Heat Island Effect on the specific section which I challege the graphs provided here.
    Response:

    [DB] A better thread for the tree ring discussion is probably Climategate: Hiding the Decline?

    As you are new to this forum, you may want to read it before proceeding further.  Respondees to this, please take it up there.

    The hockey stick challenge Roh234 issues is fair game here.

    Take heat island comments to the It's Urban Heat Island effect thread.  Please read both the Basic and Intermediate tabs to prepare yourself.

    For the record, please in the future also indicate the paternity of your sources for furnished graphics.  Ex:

    Graphic 1 above:  http://joannenova.com.au/globalwarming/hockey-stick/rcs_chronologies1v2.gif

    Graphic 2 above:  http://wattsupwiththat.files.wordpress.com/2009/09/rcs_chronologies_rev2.gif?w=420&h=360

    Graphic 3 above:  http://www.friendsofscience.org/assets/documents/FOS%20Essay/seasurface.GIF

    Graphic 4 above:  http://www.friendsofscience.org/assets/documents/FOS%20Essay/Mann%201998%20+%20Corrected.gif

    Congratulations, no peer-reviewed primary sources used.

  16. Republican Presidential Candidates vs. Climate Science
    Here's a searchable database of the environmental policy votes in the current US Congress. Relevant to this thread because Bachmann is a serving Representative and much of this will actually come to pass if more Repubs are elected. "This is the most anti-environment House in history," said Rep. Waxman. "The House has voted to block action to address climate change, to stop actions to prevent air and water pollution, to undermine protections for public lands and coastal areas, and to weaken the protection of the environment in dozens of other ways." The database offers details on each vote, including the bill or amendment number and sponsoring member, a brief summary of the bill or amendment, the vote outcome, and additional relevant information. The votes are searchable by bill number, topic, affected agency, and affected statute. Canada may not be far enough; I hear Finland is nice.
  17. CO2 is just a trace gas
    Eric @ 100, Well I'll have to say I'm sorry for my terse reply to your comment. Sorry. Based on intuition (I'm a tech, not a scientist ;) I would guess that effectively zero of the principle CO2 IR band photons emitted at ground level make it to space directly. I had to look it up, but see the figure here, from wiki: http://en.wikipedia.org/wiki/File:Atmospheric_Transmission.png The grey area along the CO2 spectrum shows that it maxes out at several absorption bands. The following description of the detectors used for water vapor images on GOES satellites says they are tweaked for sensitivity at a water absorption band or channel, (6.5-7.4 micron), which makes sense if you're interested in water vapor. http://cimss.ssec.wisc.edu/goes/misc/wv/wv_intro.html If you check that band against the figure at my first link, you'll see that 6.5-7.4 microns (on the logarithmic x axis) is where water absorbs strongly, and not much else does. (CO2's strongest absorption band is more in the 13-17 micron range.) So the black on the water vapor image, aside from being an assigned translation of the IR signal to a visible representation, and not an innate property, indicates lack of water vapor, not lack of absorbance/emission by CO2. Thanks your considered reply to my previous comments. Cheers.
  18. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    gpwayne#27: "why is Kirkby looking for a mechanism" The original its cosmic rays thread has the history. Blame the fascination with Svensmark's earlier work, suggesting a correlation between CR flux and cooling episodes; Nigel Calder hyped this to no end (still does). What I've noted is that they've lost any connection at all to the paleo record of CR-produced isotopes (such as Be10) and their correlation with cooling events. By the time rebuttals of Svensmark were published, the CLOUD funding was approved. It is an interesting academic question with valid theoretical support - ionizing radiation does indeed make 'clouds' in saturated environments (ie, cloud chambers). High energy particle physics projects take a long time to get going and tend to live for a while; look at the number of secondary authors on their papers. Once the detector is built, secondary beam time (they are not using the LHC's main beam) is relatively inexpensive. One could also suspect that the LHC administration was anxious to produce some results while waiting for the Higgs to show up.
  19. Climate Communication: Making Science Heard and Understood
    Poynter.News University offers a free, 4-hour, online, self-directed course, “Covering Climate Change.” To access it, click here.
  20. SkS Weekly Digest #15
    pbjamm: that is a delightful article. Thanks for sharing it. I hope others follow the link. I got obsessed with exoplanets a year ago because the science of detecting gases in explanet atmospheres is a logical extension of understanding our own planet's greenhouse effect. jg
  21. OA not OK: Booklet available
    “Stanford University researchers have gotten a glimpse into an uncertain future where increasing levels of carbon dioxide in the Earth's atmosphere will lead to higher levels in the ocean as well, leaving the water more acidic and altering underwater ecosystems.” Source: “Oceans' increasing acidity likely to hurt biodiversity” by Louis Bergeron, R&D, Sep 13, 2011 To access this in-depth article, click here.
  22. Climate Denial Video #6: Past climate change
    "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." Well the obvious one is where the increase in GHG is also accompanied by an increase in aerosols with a similar magnitude of forcing. However, aerosols are shortlived in the atmosphere compared to CO2, so if the GHG is CO2, then warming results as aerosol declines. As to what happens in the ice reversal, well see the appropriate thread, but when solar declines in NH, albedo increases, cooling starts, and the feedback mechanisms for GHG (methane sources freeze and then as ocean cools, CO2 is absorbed, etc) work in reverse to amplify cooling.
  23. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    "Both solar magnetic field strength and the number of cosmic rays reaching Earth have been flat over the past 50+ years..." I'm quite puzzled by this CERN experiment. When I first heard about it, I took a look at the sun's output and found the same thing - not much going on in TSI, field strength or rays. So my question is this: why is Kirkby looking for a mechanism that correlates cosmic rays with climate change, when the catalyst for the 'forcing' has been notably absent during the most dramatic increase in global temperatures?
  24. Climate Communication: Making Science Heard and Understood
    Susan, one program a group like yours could/should set up, is workshops (online?) (preferably, accompanied by some dedicated funding) for people from small nonprofits whose missions are threatened by climate change, to equip these communicators with the most important & misunderstood concepts & points so they can (& will be motivated to) communicate the basic information needed by their communities.
  25. Santer et al. Catch Christy Exaggerating
    Kevin - Bob Grumbine did a post on this a while back. He came up with 20 years as the minimum length, although 17 years is probably about long enough. There are several factors you need to consider.
  26. We're heading into an ice age
    Dana, The question is: did man change the climate 5,000 years ago to prevent the change to an ice age or was the climate not changed until the last 100 years? ASFIK that question is still under debate. With the current carbon in the atmosphere the next several ice ages have been prevented. As we emit more carbon the time until it will be removed by natural causes keeps getting longer and longer.
  27. We're heading into an ice age
    I was directed from another thread to this topic. From what I have been able to gather, the addition of man in the climate equation, has created a new hypothesis: That man contributing CO2 levels in the atmosphere have altered the climate in such a way as to prevent future ice ages from happening. The reason behind this being that CO2 is a forcing that far exceeds any counter negative feedback. If true this is a whole new direction of thought.
    Moderator Response: Click the Intermediate tab. Then read.
  28. Climate Denial Video #6: Past climate change
    Dana69, unfortunately no... you haven't made yourself clear. Why do you have a problem with orbital forcing driven CO2 increases stopping when the orbital forcing does? That would seem self-evident... yet in #21 you appear to hold it out as some sort of 'obvious flaw'. I can't figure out what you think is 'wrong' with it. If you look at the ice core CO2 records of past glaciation cycles you will see that CO2 'quickly' (~10,000 years) rises from ~180 ppm to ~280 ppm and then slowly drifts back down. Looking more closely at the current cycle CO2 levels had been at 280 ppm +/- 10 for a few thousand years prior to the industrial revolution. In short, CO2 levels had not changed significantly for a long time and thus were not causing any additional warming of the planet. As the orbital forcing reverses we would then see cooling from that... which would result in a decreasing atmospheric CO2 feedback and thus more cooling. Obviously the 'recent' large human CO2 emissions have changed this, but the point is that CO2 levels from natural emissions had leveled off... and perforce warming from them had done so as well. There wasn't any 'ongoing warming' to prevent cooling from the orbital shift. CO2 feedback effects do not self perpetuate ad infinitum... otherwise the planet would have burned to a crisp long ago.
  29. Republican Presidential Candidates vs. Climate Science
    Here’s another article similar to Dana’s. This one, however, includes quotes by the candidates on both climate science and evolution. “In Their Own Words: GOP Candidates And Science” by Corey Dade, NPR, Sep 8, 2011 To access this article, click here.
  30. Climate Denial Video #6: Past climate change
    Dana: "I am ok with this, but what I cannot wrap my tweener brain around is how to explain the opposite affect. Meaning, there must be a point where temperature reverses and starts to decline, but CO2 levels MUST be higher, YET do not affect this reversing trend of the earth falling back into an ice age. Unless the new hypothesis states that since man is contributing all this additional CO2 there will be no new ice age, and that man has permanently altered this process through the increase in man-made CO2 levels." Move this to the ice age thread.
  31. CERN - Saying Nothing About Cosmic Ray Effects on Climate
    Esop#23: "should put a rather sizeable dent in Svensmarks theory. " You're correct; this apparent contradiction should dent Svensmark right out of the park. The solar minimum was indeed accompanied by a max in GCR flux in 2009. So there should have been beaucoup clouds and much cooling. But the people who buy this 'theory' also believe warming stopped in 1998. I suppose this proves that if you believe in two simultaneous falsehoods (warming stopped and GCRs cause climate change), that makes them true.
  32. Climate Denial Video #6: Past climate change
    DSL, Let me answer your question first then ask a follow up question that has bugged me. 1) Yes I agree that humans are the source of the most recent and rapid rise of CO2 in the troposphere (not sure if the distinction is relevant) 2) Yes, I do accept that CO2 is a positive forcing on temperature. Now my main point of incongruity is from this site itself. Note: "When the Earth comes out of an ice age, the warming is not initiated by CO2 but by changes in the Earth's orbit. The warming causes the oceans to give up CO2. The CO2 amplifies the warming and mixes through the atmosphere, spreading warming throughout the planet. So CO2 causes warming AND rising temperature causes CO2 rise." I am ok with this, but what I cannot wrap my tweener brain around is how to explain the opposite affect. Meaning, there must be a point where temperature reverses and starts to decline, but CO2 levels MUST be higher, YET do not affect this reversing trend of the earth falling back into an ice age. Unless the new hypothesis states that since man is contributing all this additional CO2 there will be no new ice age, and that man has permanently altered this process through the increase in man-made CO2 levels. No matter what you label me, this is something that sticks out in my head. If this is true, there seems to circumstances which appear to counteract the conclusion that CO2 is ALWAYS a forcing. Also, I read GMB post#10 at 16:57 PM on 27 December, 2007 under CO2 lags Temperature. It was a much different take on the subject, but I notice no one answered when he states: "This idea that Malinkovitch needs CO2 feedback to do the job is clearly false. Since it relies on a WATTS-PER-SQUARE-METRE model which is a light-and-air-only model. "If we allow for the accumulation and decumulation of joules in the planet and the oceans then it is the factor of TIME ALONE that needs to be taken into account and not this sideshow of CO2-feedback. We ought to be looking at a model which relies on STRATA AND HEAT BUDGETS." I pray that I have made myself clear, because I hate all these denier labels and I know you feel these might be sophomoric questions. Thanks in advance, and oh by the way, I have read the IPCC reports, and for one in search of knowledge they are no help.
    Moderator Response: [Dikran Marsupial] you write "No matter what you label me", please can you avoid this sort of thing, SkS works best when everybody concerned keeps everything on a calm impersonal scientific basis. This sort of statement comes across badly (it implies that the other parties in the dicussion are looking to label you, which is unfair to them).

    Now if the IPCC reports are not much help, that probably means you need to start with something a little more basic (e.g. Houghton's book).

    Lastly, if there is something you don't understand, or you want to ask a question, it is best simply to ask a direct question without the extensive quoting or digressions.
  33. Climate Denial Video #6: Past climate change
    Just a note on Dikran's moderator comment to #17... I presume that the second to last sentence, "BTW, the observed rise is 100% anthropogenic", is referring to the rise in CO2 rather than the rise in temperature. I make this assumption because otherwise Dikran would be incorrect, and that just can't be the case. :]
    Moderator Response: [Dikran Marsupial] Yes, absolutely correct. The rise in CO2 is 100% anthropogenic, the rise in temperatures is not.
  34. Climate Denial Video #6: Past climate change
    Dana, do you accept that humans are the source of the recent and rapid rise of atmospheric CO2? And do you accept that increased CO2 is always a positive forcing on temp (whatever else is going on)? It's important that we establish something, or else we end up like middle-class sophomore philosophy majors: all talk and no performance--all theory and no practice. No one has the patience for that here. Most of the discussion on this site is now in the realm of determining the influence of various forcings and feedbacks beyond GHGs. The science reflected in the IPCC-supported sensitivity models is robust, and there are hundreds of links on this site that you can follow to get a feel for that robustness. Note that there is no "other side." There is no comprehensive alternative theory widely supported by some "other side." If you tried to create a physically consistent model out of all of the attacks on the theory of AGW, you'd fail miserably. That's why SkS isn't set up on an "us vs. them" either-or framework. If you want to understand sensitivity, there are plenty of other articles and threads on SkS where you can do this (with semi-live people willing to take part).
  35. Climate Denial Video #6: Past climate change
    I am not sure why it repeats, I am truly not trying to do that. Please forgive me.
    Moderator Response: [Dikran Marsupial] No problem, it has happened before. It is probably becuase you are using the reload button, or the forward and backward buttons to navigate, which in some circumstances can resend the post.
  36. Are you a genuine skeptic or a climate denier?
    From an article in CounterPunch recently by Michael Brenner (International Affairs at the U of Pittsburgh: "Of course, this last is a feature of contemporary American political culture in general. Facts are taken to be infinitely malleable, the very notion of truth is denied, speaking honestly is viewed as a life style choice, and communication is more a matter of self affirmation than an attempt to convey knowledge, emotion or intention to somebody else. We have externalized navel gazing to a remarkable degree. All the demonstrative primping and preening suggests self-licking ice cones looking for an audience. One consequence is that public discourse is not anchored by common standards of honesty. It is a maelstrom of raw opinion, emotive outbursts, mythology and primal screams. Accountability, therefore, ceases to exist. There is accountability only where there are benchmarks of veracity, a reasonably rigorous monitoring of what is said and done, and a dedication on the part of some at least to ensuring that these requirements for a viable democracy are met. The abject failure of the media to perform these functions to any reasonable degree is a hallmark of our times. The think tank and academic worlds are little better." The piece was on Obama, but this section seemed awfully relevant to the work being done at SkS.
  37. Santer et al. Catch Christy Exaggerating
    Note: The keys for Figures 6A and 6F are vitually unreadable due their tiny size. Clicking on them will generate a screen showing the complete set of graphs, A thru F, in a slightly larger size. The keys are readable on the pop-up page.
  38. Climate Denial Video #6: Past climate change
    Guys, [inflamatory snipped] "From the available evidence it is quite clear that human emissions are the main cause of the increase of CO2 in the atmosphere. There is a small influence of temperature on this increase, as warmer oceans emit some CO2 (but warmer land absorbs more CO2 in vegetation!). But the influence of temperature is limited: based on the variability of the CO2 increase around the trend, the short-term (1-6 months) ratio is about 3 ppmv/ºC (based on the 1992 Pinatubo and 1998 El Niño events). The very long term influence of temperature on CO2 levels (Vostok ice core) is about 8 ppmv/ºC. Thus at maximum, the influence of temperature on the current increase is 0.7 ºC x 8 ppmv/ºC = 5.6 ppmv of the about 100 ppmv increase since the start of the industrial revolution. There are only two fast main sources of CO2 to the atmosphere, besides the burning of fossil fuels: oceans and vegetation. Vegetation is not a source of CO2, as the oxygen deficiency (in 5.5) showed. Neither are the oceans, as the 13C trend (in 5.3) and the pCO2/pH (in 5.6) shows. This is more than sufficient to be sure that human emissions are the cause of most of the increase of CO2 in the atmosphere of the past 1.5 century. Thus we may conclude: All observed evidence from measurements all over the earth show with overwhelming evidence that humans are causing the bulk of the increase of CO2 into the atmosphere. But... That humans are the cause of the recent increase of CO2 doesn't tell anything about the influence of increased CO2 on temperature! Humans may be responsible for (a part of) the temperature increase. How much, that is an entirely different question, as that mainly depends of the (positive and negative) feedbacks that follows any increase of temperature..." Seems like everything is contained in here and gives credit to both sides. No denying, same physics, yet diverse conclusions.
    Moderator Response: [Dikran Marsupial] Please do us a favour and go and read the technical summary to the IPCC WG1 report. You will find there that not all of the observed warming is attributed to AGW, so you are arguing against a position that nobody is actually taking.

    Your statement that "That humans are the cause of the recent increase of CO2 doesn't tell anything about the influence of increased CO2 on temperature!" is also a non-sequitur. The influence of CO2 on temperatures is established by physics (theory, experiment and observation), and remains true whether we are emitting CO2 or not.

    BTW, the observed rise is 100% anthropogenic. I'll happily discuss how we know that to be true on a more appropriate thread.
  39. SkS Weekly Digest #15
    Not sure this is exactly ontopic but it seemed like as good a place as any to link to an article about climate change and the scientific method. Diamond planets, climate change and the scientific method: "And yet the diamond planet has been hugely successful in igniting public curiosity about the universe in which we live. In that sense, for myself and my co-authors, I suspect it will be among the greatest discoveries of our careers. Our host institutions were thrilled with the publicity and most of us enjoyed our 15 minutes of fame. The attention we received was 100% positive, but how different that could have been. How so? Well, we could have been climate scientists."
  40. Santer et al. Catch Christy Exaggerating
    Could somebody tell me if I'm interpreting Santer's Figure 6 correctly, particularly 6A and 6E? He took model outputs, which include hindcasting for most years, and projections for the last few years since AR4, and compared the model ensemble average TLT to the observations. Figure 6A shows the model average (hindcast + projection) differs from the model observations by just a little less than 2 standard deviations. Figure 6E (click on Skeptical Science graph to get the full graph) seems to confirm this by showing that the "weighted pf value (OBS vs 20CEN/A1B trends" is about 0.07. In other words, whether the model average TLT trend is significantly different than the observations depends upon whether one chooses 90% or 95% confidence interval.
  41. Climate Denial Video #6: Past climate change
    Yes, Dana, given the current Earth system and the likelihood of its persistence, GHGs must result in warming. Other things might overwhelm that warming, but GHGs will STILL be acting to warm. It's all about the net effect of all forcings and feedbacks.
  42. Climate Denial Video #6: Past climate change
    Dana69 - I'll have to ask you to excuse my interpretation, but you appear to be hunting for reasons to deny CO2 warming. While the epistemology of math is an interesting subject in itself, epistemology is quite a different realm from the accumulated physical evidence, and I must view your introduction of it as a red herring. The direct effect of doubling CO2 is ~1°C warming. Feedbacks look to amplify that to a climate sensitivity of ~3°C. There is essentially zero evidence for sufficient negative feedback to suppress that forcing. Please read that link for a discussion of the evidence in this regard.
  43. 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).
  44. 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.
  45. 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.
  46. 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.
  47. 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.
  48. 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.
  49. 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.
  50. 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.

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