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View Diary: Damn those lying scientists.   (159 comments)

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  •  interesting. Can you provide more information (2+ / 0-)
    Recommended by:
    RunawayRose, shpilk

    about the "mathematical trends" that suggest Arctic ice is NOT on a downward trend?

    Because this graph shows a decrease in Feb. extent of almost 3% per decade for the last 30 years.

    And this graph shows a decrease of 11% per decade for September extents.

    Similar ranges are graphed for every month of the year for the last 30 years.  Are you claiming that those trends are not real?

    "The more the Democrats pursue the center... the further to the right the "center" moves." -fellow kossack vacantlook

    by Hopeful Skeptic on Thu Mar 04, 2010 at 11:25:36 PM PST

    [ Parent ]

    •  I Am Quite Well Aware - (0+ / 0-)

      Since I have been following NSIDC and JAXA as well as other websites for many years.

      Of course, there is only a 30-year period of data. And the late 1970s were a time of extreme cold in the northern hemisphere. Since climate features such as the Arctic Oscillation have multi-decadal phases and since the AO is switching back to a highly negative pattern for the fist time since the late 1970s, it remains to be seen to what degree the pattern seen in your links is cyclical or permanent.

      http://www.cpc.noaa.gov/...

      Arctic sea ice doesn't appear to have much memory - i.e. the entire Arctic Basin refreezes each winter although first-year ice is certainly thinner than multi-year ice. Report from Soviet and other explorers suggest that when there have been years of extreme melt, they were quickly followed by a return of more normal ice conditions.

      With a 14 M sq km maximum, 6 M sq km would be a more typical minimum. Granted, many other factors come into play.  But winds forcing multi-year ice out of the Arctic Basin are the chief factor in extreme melt. Those winds are not likely to be present with a shift in the AO.

      •  there are records that go back further (1+ / 0-)
        Recommended by:
        RunawayRose

        than 30 years.  And they suggest that the current trend is well outside of normal AO variability.

        Here is one example (that link has a 450 year graph, but the paper in the PDF link shows all 800 years.):

        The 20th century sustained the lowest sea ice extent values since A.D. 1200: low sea ice extent also occurred before (mid 17th and mid 18th centuries, early 15th and late 13th centuries), but these periods were in no case as persistent as in the 20th century. Largest sea ice extent values occurred from the 17th to the 19th centuries, during the Little Ice Age, and smaller sea ice-covered areas occurred in the 16th century. Moderate sea ice extent occurred during 13th to 15th centuries. Reconstructed sea ice extent variability is dominated by decadal and multi-decadal oscillations operating at ~70-90yr, and by a North Atlantic Oscillation/Arctic Oscillation (NAO/AO) decadal component, which occurred repeatedly during the reconstructed period. Sea ice extent and NAO showed a non-stationary relationship during the observational period. The present low sea ice extent is unique over the last 800 years, and results from a decline started in late-19th century after the Little Ice Age.

        I'm still not sure what your overall point is... are you trying to suggest that anthropogenic global climate change is not a reality based simply on Arctic sea ice variability?

        Or are you simply pointing out the potential flaw in that data set, but are convinced of the global trend by the numerous other independent data sets?

        "The more the Democrats pursue the center... the further to the right the "center" moves." -fellow kossack vacantlook

        by Hopeful Skeptic on Fri Mar 05, 2010 at 01:23:36 PM PST

        [ Parent ]

        •  Didn't You Mention - (0+ / 0-)

          Proxy measurements in another post?

          If the early 2000s were to be measured in 500 years, would 2007 show in the proxy?

          •  maybe, maybe not (1+ / 0-)
            Recommended by:
            RunawayRose

            it would depend on the level of resolution of the proxy.  Some do have one year resolutions.  Others do not.

            But what would certainly be obvious in any proxy would be the trend of the last 30-100 years.

            You still have no clarified what your larger point is...  why are you so fixated on Arctic sea ice in 2007?  It's one indicator for one year... in the midst of thousands of data points.  All of which point in the same direction.

            So... I've answered you question, and have been quite civil... and I'm still wondering what are you getting at?

            "The more the Democrats pursue the center... the further to the right the "center" moves." -fellow kossack vacantlook

            by Hopeful Skeptic on Fri Mar 05, 2010 at 03:40:14 PM PST

            [ Parent ]

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