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View Diary: Want to see a real crisis? A *partial* counterpoint (44 comments)

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  •  response (none)
    well I'm sorry if you are skeptical but these graphs are believed to be correct by the scientific community and have been accepted for ~ two decades now, with known error bars.  The greenland cores are the most sampled cores, for a number of reasons, but they have been suplimented with cores from antartica, and siberia.  That 'noise' you talk about on the graph isn't noise.  If you look at the record of the past 200 years, you will notice that there are significantly finer fluctuations than in the rest of that 2400 year graph.  That is for the simple reason that measurements before that 200 year period are sigifcantly noisier, and thus were averaged to reduce the noise and reveal the signal - you are looking at I belive 50 year means for the most of that 2400 year record.  

    Online references to greenland ice core measurements can be found:

    http://www.gsf.fi/esf_holivar/johnsen.pdf

    http://www.gisp2.sr.unh.edu/GISP2/MoreInfo/Ice_Cores_Past.html

    http://www2.eurekalert.org/pub_releases/2004-09/uoca-ngr090704.php

    You cannot be part of the fact based community if you choose to selectively to pick and choose the facts because a) they dont fit in with your world view and b) you aren't an expert in that particular area and thus you can't be sure if something is correct, so its convient for you to just dimiss it.  
    You can choose not to belive the evidence if you wish, but this IS what the scientific community believes is the most accurate record of past temperatures and it IS the data on which we base our climatic models on, including events such as rapid climate change in the Gulf Stream triggering ice ages that wally Broeker talks about in my original diary.

    Yertle

    •  sheesh (none)
      some scientist you are.  as soon as i express some skepticism you accuse me of "not being part of the reality-based community."

      it's not about not believing evidence, it's about questioning methodology and what the data mean.

      i know noisy data when see it.  what i'm dubious about is taking those graphs and interpreting them as an actual record of global average temperature.  because they'e not.  they're modeled temperature variations based on isotopic ratios of oxygen in the ice of a glacier in greenland.

      and i'm not questioning the underlying GISP2 data, just the way it's being presented on the page you linked to.  again, if you take the presentation at face value you are asked to believe that between the life of julius caesar and the birth of jesus of nazareth the earth went from about 0.5 degree C warmer than present to 0.5 degree cooler.  as you note, that's a big change in climate.  even without thermometers somebody would have noticed.

      but figure 1-2 is not really a record of global climate for the last 2400 years.  it really only addresses the temperature in greenland for those years.  and only the temperature when the snow was falling, at that.  the real picture is way more complicated than that.  you need ice cores from many different locations (they have them) and thinking about ice chemistry and dust and other factors that introduce measurement bias and error.  then you need to confirm with different methods entirely.

      can you see real temperature effects from those charts?  sure.  as a first crack, i'd say that the temperature increase from the last glaciation is obvious in figure 1-3, and the little dip at 6000 BCE looks big enough to overcome the noise.  as you go to progessively longer timescales, the ups and downs should become more solid.  the question again is what does it mean?  the spikes in figure 1-4 could just mean that edge of the ice sheet (which at that point covered half of north america) was advancing and retreating, so that the site in greenland was alternately closer to the ocean versus interior.  again, you'd have to compare to other locations.

      being part of the reality-based community means expecting, nay encouraging claims of fact to be subject to critical scrutiny. even by amateurs.

      courage, faith and truth my brothers and sisters

      by zeke L on Mon Jan 24, 2005 at 08:33:29 PM PST

      [ Parent ]

      •  sheesh all you like (none)
        If you dont know the analysis that went into the data, then your claims of critical scrutiny have no basis.  I'm not arguing this with you - if you bother to find the data in the journals, you will find exactly the same data shown in those graphs.  you can choose to believe the analysis done on that data, and the peer review process or not, but you don't have any facts to challenge the data as it stands.  It is not simply enough to stand up and say I dont believe it, its noise, because it looks noisy.  I could show you a turbulent time series of velocity that looks just as 'noisy' as that temperature record, but in reality the actually noise is 2 orders of magnitude below what you are seeing.  And yes, this means you are not being reality based.

        -Yertle

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