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Unforced variations: Nov 2011

Filed under: — group @ 31 October 2011

Once more unto the open thread…

341 Responses to “Unforced variations: Nov 2011”

  1. 151
    Hank Roberts says:

    sidd, this paper might cite or lead you to sources on how long mercury lasts in strata:

  2. 152
    David B. Benson says:

    How much will it rain, a correction. From section 6.8 in Ray Pierrehumbert’s “Principles of Planetary Climate” we have the effects of the boundary lawyer upon latent heat (and so the associated water vapor). For temperature ranges of current interest the dependence seems to be a low order polynomial rather than exponential. Even though the book states slowly varying that is, IMO, only in comparison with an (approximately) exponential function; we can be sure the temperature dependence is greater than linear.

    However, I had thought I understood the final figure of the SI for
    Seung-Ki Min, Xuebin Zhang, Francis W. Zwiers & Gabriele C. Hegerl
    Human contribution to more-intense precipitation extremes
    NATURE VOL 470, 17 FEBRUARY 2011, 378–381
    but I understand now that I don’t understand.

  3. 153
    vukcevic says:

    Re: 139 Snorbert Zangox says:
    9 Nov 2011 at 7:56 AM
    For evolution of the idea see my exchange with Dr. Scafetta on:
    Although it was meant as a half-hearted comment, which is obvious from the tone of my post, but to my surprise, it was then taken seriously by Dr. Scafetta.

    I have looked into this, analysing number indicators considered as acceptable and widely available data: the sunspot record, Ap index, the Arctic’s magnetic field differential and the McCracken’s data for the strength of magnetosphere at the Earth’s orbit, no evidence was found for consistent 60 year cycle.

  4. 154

    Anyone want to discuss the Younger Dryas again? Didn’t think so.

    Colman et al. have officially weighed in here, results which I am unable to reconcile with Rayburn et al. here. Is this a huge crisis in geophysics? Or not?

  5. 155
    Brian Dodge says:

    @ Thomas Lee Elifritz — 12 Nov 2011 @ 11:09 AM re draining of Lake Agassiz into Lake Superior.

    IMHO, it’s not a crisis in geophysics. The key quote from Colman et al is “The Thunder Bay area contains none of the features observed further north in Lake Superior, which have been interpreted as flood-related from earlier seismic surveys.”
    Which means that Lake Agassiz did drain through the St. Lawrence to the North Atlantic, just not through Thunder Bay.
    Plug the coordinates 49.04957, -88.34038 into, go to terrain view and zoom out – there are a lot of features that look erosional on a large scale. Also see “this.”

  6. 156
    Dick Veldkamp says:

    Denial ain’t just a river in Egypt. Look here:

  7. 157

    The Thunder Bay area contains none of the features observed further north in Lake Superior, which have been interpreted as flood-related from earlier seismic surveys.

    Right, but they describe Nipigon floods as “post Marquette” as does everyone else. We know there has been lots of flooding there. The ‘Nipigon phase’ was much later than the Younger Dryas, when the ice sheet had clearly receded to that area. What is not clear is the extent of ice sheet decay at that time.

    For water to have flowed from Lake Agassiz at the YD interface into Lake Superior, either there must have been a serious disruption of the ice sheet at that location, or there must have been a massive subglacial flow from the Lake Kelvin (Nipigon) basin as in a sub glacial lake discharge, literally cutting a channel under and through the ice. Somebody has to admit that the water must have flowed through the Nipigon feeder networks at 13 ka, and nobody seems to want to touch that claim. Did water flow through there at 13 ka, or not? I don’t see any way around this. It looks like a crisis to me.

    A minor one, I’ll grant that. The data seems to disagree with the consensus.

  8. 158
    David B. Benson says:

    Brian Dodge @155 — That drainage further north happened long after Younger Dryas. The drainage associated with the onset of Younger Dryas was NNW into, eventually, the Arctic Ocean.

  9. 159

    (from Times Atlas thread, comment #38)

    Ira Glickstein, Might I suggest, respectfully, that we take this over to the open thread (labeled “Unforced Variations”). It would not distract from the subject there.

    Comment by Ray Ladbury — 11 Nov 2011 @ 11:23 AM

    Thanks, Ray, here I am. What would you like to discuss further? I’ll keep my eye on this thread for the next several days.

  10. 160
    Ray Ladbury says:

    Hi Ira,
    I am just curious how one can look at the aggregate of the evidence and not be very concerned about the likely effects of climate change–particularly in a world that will have ~10 billion people and likely no source of cheap energy, fertilizer or organic chemical feedstock.

    That one can accept that greenhouse gasses are responsible for ~33 degrees C of warming and think you could double CO2 in the atmosphere without significant warming simply defies logic–as well as evidence.

  11. 161
    Jim says:

    Just a note here to say that there has been an increasing spam bombardment over the last week or so. This necessitates bulk comment deletion without wading through them to pick out the legitimate ones (as I try to do).

    So, if you have any uncertainty about where your comment may have landed, probably best to send again. And of course, always execute a quick “copy” command before sending anything that you spent much time on. And we know that everyone spends *much* time on their comments.


  12. 162

    The drainage associated with the onset of Younger Dryas was NNW into, eventually, the Arctic Ocean.

    I reiterate, that appears to be in conflict with a growing body of evidence.

  13. 163
    dhogaza says:

    since it’s the open thread, McI has wasted no time in indicting Penn State’s failure to stop a butt-loving football coach with it’s so-called “failure” to go after Mann

    Because doing sound science is, after all, equivalent to showering with a 10-yr old kid and making “slapping noises” (use your imagination, or read the indictment).

    Pay particular attention to Mosher, who in recent months has been trying to paint himself as a rational “lukewarmer”. He’s being particularly vile (though not so vile as Mci).

    What’s going on over there is truly disgusting…

  14. 164
    Edward Greisch says:

    110 116 Chris R: “FWIW I think that if we crack AGW it will be because of new technology, in particular, success at implementation of fusion.” See:
    Chris Mooney’s new book: “The Republican Brain”
    “Market forces won’t allow that” means “We want to keep the status quo.”
    Any other excuse means “We want to keep the status quo.”
    No matter what alternative you propose, the answer is “We want to keep the status quo.” But the answer is always in some sort of “code” [doubletalk] that makes the answer sound reasonable.

    Why do they want to keep the status quo? It may have something to do with different sizes of certain parts of the brain; or personality traits.
    says: “Recent converging studies are showing that liberals tend to have a larger and/or more active anterior cingulate cortex, or ACC—useful in detecting and judging conflict and error—and conservatives are more likely to have an enlarged amygdala, where the development and storage of emotional memories takes place.  More than one study has shown these same results, which is why I felt it was worth investigating.”
    has pictures.
    So new technology isn’t going to gain anything. And there clearly isn’t time for evolution.
    I am presently reading “Willful Blindness” by Margaret Heffernan.

  15. 165
    David B. Benson says:

    Thomas Lee Elifritz @162 — Sorry I didn’t keep the link to the geology paper; the evidence looks fairly solid and there is exactly zero evidence of Proglacial Lake Agassiz draining eastward in the Moorhead phase. Further, there is a geology paper (which I linked towards the very end of the comments on the second-but-last Clovis Comet thread here on Real Climate) that the Proglacial lakes along the Laurentide Ice Sheet well to the east catastropically drained down the Mohawk (eventually to the Atlantic). And guess what? This was almost at the onset of Younger Dryas. [I take that ass more important than the IMO overrated drainage of Proglacial Lake Agassiz.

    The paper you cited by Rayburn et al. appears to indicate that Proglacial Lake Vermont also drained at about the same time, but the claim that Proglacial Lake Agassiz drained that way flies in the face of abundant evidence from modern Lake SUperior east. Well, well. So another large lake drains into the Atlantic. Addin those to Baltic Ice Lake I also draining into the Atlantic around the onset of Younger Dryas and quite the salinity crisis happened.

    That makes four proglacial lake (systems) all draining simultaneously. Given that all weere poised to drain I suppose that is not entirely coincidental. But it does provide some modicum of weak support for the Clovis Comet hypothesis.

  16. 166
    Chris R says:

    #162, Thomas Lee Elifritz,

    Your comments remind me of a long-held suspicion of mine.

    It’s been years since I read on the subject of the Younger Dryas. When I last did I found myself persuaded by Wunsch – that changes in the THC were not responsible for DO events, and that events such as those and the YD could be explained by changes in wind fields. i.e. the consensus view has the tail wagging the dog, whereas it was changes in wind fields modified by the advance/retreat of ice sheets that impacted ocean currents, not the ocean currents impacting the atmosphere.

    I take it you’ve read Wunsch, 2006, “Abrupt climate change: An alternative view.”

    I may be out of date and haven’t seen research that refutes Wunsch on this issue.

  17. 167

    there is exactly zero evidence

    That’s pretty scary, I guess I can’t comment on that at all.

    changes in the THC were not responsible for DO events, and that events such as those and the YD could be explained by changes in wind fields

    That’s more reasonable, but certainly fresh water forcing and ice fields and atmospheric gas changes played a role on the general climatic response to the changes brought on by the slow changes in solar insolation and isostatic rebound. Many large proglacial lakes were draining in many different places at this time, and I’m not oversimplifying the problem by making demanding statements, I’m merely interested in the Lake Agassiz eastern flow and/or flooding part of the problem. You can see the mess of things it made up there, sediments made it all the way into Lake Michigan. The question remains, Nipigon at 13 ka, or not?

  18. 168
    JCH says:

    Ira Glickstein – a layperson here who has a question about significance. I made this little graph. It shows the following trends:

    1971.83 to 2001.83, 30 years – #Least squares trend line; slope = 0.0150668 per year

    The above trend does includes very little of “the pause”.

    1981.83 to 2011.83, 30 years – #Least squares trend line; slope = 0.0177352 per year

    The above trend includes the entirety of “the pause” to date: 20 years of no pause, 10 years of “the pause”.

    1991.83 to 2011.83, 20 years – #Least squares trend line; slope = 0.0215113 per year

    The above trend includes the entirety of “the pause” to date: 10 years of no pause, 10 years of “the pause”.

    Each trend is stronger than the last. Is this significant?

  19. 169
    Hank Roberts says:
    Absence of a Younger Dryas Signal along the Southern Shoreline of …. at the beginning of the Moorhead phase (Figure 1B), when Lake Agassiz was to have drained east ….


    The history of the idea has been pretty well documented; it’s been one of those very attractive ideas that people find innately beieveable; some simply assert it must be so, others have tried to find evidence for it.

    People get caught up on ideas and _believe_. You know other examples.

  20. 170

    Many people take issue with the sparse carbon and beryllium isotope dating of heavily reworked and widely transported artifacts supplied by the Fisher and Lowell camp. Even the dating on the Athabasca and McKenzie river channels has been questioned. I am not claiming there was no NW drainage of Glacial Lake Agassiz at 13 ka, although that too is certainly a reasonable debate to have. Even the Champlain Sea sequences have not been resolved enough for a definitive chronology yet, and the Nipigon problem is similar. These conflicts have simply reached the level of a minor scientific crisis.

  21. 171
    Hank Roberts says:

    > minor scientific crisis

    This quite current main blog post seems to touch on all the main points, citing sources. A discussion worth having once in one place, rather than repetitions scattered over many different blogs simultaneously, I suggest.

    That looks like a good place to find all the bits.

  22. 172

    I’ve more or less abandoned the YD impact hypothesis, although I’m still waiting on microlithology on samples and possibly a lake coring from the area. My interest is purely paleohydraulic at this point, including and especially ‘something considerably more subtle and cryptic’ i.e. – the Younger Dryas. Including the referenced geomorphism, the last remaining contentious issue with the eastern flows is, did they occur at 13 ka, and if they did, then where? I am left with evidence clearly pointing to anomalous flooding through Nipigon, where we now have an anomalous geomorphic feature.

    The geomorphism itself can be discussed over at the blog posting you cite. Melosh’s work concerns itself mostly with head on classical impacts on airless worlds, where with the proposed YD impact would be a volatile rich oblique impact on a several kilometer thick ice sheet, creating a lateral subglacial blast wave. In that case the actual crater would be the much smaller 10 kilometer depression just to the west of Black Sturgeon Lake.

    Since most if not all concerned claimed that never happened, I am thus left looking for alternative explanations of the paleohydraulic history of the Nipigon flood channels, particularly with regard to proposed YD 13 ka flows, for which there is mounting evidence that flooding actually did occur. It may be possible to refute that scenario as well, and I’m open to that too.

    It’s just a minor crisis, I’m sure all those involved will get it sorted out.

  23. 173
  24. 174
    John says:

    jch – I just went to your graph page and changed the start date for the third series to 2001 – WOW, what a difference. I suppose ten years is considered a short time interval since we are now told that 30 years is the minimum for climatologists to see any significance.

    So, I am now confused – in this article, we are told that ten years is enough time to show long term trends (paragraph 3). Please help me if I have read this paragraph incorrectly.

  25. 175
    MARodger says:

    So where is Ira Glickstein? Is he too busy fighting off the snarky comments from skeptics at WUWT?
    Poor Ira posted a story on WUWT telling all the skeptics what a fun time he was having commenting here at RC & now he’s getting a right telling off, some more polite than others.
    Interesting to read the likes of Willis Eschenbach saying “The appearance of any serious skeptics there (at RC) gives them credibility.” and “So let me go on record as saying I won’t be a useful idiot and participate in the RealClimate farce.” I suppose this is true – in my experience it is the exception to find an idiot useful.

  26. 176
    Hank Roberts says:

    More borehole information aggregated — anything useful for climate study?

  27. 177
    Hank Roberts says:

    For “John” (and Ira G. if he comes back)
    — there’s a high-school-level explanation available at Grumbine’s blog.

    You’re confused (“thirty years” or “ten years”) because you’re reading about different data sets. The numbers are different, so the calculations, done the same way to figure how many years/observations are needed, do come out with different answers.

    It’s a pretty simple exercise. You can do the arithmetic to convince yourself that the numbers come out as people say (or that they don’t).

    (and the links posted earlier may also help you decide who’s trying to fool you and who’s trying to help you do the arithmetic — hint, if people pick only a short time span to make a claim, be skeptical; if they use all the available information and show you their work — be skeptical, and check the arithmetic, or as R. Reagan put it, “trust, but verify.”)

  28. 178
    Hank Roberts says:

    And by the way, John (and Ira G.) — Robert Grumbine sums it up and offers you what you need to check this for yourself; links in several of those posts I gave you above. For example:

    —-excerpt follows—–

    this will give you a decent start in reviewing arguments.

    Trend analysis must be done over a long enough period
    All relevant data should be considered.
    If this results in a period shorter than normally considered long enough, a specific and strong explanation must be made
    Trends cannot be computed by picking a single year to start from and a single end year and then ignore all years in between
    Average error is not sufficient. Squared errors should be used, or some other method which avoids the problems that ‘average error’ has.

    Regarding that last point, I’ll suggest some looking at the numbers yourself. I’ve made up a spreadsheet available in both Excel and OpenOffice formats for you ….

    —– end excerpt—–

  29. 179
    JCH says:

    John – I don’t see anywhere in the press release an argument for claiming a ten-year trend in GISTEMP LOTI global mean is now statistically significant, or otherwise meaningful.

  30. 180
    dhogaza says:

    John … not wanting to pile on here but …

    So, I am now confused – in this article, we are told that ten years is enough time to show long term trends (paragraph 3)

    They say:

    the long-term, net impact of aerosols on cloud height and thickness, and the resultant changes in precipitation frequency and intensity

    Ten years will give you data on many, many, many cloud events so it’s not at all surprising that a shorter timespan is sufficient for them to come up with statistically significant results. They’re not just looking at weather rather than climate, they’re looking at impacts on individual clouds and drawing trends from that.

    In contrast, detecting a climate trend takes a longer period of time because the trend is relatively small in magnitude compared to the natural variability in the system. If the trend were (say) a 20C rise per decade rather than 0.2C you probably wouldn’t need 30 years to tease out the trend from the noise … but it’s not :)

    So, as Hank has said, different data sets (derived from different phenomena) require different amounts of data for useful statistical analysis.

  31. 181
    Hank Roberts says:

    John didn’t understand the basic info about statistics.

    Once he’s read Grumbine he will understand that the calculation — how long a period is needed to detect a trend (how many observations, and how variable the data are) — comes out different if you start with different numbers taken from different data sets.

    And he’ll understand this post
    about how septics fool readers by misstating that.

    “On two occasions I have been asked, ‘Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?’ I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.” -Charles Babbage

  32. 182
    MARodger says:

    Ray Ladbury @160
    I’ve found Ida G. for you. It seems he’s still at WUWT saying he tried to post here at RC but it hasn’t emerged onto the thread. He assumes it hasn’t escaped from the clutches of Mr Moderation. He says he’ll try again but in the meantime he’s pasted the comment up at WUWT, all 780 words of it.

    An interesting number that, as according to those 780 words Ida is not concerned by 780ppm of CO2 (ie 2x390ppm) because it would take until 2200 to reach that level at present rates (or 2100 at double the rate) and this doubling of CO2 would only increase global temperatures by 4.5 – 2 deg C (IPCC) or 1 – 0.5 deg C (other experts), of course plus or minus those natural cycles etc. In fact Ira is only worried about running out of good home-produced fossil fuels which would put honest folk like himself at the mercy of foreign scoundrels.
    Of course Ida used more words to say all that.
    Folk may think it’s a bit of a cheek me paraphrasing Ida like this. Then he did paste me onto WUWT without a by-your-leave.

  33. 183
    Pete Dunkelberg says:

    Ida G et al., is someone looking for this?

  34. 184
    John says:

    Thank you for the kind responses.

    I reviewed the links given by Hank Roberts and found them easily understood.

  35. 185
    David B. Benson says:

    Rising Air Pollution Worsens Drought, Flooding, New Study Finds
    is thorough for this type of article and very interesting. Helps explain the changed patterns of precipitation around here.

  36. 186
  37. 187
    JCH says:

    David Benson – that article is about the same paper John referred to in in his comment at 174. If you lookhere, they have some graphs from the article. Figure 3 shows trends significant at 95%.

    His question was about 10 years of data allowing statistical significance in a longterm trend the paper found whereas 10 years of temperature data is insufficient to establish significance in the GMT.

    Anyway, when I was reading it, I thought it was a very interesting study in terms of recent examples of heavy rainfall events.

  38. 188
    MARodger says:

    Could the RealClimate moderators confirm whether or not Ira Glickstein had a comment blocked on this thread on 13/11/11?

    I appreciate Ira Glickstein’s motives for commenting at RC, as evinced by his post at WUWT, were/are less than genuine (which maybe part-justifies the post author editing Ida’s comment text). I appreciate that RealClimate is a commentary on climate science and not a commentary on climate scepticism. I apprecaite the moderator’s job is pretty much a thankless one.

    Yet RealClimate is being accused of blocking a “respectful'” & “serious” comment that was invited by RC readership.
    So was Ira Glickstein blocked on this thread on 13/11/11? Or did his comment disappear into a months-old obsolete thread as Pete Dunkelberg @183 noticed happened to Ida’s 11/11/11 comment?

    [Response: Don’t know but I told everyone a couple of days ago that I’m not fishing stuff out of the spam folder anymore, because there are too many messages in there to wade through. It’s very likely that at least some legitimate messages have been deleted recently. On top of that though, he needs to learn that we’re not here to answer the same old questions like he asks, that have been asked a million times before, and/or do peoples’ basic homework for them. It’s tiresome–Jim]

  39. 189
    Walter Crain says:

    what do you guys make of this? this, from the abstract, is surprising:

    “On the whole, the most scientifically literate and numerate subjects were slightly less likely, not more, to see climate change as a serious threat than the least scientifically literate and numerate ones.”

    [Response: It would depend on what exactly people thought. If there is a group of less literate people who think that climate change means the end of world sometime next Thursday, while the more literate people are following the IPCC/mainstream thinking, you could conclude the same. This is part of it, but the other part is related to the polarization in the US on this issue – many educated and literate people on one particular side of the public debate are unfortunately taking their cues on this from their leadership, and spend time looking for reasons to suspect the mainstream conclusions and this is not balanced by literate people on the other side educating themselves on why the mainstream is very likely right. Note too that this is only a conclusion for the wider public; among the scientific community, the appreciation of the severity of the problem increases dramatically as you know more about the science. – gavin]

  40. 190
    Pete Dunkelberg says:

    David Benson @ 185, this is the same study that was mentioned by John @ 174. These types of precipitation changes are predicted and observed, but the actual events exceed predictions, see for instance Allen and Soden 2006 Atmospheric Warming and the Amplification of Precipitation Extremes, although I think the same thing had been noted much earlier. So now we have the explanation.

  41. 191
    SecularAnimist says:

    Walter Cain (#189) wrote: “this, from the abstract, is surprising …”

    I would suggest that the very next sentence in the abstract makes the study less surprising:

    More importantly, greater scientific literacy and numeracy were associated with greater cultural polarization: Respondents predisposed by their values to dismiss climate change evidence became more dismissive, and those predisposed by their values to credit such evidence more concerned, as science literacy and numeracy increased.” [Emphasis added.]

    Which raises the question, just what sort of “values” would “predispose” a “scientifically literate” individual to “dismiss” the overwhelming scientific evidence for ongoing, dangerous climate change, as represented by virtually all of the peer-reviewed literature in the field, the views of virtually all publishing scientists in the field, and the public statements of virtually every national and international scientific organization that has anything to do with climatology?

    I would suggest that this is the direct result of a years-long propaganda campaign that has not only fed its audience a diet of pseudoscience (and pseudo-skepticism), but has also conflated that pseudoscience with relentless vilification of climate scientists as enemies of its audience’s ideological “values” (eg. liberty, capitalism, etc).

  42. 192
    Walter Crain says:

    yeah, the question is whether or not you’re “concerned” about climate change – not whether it’s a real phenomenon or problem. in the paper they use the terms “Hierarchical Individualists” (e.g., republicans) and “Egalitarian Communitarians” (democrats). i’ve read somewhere that the vast majority of scientists are democrats.

  43. 193
    Hank Roberts says:

    > MARodger says
    ( untruthfully attributing this description to Pete Dunkelberg)
    > … a months-old obsolete thread

  44. 194
    Ray Ladbury says:

    Walter Crain,
    In that study, the criteria for “scientific literacy” were very low. I would contend that their “scientifically literate” contingent would simply be the sort of education one would get with a priveleged education in a Western democracy. It would not be sufficient to immunize them to the Dunning-Kruger effect.

    I would also note that the test they gave to determine concentrated on an understanding of scientific facts–and not on the ability to use or assess scientific validity.

  45. 195
    Ray Ladbury says:

    Willis Eschenbach: ” “So let me go on record as saying I won’t be a useful idiot…”

    Let me go on record that I would never call Willis useful.

  46. 196
    Ray Ladbury says:

    MA Rodger,
    The overwhelming preponderance of estimates–and of evidence–favors a sensitivity of ~3 degrees per doubling–and if this is wrong–there is far more probability above than below this value. People need to look at ALL the evidence, not merely grasp a few studies as a drowning man grasps at straws.

  47. 197
    Hank Roberts says:

    “Daniel Yergin was recently interviewed on NPR’s always informative Planet Money podcast. Yergin—most famous for his 1992 Pulitzer-winning opus on 20th century petroleum development, The Prize—has penned a sequel …, The Quest is a look at those who might have to clean up the whole mess. ‘The heroes are the engineers and scientists of the energy world — the geeks, in other words.'”

  48. 198
    Jesús R. says:

    Anyone able to comment on these extraordinary suggestions?:

    “We highlight the existence of an intriguing and to date unreported relationship between the surface area of the South Atlantic Anomaly (SAA) of the geomagnetic field and the current trend in global sea level rise. These two geophysical variables have been growing coherently during the last three centuries, thus strongly suggesting a causal relationship supported by some statistical tests. The monotonic increase of the SAA surface area since 1600 may have been associated with an increased inflow of radiation energy through the inner Van Allen belt with a consequent warming of the Earth’s atmosphere and finally global sea level rise. An alternative suggestive and original explanation is also offered, in which pressure changes at the core-mantle boundary cause surface deformations and relative sea level variations. Although we cannot establish a clear connection between SAA dynamics and global warming, the strong correlation between the former and global sea level supports the idea that global warming may be at least partly controlled by deep Earth processes triggering geomagnetic phenomena, such as the South Atlantic Anomaly, on a century time scale.”

    A. De Santis, E. Qamili, G. Spada & P. Gasperini. Geomagnetic South Atlantic Anomaly and global sea level rise: a direct connection? Journal of Atmospheric and Solar-Terrestrial Physics, doi:10.1016/j.jastp.2011.10.015.

    [Response: How does this stuff get published? Another correlation != causation fail. – gavin]

  49. 199
    David B. Benson says:

    JCH @187 & Pete Dunkelberg @190 — Thank you.

  50. 200
    Hank Roberts says:

    “… the current warming is happening at least 10 times faster than anything we can find evidence of in Earth’s fossil record…. the current disturbance of the radiative balance is unique at least over the last 20,000 years ….”

    citing “Swedish Quaternary geologist Svante Björck of Lund University … in his Climatic Change publication (PDF) of three months ago. The many climatic fluctuations afterwards, including the Younger Dryas, the Holocene Thermal Maximum and The Little Ice Age, were all local disturbances.”