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Frauenfeld, Knappenberger, and Michaels 2011: Obsolescence by Design?

Posted on 2 May 2011 by Daniel Bailey

We know the planet is warming from surface temperature stations and satellites measuring the temperature of the Earth's surface and lower atmosphere. We also have various tools which have measured the warming of the Earth's oceans. Satellites have measured an energy imbalance at the top of the Earth's atmosphere. Glaciers, sea ice, and ice sheets are all receding. Sea levels are rising. Spring is arriving sooner each year. There's simply no doubt - the planet is warming.

And yes, the warming is continuing. The 2000s were hotter than the 1990s, which were hotter than the 1980s, which were hotter than the 1970s. In fact, the 12-month running average global temperature broke the record 3 times in 2010; according to NASA GISS data (2010 is tied with 2005 for the hottest year on record for GISS and tied with 1998 using HadCRUT).  Sea levels are still rising, ice is still receding, spring is still coming earlier, there's still a planetary energy imbalance, etc. etc. Contrary to what some would like us to believe, the planet has not magically stopped warming.

Humans are causing this warming

There is overwhelming evidence that humans are the dominant cause of this warming, mainly due to our greenhouse gas emissions. Based on fundamental physics and math, we can quantify the amount of warming human activity is causing, and verify that we're responsible for essentially all of the global warming over the past 3 decades.  In fact we expect human greenhouse gas emissions to cause more warming than we've thus far seen, due to the thermal inertia of the oceans (the time it takes to heat them).  Human aerosol emissions are also offsetting a significant amount of the warming by causing global dimming.

The Original Frozen Tundra

In October of 2010, The National Oceanic and Atmospheric Administration (NOAA) released the Arctic Report Card. The report contains a wealth of information about the state of climate in the Arctic Circle (mostly disturbing).  Especially noteworthy is the news that in 2010, Greenland temperatures were the hottest on record. It also experienced record setting ice loss by melting. This ice loss is reflected in the latest data from the GRACE satellites which measure the change in gravity around the Greenland ice sheet (H/T to Tenney Naumer from Climate Change: The Next Generation and Dr John Wahr for granting permission to repost the latest data). 

 

Figure 1: Greenland ice mass anomaly - deviation from the average ice mass over the 2002 to 2010 period. Note: this doesn't mean the ice sheet was gaining ice before 2006 but that ice mass was above the 2002 to 2010 average.

Additionally, Tedesco and Fettweiss (2011) show that the mass-loss experienced in southern Greenland in 2010 was the greatest in the past 20 years (Figure 2 below).

Tedesco

Figure 2: Greenland melting index anomaly (Tedesco and Fettweiss (2011))

The figure above shows the standardized melting index anomaly for the period 1979 – 2010. In simple words, each bar tells us by how many standard deviations melting in a particular year was above the average. For example, a value of ~ 2 for 2010 means that melting was above the average by two times the ‘variability’ of the melting signal along the period of observation. Previous record was set in 2007 and a new one was set in 2010. Negative values mean that melting was below the average. Note that highest anomaly values (high melting) occurred over the last 12 years, with the 8 highest values within the period 1998 – 2010. The increasing melting trend over Greenland can be observed from the figure. Over the past 30 years, the area subject to melting in Greenland has been increasing at a rate of ~ 17,000 Km2/year.

This is equivalent to adding a melt-region the size of Washington State every ten years. Or, in alternative, this means that an area of the size of France melted in 2010 which was not melting in 1979.

Selective Science = Pseudo-Science

Into this established landscape comes a new paper which presents a selective Greenland melt reconstruction. During the review process the papers’ authors were urged to, yet chose not to, include record-setting warm year 2010 temperatures. Had the authors considered all available data, their conclusion that ‘Greenland climate has not changed significantly’ would have been simply insupportable.

They write:  

“We find that the recent period of high-melt extent is similar in magnitude but, thus far, shorter in duration, than a period of high melt lasting from the early 1920s through the early 1960s. The greatest melt extent over the last 2 1/4 centuries occurred in 2007; however, this value is not statistically significantly different from the reconstructed melt extent during 20 other melt seasons, primarily during 1923–1961.”

Designed Obsolescence?

Their selective ‘findings’ were obsolete at the time the paper was submitted for publication in December of 2010. In the review process, the authors and journal editors were made aware that important new data were available that would change the conclusions of the study. Unfortunately, the paper represents not only a failure of the review process, but an intentional exclusion of data that would, if included, undermine the paper’s thesis.

Dr. Jason Box has chosen to share for the record a timeline of important events associated with this article’s publication:

  • 26 August, 2010, I was invited by Dr. Guosheng Liu – Associate Editor – Journal of Geophysical Research (JGR) – Atmospheres to review the article. Sara Pryor was the JGR chief editor ultimately responsible for this paper’s review.
  • 27 August, 2010, I accepted the review assignment.
  • 22 September, 2010, I submitted my review, in which I wrote: “The paper may already be obsolete without considering the extreme melting in 2010. I would therefore not recommend accepting the paper without a revision that included 2010.” I post my review posted verbatim here. At this time, I indicated to the editors that I did not wish to re-review the paper if the authors chose not to include 2010 temperatures. It was clear by this date, from the readily-available instrumental temperature records from the Danish Meteorological Institute and other sources such as US National Climate Data Center and NASA GISS that the previous melt season months were exceptionally warm.
  • 16 October, 2010, a NOAA press release publicized record setting Greenland temperatures. The press release was linked to this Greenland climate of 2010 article, live beginning 21, October 2010.
  • 27 December, 2010, I was invited to re-review the paper. I again stated that I did not wish to re-review the paper if the authors chose not to include 2010 temperatures. By this date, it was more clear that 2010 temperatures were exceptionally warm.

Another very important point: the excuse that the data was not available just is not reasonable given that both the Tedesco and Fettweiss 2011 and Mernild et al 2011 papers each managed to reference this 2010 data in publications that came out prior to that of Frauenfeld, Knappenberger, and Michaels.

Dr. Box:  

"The Editor’s decision whether or not to accept the paper would have been made sometime in early 2011. This paper should not have been accepted for publication without taking into account important new data."

Figure 3:  Positive Degree Day reconstruction for the Greenland ice sheet after Box et al. (2009). The "regression changes" presented here are equal to the linear fit (dashed lines in the graphic) value at the end of the period minus the beginning of the period, for example, the 14-year change is the 2010 value minus the 1997 value. The blue Gaussian smoothing line is for a 29 year interval. The dark red smoothing line is for a 3 year interval.  PDDs are the sum of positive temperatures. A PDD sum of 10 has twice the melt potential as a PDD sum of 5. Note that not only is the recent melting convincingly distinguishable from that of the 20th Century, but that summer and annual average temperatures in recent years are increasingly above values in the 1920s-1930s. (Courtesy Dr. Jason Box)

Greenland’s past temperatures

Including year 2010 data reveals (as seen in Figure 5 at bottom), in contrast to the message of the Frauenfeld, Knappenberger, and Michaels paper, that recent Greenland temperatures are warmer than at any time during the 20th Century for the summer, autumn, and annual periods. The 1925-1935 spring season was warmer in 1930 than 2010, but not warm enough to make the corresponding annual average exceed that of the recent times.  Important for a melt reconstruction, what Frauenfeld, Knappenberger, and Michaels neglected to include, was that recent summer temperatures exceed those of any time during the past century.  As a result glaciers in southern Greenland have retreated far behind their meltlines from the early 20th Century.  Evidence of this can be seen in Mittivakkat Glacier (Figure 4 below):

Mittivakkat Glacier

Figure 4: Mittivakkat Glacier in Southern Greenland.  Note the red line indicating the 1931 extent of the glacier relative to the yellow line depicting its position in 2010 (Mernild et al, 2011)

One thing to remember is that the regional warming that Greenland experienced in the early 20th Century came at a time when the world overall was colder than it is today.  And that the warming then was a result of multiple forcings (in which GHG warming played a role) and is thus fundamentally different than the anthropogenic global warming of the most recent 30 years (in which GHG warming plays by far the predominant role).  Additionally, the global cryosphere (the parts of the world covered in ice) has experienced much greater warming (in terms of volume and global extent) in this the most recent period than in the time of supposedly similar warming (the early 20th Century).

Given the thermal lags of oceans and ice, it is clear that Greenland has yet to fully respond to the warming forced upon it, so a reasonable approximation of another 1-2° C is yet in its pipeline.  This will translate into yet greater mass losses to come, which evidence indicates may be experienced in non-linear fashion.

2010Anomalyvs1923-1961

Figure 5: Where 2010 ranks relative to the warm period observed from 1923-1961 by Frauenfeld, Knappenberger and Michaels (Source)

Two lingering questions remain:

  1. Why did Frauenfeld, Knappenberger, and Michaels not include year 2010 data when they were asked to and when the data were readily available, yet the other papers containing the 2010 data published before theirs did?
  2. Why did the journal publish this paper without the requested revisions?

Climate Warming is Real

Dr. Box:  

"Multiple lines of evidence indicate climate warming for which there is no credible dispute. No scientific body of national or international standing has maintained a dissenting opinion. I personally have found no credible science that disproves that human activity significantly influences climate.

An enormous and overwhelming body of science leads rational thinkers to the conclusion that humans influence climate in important ways. For decades, the science has indicated that human activity has become the single most influential climate forcing agent."

National and international science academies and scientific societies have assessed the current scientific opinion, in particular on recent global warming. These assessments have largely followed or endorsed the Intergovernmental Panel on Climate Change (IPCC) position of January 2001 which states:

An increasing body of observations gives a collective picture of a warming world and other changes in the climate system… There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.

Acknowledgements

  • Dr. Jason Box, Assoc. Prof., Department of Geography, Byrd Polar Research Center, The Ohio State University, Columbus, Ohio, USA for his invaluable assistance, advice, knowledge and patience
  • Dr. Mauri Pelto, Professor of Environmental Science, Science Program Chair; Director, North Cascade Glacier Climate Project, Nichols College, Dudley, MA, USA for his timely insights and suggestions

Without the expertise of these two fine climate scientists this article could not have come to pass.

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Comments 51 to 100 out of 107:

  1. Raymond F Smith, just in case you do return here, you would do well to (as well as go to the pages recommended by the moderator) have a look at skeptical arguments sorted by taxonomy. There you can type in most of your assertions (warmer before, ice-free Arctic ocean, green Greenland, current temperature rise, etc.) and find responses giving you the facts and figures.
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  2. Guys,

    Since Jason Box posted his inital review of our paper (that he submitted to JGR), we have now gone ahead and posted our response to that review (that we submitted to JGR).

    It is available at:

    http://www.worldclimatereport.com/index.php/2011/05/02/attempts-to-box-us-out/

    Perhaps the information therein will serve to provide more insight into the review process of our paper.

    -Chip Knappenberger
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    Moderator Response:

    [DB] In the interests of full disclosure, since you've already linked therein to Judith's and Lucia's blog posts on the subject, I'm sure you will be also linking to this post expeditiously. Thanks, Chip!

  3. Sure Daniel. I added a link to your post as the third "here" in that section of our text.

    -Chip
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    Moderator Response: [DB] Thanks again, Chip!
  4. Chip... In your linked article you state: "Response: While we sympathize with the reviewer and would love to have our paper as updated as possible, practical issues get in the way."

    That's as disingenuous a statement as I think I've ever read. How can "practical issues" get in the way of publishing a paper whose conclusions would immediately become obsolete when published? That doesn't seem at all "practical." It seems "convenient" for the Cato Institute.
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  5. Chip,

    Thanks fro dropping in. I'm afraid you are making an incredibly weak case here and elsewhere on 'skeptic' and 'lukewarmer' blogs.

    And what is not helping your already weak case is that at least one of your co-authors (Michaels) is actively using your obsolete findings to mischaracterize the events unfolding in Greenland, and indeed globally. In fact, we have seen this very trick used before by "skeptics".

    It is now quite obvious why this paper was published in the first place, and why you were so reticent to include the 2010 melt data. Further, Tedesco and Fettweiss (2011) and Mernild et al (2011) managed to include those 2010 data, so you have no excuse.

    The narrative your paper is designed so as to play down the current events, and plays to the myth that "it has happened before", which is part of the "skeptical" memes that "it is not us" and "it won't be bad". Also, by you trying to keep people focussed on the past they are less inclined to think about where we are heading, and that is very much about what this is about, and you know that.

    Also, that spell of warmer temperatures between 1925 and 1960 and associated increased melt was regional and transient in nature. That is not what we are facing now or in the future. Down the road the warming will only increase as the radiative forcing from anthro GHGs increases (in addition to the natural release of GHGs as the permafrost continues to thaw, for example).

    I'll let you ponder this Figure:



    [Source]
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  6. Rob,

    I appreciate your concern.

    Our work that was published in JGR grew out of a presentation that Oliver Frauenfeld gave to the Association of American Geographers Meeting in April of 2010 (abstract here) and an earlier presentation at the AGU’s in December 2008 (abstract here). At the time, our analysis only went through 2007. Following the AAG presentation, we decided to submit our research to JGR, and before doing so we gathered the latest data available and were able to update the analysis through melt season 2009 and submitted the paper to JGR in late summer 2010. We did not re-do the analysis between submission and final acceptance of our JGR paper for the reasons given in our response to (Box’s) comments which, as I stated earlier, can be found here.

    I hope that helps clear things up.

    -Chip Knappenberger
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  7. Chip... That is exactly where I read the comment. Can you tell me honestly, if this were any other topic of research, if a reviewer had notified you of additional information that would change the conclusion of your research would you only "note" the additional information?

    From reading both sides I get the sense that the issue is how the additional information is treated. Your group chose to note the additional information. Dr Box is saying that's not enough because the additional information fundamentally changes the conclusion of the paper.

    I'm I accurate?
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  8. Rob,

    We stated clearly in our response to the reviewer’s (Box’s) comments why we thought it unnecessary to delay our paper until we were able to obtain the melt data for the summer of 2010:

    “We would like to note that waiting for one more year of data is not going to materially affect our analysis or conclusions. While the melt across Greenland has been elevated for the past 10 to 15 years (and continues in 2010), this period of time is still only about half as long in duration as the elevated (reconstructed) melt across Greenland from the 1920s through the early 1960s. So the addition of one more year of melt data (i.e., 2010), will not impact this comparison.”


    Prior to that comment, we explained why there would be a delay in updating our paper to include data for the melt season of 2010:

    “We don’t collect any data ourselves, but instead, obtain the processed melt data from various research groups, each operating on their own time schedule. The final/official release of the SSM/I brightness temperatures also takes about 6 months before it is available to centers like NSIDC. The updates in past years were therefore usually not made available to us until 6 to 9 months after the end of the melt season. In fact, the timing (August) of our original submission coincided with us finally obtaining the 2009 updates. Thus, waiting for the 2010 melt data would push the submission of our revised paper back until late spring or summer of 2011, at which point we may find ourselves again experiencing an interesting melt season which reviewers might feel important to include.”


    If Jason Box knew that we had erred in assessing the availability of the melt data we required, and that in actuality it was available at the time, he should/could have pointed this out in response to our justification to the editor—and the paper perhaps could have been updated accordingly. However, as far as I can tell, Jason did not see our response to his comments (at his own instruction—although the editor may have thought it unnecessary to send it to him in any case, I don’t know for sure), and so such a clarification was never made.

    -Chip
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  9. There is considerable research that indicates positive degree days are a reasonable first approach to glacier melt. Figure 3 above indicates that 3 of the 5 highest PDD days for Greenland have occurred in the last decade. Further given this graph of PDD where are the 20 years in the 1923-1961 period that FKM maintain, without providing any actual annual values, are statistically not different from 2007. Given the extraordinary melt season of that year and 2003 it is hard to see how there could be more than four years that would even be in the consideration. What was the actual difference between 2007 and those other 20 years? How are those years found to not be statistically different? That is the science question that FKM did not delve into as the results will highlight the unusual nature of recent melt. It is not just the 2010 data that is glossed over. Petermann Glacier is just one example of the canary that indicates the reality.
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  10. Dr. Pelto,

    Thanks for your comment.

    If PDDs are a good predictor of melt extent across the Greenland ice sheet, then their use as a proxy for a longer–term reconstruction should most definitely be explored. However, that was not the method that we used (which combined summer temperature and winter NAO). Perhaps our results could be furthered by examining the potential of incorporating PPDs.

    As far as “How are those [20] years found to not be statistically different?” we mean that the observed melt extent for 2007 lies within the 95% confidence bounds we determined for 20 of our reconstructed ice melt values. In our paper, we describe how we established those 95% confidence bounds.

    -Chip
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  11. Chip,

    With respect,I agree with Rob's assessment that you are being disingenuous and not making a compelling argument. You claimed in your response that:

    "We would like to note that waiting for one more year of data is not going to materially affect our analysis or conclusions."

    We know that claim in demonstrably false, because the melt data for 2010 surpassed those for 2007, which renders the following from your abstract obsolete (i.e., including those 2010 would have very much have affected your conclusions):

    "The melt extent observed in 2007 in particular was the greatest on record according to several satellite-derived records of total Greenland melt extent."

    Including those 2010 data also renders the first part of this conclusion in your abstract obsolete, while also calling into question the validity of the second part of the following:

    "The greatest melt extent over the last 2 1/4 centuries occurred in 2007; however, this value is not statistically significantly different from the reconstructed melt extent during 20 other melt seasons, primarily during 1923–1961"

    So contrary to your claims made here and elsewhere, the 2010 do very much affect your conclusions and desired narrative. Regardless, the "skeptics" and those in denial about AGW now have a (obsolete) paper to point to which enforces their delusion and to demand delay in taking action. Congratulations.
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  12. I think an additional point to make, and one that the paper deals with very poorly in its conclusions, is that melt is not the only component of mass loss, and therefore sea level rise, from Greenland. Much mass is lost through calving, and termini such as Ilulissat (Jakobshavn Isbrae) have been observed to accelerate substantially between the middle and the end of the 20th Century. I would guess that the total volume of ice discharged by this prodigious glacier also increased substantially during that time (the glacier has since slowed, but also has a much wider calving front these days).

    So while surface melt values may be arguably statistically close to values in the mid-20th Century (notwithstanding Mauri Pelto's pertinent comment at #59), it is reasonable to think that total mass loss values, and sea level contribution are notably higher now than in the mid-20th Century due to extra calving? The relationship between degree-day melt and mass loss necessarily assumes a consistent relationship between PDDs and calving rate across many decades, ignoring that surface melt is immediate, but the calving mass loss has a time-dependent dynamical component. I may be wrong in this assumption, but it would partially explain how they got away with publishing their dubious statement on sea level.

    A strange paper - if you didn't know the subtext you'd say it looks OK for much of the way through, but then raises a whole bunch of red flags for the conclusions and especially the last sentence comparing past decades to the last few years.
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    Moderator Response: [DB] Consider also the millennia-old ice shelves, widespread in the early-to-mid 20th Century, now gone.
  13. (correction to my last comment: I've just mixed my reading of Mauri's mention of PDDs with the paper's use of average summer temperatures, but you can swap 'degree days' for summer melt in my comment anyway.)
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  14. One last question from me - their last statement about statistical similarity depends entirely on their calculation of 95% confidence limits (2x RMSEv, according to their methods). For the statisticians here - is this error calculation reasonable?
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  15. skywatcher @64, I am also interested in that question. In particular, I am wondering about the idea of testing statistical significance against the subset of the 20 highest melt years. why not test for statistical significance against all years?
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  16. Chris @50, it is rather awkward for you that you agree with me, for I was disagreeing with you. In particular, I was indicating that "‘Greenland climate has not changed significantly’" seems like a very reasonable summary of the author's intended take home message. That take home message, according to Knappenburger is:

    "Our general conclusions were:

    • several recent years (in particular 2007 and from preliminary observations 2010) likely had a historically high degree of surface ice melt across the Greenland ice sheet,

    • on a decadal scale, there were several 10-yr periods during the 1930s through the early 1960s during which the average annual ice melt extent across Greenland was likely greater than the most recent 10 years of available data in our study (2000-2009),

    • that the ice melt across Greenland was particularly low at the start of the era of satellite observations (which began in 1979), such that a sizeable portion of increasing ice melt observed by satellite-borne instruments since then could potentially be part of the natural variability about the mean state,

    • that, for the next several decades at least, Greenland’s contribution to global sea level rise was likely to be modest."

    (My emphasis)

    That's two out of three authors now publicly running the line that its all just natural variation, and that that was the conclusion of their paper.

    If you agree that that line is an over interpretation of the data to 2009, then including 2010 would have underscored that point and the omission of detailed discussion (if not a full analysis) becomes unwarranted.
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  17. You see, this is the one thing that keeps being ignored-even if the total glacial melt between 1923 & 1961 could be shown to be equal or greater to the melt we've seen between 1995 & 2010, there'd still be the fact that we *know* what caused the former glacial melt (rising temperatures due to increasing solar irradiance), but *cannot* explain the current glacial melt with any known natural causes. So that *really* leaves only rising CO2 emissions as the culprit. If so, then unlike the 1923-1961 melt, there'll be no end to the current melt *unless* we stop pumping more CO2 into the atmosphere.
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  18. Tom Curtis at 12:18 PM on 3 May, 2011

    Tom, I can only say again that I agree with you.

    As you pointed out above, and I pointed out here (see point [4]), there are some categorically incorrect statements in the paper that simply shouldn't have been allowed to stand. Unfortunately the main reviewer of the paper chose not to address these. So we can only complain about the situation after the fact. In my opinion Dr. Box could hardly have done a better job of playing into the hands of the misrepresenters. It's unfortunate to have to say so.

    Dr. Box had an opportunity to re-review the paper in early Jan 2011. Apparently the temperature/melt data used to compile the MKF reconstruction wasn't available to update their model to include 2010, and the editor chose to over-rule the recommendation that the authors delay publication to wait for this (an acceptable editorial decision in my opinion).

    However the melt data described elsewhere was available at least by late December. Therefore Box was in a very strong position in early Jan 2011 to give very strong guidance to the editor that categorically false statements MUST be removed from the paper in the light of independent data that shows the 2010 melt to be a new record. If this was done MFK would have been in a much weaker position in their attempts to misrepresent the relationship between contemporary and historical melt.
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  19. skywatcher at 10:45 AM on 3 May, 2011

    No I don't think it's reasonable at all. One cannot make interpretations about statistical significance when comparing empirical contemporary data determined using one method, with historical data constructed with a model.

    This is partly the reason that the IPCC use qualitative estimates in these sorts of comparisons ("likely"; "very likely" etc),and why papers on paleotemperature reconstructions don't include measures of statistical significance.

    It's easy to see some of the problems. For example historical date reconstructed with a model have large associated uncertainties. All it requires for contemporary data to be "not statistically significant" with respect to the historical reconstruction, is that one has large error bounds on the historical data. It then becomes very difficult for differences in the contemporary data to achieve statistical significance, especially at the 95% confidence level.

    So I think the inclusion of statistical significance was entirely unwarranted, and the truly offending statement shuld have been removed from the abstract. Unfortunately, at least one reviewer of the paper gave the authors a free pass on this. He's shown us his confidential review which remarkably classed the methodology as "good" and raised not a peep about the statistical analysis. It's very unfortunate....
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  20. Chip Knappenberger


    1 - Why are comments not allowed in response to your post on this paper at worldclimatereport.com?

    2 - How is interesting historical data from a few sites relevant to the multiple integrated observations of warming and melting over most of Greenland, the Canadian Archipelago and indeed the entire Arctic?

    I ask question 2 in the context of Patrick J. Michaels' post at the Cato Institute in which he uses this already obsolete paper in conjunction with another debunked paper to conclude that:
    "...the recent increase in melt across Greenland (contributing to a negative trend in SMB) may in part a result of rising temperatures from sources other than dreaded greenhouse warming, and therefore extrapolating the observed trends in SMB forward may not be such a great idea."
    http://www.cato.org/...

    It is interesting that Michaels seems focused on the idea that beachfront property is - presumably - a good investment because coasts are not at risk. Would you do him the kindness of directing him to recent studies which show that he should rapidly dump any such investments which he may have in more northern latitudes?
    http://www.sciencenews.org/view/generic/id/73737/title/With_warming,_Arctic_is_losing_ground


    It is ironic that Michaels posts under the banner 'current wisdom'. Wouldn't the banner 'obsolete folly' be more apt?
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  21. chris@69 There is no reason why tests of statistical significance cannot be used to compare observations with model hindcasts/reconstructions - it is done quite regularly by climatologists working with specialist statisticians (e.g. the Santer 17 paper). If you have a reason why this particular comparison is invalid, then you need to explain why in more detail.

    Secondly, the IPCC do not use qualitative estimates - if you look at box TS1 on pages 22 and 23 of the most recent WG1 report, you will find those "qualitative" terms map directly onto quantitative probability ranges.

    Without tests of statistical significance, how do you suggest scientists working with models avoid drawing conclusions from spurious correllations?

    Having said which, frequentist hypothesis testing is a bit of a mess anyway and many scientists and most of the general public tend to misinterpret the results of such tests.
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  22. O.K. fine Dikram. Yes the IPCC's designations ("likely", very likely") map onto estimates of probability ranges. However they don't address these with a numerical statistical analysis and assign measures of statistical significance to comparisons of contemporary and historical (paleo) parameters

    Santer's paper was addressing something quite specific - the question of the extent to which uncertainties in tropical tropospheric temperature could be used to validate expectations from models. Since a (pseudo) statistical analysis was used by ohers to attempt to infer that empirical measures and their uncertainties showed that empirical measures were inconsistent with models, it was appropriate for Santer et al to address the comparison with a statistical analysis. [apols for the long sentence!]

    However (and I may be wrong, since I haven't devoured every last bit of published data), I haven't seen any attempt by the paleo community to assign statistical significance to comparisons of contemporary and historical data (e.g. the paleo analyses of Mann, Briffa etc.). The reasons why this is a dubious approach is indicated in my post you just responded to.

    Of course one can do a statistical analysis of anything and assess apparent statistical significance in differences between whatever one choses. However attempts to do this in comparing paleodata with large uncertainties, to contemporary data with lesser uncertainty is playing at numerology.

    Of course if the authors of the paper were to test the statistical significance of differences between their model of paleo melt and their model of contemporary melt, that would be more acceptable even if the 95% confidence level significance is still somewhat meaningless in relation to what we'd really like to know (difference in real melt now and real melt then).

    But it's not up to me to address this in detail. That's the role of the reviewers of the paper...
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  23. since we're being pedantic, I really should have said:

    "Santer's paper was addressing something quite specific - the question of the extent to which uncertainties in tropical tropospheric temperature could be used to invalidate expectations from models."

    And even that's not quite right, but I haven't got time right now to rewrite that sentence, and I expect you can see what I'm trying to say...
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  24. chris@73 I suspect the reason paleoclimate people don't perform such a statistical analysis isn't because there is any methodological problem but simply that it doesn't tell you anything interesting whatever the result. It is not a valid argument to cliam that thr FKM test is invalid/inapropriate because paleoclimate people don't use that test - there has to be a first time for everything. So far you have given no statistical reason why the test is not valid (the data being too noisy is not a good statistical reason - it certainly doesn't make it "numerology"). The interpretation of the result of the test is another matter (c.f. my comment regarding frequentist statistical tests - being unable to reject the null hypothesis does not mean the null hypothesis is true, it never has and it never will).

    BTW, there was nothing "pseudo" about the statistical analysis of Douglass et al. They correctly applied the wrong test, but the test itself was perfectly correct statistics, it just didn't test what they thought they were testing.
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  25. Exactly Dikram... it doesn't tell you anything interesting.. it's obvious really.

    And yet the abstract of the paper we're discussing contains the sentence:

    ”The greatest melt extent over the last 2 1/4 centuries occurred in 2007; however, this value is not statistically significantly different from the reconstructed melt extent during 20 other melt seasons, primarily during 1923–1961.”

    Call me picky, but apart from the falsehood of the sentence about greatest melt extent, the sentence contains a statement that I think we both agree doesn't tell you anything interesting. My point, which I keep banging on about (and I believe we both agree on) is that a reviewer might be expected to pick up on that. That sentence simply shouldn't be there.

    I have a feeling you are arguing for the sake of it somewhat (or seeing who can raise pedantry to its most extreme level - you might be inching ahead now!). The point about the Douglass analysis is that it was an inappropriate test of the comparison of empirical and model data to assess whether models could be invalidated (shown to be inconsistent with...) on the basis of some statistical analysis of uncertainty associated with the empirical data. They did it to attempt to pursue a misrepresentation most likely. I'd say that is a "pseudo" analysis. A pedant might disagree! But since I've hopefully made clear exactly what I mean when I use the prefix "pseudo" in this context, there really shouldn't be cause to quibble, should there?

    It's very important in science to try to convey clear what one means. Would that reviewer's of papers would be so careful...
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  26. apologies, I shouldn't call you Dikram when your name is clearly Dikran...my bad
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  27. Has anyone done the numbers to determine if the idea that,

    "...waiting for one more year of data is not going to materially affect our analysis or conclusions. While the melt across Greenland has been elevated for the past 10 to 15 years (and continues in 2010), this period of time is still only about half as long in duration as the elevated (reconstructed) melt across Greenland from the 1920s through the early 1960s. So the addition of one more year of melt data (i.e., 2010), will not impact this comparison.”

    ?

    I'm not sure that Dr Box's comments hit on that specifically - but i'm a layman and might be reading things improperly.

    From what I've learned of the review process, disclosing review comments, the identity of reviewers (even if oneself) and the editor immediately after a paper has been published, especially in an effort to rebut the paper, undermines the process.

    When skeptics disagree with a study/theory/conclusions/methodologies, we encourage them to do some work and submit. Dr Box, of course, is in the perfect position to do this. I'm not sure if submitting a direct rebuttal is kosher for a reviewer of a paper, but if so, that avenue is wide open to Dr Box. Disseminating information that is meant to be confidential in a blog (or series of) is not meritiricious, no matter the reason. Dr Box may or may not be right here (I don't know), but it seems to me we've sidled towards the contrarian's way of doing things.

    Signed - regular follower and great appreciator of skepticalscience.
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  28. chris@79 Until I got to the bit that said "I have a feeling you are arguing for the sake of it somewhat (or seeing who can raise pedantry to its most extreme level - you might be inching ahead now!).", I was going to reply to your post, but I see little point if you can't conduct a scientific discussion in a civil manner. Especially after calling my interpretation of the review "silly" because I based in on words Box had actually used.

    No, I haven't been engaging in pedantry, merely stating my opinion on Box's review and correcting a few errors in your responses.

    As it happens the statement that you object to in the abstract, seems fine to me. Yes, it is uninteresting, but I am in favour of papers that place bounds on the strength of conclusions that can be drawn. Unless you can identify a methodological flaw in the statistical test that supports that statement, then there is nothing wrong with it.

    Unless you can behave in a more scientific manner, that is the end of the discussion for me.

    P.S. No problem about the "Dikram", it is not my real name anyway.
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  29. Seems to me there are several issues that come out -

    1: statistical significance of the recent years in relation to past years according to the model. Whether or not they are technically correct is actually less of an issue than their avoidance of the modern trajectory of change. It's quite disingenuous to talk of that trajectory earlier in the paper, yet leave it out of the conclusions.

    2: Avoidance of the issue of mass loss versus surface melt - mass loss includes ice loss through calving, which has accelerated since the mid-20th Century. Surface melt is not necessarily therefore a good proxy for sea level rise resulting from Greenland.

    Both the above points allow two of the authors, as noted by others above, to falsely suggests that 'there's nothing to see here' in Greenland, despite all the evidence of accelerating mass loss described by Daniel Bailey.

    3: The review process. I have to say I agree with barry here - I don't like the airing of private reviewer comments such as has happened here. That does not seem to me to be good academic discourse. Aside from that, I feel Dr Box should have conducted the second review, and insisted on paper rejection as the changes had not been made. Had he done that, and the paper still been accepted, he would have a stronger case. But having not done that, he was not in a good position to cry foul that the paper got through. That the other (anonymous) reviewer gave the paper a free pass as far as can be seen, is perhaps more of an issue, but the natural process of academic discourse should be allowed to progress - ie that relevant academics submit responses critiquing the paper. Given how (deliberately) poorly-written the conclusions are, and that it is already out-of-date, I suspect this will happen.
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  30. skywatcher wrote : "Aside from that, I feel Dr Box should have conducted the second review, and insisted on paper rejection as the changes had not been made. Had he done that, and the paper still been accepted, he would have a stronger case. But having not done that, he was not in a good position to cry foul that the paper got through."


    I'm not so sure about that - remember the kerfuffle over O'Donnellgate, with regard to the Antarctic ?

    It seems that there would be an outcry no matter where in the chain these criticisms are made, and if a paper is refused publication because of the involvment of someone whom the so-called skeptics could claim was censoring 'opposing' views...well, that would unleash a great wailing and gnashing of teeth in the Denialosphere !
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  31. Barry@77

    Yes it is perfectly acceptable for a reviewer to submit a rebuttal of a paper which they reviewed but which they consider has major flaws. From reading Dr Box's blog it appears he is doing so.

    Regarding the authors statement that "one more year of data is not going to materially affect our analysis or conclusions" I agree with Albatross@61.
    The last few lines of a papers' abstract is where you put your "take home" message/ most important conclusions. It is very clear that including 2010 data would have required a rewrite to this section, because it would have altered their "take home" message. To state otherwise, as Chip and Co did, is simply incorrect.


    Otherwise if Chip@58 is still around I have a question or two as my uni (oddly enough) doesn't have an online subscription to JGR.

    1) You tested whether the melt in 07 was sig diff to the melt between 1923-1961. Why did you test against 20 specific years, instead of the whole high melt period?

    2) Why does your paper emphasis the duration of the historical high melt period vs present melting? Given that temperature increases in Greenland (and hence melting) are only just getting started, wouldn't the magnitude of the melting and trend of melting be more important?
    Or to rephrase, the current high melt is almost certain to last for longer than the previous, why is the fact that is hasn't (yet) particularly important?
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  32. Several commentors here seem to have taken issue with the idea that some of the positive trend in ice melt observed across Greenland from 1979-2010 could potentially have resulted from natural variability. The reason the results of our paper suggests this, to me at least, is that the ice melt in late 1970s and early 1980s (i.e. the early years of the satellite record) was considerably below the long-term average (or at least as we have reconstructed it). So, even without any positive forcing from a greenhouse effect being enhanced by anthropogenic influences, a return to the long-term mean (at some point) would seem a reasonable expectation. I doubt that the entirety of the trend in ice melt extent across Greenland from 1979-2010 results from natural variability, but it would seem a bit foolish to rule out the possibility of any contribution whatsoever, based upon our results. So, to me, the contribution is probably greater that zero and less than a 100%--so I am comfortable with my characterization that a “sizeable” portion “could potentially” be a result of natural variability.

    -Chip Knappenberger
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  33. The Skeptical Chymist,

    I am not sure that you have it quite right when it comes to our statistical tests. There are 20 years during our reconstructed period (1784-1978) in which the observed melt index for 2007 was contained within the 95% confidence bounds about the reconstructed value. So our “test” was on individual years, not a particular period. If this explanation doesn’t answer your question, then perhaps I am not understanding it correctly.

    As far as whether or not the current melt extent and trend are important or not, our point was that there seems to have been another extended period of positive melt anomalies across Greenland for several decades in the early/mid 20th century, and that period did not result in a large uptick in the rate of sea level rise (although there is some evidence that the rate of sea level rise did increase a bit during that period). This led us to conclude that if the current melt extent stayed somewhat equivalent to what it was back then, we wouldn’t expect a big jump in the rate of sea level rise as a result of cryospheric processes (surface melting and dynamic ice loss from glaciers). Clearly, if the melt (and other losses) where greater than back then, then so too will be the contribution from Greenland. 2007 and 2010 were years with a lot of melt. 2008 and 2009 were not.

    -Chip Knappenberger
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  34. Chip Knappenberger@82 There was signficant anthropogenic influence on the greenhouse effect in place in the late 1970s and early 80s (and decreasing negative forcing due to aerosols) so to use that as evidence that without positive forcing from AGW a return to the long term mean is a non-sequitur. Perhaps there is something missing from your post?

    There is no reason to expect a return to the long term mean according to mainstream climate science, which includes the CO2 being a greenhouse gas, climate sensitivity being of the order of a couple of degrees C per doubling and albedo feedback. All three of those suggest a return to the long term mean is unlikely.
    0 0
  35. Dikran@84,

    I was referring to a return from the negative ice melt anomalies in the late 1970s/early 1980s. With or without anthopogenic forcing, natural variability still exists, and since there is the possibility that positive climate forcings from human activities is not what led to the negative ice melt anomalies in the late 70s/early 80s, then a non-anthopogenic-induced return from those anomalies should not be out of the question.

    Right?

    -Chip
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  36. Chip @ 58... Your response is not very compelling to me for a couple of reasons.

    First, on an interpersonal level you're not responding to what I'm saying. You're merely speaking "at" me, not to me, and reposting things that I've already read.

    Second, your case is still not compelling, and is fact extremely concerning, in that you're essentially abdicating responsibility to get the research right. On one hand you're saying, "We didn't do the actual research" and then you're contradicting statements from one of the key people who DOES do the actual research. And those statements (from Dr Box) have been, obviously, quite forceful in their condemnation of the conclusions of FKM2011.
    0 0
  37. In addition to Dikran's point, #84, the appeal to 'naural variability' does not stand up. There has to be a process driving that change - presumably you (FKM) envisage that process reversing? What forced the variability, and why would melt be at all likely to return to some 'natural' base level given the well-understood climatic forcings in place at present?
    0 0
  38. skywatcher@87,

    Perhaps I am missing something here. You and Dikran are suggesting that the negative melt anomalies in the late 70s/early 80s are the result of positive anthropogenic climate forcings? Or that they are not really negative anomalies, but rather represent the mean climate state at the time? Or perhaps even that the natural state was trending downward and then anthropogenic positive forcing stopped that downward trend and turned it positive? I guess all of these things are possibilities that would invalidate my conclusion. It is just, that in my opinion, I don't ascribe to any of them...but, admittedly, I could be wrong.

    -Chip
    0 0
  39. I agree that the early to mid 20th century period of warmth did not lead to a substantial increase in volume loss for the GIS. However, the conclusion that are current period of warmth will not, is already wrong. There are too many different studies using different techniques that have shown the volume losses of GIS have increased dramatically in the last decade. That is what marks the current period as different. When I first worked on GIS glaciers most were in essential equilibrium, such as our main focus the Jakobshavn. Today the list of glaciers that have had substantial volume losses is long and covers many types of glaciers from calving to grounded termini glaciers as we noted in a, previous post at SkepticalScience. This includes Humboldt Glacier the glacier with the longest calving front. Not only are there volume losses but there have been some fundamental changes in glacier behavior that would have been observed if they had occurred in the mid-century period of warmer conditions. The proof that the current warming is generating more melting is in the response of the glaciers.
    0 0
  40. Chip@85 Sure natural variability exists, but you can't attribute a change to natural variability until you have seen what can be explained by changes in forcings (all of them including e.g. aerosols).

    As a statistician, I am not greatly impressed by merely statistical evidence that something is not ruled out. I understand the limitations of quasi-Fisherian significance testing, and I know that failing to reject the null hypothesis actually means rather little (Fisher knew that as well). For a start, it can only mean there is no reason to rule it out based on that one statistic considered in isolation. But why should we look only at that statistic in isolation and ignore all of our knowledge of climate physics that points strongly against a recovery due to natural variability?

    It seems to me that you are over-interpreting the significance of your test. AFAICS, the only value in it is that it shows those who would claim that the recent decline is unprecedented perhaps need to qualify exactly what they mean by "unprecedented". It doesn't tell you anything about attribution.
    0 0
  41. Chip Knappenberger - You've presented a few reasons for not incorporating the 2010 data. However, given your paper's focus on surface melt (not considering other issues such as glacial speed/behavior and calving events, or the multiple tracks of evidence indicating greatly increased mass loss over the last decade), and the lack of the 2010 data, your paper was obsolete on publication date.

    At the very least the available 2010 data should have caused you to revise your summary and conclusions. Inclusion of other mass loss data should have reversed the conclusions entirely.

    Given these issues, I don't think the paper adds much to the science. I expect, given the track record, that it will be used to argue that "it's not happening", presented as up to date by (for example) the Cato Institute and others. But it's obsolete.
    0 0
  42. Chip@88 no, just that you need to consider all forcings in order to determine whether something is attributable to "natural variability".

    There is also the fact that a recovery in the 70s/80s that is attributable to "natural variability" isn't any reason to think that levels will return to the long term mean in the face of rising CO2 radiative forcing/albedo feedback.
    0 0
  43. Dikran@92,

    I don't think I said anywhere that I expect a (much of a sustained) return towards the mean from current levels (not meaning 2010, per se, but rather, the current 10-yr or so average). Just that some of the return (from negative territory) towards the mean early in the satellite record could/should not be summarily ruled out as being a result of natural variability.

    -Chip
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  44. Chip@93 Sure, but not being able to rule something out doesn't actually mean much and isn't support for a return towards the mean, because it ignores the fact that CO2 radiative forcing is positive and incresing (and arctic temperatures are rising as expected) and there will be an albedo feedback effect. Physics trumps statistics every time - I know that - I am a statistician.
    0 0
  45. KR@91 et al.,

    You all keep saying that our paper is obsolete. But this seems a wee bit over the top (to say the least).

    Granted, incorporating the melt extent for the summer of 2010 into the methodology as described in our paper may have required a few minor tweaks to some of the wording (and a few specific numbers). But, by and large, as I have said many times, I strongly believe (although I have not done the analysis) that the changes would not have altered the general nature of our conclusions (as we explained to the JGR editor).

    -Chip Knappenberger
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  46. Chip #88, Dikran's already answered your question I think, and his first paragraph in post #90 is the key point I think. You can't blindly attribute a statistical derivation of only one component of Greenland's sea level contribution to 'natural variability' without first examining all the forcings, notably the significant aerosol forcings of the 1960s to 1980s.

    Furthermore, you can't then suggest that Greenland is not contributing significantly to sea level rise without assessing the magnitude of Greenland's contribution, and the proportion of that which is due to melting, rather than calving. Would the changes in Greenland melt contribution have been detectable, let alone significant, in the 20th Century sea level curve? I cannot tell from your paper, as you do not appear to have quantitatively examined this. It would appear that changes in ice discharge/calving would be detectable (Rignot & Kanagaratnam 2006), but you make no quantitative assessment of the component that you have modelled (melt).

    Why did you state that sea level rise would have to have exceeded 3mm/year earlier this century before you would consider Greenland's effect on sea level rise to be other than 'modest'? There are many more components to sea level rise than Greenland's ice alone, as you can find out at this website! That last paragraph in FKM 2011 looks worse every time I read it.
    0 0
  47. I should say that although I've asked a lot of fairly strong questions about this paper, I very much appreciate Chip's coming here and discussing it.
    0 0
    Moderator Response: [Dikran Marsupial] Well said, I agree completely!
  48. Guys (skywatcher, Dikran, et al.),

    We probably have labored over the point about contributions to the recent trend long enough, I am not sure we are making any headway. I previously have said that there exists a set of conditions for which my suggestion that natural variability may play some role in the recent trend is wrong. Just that from what I know now, I don’t think those conditions represent what was occurring.

    So as a parting thought about this, I offer up this excerpt from our paper where we talk about this topic:

    “It is worth noting that the satellite observations of Greenland’s total ice melt, which begin in the late 1970s, start during a time that is characterized by the lowest sustained extent of melt during the past century (Figure 2). Thus, the positive melt extent trend includes nearly equal contributions from the relatively high melt extents in recent years but also from the relatively low ice melt extent in the early years of the available satellite record. The large values of melt extent observed in recent years are much less unusual when compared against conditions typical of the early to mid 20th century, than when compared against conditions at the beginning the of the satellite record.”


    Now we did not explicitly mention “natural variability” but we did talk about “relatively low melt extent” at the beginning of the satellite record and its contribution to the recent observed trend. I doubt that many people attribute the “relatively low melt extent” to increasing positive forcings from anthropogenic activity.

    Jason Box had a comment pertaining at least to the first sentence of this paragraph:

    line 221-223: a good point: “It is worth noting that the satellite observations of Greenland’s total ice melt, which begin in the late 1970s, start during a time that is characterized by the lowest sustained extent of melt during the past century (Figure 2).”


    I just don’t think I am completely off base here, but, I suppose you all are free to think otherwise!

    -Chip
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  49. @97,

    Thanks to the commentors and moderators for keeping the overall tone of the discussions very positive. It is much more enjoyable (and probably more instructive) to have discussions about things (even when we disagree) in such an environment.

    Thanks again!

    -Chip
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  50. Chip Knappenberger at 02:34 AM on 4 May, 2011
    KR@91 et al.,   You all keep saying that our paper is obsolete. But this seems a wee bit over the top (to say the least).
    ~ ~ ~ ~ ~ ~ ~

    In light of
    THE ARCTIC AS A MESSENGER FOR GLOBAL PROCESSES –
    CLIMATE CHANGE AND POLLUTION ~
    COPENHAGEN MAY 3-6 2011
    see Press Release
    see Abstract
     

    Seems to me it has been steamrollered into an irrelevant example of massaging the message.  Then leaving it out there to dangle for the “skeptical” echo-chamber to morph it into another “aluminum tubes into nuclear weapons” distortion, then blast the soundbite through their media machine.
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