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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 75201 to 75250:

  1. 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.

  2. 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.

  3. 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.

  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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
  9. 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.
  10. 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.
  11. 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?
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. 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.
  18. 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.
  19. 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.
  20. 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.
  21. 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.
  22. 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).
  23. 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.
  24. 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.
  25. 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.
  26. 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.
  27. 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."
  28. 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.
  29. 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.
  30. 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.
  31. 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).
  32. 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.
  33. 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.
  34. 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.
  35. 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.
  36. 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.
  37. 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.
  38. 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.
  39. 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.
  40. 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
  41. 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
  42. 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.
  43. 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.
  44. 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.
  45. 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.
  46. 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.
  47. 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.
  48. 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.
  49. 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.
  50. 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.

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