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On Tue, 19 Dec 2006 18:29:39 -0800, "D. Patterson"
<proamer@xxxxxxxxxx> wrote:
--- snip ----
>> As for the claim that th Norse period in Greenland was warmer than today,
>> please see figure 2 in http://tinyurl.com/vn7w7, it wasn't. The whole MOG
>> 31 report can be downloaded from http://www.dpc.dk/sw784.asp
>
>As is so often the case, the tinyurl and pdf you provided as citations fail
>to load. Since you have failed to provide the name of the series for the
>volume and failed to indicate the particular text and/or images and their
>relevance to the discussion even if the volume could be found, your
>citations are meaningless and valueless to the discussion. They certaintly
>contribute nothing whatsoever to any claim by you in regard to such Norse
>journeys being "impossible" to accomplish.
The sites cited do load but the PDF files are large and DU Meter tells
me the download rates are consistently slow.
The figure Erik Hammerstadt referred to is a diagram which shows that
the current temperature is approximately 0.15 degrees C more than in c
1200 AD.
The title of the figure describes it as
"The sequences of climatic and cultural events in Greenland
(climatic sequences adapted from Fredskild and BÃcher 2001:61)."
I have not been able to discover the nature of "Fredskild and BÃcher
2001" but I have been able to establish that F & B work primarily with
zoological remains. Apart from the question of the nature of the
adaptation of F & B's work, I would also question whether or not one
can safely rely on zoological proxies to establish the existence of
small temperature differences (0.15 degrees C) over a period of 8
centuries.
A search of the text of the PDF cited by Erik Hammerstadt shows that
the authors rely on figure 2 primarily for cultural aspects.
However, on (their) page 23 the authors say:
"When the Saqqaq people first arrived at Nipisat, it
was a smaller island, probably surrounded by a broader
sound than today due to isostatic factors (Fig. 196).
Nipisat was part of a pristine archipelago with numerous
breeding species of both mammals and birds, and
with a good vantage point over the sound. Even
though the postglacial climatic optimum had peaked
when humans settled on Nipisat, the climate was
milder than today (Fig. 2). In addition it has been suggested
that there was a more pronounced seasonality
2500 years ago, with a greater June insolation (P.
Mayewski pers. comm. 1999; OâBrien et al. 1995).
These factors may, to some extent, have influenced the
timing of arrival and departure of migrating species,
in addition to the breeding period. Nevertheless,
based on our knowledge of game animals from recent
and historical times, the species found at Nipisat must,
by and large, have had a seasonal occurrence in the
Nipisat area as depicted in Fig. 9."
Nipisat is in the Sisimut region which Google Earth tells me is at
approximately 77 degrees North latitude while any passage around the
north of Greenland will be at about 82 degrees north. I do not know
the temperature differences are between these two latitudes but I
suspect that, as you have already suggested, the formation of polynyas
will be the decisive factor. Polynyas depend on the upwelling of
subsurface ocean water and it has been shown that the chemical and
thermal parameters describing such flows can lag by a century or more
behind the original surface conditions which drive them. I don't think
there is any simple means by which we can reach a conclusion and we
will have to wait and see what happens.
Eric Stevens
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