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  1. #13891
    owedtojoy owedtojoy is offline
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    A brand-new, freshly minted paper by two Italian physicists giving a minimum bound for average sea level rise by 2100 as 80cm.

    ScienceDirect.com - Global and Planetary Change - Lower bounds to future sea-level rise

    Unfortunately, pay-walled for the moment.
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  2. #13892
    Steve Case Steve Case is offline
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    Quote Originally Posted by owedtojoy View Post
    A brand-new, freshly minted paper by two Italian physicists
    giving a minimum bound for average sea level rise by 2100
    as 80cm.

    ScienceDirect.com - Global and Planetary Change - Lower bounds to future sea-level rise

    Unfortunately, pay-walled for the moment.
    They say:

    We find that, in spite of fossil-fuel depletion,
    sea level is predicted to rise by at least ~ 80 cm at the end
    of this century...

    That means sea level rise has to average over 9 mm/yr for
    the next 88 years. Currently it's not even rising 3 mm/yr
    and the acceleration over the last 20 years is negative. So
    when is this spectacular turnaround going to happen? Well
    the paper is behind a pay wall so I don't know if in fact they
    include enough detail to deduce a schedule of sea level rise
    increases and why. I see that they have some charts:




    As I pointed out earlier the trend over the last 20 years or more
    if extrapolated out to 2100 looks like this:



    And again, I'm not saying that's a prediction, just that it flies
    in the face of anyone who claims that the rate of sea level
    rise is accelerating or is about to.
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  3. #13893
    owedtojoy owedtojoy is offline
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    Quote Originally Posted by Steve Case View Post
    They say:

    We find that, in spite of fossil-fuel depletion,
    sea level is predicted to rise by at least ~ 80 cm at the end
    of this century...

    That means sea level rise has to average over 9 mm/yr for
    the next 88 years. Currently it's not even rising 3 mm/yr
    and the acceleration over the last 20 years is negative. So
    when is this spectacular turnaround going to happen? Well
    the paper is behind a pay wall so I don't know if in fact they
    include enough detail to deduce a schedule of sea level rise
    increases and why. I see that they have some charts:



    o.
    You know by now I think your "deceleration" is fictitious. You can not even tell me how it is derived - just pulled off a slide on the web, not from a peer-reviewed paper. How did the poster arrive at that figure? Seems to me it is just an "instantaneous" figure for 2010 and not a 20-year figure.

    Since sea level rise will probably accelerate (why not? most parameters associated with global warming are accelerating - Arctic sea ice melt, Greenland Ice Cap melt, West Antarctica Ice Cap melt, glacier melt, summer snow pack melt) so an increase from 3mm/year to over 9mm/year is perfectly reasonable.

    You should write to the authors of the paper for clarification - that is what corresponding authors are for.

    Meanwhile, send your work out for a critique.
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  4. #13894
    Earthling Earthling is offline
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    What's with this peer review anyway, apart from giving like minded friends something to do?

    BTW, hat tip to he who sent me the PM about my metric brain fart.
    And no, it wasn't the guy who has trouble separating quotes from his own work.

    I'm sure sea level rise of 30 mm/yr is about to happen, in a Hollywood movie.
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  5. #13895
    owedtojoy owedtojoy is offline
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    Found this link to a great talk by Professor David Barbour of the University of Manitoba in 2010 at the Oslo International Polar Year conference.

    Barbour is an old Arctic hand - he says that in the 1970's, he was a skeptic about climate change, in the 1980s, he thought Arctic Ice would last until 2100, but in each decade he as changed his mind until he believes now that it will be gone by 2030. I wonder what he thinks of this year's melt.

    Webcast - Oslo Science Conference

    Here is Barbour, looking considerably more unkempt, talking about an experience with Arctic Ice in a short clip.

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  6. #13896
    owedtojoy owedtojoy is offline
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    Professor John Nielson-Gammon gives a synopsis of the greenhouse effect. JN-G is at Texas A&M and is State Climatologist.

    He should be popular here because the wants the expressions "greenhouse effect" and the "greenhouse gas" to be replaced by the words "Tyndall effect" and "Tyndall gas" in recognition of the great Irish physicist who discovered the heat-absorbing of CO2.

    Remember the days when a plethora of science deniers would arrive to claim the greenhouse effect is not true? Couldn't happen again, could it?

    Based on multiple lines of evidence, including past climate changes including glacial-interglacial cycles, recent large climate system perturbations due to volcanic eruptions, and simulations of the climate system with computer models, the total change in average global temperature due to an energy imbalance of 3.7 W/m2 is somewhere between 1.5 K and 4.5 K, with the most common estimates being around 2.5-3.0 K.
    The Best Ever Description of the Atmospheric Greenhouse Effect | Climate Abyss | a Chron.com blog
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  7. #13897
    Steve Case Steve Case is offline
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    Quote Originally Posted by owedtojoy View Post
    You know by now I think your "deceleration" is fictitious.
    You can not even tell me how it is derived - just pulled
    off a slide on the web, not from a peer-reviewed paper.
    How did the poster arrive at that figure? Seems to me it
    is just an "instantaneous" figure for 2010 and not a
    20-year figure.

    Since sea level rise will probably accelerate (why not?
    most parameters associated with global warming are
    accelerating - Arctic sea ice melt, Greenland Ice Cap melt,
    West Antarctica Ice Cap melt, glacier melt, summer snow
    pack melt) so an increase from 3mm/year to over 9mm/year
    is perfectly reasonable.

    You should write to the authors of the paper for clarification -
    that is what corresponding authors are for.

    Meanwhile, send your work out for a critique.

    You know by now I think your "deceleration" is fictitious.
    You can not even tell me how it is derived

    I told you how it's derived. As a matter of fact, I figured
    it out before I ever saw the Steve Nerem slide show. I
    stumbled upon it one day and muttered, "Holy Sh*t, there's
    my graph!" But you want to know how don't you?

    Go to Colorado University's Sea Level Research Group.
    CU Sea Level Research Group | University of Colorado
    You will find just below the main graph:

    Data
    Raw data (ASCII) | PDF | EPS

    Click on Raw data (ASCII)

    You will get data in the format:

    year msl_ib_ns(mm) #version_2012_rel3
    1992.9595 -4.770
    through
    2012.3161 51.102

    674 lines in all

    Paste in Excel to Cell [A1]
    Use Excel's Text to Columns tool under Data. When done
    you should have the year in Column "A" and the data in
    Column "B".

    Select the data in Column "B" and graph it out, I use [F11]

    Change the chart to a line graph (you don't have to); and then
    hover over a data series point until it opens up; then right click
    your mouse; and select Add Trendline... ;Choose Polynomial,
    (2nd order is the default) And you’re done.
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  8. #13898
    barry schwarz barry schwarz is offline

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    Steve,

    Church and White get a trend of 2.8mm/yr (+/-.08mm/yr) over Jan 1993 to Dec 2009 for the tide guage record after adjusting for land-level changes and GIA.

    The figure of 3.2mm/yr is derived from satellite data for the period Jan 1993 to Dec 2009, not tide guages. As there is so much variability in both the satellite and tide guage records, this length of time means that data added to either end of the stream can result in a markedly different trend. It appears you have used the value for satellite data, which starts in 1993 and compared that with the tide guage data, which apparently you have started in 1988. Are you comparing tow different time periods?

    If you wish to compare tide guage data with the satellite record, the periods must match.

    If you wish to compare with Church and White's estimate of tide guage data for the same period, then the value is 2.8mm/yr (+/-0.8mm).

    Church and White are hardly the only researchers acknowledging and wrestling with the deficiencies in the tide guage record. With an error margin of 0.8mm/yr (owing partly to sparser information - stations slow to report data - in the very latest part of the record), it is obviously a fairly uncertain record. The error margin for the satellite record is half as large. Nevertheless, there is overlap.

    I'm curious to know the trend estimate you get for your tide guage comparisons if you match the time period (January 1993 to December 2009)

    Neither of us are in a position to effectively critique their selection methods. However, their estimates are in line with other groups that use different methods, so they are at least corroborated by other work.
    Last edited by barry schwarz; 22nd August 2012 at 01:42 AM.
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  9. #13899
    barry schwarz barry schwarz is offline

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    Steve, I think that the problem with your analysis is that while a linear trend is statistically significant, the trend from a second order polynomial is not. Do you know how to test for statistical significance using the software you're using? From eyeballing it appears that the error margin will be greater than the trend change, making it statistically insignificant.

    IOW, the variability could change the sign of the 2nd order polynomial trend with just one more year's data.
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  10. #13900
    barry schwarz barry schwarz is offline

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    owedtojoy/Earthling,

    you are comparing land-surface temps (BEST to present) with land and ocean (HadCRU to 2005). That's the major reason for discrepancies in the trends owing to the greater degree of warming over land than sea surface. The difference in time period is a secondary factor in the discrepancy.

    There's nothing wrong with using either daa set, but it depends on what you are talking about.
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